Gives Comprehensive info about sand castingFull description
A laboratory report for a sand casting experimentDescripción completa
yüksek basınçlı döküm 1Full description
Workshop 2 UTHMFull description
Laporan Praktikum IMKG
imkg praktikum
Manufacturing Processes-Ⅰ Pressure Die Casting Lab Report
Submitted by:
Name: Rimsha Nadeem Reg. #: 2!"-M-!$ Submitted to: Mrs. Sana Ehsan
Title: Pressure Die Casting Page % !
INDUSTRIA ! MANU"ACTURIN# EN#INEERIN#
Uni$ersity o% Engineering !Te&hnology' ahore Die Casting: &his is a manufacturing process 'here so(id meta(s are me(ted and heated to a desired temperature after 'hich) it is poured into a ca*it+ or mo(d 'ith proper shape. •
•
•
•
&he me(ting and heating process ma+ re,uire dierent furnace heating temperatures. Moreo*er) dierent chemica( substances ma+ be added to modif+ chemica( composition of meta(s. t is this mo(d that contain the desired shape and sie. &he process ma+ be a sing(e step of a series steps depending on the comp(e/it+ of the meta( substance. 0nd 1na( product can ha*e *irtua((+ an+ sie depending on 'hat designer desires. Cast parts ma+ range from fraction of inches to o*er $" feet. t 'i(( depend on the design of mo(d or end product.
Here are three key points to note: Page % 2
•
•
•
Meta( die casting process has a short c+c(e time Meta( o' is faster in die casting due to e/istence of e/terna( force Mo(ds in die casting are not as thic3 as those used in the sand casting or in*estment casting processes
Meta( die casting process is used to produce *arious shapes from a number of non-ferrous meta(s such as brass' (in&' aluminum' magnesium and &o))er among other metals. •
•
t is one of those manufacturing processes 'ith the abi(it+ to produce high detai(ed and accurate parts. t is a(so preferred for mass )rodu&tion of components as opposed to other manufacturing processes.
History Of Die Casting: &he
histor+ of this manufacturing techni,ue cou(d be traced bac3 to the !44s. t 'as during this time that a )atent 'as a'arded to Sturges in *+,-. &his 'as after the in*ention of a manua((+ operated machine that 'as used for the casting printing t+pe. 2 +ears (ater) the techno(og+ 'as main(+ used for tin and (ead. &his 'as before the techni,ue 'as used for other meta(s such as a(uminum and inc in the !52s. 6ince then) there are a number of techno(ogica( ad*ancements that ha*e been 'itnessed in the industr+. &his inc(ude a number of meta((urgica( contro( measures that ha*e impro*ed the manufacturing and processing criteria.
The te&hnologi&al ad$an&ements %o&us on the %olloing /ey as)e&ts: !. ncreasing the die casting capacit+) thus higher production7short production runs. Page % $
2. 6ophisticated die construction processes. $. 0n ad*anced casting capabi(it+ 'ith a number of meta(s such as stee(s and brass being inc(uded in the process.
Die Casting Materials: Not a(( meta(s or a((o+s can be die cast. &his is due to the *ar+ing chemica( and ph+sica( properties. 0s 'e a(( 3no') die casting in*o(*es heating the meta( unti( it me(ts and forcing it under pressure into re-usab(e mo(ds .
The Die Casting Material Selection Criteria
&his shou(d be based on research and not a tria( and error or unappro*ed theories. t is through a proper understanding of each meta( or meta( a((o+ that one 'i(( be ab(e to choose the right materia( and die casting techni,ue.0s a matter of fact) these a((o+s and meta(s ha*e dierent mechanica( and ph+sica( properties. &his e/p(ains the reason 'h+ the+ react dierent(+ 'hen sub8ected to certain manufacturing processes.
Page % 9
t is ad*isab(e to 'or3 c(ose(+ 'ith e/perts to estab(ish the right materia( for an+ gi*en app(ication . . Most
common(+ used a((o+s are of inc and a(uminium) stee()
brass.
Equipment: &here are t'o basic t+pes of die casting machines: hot-chamber machines and cold-chamber machines . &hese are rated b+ ho' much c(amping force the+ can app(+. &+pica( ratings are bet'een 9 and 9) st 2)" and 2")9 3g;.
1. Hotcham!er "ie casting:
Figure 1: hot-chamber machine
&herefore hot-chamber machines are primari(+ used 'ith inc-) tin-) and (ead-based a((o+s.
#. Col"cham!er "ie casting:
Figure 2: cold-chamber die casting machine.
&hese are used 'hen the casting a((o+ cannot be used in hotchamber machines> these inc(ude a(uminium) inc a((o+s 'ith a (arge composition of a(uminium) magnesium and copper. &he process for these machines start 'ith me(ting the meta( in a separate furnace. &hen a precise amount of mo(ten meta( is transported to the co(d-chamber machine 'here it is fed into an unheated shot chamber or in8ection c+(inder;. &his shot is then dri*en into the die b+ a h+drau(ic or mechanica( piston. &he biggest disad*antage of this s+stem is the s(o'er c+c(e time due to the need to transfer the mo(ten meta( from the furnace to the co(d-chamber machine.
•
Open tooling and injection nozzle
•
Page % ?
Complete working cell
Process:
&he fo((o'ing are the four steps in traditional die casting) a(so 3no'n as high-pressure die casting) these are a(so the basis for an+ of the die casting *ariations: die preparation) 1((ing) e8ection) and sha3eout. &he dies are prepared b+ spra+ing the mo(d ca*it+ 'ith lubri&ant. &he (ubricant both he(ps contro( the temperature of the die and it a(so assists in the remo*a( of the casting. &he dies are then c(osed and mo(ten meta( is in8ected into the dies under high pressure> bet'een ! and !@" mega pasca(s !)" and 2")9 psi;. Ance the mo(d ca*it+ is 1((ed) the pressure is maintained unti( the casting so(idi1es. &he dies are then opened and the shot shots are dierent from castings because there can be mu(tip(e ca*ities in a die) +ie(ding mu(tip(e castings per shot; is e8ected b+ the e8ector pins. Bina((+) the sha3eout in*o(*es separating the scrap) 'hich inc(udes the gate) runners) s)rues and 1ash) from the shot. &his is often done using a specia( trim die in a po'er press or h+drau(ic press. Ather methods of sha3ing out inc(ude sa'ing and grinding. 0 (ess (abor-intensi*e method is to tumb(e shots if gates are thin and easi(+ bro3en> separation of gates from 1nished parts must fo((o'. &his scrap is rec+c(ed b+ re me(ting it. &he +ie(d is appro/imate(+ ?@. &he high-pressure in8ection (eads to a ,uic3 1(( of the die) 'hich is re,uired so the entire ca*it+ 1((s before an+ part of the casting so(idi1es. n this 'a+) dis&ontinuities are a*oided) e*en if the shape re,uires dicu(t-to-1(( thin sections. &his creates the prob(em of air entrapment) because 'hen the mo(d is 1((ed ,uic3(+ there is (itt(e time for the air to escape. &his prob(em is minimied b+ inc(uding *ents a(ong the parting (ines) ho'e*er) e*en in a high(+ re1ned process there 'i(( sti(( be some porosit+ in the center of the casting. Most die casters perform other secondar+ operations to produce features not readi(+ cast ab(e) such as ta))ing a ho(e) po(ishing) p(ating) bung) or painting. Page % @
nspection : 0fter the sha3eout of the casting it is inspected for defects. &he most common defects are misruns and &old shuts. &hese defects can be caused b+ co(d dies) (o' meta( temperature) dirt+ meta() (ac3 of *enting) or too much (ubricant. Ather possib(e defects are gas porosit+) shrin/age )orosity) hot tears ) and o' mar3s. Flow marks are mar3s (eft on the surface of the casting due to poor gating) sharp corners) or e/cessi*e (ubricant.
Lubricants Eater-based (ubricants) ca((ed emulsions) are the most common(+ used t+pe of (ubricant) because of hea(th) en*ironmenta() and safet+ reasons. Fn(i3e so(*ent-based (ubricants) if 'ater is proper(+ treated to remo*e a(( minera(s from it) it 'i(( not (ea*e an+ b+-product in the dies. f the 'ater is not proper(+ treated) then the minera(s can cause surface defects and discontinuities. &here are four t+pes of 'ater-based (ubricants: oi( in 'ater) 'ater in oi() semi-s+nthetic) and s+nthetic. Ai( in 'ater is the best) because 'hen the (ubricant is app(ied) the 'ater coo(s the die surface b+ e*aporating 'hi(e depositing the oi() 'hich he(ps re(ease the shot. 0 common mi/ture for this t+pe of (ubricants is thirt+ parts 'ater to one part oi() ho'e*er in e/treme cases a ratio of !:! is used. Ai(s that are used inc(ude hea$y residual oil 23R45' animal %ats' $egetable %ats) and s+nthetic fats. these in&lude gra)hite' aluminium' and mi&a. Ather chemica( additi*es are used to inhibit rusting and o6idation. Emulsi7ers are added to 'ater-based (ubricants) so that oi( based additi*es can be mi/ed into the 'ater> these inc(ude soa)) al&ohol esters' and ethylene o6ides.
e/p(osion occurred during each shot) 'hich (ed to a bui(d-up of carbon on the mo(d ca*it+ 'a((s.
$"%antages of pressure "ie casting &here are se*era( reasons 'h+ manufactures prefer it to other die casting techni,ues. &hese inc(ude: !. t can produce parts 'ith superior mechanica( properties. &hat is) the parts ha*e a good 1nish and tight dimensiona( to(erance7accurac+. &his ma3es it a perfect choice for producing intricate machine parts. 0gain) it is the main reason for its popu(arit+. 2. t is suitab(e for (arge sca(e production of parts. &his is because the pressure increases rate of o' of mo(ten meta(.
Disa"%antages of pressure "ie casting &his meta( part manufacturing process is associated 'ith the fo((o'ing main disad*antages: Page % 5
!. &he entire process is on(+ suitab(e for (arge sca(e meta( part production. 2. &he initia( set up costs is re(ati*e(+ high. &his is due to the techno(og+ in*o(*ed. $. &he process is main(+ suitab(e for high-uidit+ meta( parts. n short) this is an o*era(( o*er*ie' of pressure die casting. 6o) 'e need to discuss the *arious t+pes of meta( die casting techno(og+.
$pplications of "ie casting: •
•
•
•
&he stee( die casting is popu(ar in *er+ man+ industria( app(ications. &hat is) automoti*e) manufacturing) production) energ+ production a(ternati*e energ+) etc. Burthermore) the+ are used to ma3e the meta( die casting too(s. &his is due to the superior ph+sica( and chemica( properties. &he stain(ess stee( is used to die cast medica( e,uipment and instruments parts. t doesnIt rust thus) the components can guarantee optima( performance. dea((+) this materia(s can be used in *er+ man+ industries such as: aerospace) automoti*e) chemica( processing) a(ternati*e and decorati*e industr+) 8ust to mention a fe'.
&eferences: Properties, The North American Die asting Association, retrie!ed "#-12-2""$
Alloy
Parashar , Nagendra %2""#&, Elements of Manufacturing Processes , it': (rentice-)all o* +ndia (!t. td, p. 2#
