Mechanical Engineering 101 - University of California ...courses.me.berkeley.edu/ME101/2012_me101_lecture_17.pdf · Mechanical Engineering 101 University of California, Berkeley Lecture

© 2003‐2012, McMains, DornfeldME 101 lecture 17 1

Mechanical Engineering 101

University of California, Berkeley

Lecture #17

© 2003‐2012, McMains, Dornfeld ME 101 lecture 17 2

Today’s lecture

• Capacity planning• Kanban intro


MRP

• Last lecture: MRP scheduling– Materials Requirements Planning: MRP

• This lecture: Capacity planning– Manufacturing Resources Planning : MRP II


B: lead time = 1period 0 1 2 3 4 5 6GR 1000 1000 1000 1500SRI 1106 106NR 894 1000 0 0 1500POR 894 1000 0 0 1500 0

Lot‐for‐lot MPS plan from last lecturelast time

• MPS for B?

Xperiod 0 1 2 3 4 5 6POR 1000 1000 1000 1500

X

B A

C

1 each

1 ea 1 ea

1 ea


Manufacturing Resources Planning

• Standard MRP scheduling ignores workstation capacity– assumes infinite!

• Capacity planning– Rough cut capacity planning (RCCP)– Capacity requirements planning (CRP)


Rough cut capacity planning

– resource profile• graphically shows precedence, lead times• annotated with work center (WC), time per unit

Week-5 -4 -3 -2 -1 -0

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100

0.05 hr/unitWC3000.15 hr/unit

WC2000.20 hr/unit

Fpurchased

Askin fig. 8.10


RCCP

Week-5 -4 -3 -2 -1 -0

period (week)1 2 3 4 5 6

POR(A) 50 75 25 50 200

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit


E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

1 2 3 4 5 6

WC 300 example,week 3 capacity req’s:resource profiles for therelevant weeks


E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

50 75 QA3=25 QA4=50 QA5= 200

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

200*

200*

50*

50*

25*

25*

WC 300 example


RCCP

• rijk = resources (time) per unit of end item i in work center j in kth period before i completed

• rA,100,0 = ? hrs1. 02. .053. .104. .15 5. .20 6. .257. .308. .359. .4010. none of the above Week

-3 -2 -1 -0

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit


RCCP


• rA,200,2 = ? hrs1. 02. .053. .104. .15 5. .20 6. .257. .308. .359. .4010. none of the above Week

-3 -2 -1 -0

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit


Resource profile

• rA,j,k is for single end item A work-content/work-center/period for A

Week-5 -4 -3 -2 -1 -0

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

periodwork center 0 -1 -2

100 0.05200 0.2 0.1300 0.15 0.15


RCCP

Week-5 -4 -3 -2 -1 -0

period (week)1 2 3 4 5 6

POR(A) 50 75 25 50 200

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

periodwork center 0 -1 -2

100 0.05200 0.2 0.1300 0.15 0.15


Work center load


• Qit = production quantity end item i in period t– from MPS


Work center load


• Qit = production quantity end item i in period t– from MPS

• wjt = load (time) on work center j in period t– make sure it’s w/in capacity limits!

ik

T

tktkji

n

ijt Qrw

,,1


.Work center load

• k=3: rA,300,3-3 = 0.0 , QA3 = 25• k=4: rA,300,4-3 = .15 , QA4 = 50• k=5: rA,300,5-3 = .15 , QA5 = 200• k=6: rA,300,6-3 = 0.0 , QA6 = 0

rA periodwork center 0 -1 -2

100 0.05200 0.2 0.1300 0.15 0.15

period1 2 3 4 5 6

POR(A) 50 75 25 50 200

ik

T

tktkji

n

ijt Qrw

,,1

...3,300w

WC 300 Example


E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

50 75 QA3=25 QA4=50 QA5= 200

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

200*

200*

50*

50*

25*

25*

. WC 300 Example


Work center load

rA periodwork center 0 -1 -2

100 0.05200 0.2 0.1300 0.15 0.15

period1 2 3 4 5 6

POR(A) 50 75 25 50 200

ik

T

tktkji

n

ijt Qrw

,,1

?...2,200 w

1. 0<=w200,2<52. 5<=w200,2<103. 10<=w200,2<154. 15<=w200,2<205. 20<=w200,2<25

6. 25<=w200,2<307. 30<=w200,2<358. 35<=w200,2<409. 40<=w200,2<4510. 45<=w200,2


E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

E

C C

A

D

Op#1WC200

0.10 hr/unit

Op#2WC300

0.15 hr/unitWC100


WC2000.20 hr/unit

50*

50*

25*

25*

75*

75*

50 75 QA2= 75 QA3=25 QA4=50

. WC 200 Example


Announcements

• HW6 late deadline 4pm Friday!• So all can be graded and returned next Tuesday

• Midterm next Thursday 10/25– HW 1-6, movies, lecture material through this week– Try the posted samples!!!– Review section Monday 6 pm 1165 EtcheverryBring:– 3x5 inch card of notes, handwritten, one side only – Calculator

• Hewlett Packard: The HP 33s and HP 35s models, but no others.

• Texas Instruments: All TI-30X and TI-36X models.• Casio: All fx-115 models.


Capacity Requirements Planning

• What does RCCP ignore?– inventory– setup times– larger batch production of components w/ POQ

• CRP looks at detailed production plans– add capacity resources in MRP explosion as

additional “components” – inventory = stored capacity

• not flexible capacity, though!


Work center load report

planned order releases

open shop orders

Time periodLate 1 2 3 4

Hou

rs

70

60

50

40

30

20

10

available capacity

Time period1 2 3 4

70

60

50

40

30

20

10

available capacity

Hou

rs


MRP II

• links additional modules to traditional MRP scheduling:– capacity planning– BOM processor– ECO management– customer order entry– financial planning– forecasting– inventory & warehouse management– purchasing

• 2-way communication between modules


Enterprise Resources Planning (ERP)

• beyond individual company– whole supplier-producer-customer network

• use electronic data interchange (EDI)


MRP assumptions

• known, constant lead times• dependent demand• adequate capacity• accurate BOM• good demand forecasts• predictable scrap rates• accurate inventory records


Ensuring accurate inventory data

• Why off?– scrap not recorded correctly– parts cannibalized– just plain lost

• One solution: hire “cycle counter”– given list of part numbers to count– find and count

• on shop floor, in storage

– update electronic record


ECOs

• Engineering Change Orders• lag

– existing inventory– implementation of process change– vendor qualification

• coordination– purchasing– manufacturing– engineering: testing, analyzing


Today’s lecture

• Capacity planning• Kanban intro

© 2003‐2011, McMains, Dornfeld, Min ME 101 lecture 19 35

Product Design: Push vs. Pull• Market oriented (pull system)

– Customer defines product– Competency

• Exceptional service• Low cost• Variety of choices and features

• Technology oriented (push system)– Technology defines product– Competency

• Scientific research• Unique product with market niche


Production Systems: Push vs. Pull

• Push: build inventory based on forecasts– promotions to sell off the green cars

• Pull: just-in-time (JIT) systems– replace inventory only as needed

p.36 fig 2.12 Askin (mis-keyed in Askin)




• Pull: just-in-time (JIT) systems– replace inventory only as it is removed




• Pull: just-in-time (JIT) systems– replace inventory only as needed– smaller buffers, no stockrooms, little WIP– specific production orders generated when mfg

start time nears


JIT benefits

• reduced inventory sizes– reduced lot size inventories– reduced buffer inventories– reduced finished goods inventories

• reduced inventory costs– less inventory space– less equipment to handle inventories– less inventory accounting– less inventory control effort

• reduced impact of forecasting errors• reduced scrap and rework


Kanban: a method for controlling pull system

• Japanese roughly translated as “card”– used for production authorization

• each kanban includes info on– part type– number of units authorized– possible additional info

• often used together with transport container– possibly color-coded to match– empty container “pulls” parts / triggers production– kanban card is “work order”– transfer lot size = container size


Kanban

Z

Step N manufacturer

• kanban card (and empty container) = request to supplier to make a container of “Z” and deliver ASAP– send request when remaining WIP/material just

covers lead time for replenishment

Z

Step N supplier


Kanban example [Mahoney]

• one-card kanban• low mix/high volume environment• products X and Z

– each has 3 steps performed at same 3 stations A,B,C

– one worker per station (aka Point Of Use, POU)

– storage after each station

Process A+B+CProcess A+BProcess A


Model number

Replenishment quantity

X

1

X1

“Z” product:

Kanban card for example

“X” product:

card located with product throughout the system


Product specific one-card kanban system

Product Zafter process A

Process AProcess BProcess C

Process A+B+CProcess A+B

Finished product X

Product Xafter process A

Finished product Z

product X kanban card

Process A

LMHV

Location after process A


Signals from parts and cards

Product Z removed from FGI

Product Z Kanban card put up at C

Z1

Authorizes another product Z to be started


More details……process B & C

Z1Completed Z after process C goes with card to FGI

Z1

Z1

Z kanban put up at B to schedule production of another Z product

C removes partially completed Z from input buffer


Moving further upstream….

Completed Z after process B goes with card to output buffer

Z1

Z kanban put up at A to schedule production of another Z product

Z1

B removes partially completed Z from input buffer


Last step……...

Z and kanban card placed in step A output buffer

process step A creates product Z


Idle state

• no kanban cards at any process stage– no production occurs– removing an X or Z from FGI would restart process

50

Homework 7 (due after midterm)• Reading

– Askin 269-291, 299-307• Askin (watch your lead times!)

– 8.14 (LFL)– 8.15 (POQ)– 8.21 (LFL, then CRP)– turn in 2 print-outs of your spreadsheet output for each

• With formulas (or matlab code, but Excel highly recommended)• With values

• Referring to the article “Piecing Together a Supply Chain”:

a) What happened to scheduled receipts of mass air flow sensors that G.M. had already ordered earlier in March?

b) Hypothesize how you think their planned order releases for this part (mass air flow sensors) changed.

c) How did their planned order releases for build orders for vehicles that used this part change?

Be sure to use the bold-faced MRP terminology in each answer. © 2003‐2012, McMains, Dornfeld ME 101 lecture 17

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Mechanical Engineering 101 - University of California ...courses.me.berkeley.edu/ME101/2012_me101_lecture_17.pdf · Mechanical Engineering 101 University of California, Berkeley Lecture