Descripción: For the book Bertsimas/Freund: Data, Models, and Decisions , solution
Principles of marketing chapter 9 TB
Full description
Full description
Faculty of Engineering Industrial Engineering Department,3rd year Sheet 3 Charting and Diagram
1- A foundry uses the following steps in its procedure for high production of investment casting process: (1) The rst step is to produce wax patterns by injection molding (!) The wax patterns are transported to an assembly wor" area where they are manually assembled to a wax sprue forming a pattern tree The entire tree is made of wax (#) The pattern tree is moved to a separate room where the tree is coated with a thin layer of refractory material ($) %n the same room& the tree is coated with success layers of refractory material to ma"e it a rigid structure that will become the mold for casting (') The tree is moved to a furnace room& where it is held in an inverted position and heated to melt the wax out of the mold cavities ith the wax removed& the rigid structure is now a multiplecavity mold with runners leading to each cavity from the sprue cavity (*) %n the same furnace room& the mold is now heated to a high h igh temperature to ensure that all contaminants are removed from the mold (+) ith the mold still heated at an elevated temperature and in an upright orientation& molten metal is poured into the sprue and ,ows through the runners ru nners to each cavity (-) After cooling and solidication of the metal& the assemblage is moved to a nishing room& where the mold is bro"en bro"en away from the cast metal and the parts are separated from the runners and sprue (a) .evelop the ,ow process chart for this casting process (b) /ased on your ,ow process chart& what are some changes in the investment casting procedure that you would recommend0 Solution: (a) low process chart 2o times or distances are included The application of the ,ow process process chart analysis for this problem is is somewhat unusual because the materials being processed change several times during the se3uence The starting material consists of wax patterns& which are used to fabricate the mold for the casting operation inally& inally& the mold is used to produce investment castings of an unspecied metal
Activity description %njection molding of wax patterns Allow patterns to cool 9ove patterns to assembly wor" area Assemble patterns to sprue for pattern tree 9ove pattern tree to refractory room 7oat pattern tree with refractory material 7oat tree with refractory multiple times 9ove tree to furnace room %nvert pattern tree and heat to melt wax Ceheat tree to remove contaminants 6osition mold upright& pour molten metal Allow time for cooling and solidication 9ove tree and casting to
;ym Tim .istan Analysis notes bol e ce = . 9 = 9 = = 9 = = = . 9
.istan ces
1$
nishing room /rea" mold and separate sprue from casting
=
1 7hange the casting process from investment casting to die casting& which is a much simpler process consisting of fewer steps unctional re3uirements of the part may argue against this recommendation ! ;et up all processing steps in one room to eliminate moves between separate rooms # %n addition to all steps being carried out in one room& could a wor" cell be designed to provide a more se3uential wor" ,ow between operations $ here are the inspections0 2o inspection operations are listed among the investment casting steps or a rather complex se3uence& inspections should be included to ma"e sure that further processing is not performed using defective patterns or molds
2- A supplier of machined components for industrial machinery (eg& power tools& pumps& motors& compressors) operates a factory that includes a forge shop& machine shop& and nishing department 9any of the parts produced by the company are fabricated through these three departments /ecause of this& the factory is laid out as three large s3uare rooms& arranged inline to form a rectangle with an aspect ratio of threetoone Dach room is !?? ft by !?? ft The rectangle runs from north to south& with the forge shop on the south end and the nishing department on the north end Earge doors are located on the south wall for wor" entering the factory and on the north wall for nished products exiting the factory or one part of particular interest here& the raw material is a steel billet that is purchased from a steel wholesale supplier The billets arrive in pallet loads of 1?? billets at the shipping and receiving department& which is a building that is #' ft by '? ft located !' ft from the south wall door of the factory The shipping and receiving department inspects the parts and sends them by for"lift truc" to be stored in the companyFs warehouse that is located in another building '?? ft away from the factory in a southerly direction The warehouse is !?? ft by !?? ft with its entrance door on the north wall hen a production order for the part is received& a factory for"lift truc" is dispatched to the warehouse to retrieve the billets The for"lift truc" must wait while the warehouse crew locates the billets in storage& ta"es a pallet out of storage using the same type of for"lift truc"& and delivers the pallet to the doc" where it is transferred to the factory for"lift The pallet is then brought bac" to the factory and delivered to the forge shop The billets must wait their turn in the production schedule before being pressed into the desired shape by one of the forge presses rom the forge shop& the parts are moved to the machine shop where they are machined on two diGerent machine
tools& a milling machine and a drill press rom the machine shop& the parts travel to the nishing department for painting and ba"ing (to cure the paint) rom the nishing department& the parts are moved bac" to the machine shop& where additional milling is accomplished to provide two machined metal surfaces that will mate with other components in the nal product The parts are then moved to the shipping and receiving department for shipment to the customer (a De!elop the "o# process chart
;olution : Flow Process Chart
Date: XX/xx/2XXX
Analyst: MPG Job: Forged machinery part
Approval: Part No:
Material: Steel billet #escription: Steps in processing of steel billets& $b)ect of study is steel billets&
Se. & + 2 6 -
8 %
Page ___ of ____
Activity description /nloading of pallet load at S01 #ept 'nspection of billets Move billets to 3arehouse Move billets into storage at 3arehouse Storage at 3arehouse* a3aiting order (For5lift dispatch from factory to 3arehouse (For5lift 3aits at 3arehouse Pallet of billets retrieved from storage For5lift transports billets bac5 to forge shop
Summary of Activities Activity (symbols $perations ( ⃝ 'nspections
, $
( >, '
!ount
+
#elays (Ⅾ& #)
Storages ( * S
$ ' M M S M # M M
"
#is
#istances
%
Moves (→* M
Sym
"ime
+,,- ft
Analysis notes
-44 ft 44 ft
"ransport by for5lift truc5 #ifferent for5lift inside 3arehouse
-44 ft
7illets are not moved yet For5lift 3aiting for billet retrieval
7illets 3aiting to be processed 7illets moved to forge press Forging operation on billets "emporary storage after forging Move forgings to machine shop (milling "emporary storage before milling Milling operation "emporary storage after milling Move parts to drill press "emporary storage before drilling #rilling operation "emporary storage after drilling Move machined parts to finishing dept "emporary storage before painting Painting operation Move parts directly to ba5ing operation 7a5ing operation to cure paint "emporary storage after ba5ing Move parts bac5 to machine shop "emporary storage before milling Milling operations on t3o surfaces "emporary storage after milling Move parts to S01 #ept for shipping
# M $ # M # $ # M # $ # M # $ M $ # M # $ # M
44 ft
+44 ft
#ept centertocenter distance "ypical of batch production
44 ft
"ypical of batch production #istance 3ithin machine shop "ypical of batch production
+44 ft
"ypical of batch production #ept centertocenter distance "ypical of batch production
84 ft
+44 ft
2+- ft
"ypical of batch production #ept centertocenter distance "ypical of batch production "ypical of batch production 1oute is through forge shop
3- %n igure B+ in the text& which refers to Dxample !1 in 7hapter !& consider the allocation of time between the right hand and left hand in the activity chart (a) %f the wor"place were redesigned using a wor" holding xture& and the wor"er were trained to use both hands simultaneously to perform the tas"& construct a righthand5lefthand activity chart for the revised method& estimating the amounts of time for each step in the method (b) hat is the percent reduction in cycle time0 1- $riginal case (#or%er use left hand to holding and use the other hand to pic%s leg
2- the #or%place #ere redesigned using a #or% holding &'ture, and the #or%er #ere trained to use oth hands simultaneously to perform the tas%
Solution:
Left hand Pick up board, put in workholder
Time
Right hand
0.08 min
Cum. time 0.08 min
0.04 min
Close workholder
0.! min
Pick up 4 pegs from tra"
0.0# min
Pick up 4 pegs from tra"
0.$ min
%nsert 4 pegs into holes in board
0.0 min
%nsert 4 pegs in holes in board
0.!$ min
0.0& min
'pen workholder
0.&0 min
Remo(e board, place in tote pan
0.0$ min
0.&$ min
The cycle time is reduced from ?*! min to ?#+ min& which is a $?H reduction in cycle time
)- The repetitive wor" cycle in a wor"ermachine system consists of the wor" elements and associated times given in the table below As the table shows& all of the operatorFs elements are external to the machine time (a) 7onstruct a wor"ermachine activity chart for this wor" cycle (b) 7an some of the wor"erFs elements be made internal to the machine cycle0 %f so& construct a wor"ermachine activity chart for the revised wor" cycle hat is the approximate cycle time for the revised cycle0
(A) Se*+
or% element description
or%er time
achine time
1
or%er #al%s to tote pan containing ra# stoc%
.+13 min+
(idle
2
or%er pic%s up ra# #or%part and transports to machine
.+23 min+
(idle
3
or%er loads part into machine and engages machine semi-automatic cycle
.+12 min+
(idle
)
achine semi-automatic cycle
(idle
.+/0 min+
0
or%er unloads &nished part from machine
.+1. min+
(idle
or%er transports &nished part and deposits into tote pan
.+10 min+
(idle
otals
.+/3 min+
.+/0 min+
(/)
Solution (a or%er-machine acti!ity chart+ his is ased on E'ample 2+1. in Chapter 2+ )orker
Time
*achine
Time
Cum. time
)alk to tote pan
0.&
0.&
Pick up raw workpart and transport to machine
0.!&
0.&+
Load workpart and engage automatic c"cle
0.!
0.48
*achine c"cle
0.$#
.!&
nload finished part from machine
0.0
.&&
Transport part and deposit in tote pan
0.#
.48
( 4e!ised #or%er-machine acti!ity chart+ )orker
Time
nload finished part from machine
0.0
0.0
Load raw part, engage auto c"cle
0.!
0.!!
Transport finished part, deposit in tote pan, walk to raw parts tote pan, pick up and transport to machine
*achine
0.#
Time
0.$#
Cum. time
0.-$
*achine c"cle
Summary he cycle time for the re!ised cycle is .+5/ min, a 306 reduction from the original cycle time of 1+)7 min+
4elationship Chart
0- A factory has ve production departments: 9 (milling)& . (drilling)& T (turning)& (grinding)& and (nishing) 6roducts are routed for processing through these departments in the 3uantities and se3uences indicated in the table below (a) /ased on these data& construct the fromto chart (b) .evelop the activity relationship chart for these ve departments& given that the fromto chart is the only basis for it 8roduc t
9uantities per day
Se*uence
1
20
-D-:
2
0
3
1.
-F
)
0.
D--D-:-F
0
20
--F
10
-:
-:-F
Solution: (a) romto chart and (b) activityrelationship chart To determine the closeness ratings in (b)& the following divisions were used: IAJ K number of trips L +'M IDJ K number of trips K '? to +'M I%J K number of trips K !' to $BM I=J K number of trips K 1 to !$& and INJ K Oero trips (a From-to chart From< o
( ;cti!ity-relationship chart
D
:
-
/0
20
10
D
0.
-
/0
D
: F
-
F
0
30
-
00
:
-
F
D
:
F
-
;
I
$
=
-
=
E
=
-
$
I
-
E -
- A college oPce building has ve departments: A (accounting oPce)& / (bursarFs oPce)& 7 (credit department)& . (data processing department)& and D (educational support services) 6aper forms are routed for processing through these departments in the 3uantities and se3uences indicated in the table below (a) /ased on these data& construct the fromto chart (b) .evelop the activity relationship chart for these ve departments& given that the fromto chart is the only basis for it 8rodu ct
9uantities per day
Se*uence
1
2.
;->-D
2
13
>-E-;
3
1.
E-C
)
3.
D-;->-D
0
20
;-C-E->
17
C->-E-D-;
Solution: (a) romto chart and (b) activityrelationship chart To determine the closeness ratings in (b)& the following divisions were used: IAJ K number of trips Q '?M IDJ K number of trips K #' to $BM I%J K number of trips K !? to #$M I=J K number of trips K 1 to 1B& and INJ K Oero trips (a From-to chart From< o
;
>
C
;
-
0.
20
>
-
C
17
D
)7
E
13
( ;cti!ity-relationship chart D
E ;
0. -
31
>
20
C
20
1.
17
D -
E
;
>
C
D
E
-
;
I
E
$
-
$
;
;
-
=
E
-
$ -
/- A manufacturing plant has six production departments: 9 (milling)& . (drilling)& T (turning)& (grinding)& (nishing)& and A (assembly) 6roducts are routed for processing through these departments in the 3uantities and se3uences indicated in the table below (a) 7onstruct the fromto chart for the data (b) .evelop the activity relationship chart for the six departments& given that the fromto chart is the only basis for it 8rodu ct
9uantities per day
Se*uence
1
).
-D-F-;
2
0.
-:-F
3
2.
-D-F
)
.
:-F-;
0
/.
-D--:F
3.
--F-;
/
1.
--:
Solution: (a) romto chart and (b) activityrelationship chart To determine the closeness ratings in (b)& the largest total number of trips (1-?) was divided by $ to specify divisions The following divisions were used: IAJ K number of trips K 1#' to 1-?M IDJ K number of trips K B? to 1#$M I%J K number of trips K $' to -BM I=J K number of trips K 1 to $$& and INJ K Oero trips From< o
