VDA Recommendati Recomm endati on Geometrical Product Specifications Specifications Engineering Drawings
Specif Specif ication o f Surface Textu Textu re Descriptors: . n r e v o g l l a h s n o i s r e v n a m r e G e h t s e i c n a p e r c s . i ) d f 0 0 o 0 e 1 s 0 a c W n V I . e e t e s a r ( u e c i c c t a c e a b r p o O t d I S e v t o e i l e g n b i r s d i o n c o c i t a a n l s i o n t a a r t t o n h l s i l a g i c n r E e e m h u T N
February 2007 2007
VDA 2005
surface texture, surface roughness, roughness, roughness, engineering engineering drawing drawing specification, drawing note
Contents Page
1 2 3 3.1 3.2 3.3 3.4 3.5 4 4.1 4.1.1 4.2 4.3 5 5.1 5.2 5.3 5.4 6 6.1 6.1.1 6.1.2 7 7.1 7.2 7.3 7.4 7.5 8
Scope ............................................................................. ........................................................................................................................................ .....................................................................4 ..........4 Normative references references........................................................................ ..........................................................................................................................4 ..................................................4 Terms ...................................................................... ........................................................................................................................................ ............................................................................5 ..........5 Basic symbol symbol ....................................................................................... .......................................................................................................................................5 ................................................5 Expanded symbol................................................................................. symbol................................................................................................................................5 ...............................................5 Complete symbol.............................................................................................................. symbol.................................................................................................................................5 ...................5 Surface (texture) parameter .............................................................................. ................................................................................................................5 ..................................5 (Surface) parameter symbol........................................................ symbol................................................................................................................5 ........................................................5 Specification of surface texture...........................................................................................................6 Profile parameters parameters.............................................................................. ...............................................................................................................................6 .................................................6 Parameters Parameters based on the material ratio curve (DIN EN ISO 13565-2)...............................................6 Evaluation length ln ........................................................................... .............................................................................................................................7 ..................................................7 Tolerance limits limits for numerical values of surface parameters parameters .............................................................7 Graphical symbols symbols for the indication of surface texture ......................................................................7 Basic symbol for the indication of surface finish .............................................................................. .................................................................................7 ...7 Symbol for material material removal removal ........................................................................................ ...............................................................................................................8 .......................8 Symbol, if material removal removal is prohibited .................................................................................... ............................................................................................8 ........8 Complete symbol.............................................................................................................. symbol.................................................................................................................................8 ...................8 Specification of requirements..............................................................................................................9 requirements..............................................................................................................9 Position of the surface texture specifications on the complete symbol...............................................9 Surface texture symbols (surface parameters, positions a and b)....................................................10 Number of sampling sampling lengths lengths .................................................................................... .............................................................................................................10 .........................10 Illustration..........................................................................................................................................11 Design and size size of symbols ............................................................................. ..............................................................................................................11 .................................11 Arrangement Arrangement of symbols symbols on surfaces surfaces ......................................................................................... ...............................................................................................12 ......12 Collective specifications in the field provided in the drawing frame..................................................13 Requirements Requirements on depth of waviness waviness Wt ...........................................................................................14 Surface requirements requirements on dominant waviness ...................................................................................15 Preferred values ........................................................................................ ................................................................................................................................15 ........................................15
Page 1 of 32 VERBAND DER AUTOMOBILINDUSTRIE AUTOMOBILINDUSTRIE E.V. (VDA)
Westendstraße Westendstraße 61, 60325 Frankfurt
Distribution: DOKUMENTATION DOKUMENTATION KRAFTFAHRWESEN E.V. (DKF) Ulrichstraße 14, D-74321 Bietigheim-Bissingen
Page 2 VDA 2005: 2007-02 9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.10.1 9.11 9.12 9.13 9.14 10 10.1 10.2
Examples of entry entry ............................................................................ ............................................................................................................................. ................................................. 16 Tooth flanks ............................................................................. ...................................................................................................................................... ......................................................... 16 Repeated form elements ........................................................................... .................................................................................................................. ....................................... 16 Symmetrical parts .................................................................................... ............................................................................................................................. ......................................... 17 Different requirements requirements on on one surface surface .......................................................................................... ............................................................................................. ... 17 Contact surfaces................................................................... surfaces ............................................................................................................................... ............................................................ 17 Radii, chamfers chamfers........................................................................... ................................................................................................................................. ...................................................... 18 Radii and chamfers chamfers without specific surface surface requirements requirements .............................................................. 19 Multiple requirements requirements ........................................................................... ....................................................................................................................... ............................................ 19 Production process, process, surface character character ..................................................................................... ............................................................................................. ........ 20 Evaluation length .................................................................... .............................................................................................................................. .......................................................... 20 Length of the evaluation evaluation length in the event of dominant waviness................................................. 21 Specification of the surface grooves................................................................................................. grooves................................................................................................. 21 Specification of the machining machining allowance......................................................................................... 23 Simplified specification ........................................................................................ ..................................................................................................................... ............................. 23 Examples of entries for porous porous and plateau-like heavy-duty heavy-duty contact surfaces surfaces ................................ 24 Surface parameter parameter for special special functions ............................................................................... ........................................................................................... ............ 24 Specification of transmission characteristic...................................................................................... characteristic...................................................................................... 24 Meaning and specification specification of the evaluation length length and the sampling length for special special cases ...... 24
Appendix Appendix A Summary tables tables (informative)....................................................................................... (informative)...................................................................................................... ............... 27 Appendix B Examples (informative)................................................................................................................ (informative)................................................................................................................ 29 Referenced standards standards............................................................................. ...................................................................................................................................... ......................................................... 32
Page 2 VDA 2005: 2007-02 9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.10.1 9.11 9.12 9.13 9.14 10 10.1 10.2
Examples of entry entry ............................................................................ ............................................................................................................................. ................................................. 16 Tooth flanks ............................................................................. ...................................................................................................................................... ......................................................... 16 Repeated form elements ........................................................................... .................................................................................................................. ....................................... 16 Symmetrical parts .................................................................................... ............................................................................................................................. ......................................... 17 Different requirements requirements on on one surface surface .......................................................................................... ............................................................................................. ... 17 Contact surfaces................................................................... surfaces ............................................................................................................................... ............................................................ 17 Radii, chamfers chamfers........................................................................... ................................................................................................................................. ...................................................... 18 Radii and chamfers chamfers without specific surface surface requirements requirements .............................................................. 19 Multiple requirements requirements ........................................................................... ....................................................................................................................... ............................................ 19 Production process, process, surface character character ..................................................................................... ............................................................................................. ........ 20 Evaluation length .................................................................... .............................................................................................................................. .......................................................... 20 Length of the evaluation evaluation length in the event of dominant waviness................................................. 21 Specification of the surface grooves................................................................................................. grooves................................................................................................. 21 Specification of the machining machining allowance......................................................................................... 23 Simplified specification ........................................................................................ ..................................................................................................................... ............................. 23 Examples of entries for porous porous and plateau-like heavy-duty heavy-duty contact surfaces surfaces ................................ 24 Surface parameter parameter for special special functions ............................................................................... ........................................................................................... ............ 24 Specification of transmission characteristic...................................................................................... characteristic...................................................................................... 24 Meaning and specification specification of the evaluation length length and the sampling length for special special cases ...... 24
Appendix Appendix A Summary tables tables (informative)....................................................................................... (informative)...................................................................................................... ............... 27 Appendix B Examples (informative)................................................................................................................ (informative)................................................................................................................ 29 Referenced standards standards............................................................................. ...................................................................................................................................... ......................................................... 32
Page 3 VDA 2005: 2007-02
Preface Essential points relating to the indication of surface texture were changed in the standard DIN EN ISO 1302:2002 with respect to the preceding issue DIN ISO 1302:1993. The new issue contains surface parameters, some of which are not common in the automotive industry, while other, previously common parameters are no longer standardized. In addition, new rules, which were previously not the norm, were introduced to describe exactly the nature of the surface along with new filters. This Recommendation was developed in order to maintain the continuity of the previous specifications and to keep the possible number of specifications for the general case under control. The following metrological basis applies: The standardized filter is the Gaussian filter according to DIN EN ISO 11562. The standard evaluation length for the R profile comprises 5 sampling lengths. The original meaning for the maximum roughness depth, Rmax, and the designation are retained and defined in VDA 2006. The use of the short wave filter λs is not permitted unless specifically requested in the technical product documentation. documentation. The long wave filter λc is used. The 16% rule is not applied. The actual values must not exceed or fall below the specified roughness values, as appropriate. The motif parameters according to DIN EN ISO 12085 and the description of the height of surfaces from two vertical random components using the material probability curve according to DIN EN ISO 13565-3 are not used because there is no experience with them. Comp aris on of DIN EN EN ISO 1302/ 1302/VDA VDA 2005 DIN EN ISO 1302
VDA 2005
Motif parameters
Not permissible
Rzmax 2,5
Rz 2,5
No longer standardized standardiz ed
Rmax
Rz1max 2,5
Not permissible
Rz3max 2,5
0,8x3 / Rz 2,5
Rtmax 2,5
Not permissible
16% rule
Not permissible
0,08-2,5 / Rz 6,3
Not permissible
Changes The following changes have been made as compared to the 2002-07 issue: •
The robust robust Gaussian Gaussian regression regression filter filter according according to VDA 2008 2008 has been integrated integrated into into this standard, the Sections 2, 4.1.1, 4.2, 10.2 as well as the examples B.9, B.10 and B.11 have been adapted accordingly.
•
In VDA 2007 only only one dominant form of waviness is is defined, defined, the Sections 7.5, 7.5, 9.10.1 and the examples B.11 and B.12 have been adapted accordingly. The Figures B.13 and B.14 have been added.
•
Section 7.3: 7.3: In the Figures 15 and 16, the letter "f" has been replaced by an "a".
Page 4 VDA 2005: 2007-02 1
Scope
This Recommendation describes the rules applicable for specifying surface texture in technical product documentation (e.g. drawings, specifications, contracts, reports) within the automotive industry by means of graphical symbols and textual indications. Its aim is to simplify the use of the new edition of DIN EN ISO 1302 and it describes the normal case. The surface specifications listed are recommendations. Particular requirements may necessitate the use of other surface specifications. The Figures given in this standard are examples to illustrate the relevant rule. They are complete only insofar as they represent the described situation. This Recommendation does not describe the specification of requirements for surface imperfections, such as pores and scratches. The rules and procedures for assessing surface texture are defined in VDA 2006. 2
Normati ve references
The following normative documents contain specifications that, through reference in this text, constitute provisions of this VDA Recommendation. For dated references, subsequent amendments or revisions to this publication do not apply. Users of this VDA Recommendation are nevertheless requested to check whether it is possible to use the latest versions of the following normative documents. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain directories of the valid international standards. DIN 6790-1:1980, Specification by Terms in Technical Drawings; Terms DIN EN ISO 1302:2002, Geometrical Product Specifications (GPS) - Indication of Surface Texture in Technical Product Documentation DIN EN ISO 3098-2:2000, Technical Product Documentation - Lettering - Part 2: Latin Alphabet, Numerals and Marks DIN EN ISO 4287:1998, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Terms, Definitions and Surface Texture Parameters DIN EN ISO 4288:1998, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Rules and Procedures for the Assessment of Surface Texture DIN EN ISO 11562:1998, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Metrological Characteristics of Phase Correct Filters DIN EN ISO 12085:1998, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Motif Parameters DIN EN ISO 13565-1:1998, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Surfaces having Stratified Functional Properties – Part 1: Filtering and General Measurement Conditions DIN EN ISO 13565-2:1998, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Surfaces having Stratified Functional Properties – Part 2: Height Characterization Using the Linear Material Ratio Curve
Page 5 VDA 2005: 2007-02 DIN EN ISO 13565-3:2000, Geometrical Product Specifications (GPS), Surface Texture: Profile Method – Surfaces having Stratified Functional Properties – Part 3: Height Characterization Using the Material Probability Curve VDA 2006: 2003, Geometrical Product Specifications (GPS), Surface Texture: Rules and Procedures for the Assessment of Surface Texture VDA 2007: 2006, Geometrical Product Specifications (GPS), Surface Texture: Definitions and Parameters of the Dominant Waviness VDA 2008: 2006, Geometrical Product Specifications (GPS), Surface Texture: "Robust Gaussian Regression Filter" Definition and Application 3
Terms
3.1
Basic symbol
Graphical symbol indicating that surface texture requirements exist, Figure 1. 3.2
Expanded sym bol
Expanded basic symbol indicating that material is to be either removed or not removed in order to obtain a required surface texture, Figures 2 and 3. 3.3
Complet e sym bol
Basic or expanded symbol to facilitate the indication of additional surface texture requirements, Figure 4. 3.4
Surface (textur e) parameter
Parameter expressing micro-geometrical properties of a surface. 3.5
(Surface) parameter sym bol
Symbol indicating the type of surface texture parameter. NOTE: Parameter symbols comprise letters and numerical values, e.g.: Ra 4, Rz 16, Rmax 25, Rpk 0,6, etc.
Page 6 VDA 2005: 2007-02 4
Specific ation of surface texture
Surface specifications should only be made if they are required for the function of the surface. In general, the following shall apply: ─ ─
as coarse as possible and no finer than necessary for the drawing note, as fine as necessary for production (even more so if this does not cause additional expenditure)
Surface specifications can be omitted if the normal production processes ensure that the end condition of the surface is appropriate. The parameter designation and the associated numerical values contain five pieces of information that are essential for the interpretation of the requirement: which of the three surface profiles (R, W or P) is indicated (see Section 4.1); which characteristic of the profile is indicated; how many sampling lengths make up the evaluation length (if this is significant, see Sections 4.2, 6.1.2, 9.10, 9.10.1 and 10.2); how the indicated specification limits must be interpreted (see Section 4.3); what cut off is used for measurement (see DIN EN ISO 4288).
─ ─ ─
─ ─
The indication of a surface texture requirement must therefore contain both the designation of the parameters and the numerical value of the specified limit. 4.1
Profi le parameters
Profile parameters are standardized for the three surface profiles (R, W and P profiles). Profile parameters are defined using the Gaussian filter according to DIN EN ISO 11562. 4.1.1
Parameters based on the mater ial rati o cu rve (DIN EN ISO 13565-2)
Table 1 lists designations of parameters that relate to the linear material ratio curve. The parameters are only defined for the R profile. Unless otherwise specified, the definition of parameters is based on a filter process according to DIN EN ISO 13565-1. The indication of the filter type according to VDA 2008 takes precedence and overrules the compulsory combination of special filter procedures and Rk parameter calculation. Table 1 – Designation of parameters based on th e material ratio curve accordin g to (DIN EN ISO 13565-2) Parameter Roughness profile parameters acc. to DIN EN ISO 13565-2 Filtering acc. to DIN EN ISO 13565-1 or VDA 2008
Rk
Rpk
Rvk
Mr1
Mr2
Page 7 VDA 2005: 2007-02
4.2
Evaluation length ln
The surface texture requirements apply to the evaluation length. If no indications are given for the evaluation length in the technical product documentation, e.g. in the drawing, then the standard evaluation length applies to the R profile. This is made up of 5 sampling lengths. The length of a sampling length corresponds to the wave length limit λc. For small surfaces, it must be noted that the scanned length comprises the standard evaluation length, the running-in length and the running-out length. As the running-in length and running-out length correspond to λc/2 or λc (depending on the measuring device and on the implementation of the filter), the scanned surface must be longer by λc or λ2c than the length to be evaluated (in general 6 x λc or 7 x λc). However, the robust Gaussian regression filter according to VDA 2008 does not involve filter running-in and running-out lengths. Hence, the complete scanned length can be used for evaluation when evaluating measurement data of a plateau-like surface using the robust Gaussian regression filter. If the surface to be measured is smaller than this, the number of evaluation lengths must be indicated (see also Sections 6.1.2 und 9.10). The length of the sampling length is stipulated in DIN EN ISO 4288:1998 in Tables 1 to 3. For the P profile, the standard evaluation length according to DIN EN ISO 4288 has the same length as the geometrical element to be measured. In the event that this cannot be realized e.g. due to equipment-related reasons, the evaluation length must be indicated appropriately. 4.3
Tolerance limit s for numerical values of surf ace parameters
In the automotive industry, the following applies:
If a value is specified for surface roughness, it represents the highest permissible value for the parameter (see also VDA 2006). If a lower limit is specified, then this must be achieved.
NOTE: The 16% rule is not applied. 5
Graphical symbol s for the indicatio n of surface texture
All the symbols indicated in DIN EN ISO 1302 are permitted. The symbol “for all surfaces around a workpiece outline” shall be avoided. 5.1
Basic symbol for the indic ation of surface finis h
The basic symbol shall consist of two straight lines of unequal lengths inclined at approximately 60° to the line representing the surface in question, as shown in Figure 1. If the basic symbol according to Figure 1 is used alone (without additional information), this is not deemed to be a requirement.
Figure 1 – Basic sym bol for indicatio n of surf ace texture If the basic symbol is used with additional information (see Section 6), then no decision has yet been made as to whether removal of material is necessary in obtaining the specified surface (see Section 5.2) or whether removal of material is prohibited (see Section 5.3).
Page 8 VDA 2005: 2007-02 5.2
Symbol for material removal
If removal of material, e.g. by machining, is required to obtain the prescribed surface, a cross bar, as shown in Figure 2, shall be added to the basic symbol. The expanded basic symbol according to Figure 2 alone (without additional information) is still not a requirement.
Figure 2 – Expanded symbol for material removal 5.3
Symbol, if material removal is prohib ited
If removal of material is not permitted to obtain the specified surface, a circle shall be added to the basic symbol, as shown in Figure 3.
Figure 3 – Expanded symbo l, if removal of material is pro hibit ed 5.4
Complete sym bol
When additional requirements for surface texture characteristics have to be indicated (see Section 6), a line as shown in Figure 4 shall be added to the longer of the two lines in the graphical symbols illustrated in Figures 1 to 3.
a a) b) c)
b
c
Any production process allowed Material removal is required Material removal is prohibited Figure 4 – Complete symbo l
For textual indications, e.g. in reports or contracts, the following abbreviations shall be used, bearing the following meanings: Figure 4, Symbol a
APA (any process allowed)
Figure 4, Symbol b
MRR (material removal required)
Figure 4, Symbol c
NMR (no material removal)
Page 9 VDA 2005: 2007-02
6
Specific ation of requirements
The following surface parameters are used in the automotive industry to describe surface texture: For homogenous surfaces (average) roughness Rz ─ (arithmetic) average roughness Ra (see note) ─ maximum roughness Rmax ─ overall height of waviness profile Wt ─ overall height of the profiles of the dominant waviness WDt ─ average height of the profiles of the dominant waviness WDc ─ overall height of the primary profile Pt ─ NOTE: The arithmetic average roughness Ra is the arithmetic average of the absolute amounts from the individual roughness values within the evaluation length after the waviness has been filtered out. One disadvantage here is that individual outliers are not taken into consideration and the level of information provided is thus very low. Nonetheless, the arithmetic average roughness has its legitimacy e.g. for providing surface specifications for semifinished products. For porous and plateau-like heavy-duty contact surfaces reduced peak height Rpk ─ core peak-to-valley roughness Rk ─ reduced score depth Rvk ─ For special applications, it may be necessary to specify other requirements in addition to a surface parameter and its numerical value, such as e.g. Mr1 and Mr2, sampling length, production process, surface position and orientation, machining allowance or other roughness parameters. See Appendices A and B for further details. NOTE: The motif parameters according to DIN EN ISO 12085 and the description of the height of the surface from two vertical random components using the material probability curve according to DIN EN ISO 13565-3 are not used because there has been no experience with them. 6.1
Position of the surf ace texture specificatio ns on the compl ete symbo l
The positions of the different surface requirements on the symbol are shown in Figure 5. a = Surface parameter and numerical value (numerical value in µm) c = Production process b = Second surface texture requirement (surface parameter, numerical value in µm) d = Indication of the surface grooves e = Machining allowance (numerical value in mm)
e
c a d b
Figure 5 – Positions (a to e) indicatin g addition al requirements (designation areas on t he complete symbol) If a third or further requirements are to be indicated under position b, the symbol must be enlarged accordingly in the vertical direction to create space for more lines. Positions a and b move upwards when the symbol is enlarged.
Page 10 VDA 2005: 2007-02 6.1.1
Surface texture symbol s (surface parameters, posit ions a and b)
If a value is indicated for the surface roughness and this is not marked with an L, it always represents the highest permissible roughness value for the surface and may not be exceeded. If there is only one surface texture requirement, then the surface parameter (e.g. Rz) and the numerical value (e.g. 10) shall be arranged at position ”a” in the complete symbol, see Figure 6.
a Figure 6
If a minimum dimension is required, the surface parameter, numerical value and the letter L (lower) shall be arranged at the position “a” in the complete symbol, see figure 7. The minimum dimension must be achieved.
La Figure 7
If two surface texture requirements are required, i.e. if an upper and lower limit are to be specified, the maximum dimension shall be arranged at position “a” and the minimum dimension at position “b” in the complete symbol, see figure 8. NOTE: U (for upper) and L (for lower) shall only be positioned before the surface parameter if there is a risk of confusion.
a b Figure 8 A blank space shall be left between the indicated parameter and the limit value. 6.1.2
Number of sampling lengths
If it is necessary to indicate the number of sampling lengths (in the R and W profiles) or the length of an evaluation length (in the P profile), this shall be entered at position “f“ as shown in Figure 9, separated by an oblique stroke (see also Section 9.10). In the R profile and the W profile, the λc filter shall always be indicated with the number of sampling lengths.
f/a
λc x
f/a
P Profile R Profile or W Profile f = length of the evaluation length (P profile) Number of sampling lengths (R or W profile) Figure 9 NOTE: The wave length limit for the long wave filter λc is also designated as sampling length.
Page 11 VDA 2005: 2007-02
7
Illustration
7.1
Design and size of symbo ls
The size and line width of symbols is dependent on the lettering size used in the drawing to note dimensions, see Figures 10 and 11. It is not permitted to change the symbols, e.g. mirror-image presentation. depending on length of specification
Figur e 10
Figur e 11 The lettering in field c, Figure 11, can contain upper and/or lower case letters; the height of the field can be larger than h, in order to accommodate a range of additional specifications. The dimensions of the symbols and additional specifications shall comply with Table 2. Table 2 Dimensions in millimeters Size of numbers and letters, see DIN EN ISO 3098-2
2,5
3,5
5
7
10
14
20
Line width for symbols and letters
0,25
0,35
0,5
0,7
1
1,4
2
H1
3,5
5
7
10
14
20
28
H2
8
11
15
21
30
42
60
h d1
1)
1) In CAD systems the line widths closest to these values shall apply.
Page 12 VDA 2005: 2007-02 7.2
Arrangement of symbol s on surf aces
Symbols and lettering (same size as dimension figures) are to be arranged such that they can be read from the bottom or from the right hand side of the drawing, with the drawing placed in the normal reading position. The symbol points from the outside either directly to the part edge, to an extension line used as a lengthening of the part edge or if needed, to a datum line, the arrow of which is to point from the outside to the edge of the part or extension line, see Figure 12. The symbols of Figures 1 to 3 can be arranged as desired; however, the lettering is to be entered according to the above-mentioned rule.
Figur e 12 In general, surface requirements shall be entered individually on all surfaces where they are required. This also applies to opposing surfaces with the same surface texture. In accordance with the basic principles of dimensioning, the symbol is to be entered only once for a given surface, preferably in the view that also includes the dimensions of the surface. For rotating parts the surface specifications are to be entered only once for each plane of a symmetrical representation, see Figure 13.
Figur e 13
Page 13 VDA 2005: 2007-02
7.3
Collective specific ations in the field provi ded in the drawing frame
By way of example, letters are assigned to the symbol for the individual surface textures in Figures 14 to 16. If the same specification applies to all the surfaces of a part, then only a collective specification shall be entered in the field ”Surface finish” (if present) or near the title block, see Figure 14.
Oberflaechenbeschaffenheit Surface finish
xx
VDA 2005
Figur e 14 If the same specification applies to most of the surfaces of a part, the collective specification shall likewise be entered in the ”Surface finish” field (if present) or near the title block, together with an additional parenthesized basic symbol as shown in Figure 1, without further information. NOTE: When using collective specifications, it can arise that small surfaces are overlooked and cannot be measured as a result of the necessary evaluation length (for the R profile). In this case, Pt can be measured or the surface texture can be compared visually, e.g. with surface comparison samples.
Page 14 VDA 2005: 2007-02 Symbols with surface specifications that indicate exceptions to the majority of the surface texture shall be specified at the respective surfaces in the drawing, see Figure 15. If the deviating surface specifications on the drawing are uncomplicated and of limited scope, the complete surface texture may be parenthesized (see Figure 16) instead of the basic symbol according to Figure 15. NOTE: The letters and numbers are provided by way of example.
Oberflaechenbeschaffenheit
Oberflaechenbeschaffenheit
Surface finish
Surface finish
VDA 2005
a1
Figure 15
7.4
a1
VDA 2005
a2
Figure 16
Requirements on depth of waviness Wt
If the Wt value is specified below the roughness parameter Rz, both measuring values are valid independently, see Figure 17. NOTE: The waviness shall only be specified if the function demands it.
Rz 25 Wt 10 Meaning:
Rz ≤ 25 µm Wt ≤ 10 µm Figure 17
Page 15 VDA 2005: 2007-02
7.5
Surface requirements on dominant waviness
There are 2 criteria for specifying the dominant waviness: ─ ─
Dominant characteristics are permitted up to an upper limit value. Dominant characteristics are permitted to a limited extent in a period length range with an upper limit or with an upper and lower limit at the same time.
The specification in the drawing is entered as follows, without indication of the validity range:
WDc 1,6 WDt 2,5 if the upper limit value for the average height of the profile elements from the dominant waviness profiles (WDc) must not exceed 1,6 μm and the maximum height of the WD profile (WDt) must not exceed 2,5 μm. The indication of the validity range in the drawing note is preferred. The indications in the drawing for a limited period wave range and indications as to the evaluation length are described in Section 9.10.1. 8
Preferred values
It is economically sensible to stipulate preferred values for surface parameters, considering that no more than one digit after the decimal comma should be allowed. For Rz, values from the following series should be selected: 0,4
0,6
1
1,6
2,5
4
6,3
10
16
25
40
63
100
160
Page 16 VDA 2005: 2007-02 9
Examples of entry
The following figures and the corresponding requirements are examples of surface texture specifications in technical product documentation (TPD), e.g. drawings. 9.1
Tooth flanks
In order to indicate the surface texture of tooth flanks that are not shown in the drawing, the surface specification shall be located on the reference circle, either in the section or in the view, see Figure 18.
or
Figur e 18 9.2
Repeated for m elements
The surface texture of repeated form elements shall only be specified once, together with the dimension entry, as long as confusion with similar form elements is not possible, see Figure 19.
Figur e 19
Page 17 VDA 2005: 2007-02
9.3
Symmetrical parts
The surface texture of clearly and obviously symmetrical parts with a symmetry axis shall only be entered once, see Figures 20 and 21.
Figur e 20 9.4
Figur e 21
Different requirements on one surface
In the event of different surface textures on one surface, the area of the deviating requirement is designated and dimensioned with a wide dash-dot line, see Figure 22.
Figur e 22 9.5
Contact sur faces
In the case of contact surfaces of parts drawn in the assembled condition with identical surface textures, the requirements are entered according to Figure 23.
Figur e 23
Page 18 VDA 2005: 2007-02 9.6
Radii , chamf ers
The surface texture for concave radii (fillets), convex radii and chamfers shall be indicated on the dimension line of the radius or on a special line that points to every form element, see Figure 24.
Figur e 24
If the surface texture of all radii is the same, a general note with the corresponding symbol is entered in the “Surface finish” field (if present) or near the title block, see figure 25. As a result, the individual specification on the drawing is omitted. NOTE: When specifying the surface texture for radii and chamfers, it is important to note that it is often impossible to perform an actual measurement because the available evaluation lengths are too short. In this case, a visual inspection, e.g. using surface comparison samples, may be performed, see also Section 9.7.
Oberflaechenbeschaffenheit Surface finish VDA 2005
Rz 25 Radii
Figur e 25
Page 19 VDA 2005: 2007-02
9.7
Radii and chamfers witho ut specific surf ace requirements
If both the surfaces adjacent to the radii or chamfers can be measured using the relevant measuring equipment, the following rule shall apply: Concave radii (fillets) for which no surface textures are expressly specified shall have the finish of the smoother adjacent surface requirement, see Table 3. Table 3
Drawing example
Design of concave radii and chamfers
Rz 6,3
Rz 2,5
Rz 16
Rz 25
Convex radii and chamfers for which no surface textures are expressly specified shall have the finish of the rougher adjacent surface requirement, see Table 4. Table 4
Drawing example
Design of convex radii and chamfers
Rz 6,3
Rz 25
Rz 25
Rz 25
If only the longer of the adjacent surfaces can be measured using the relevant measuring equipment, the same surface specification shall apply to the adjacent radius or chamfer. 9.8
Multiple requirements
If minimum roughness information is also required on specific functional surfaces, e.g. for ensuring the adhering capabilities of an oil film or for surfaces that are to be joined using an adhesive, then the maximum value shall be specified on the symbol above the minimum value, see Section 6.1.1 and Figure 27. If several different roughness requirements are necessary on one surface, they shall be positioned one under the other, see Figures 26 and 27.
Rmax 4 Rz 1,6
Figur e 26
Rmax 25 Rz 16 Rz 4
Figur e 27
Page 20 VDA 2005: 2007-02 9.9
Productio n process, surface character
If a specific production process or surface character is required for individual surfaces, this shall be noted in unabbreviated format on the extension line of the symbol. The terms refer to the final surface condition. Caution! The final surface condition is called, e.g. according to DIN 6790-1, ”lapped” not ”lap”, see Figures 28 to 34. If a surface with a specific surface texture must be post-treated, the area shall be identified with a wide dash-dot line on which the process shall be entered, see Figure 35. honed
lapped
plunge-cut ground
polished
Rz 1
Rz 1 6
Rz 6,3
Rz 1,6
Figur e 28
Figur e 29
Figur e 30
Figur e 31 30
shot-peened
twist-free
Rz 1
Rmax 6,3
Rz 25
Figur e 32 9.10
bright
burnished
Figur e 33
Rz 4
Figur e 34
Figur e 35
Evaluation lengt h
For the P profile, the standard evaluation length according to DIN EN ISO 4288 has the same length as the geometrical element to be measured. In the event that this cannot be realized, e.g. due to equipment-related reasons, the evaluation length must be specified. In Figure 36, the evaluation length is specified as 4 mm. For the R profile, the standard evaluation length comprises 5 sampling lengths (5 x λc), see also Section 4.2. If the surface to be tested is too small, the number of sampling lengths can be reduced and specified, see Figure 37. 4 / Pt 25
Figur e 36
0,8x3/Rz 6,3
Figur e 37
Page 21 VDA 2005: 2007-02
9.10.1
Length of the evaluation length in the event of dominant waviness
The evaluation length is specified according to DIN EN ISO 4288, Table 2. The designer also ensures that the wave lengths of dominant waviness lie within the evaluation zone. When specifying a validity range, the evaluation lengths must be at least five times the period length (see VDA 2007). The upper and lower limits of the period lengths are dependent on the function of the surface; the minimum lower limit is 0,02 mm. An example of a drawing specification with an upper limit value for the period length is provided in Figure 38, while one with an upper and lower limit is illustrated in Figure 39.
1,2x5/WDc 1,6
Figur e 38
9.11
0,3-1,2x5/WDc 1,6
Figur e 39
Specific ation of the surf ace grooves
If a specific groove direction is required, the appropriate symbol as indicated in Table 5 shall be added to the surface texture symbol, see Figure 40.
Whenever the groove direction cannot be clearly described by a symbol from Table 5 or if a specific groove direction is to be excluded, this information shall be added to the production process details, see Figure 41.
ground
ground
grooves not in
Rz 16
Rz 16
axial direction
⊥
Figur e 40
Figur e 41
Page 22 VDA 2005: 2007-02 Table 5 – Symbols for the groove directi on Symbol
=
Explanation
Parallel to the plane of projection of the view in which the symbol is used. groove direction
Perpendicular to the plane of projection of the view in which the symbol is used. groove direction
X
Crossed in two oblique directions relative to the plane of projection of the view in which the symbol is used. groove direction
M
Multi-directional
C
Approximately centrical relative to the center of the surface to which the symbol applies.
R
Approximately radial relative to the center of the surface to which the symbol applies.
P
Non-grooved surface, undirectional or pitted
NOTE: If a groove direction that is not clearly captured by a symbol is to be indicated, it shall be described in an additional note in the drawing, see Figure 41.
Page 23 VDA 2005: 2007-02 9.12
Specifi cation of the machining allowance
The machining allowance is generally specified only in those cases where several process stages are illustrated in the same drawing. Machining allowances are therefore found e.g. in blankcomponent drawings of cast and forged workpieces, in which the finished workpiece is shown in the blank-component drawing. The indication of machining allowances by a defined symbol is not applicable to textual indications. When the machining allowance is specified, it may occur that this requirement is the only requirement added to the complete symbol. The machining allowance may also be specified in conjunction with a normal surface texture requirement, see Figure 42. turned
Figur e 42 9.13 Simplified specification If complicated entries are to be repeated or if there is insufficient space on the drawing, the basic symbol is entered for the relevant surface with a letter and the meaning is explained near the drawing title block, see Figure 43. Lower case letters should be used to this end, preferably from the end of the alphabet. ground
Oberflaechenbeschaffenheit Surface finish VDA 2005
Figur e 43
Page 24 VDA 2005: 2007-02 9.14
Examples of entries for porous and plateau-like heavy-duty contact surf aces
The surface parameters Rpk, Rk and Rvk are entered in the drawing as described in Section 6, see Figure 44.
Figur e 44 10 Surface parameter for special funct ions For special functions, it may be necessary to deviate from the normal specifications described in the foregoing sections and to stipulate different surface texture requirements. In this event, Figure 45 shall be used as t he basis. NOTE: Examples for surface texture specifications, see Appendices A and B. 10.1
Specific ation of transmiss ion characteristic
As a rule, a short wave filter λs, in addition to the long wave filter, is not permitted according to VDA 2006. The exception to this rule is where this is expressly specified in a drawing. In this case, the transmission characteristic shall be specified before the parameter designation, separated by an oblique stroke (/). The transmission characteristic is specified in the form of the values of the filters' wave length limits (in mm), separated by a hyphen (-). The short wave filter is given first, followed by the long wave filter, e.g.:
MRR 0,0025-0,8 / Rz 4
in text 10.2
0,0025-0,8 / Rz 4
in drawings
Meaning and specificatio n of the evaluation length and the sampling length for special cases
Certain parameters are defined on the basis of the sampling length while others are defined on the basis of the evaluation length. If the evaluation length is not specified before the parameter designation, this means that the requirement is based on the standard evaluation length, see Section 4.2. If a particular evaluation length is required, e.g. 0,8x16 / Rz 6,3, this yields an evaluation length of 0,8x16 = 12,8 mm. As this evaluation length cannot be processed by all measuring equipment – particularly older models – the evaluation length that comes closest to the limit value shall be set on the device, e.g. 12,5 mm. NOTE: In those cases where the number of sampling lengths within the evaluation length is not defined, this must be specified.
Page 25 VDA 2005: 2007-02
a
b Lower specified limit L
L
c
d
e
f
Type of filter
Transmission characteristic
Number of sampling lengths
Surface parameter ParaProfile meter
“ X“
0,08 – 0,8
3
Rz
g Limit value
3,3
ground L ” X”
h
i Type of production
a) b)
c) d) e) f) g) h) i) k)
0,08 - 0,8 x 3 / Rz 3,3
k Direction of surface grooves
Production process
Specification of the lower (L) specified limit – refer to Section 6.1.1 for details Filter type “X”. The standardized filter is the Gaussian filter (DIN EN ISO 11562). The previously standardized filter was the 2 RC filter. During the transition period, it may be appropriate for some companies to specify the filter type in the drawing. The filter type can be specified as “Gaussian” or “2RC”. This is not standardized, but specification of the filter designation as suggested here is unambiguous. Other filters shall be specified. When using the robust Gaussian regression filter acc. to VDA 2008, "FPRRG" is indicated. The transmission characteristic is specified as short-wave, long-wave filter, see Section 10.1. Number of sampling lengths - refer to Sections 4.2, 6.1.2, 9.10 and 10.2 for details. Profile parameter – refer to Section 6 for details. For general purposes, the normal parameter is Rz. See Section 6. For porous and plateau-like heavy-duty contact surfaces Rk, Rpk and Rvk shall be indicated. Limit value in micrometers Type of production – refer to Sections 5.2, 5.3 and 5.4 for details. Surface groove direction - refer to Section 9.11 for details. Production process - refer to Section 9.9 for details. Figure 45 - Specific ation of t he surface texture requirements in engin eering d rawings fo r special functions
Page 26 VDA 2005: 2007-02 Table 6 lists surface parameters for auxiliary and special functions and their meaning. Figure 45 illustrates how the different determining elements are to be indicated in the drawing. Table 6 - Surface parameters f or auxil iary and special fu ncti ons Code Zt Pp, Rp, Wp Pv, Rv, Wv Pz Wz Pc, Rc, Wc Rt Pq, Rq, Wq Psk, Rsk, Wsk Pku, Rku, Wku Psm, Rsm, Wsm Pδq, Rδq, Wδq Pmr, Rmr, Wmr Pδc, Rδc, Wδc Mr1 Mr2 Rpq, Ppq Rvq, Pvq Rmq, Pmq Pmr(c) Rmr(c) Wmr(c)
Parameter Height difference of the profile element
Defining standard VDA 2006 and DIN EN ISO 4287 Heigt of the largest VDA 2006 and profile peak DIN EN ISO 4287 Depth of the largest profile VDA 2006 and trough DIN EN ISO 4287 Average profile height VDA 2006 and DIN EN ISO 4287 Average depth of waviness VDA 2006 and DIN EN ISO 4287 Average height of the VDA 2006 and profile elements DIN EN ISO 4287 Overall height of the VDA 2006 and roughness profile DIN EN ISO 4287 Quadratic average roughness VDA 2006 and DIN EN ISO 4287 VDA 2006 and Incline of the amplitude density DIN EN ISO 4287 Steepness of the amplitude VDA 2006 and density DIN EN ISO 4287 Average groove width VDA 2006 and DIN EN ISO 4287 VDA 2006 and Quadratic average value of the profile slope DIN EN ISO 4287 Material ratio VDA 2006 and DIN EN ISO 4287 Height difference between VDA 2006 and 2 intersection lines DIN EN ISO 4287 Material ratio VDA 2006 and DIN EN ISO 13565-2 Material ratio VDA 2006 and DIN EN ISO 13565-2 Parameters for surfaces with VDA 2006 and dual machining DIN EN ISO 13565-3 Material ratio curve (Abbott curve)
VDA 2006 and DIN EN ISO 4287
Explanation Pz always equals Pt Parameter is not suitable for characterizing roughness Corresponds to the standard deviation of the amplitude density Pmr identical to former tpa and Rmr identical to former tpi Surface portion at the upper limit of the bearing roughness core profile Surface portion at the lower limit of the bearing roughness core profile In the event of dual machining or wear inspections For measurement result documentation; load-bearing characteristics
Page 27 VDA 2005: 2007-02
Ap pendi x A A.1 No.
Summar y t ables (i nf or mat iv e)
Symbo ls wi th su rf ace t ext ur e sp eci fi cat io n Symbol
Rz 25
A.1.1
Rmax 4
A.1.2
Ra 3,2
A.1.3
0,8x3 / Rz 2,5
A.1.4
A.1.5
Rz 40 Rz 25
Pt 25
A.1.6
Meaning / Explanati on Machining that removes material is not permitted, unilateral specified upper limit, R profile, largest average roughness 25 µm (maximum permissible roughness value), evaluation length comprising 5 sampling lengths Material must be removed by machining, maximum roughness within the whole evaluation length, R profile, largest maximum roughness 4 µm, evaluation length comprising 5 sampling lengths Material must be removed by machining, unilateral specified upper limit, R profile, largest average roughness 3,2 µm (maximum permissible roughness value), evaluation length comprising 5 sampling lengths Material must be removed by machining, unilateral specified upper limit, R profile, largest average roughness 2,5 µm (maximum permissible roughness value), evaluation length comprising 3 sampling lengths Machining that removes material is not permitted, bilateral specified upper and lower limit, R profile, upper limit: average roughness 40 µm, lower limit: average roughness 25 µm, evaluation length comprising 5 sampling lengths, upper and lower limit must not be exceeded or fallen below. Material must be removed by machining, unilateral specified upper limit, P profile, profile overall height 25 µm (maximum permissible value), evaluation length is the same as the workpiece length. (This is not economical for long lengths; in such cases the evaluation length may have to be limited, e.g. to 8 mm.) 8 / Pt 25
Page 28 VDA 2005: 2007-02
A.2
Symbo ls wi th su pp lement ary sp eci fi cat io ns
(These specifications can be used together with appropriate symbols from A.1). No.
Symbol
Meanin g Production procedure, milled (see 9.9)
milled A.2.1
Surface pattern: groove direction at right angles to the plane of projection of the view (see 9.11)
A.2.2
⊥ Machining allowance 3 mm (see 9.12)
A.2.3 3 NOTE: The manufacturing method, the surface sample and the machining allowance are only given as examples.
A.3 No.
Symbo ls fo r s im pl if ied dr awi ng no tes Symbol
Meanin g
A.3.1 The meaning of the symbol is specified in the drawing near the title block (see 9.13)
A.3.2
y
z
Page 29 VDA 2005: 2007-02
Ap pendi x B
Exam pl es (inf or mat iv e)
No. B.1
Specifi cation
Example:
Surface rough ness: - Bilateral specification - Upper limit of the specification, Rz = 25 µm - Lower limit of the specification, Rz = 6,3 µm - Both: highest permissible roughness value - Standard evaluation length (5x λc) - Surface grooves approximately circular around the center -
milled 0,8x5 / Rz 25 0,8x5 / Rz 6,3 c
point Production process: milling
NOTE: Given the large roughness tolerance, a variable cut off would have to be used for measurement. As this is not economical, the cut off is specified.
B.2
Surface roughness on all individual excluding one: - Single, unilateral specification of upper limit - Rz = 6,3 µm - Highest permissible roughness value - Standard evaluation length (5x λc) - Surface groove direction, no requirement - Production process: material is removed
surfaces
The individual surface with a different requirement has the following surface roughness: - Single, unilateral specification of upper limit - Ra = 1,6 µm - Highest permissible roughness value
-
Standard evaluation length (5x λc) Surface groove direction, no specification Production process: material is removed
NOTE: Can only be specified if the standard evaluation length can be used on all surfaces.
B.3
Surface rough ness: -
Two unilateral specified upper limits
-
Rz = 1,6 µm Highest permissible roughness value
-
Standard evaluation length (5x λc)
-
-
Rmax = 6,3 µm Maximum roughness
-
Standard evaluation length (5x λc)
Surface groove direction approximately at right angles to the plane of projection of the view Production process: grinding
ground Rmax 6,3 Rz 1,6 ⊥
Page 30 VDA 2005: 2007-02 No. B.4
B.5
Specific ation Surface roughn ess: - Single, unilateral specification of upper limit - Rz = 1 µm - Highest permissible roughness value - Standard evaluation length (5x λc) - Surface groove direction, no specification - Surface treatment: nickel/chromium coating Surface roughn ess: - A unilateral upper specification and a bilateral specification -
Unilateral, Ra = 3,2 µm Highest permissible arithmetic average roughness
-
Standard evaluation length (5x λc)
-
Bilateral Specified upper limit Rz = 16 µm Specified lower limit Rz = 6,3 µm
-
Both: Standard evaluation length (5x λc) but different cut off
-
-
B.6
Surface groove direction, at right angles to the plane of projection Surface treatment: nickel/chromium coating
The surface texture specification and the dimensioning can be combined by using the same extension line. Surface roughness on the chamfer:
-
Single, unilateral specification of upper limit
-
Rz = 2,5 µm Highest permissible roughness value Standard evaluation length (5x λc) Surface groove direction, no requirement
Production process: material is removed Surface roughness on the side surfaces of a key groove: ─ ─ ─ ─ ─ ─
B.7
Example:
Single, unilateral specification of upper limit Rz = 6,3 µm Highest permissible roughness value Standard evaluation length (5x λc) Surface groove direction, no specification Production process: material is removed
Surface texture and dimensioning can be specified together on an extension line or separately on the relevant projection and dimension lines. Common parameters for all three roughness requirements in the example are: - Single, unilateral specification of upper limit - One after the other: Rz = 1,6 µm; Rz = 6,3 µm; Rz = 40 µm - Highest permissible roughness value
-
Standard evaluation length (5x λc) Surface groove direction, no requirement Production process: material is removed
Fe//Ni20pCrr Rz 1
Fe//Ni10bCrr
⊥
Ra 3,2 Rz 16 Rz 6,3
Page 31 VDA 2005: 2007-02
No. B.8
B.9
Specification
Example:
Specification of surface texture, dimensioning and machining process. The example illustrates three consecutive production processes or stages. st 1 stage: Single, unilateral specification of upper limit ─ Rz = 1,6 µm ─ Highest permissible roughness value ─ Standard evaluation length (5x λc) ─ ─ Surface groove direction, no requirement Production process: material is removed ─ nd 2 stage: No surface requirements, other than: Chromium coating ─ rd 3 stage: ─ A single, unilateral specified upper limit, only valid for the first 50 mm of the cylinder surface Rz = 6,3 µm ─ Highest permissible roughness value ─ Standard evaluation length (5x λc) ─ Surface groove direction, no requirement ─ Production process: grinding ─
ground
Surface roughness: ─ ─ ─ ─
The application of the robust Gaussian regression filter is compulsory. Specification of the upper limits for Rpk, Rk, Rvk Standard evaluation length (5x λc) Production process: material is removed
FPRRG / FPRRG / FPRRG /
Rpk 0,5 Rk 1,2 Rvk 1,5
B.10 Surface roughness: ─ ─ ─ ─ ─
The application of the robust Gaussian regression filter is compulsory. Specification of the measurement conditions: λc=0,8 mm, 16 sampling lengths Specification of the upper limits for Rpk, Rk, Rvk Specification of the lower limit for Rvk Production process: material is removed
FPRRG 0,8 x 16/Rpk 0,5 FPRRG 0,8 x 16 /Rk 1,2 FPRRG 0,8 x 16/Rvk 2 FPRRG 0,8 x 16/Rvk 0,8
B.11 Dominant waviness : ─ ─ ─ ─
The application of the robust Gaussian regression filter is compulsory. Dominant projections are not permitted A unilateral specified limit for the surface roughness Rz = 1,6 µm Production process: grinding
B.12 Dominant waviness : ─ ─ ─
Upper limit value for the average profile height of the dominant waviness 1,6 µm Maximum roughness Rmax = 6,3 µm Production process: turning
ground FPRRG
Rz 1,6 WDc 0
turned Rmax 6,3 WDc 1,6
Page 32 VDA 2005: 2007-02 B.13 Dominant waviness: ─ ─ ─ ─
Definition of the validity range from 0,02 to 1,2 mm Minimum evaluation length = 6,0 mm Upper limit value for the average profile height of the dominant waviness 1,6 µm within the validity range A unilateral specified limit for the surface roughness Rz = 6,3 µm
Rz 6,3 1,2x5/WDc 1,6
B.14 Dominant waviness: ─ ─ ─ ─
Definition of the validity range from 0,3 to 1,2 mm Minimum evaluation length = 6,0 mm Upper limit value for the overall height of the WD profile 2,5 µm within the validity range Maximum roughness Rmax = 6,3 µm
Rmax 6,3 0,3-1,2x5/WDt 2,5
Referenced standards 1 DIN EN ISO 3274:1998, Geometrical Product Specifications (GPS) - Surface Texture: Profile Method - Nominal Characteristics of Contact (Stylus) Instruments DIN EN ISO 5436-1:2000, Geometrical Product Specifications (GPS) - Surface Texture: Profile Method; Measurement Standards - Part 1: Material Measures
1
In this Section, terminological inconsistencies may occur as the original titles are used.
VDA-Recommendation
July 2002
Geometrical Product Specifications Technical Drawings
Specification of Surface Texture Brief Version
Descriptors:
1
VDA 2005 Appendix 1
surface finish, surface texture, surface roughness, roughness, technical drawing, drawing specification, drawing entry, drawing note
Scope
This appendix describes standard cases for the specification of surface texture in technical production documentation for the automobile industry. It is a summary of VDA 2005. 2
Basis
2.1
General principles
Surface specifications should only be made if they are required for the function of the surface. In general, the following shall apply: - as coarse as possible and no finer than necessary for the drawing entry, - as fine as necessary for production (even more so if this does not cause additional expenditure) Surface texture specifications can be omitted if the normal production processes ensure that the end condition of the surface is appropriate. The specified limit value represents the highest permissible value. If a lower limit is specified, then this must be achieved. The 16% rule is not applied.
Page 1 of 5 VERBAND DER AUTOMOBILINDUSTRIE E.V. (VDA)
Westendstraße 61, 60325 Frankfurt
Vertrieb: DOKUMENTATION KRAFFAHRTWESEN E.V. (DKF) Ulrichstraße 14, D-74321 Bietigheim-Bissingen
Page 2 VDA 2005 Appendix 1: 2002-07
2.2
Metrological basis
The standardized filter is the Gaussian filter according to DIN EN ISO 11562. The normal evaluation length comprises 5 sampling lengths. Rz is the arithmetic average of the heights of the largest profile peaks and the depths of the deepest profile troughs of five consecutive sampling lengths Z + Z2 + Z3 + Z 4 + Z5 (see figure 1) Rz = 1 5 The original meaning and the designation of the maximum roughness Rmax are retained. Rmax is the highest value of the measurement of all sampling lengths (see figure 1). The use of the short wave filter λs is not permitted. The long wave filter λc is used.
Run-in length
Run-out length
Figure 1 – Forming the parameter Rmax from the roughness profile
Figure 2 - Arithmetic average roughness Ra
The arithmetic average roughness Ra is the arithmetic average of the absolute amounts from the individual roughness values within the evaluation length after the waviness has been filtered out. One disadvantage here is that individual freak values are not taken into consideration and the level of information it provides is thus very low. Nonetheless, the arithmetic average roughness has its legitimacy, e.g. for providing surface specifications for semifinished products.
Page 3 VDA 2005 Appendix 1: 2002-07
3
Division of the possible surface specifications into individual elements
Lower specified limit L (if necessary)
Type of filter (if deviating from 2.2)
Sampling length
Number of sampling lengths (if deviating from 2.2)
Surface parameter Limit value Profile
Parameter
ground L “X” 0.8 x 3 / Rz
Type of production
Production process
Surface lay
3.1
Explanation of the individual elements
3.1.1
Specifications of upper and lower (L) limits
Normally:
3.3
Generally only the upper limit (surface parameter + limit value) is specified, e.g.:
Rz 25 The upper limit must not be exceeded. Special case: In exceptional cases, there is the option of specifying only the lower limit (with the prefix L). If both the upper and lower limits are specified, then the upper limit is positioned on top with the lower limit beneath it (without additional marking), e.g.:
L Rz 6.3
Rz 25 Rz 6.3
The upper limit may not be exceeded and the lower limit must be achieved.
Page 4 VDA 2005 Appendix 1: 2002-07
3.1.2
Type of profile filter
The standardized filter is the Gaussian filter (DIN EN ISO 11562). No specification is required.
3.1.2.1 Wave length limit If there is a deviation from the wave length limit λc (cut off) assigned to the roughness (see DIN EN ISO 4288), the wave length limit and the number of evaluation lengths must be specified even if the normal evaluation length is used, e.g. 0.8x5/Rz 0.4
3.1.3
Surface parameter
For all general applications, the normal roughness parameter Rz (according to DIN EN ISO 4287) shall be entered in the drawing. In individual cases (e.g. surface specifications for semifinished products) it is useful to specify the Ra value. Depending on the function, it can be useful to specify further parameters such as Rmax. For porous and stratified heavy-duty contact surfaces, e.g. cylinder faces, the normal roughness parameter Rk may be supplemented by Rpk and Rvk (according to DIN EN ISO 13565-2). For special applications, the appropriate parameter must be taken from the standards DIN EN ISO 4287 and DIN EN ISO 13565-2. 3.1.4
Evaluation length
Normally:
No evaluation length is specified for roughness parameters. Thus the normal evaluation length applies. The normal evaluation length ln comprises five sampling lengths lr (see figure 1).
Rz 25 E.g.: Special case:
If, e.g., the workpiece surface is very small such that the normal evaluation length cannot be used, the number of sampling lengths must be specified on the symbol.
2.5x3/Rz 25 E.g.:
