5.masterprodscheduling

7/29/2019 5.MasterProdScheduling

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A endaDefine Master Production Schedule (MPS) and

Discuss Some Key Issues Managing Master

MPS & competitive environments [MTS, ATO MTO]

Structuring of Bill of Materials (BOM)Lead Time and Time fences

Creating Master Schedule

,Available to Promise

Rough Cut Capacity Planning


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Manufacturin Resource Plannin - MRP-II

MATERIAL PLAN(PRODUCTION

CAPACITY PLAN(RESOURCE USE PLAN)PLANNING

HORIZON

Input from Higher Level Business Plan

Production Resource RequirementL ong Term

Master Plan

Sales Planning

ann n

Rough Cut Capacity

Planning (RCCP)

an

M aster Production

Scheduling (MPS)M edium Term

DemandM anagement

Aggregate Planing

M aterial RequirementPlanning (mrp)

Capacity RequirementPlanning (CRP)

Production ActivityControl/Shop Floor CtrlShort Term

Execution Plan

Hierarchy of Planning in MRP-I I


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Relationship between Aggregate Plan (Overall

- family total quantity of mattress in production plan is disaggregated to plannedproduction quantities of three models or end items in MPS for first 9 weeks

Month 1 2 3 4 5 6Matress Production 1000 900 950 950 900 900

ggrega e ro uc on an or Mattress Famil Pseudo Part Name

Week 1 2 3 4 5 6 7 8 9

Model-327 200 200 100 100

-Model-749 200 100 100 250Total 200 200 200 200 200 200 200 250 250

Master Production Schedule (MPS) for

Mattress Models Real Parts


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Master Production Schedule (MPS)

-

what the company plans to produce expressedin specific configurations, quantities, and dates.

Master Production Schedule (MPS) is definedlikely to be build] for those items assigned tomaster scheduler. It drives material

.


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[Although term MS is used interchangeably with MPS sometime it

The master schedule (MS) is a time-phased,

including the forecast and the backlog

(customer orders received), the masterpro uc on sc e ue e suppy pan , eprojected on hand (POH) inventory, and theavailable-to- romise ATP uantit .

It helps the master scheduler creating masterproduction schedule (MPS).


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An Example Master Schedule [MS]Week

0 1 2 3 4 5Month

Total

Aggregate forecast 100 200 150 150 200 800

Production 150 150 150 150 150 750Aggregate inventory 400 450 400 400 400 450Item AForecast 60 120 90 90 120 480Production (MPS) 150 150 150 450

Inventory 300 390 420 480 390 270Item BForecast 40 80 60 60 80 320Production (MPS) 150 150 300Inventory 100 60 -20 -80 10 80

Total Production 150 150 150 150 150

Aggregate plan capacity 150 150 150 150 150Deviation 0 0 0 0 0

Total Inventory 400 450 420 480 400 350

Deviation 0 -20 -80 0 0


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Manufacturing Environments and MPS

The competitive strategy of an organization may be

any of the following:MTS: Make finished items to stock (sell fromns e goo s nvenory

ATO: Assemble final products to order and make, ,

MTO: Custom design and make-to-order

It is not unusual for an organization to havedifferent strategies for different product lines and,t us, use erent approac es.


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MPS in Make-to-Stock Environment

Limited number of end items assembled from relatively largenumber of components. e compe ve s raegy o ma e- o-soc emp aszes

immediate delivery of reasonably priced off-the-shelf standarditems. In this environment the MPS is the anticipated buildschedule of the items required to maintain the finished goods at

the desired level. Note that the MPS is the same as the final.

End Item/Product

RawMaterial/Components


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Product Structure Tree or Bill of Material

THE BILL OF MATERIAL (BOM): An inclusivedefinition of a final roduct includes a list of the items,

ingredients, or materials needed to assemble, mix, orproduce that end product. This list is called a bill of material.

Table

. .,in Make-to-Stock environment.


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MPS in Assemble-to-Order

In this environment, options, subassemblies and components are.

to be able to supply a large variety of final product configurationsfrom standard components and subassemblies within a relativelyshort lead time.

End Item/Product

FASExample: automobile may

MPS Assemblies/options

be ordered with or withoutair conditioning, an option.

MPS for the options,accessories, and common

Raw Material/Components

componens as we as na

assembly schedule (FAS).


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MPS in Make-to-Order Environment

on customer orders.In many situations the final design of an item is part of what ispurchased. The final product is usually a combination of standarditems and items custom designed to meet the special needs of thecustomerExample, special trucks for off-the-road work on utility lines and

facilities are another. Thus, there is one MPS for the raw material

End Item/Product

, ,stock and another MPS for the custom engineering, fabrication,and final assembly.

FAS

Raw Material/ComponentsMPS


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Structuring of Bills of Material forn envronmen s

Requires forecast of options as well as totaldemand.

or op ons, accessores commoncomponents developed based on anticipated orforecast demand.

FAS for end item should be developed based onbooked orders.

Modular Bill of Material, a planning bills ofmaterial is used for this purpose


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Modular BOM(A type of planning BOM)

Modular billsModular bills--Product assembled from ma orProduct assembled from ma or

subassemblies & customer optionssubassemblies & customer options

--Modular bil l kept for each majorModular bill kept for each majorsu assem ysu assem y

--Simplif ies forecasting & planningSimplif ies forecasting & planning

slide)slide)Total: 3 x 8 x 3 x 8 x 4 = 2 304Total: 3 x 8 x 3 x 8 x 4 = 2 304

configurationsconfigurations

Only: 3 + 8 + 3 + 8 + 4 = 26 modular billsOnly: 3 + 8 + 3 + 8 + 4 = 26 modular bills


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Modular Bills of Material

-Disa re ate the rou total to the to module/o tion total based onproportion factors shown in modular BOM

-Safety stocks for options to absorb variations in mix can be included

X-10 Automobile

Engine(1 of 3)

Exterior color

(1 of 8)

Interior

(1 of 3)

Interior color

(1 of 8)

Body

(1 of 4)

44--Cylinder (.40+.1)Cyl inder (.40+.1) Br ight red (.10)Bright red (.10) Leather (.20)Leather (.20) Grey (.10)Grey (.10) Sports coupe (.20)Sports coupe (.20)

66--Cylinder (.50)Cylinder (.50) White linen (.10)White linen (.10) Tweed (.40)Tweed (.40) Light blue (.10)Light blue (.10) TwoTwo--door (.20)door (.20)

-- y n er .y n er . u p ur ye ow .u p ur ye ow . us .us . ose .ose . our our-- oor .oor .

Neon orange (.10)Neon orange (.10) Off Off--white (.20)white (.20) Station wagon (.30)Station wagon (.30)

Metalli c blue (.10)Metallic blue (.10) Cool green (.10)Cool green (.10)

Emerald green (.10)Emerald green (.10) Black (.20)Black (.20)

Jet black (.20)Jet black (.20) Brown (.10)Brown (.10)

Champagne (.20)Champagne (.20) B/W checked (.10)B/W checked (.10)


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Plannin Horizon of MPS The planning horizon is the amount of time the master schedule extends into

the future. A rinci le of lannin is that a lan must cover a eriod at least e ual to the

time required to accomplish it. This means that the MS planning horizon must

be at least as long as the lead time required to fabricate the MS items. Thisincludes production and procurement time as well as engineering time in acustom design environment. This is normally set to cover a minimum of

-


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o c es: me ences MPS is a link between operations (production) and sales.

Hence need to have some policies in maintaining MPS,

otherwise it may cause confusions. Many organizations divide the planning horizon into periods

with different controls on schedule chan es. The closer aperiod is to the present, the tighter are the controls onschedule changes.

Varying lead times, market condit ions, and processing.execution and manufacturing approaches, labor and materialare committed. A change in the schedule can be disruptive andcostly, and the costs must be compared with the benefits of the

- -. ,realistic lead time constraints and competitive factors, willresult in an MPS that promotes manufacturing stability andproductivity while providing reasonable flexibility in meeting

.


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Demand Time Fence (DTF): DTF is future master schedule period inside towhich chan es to MPS are t icall not acce ted due to excessive cost caused b theschedule disruption.

Planning Time Fence (PTF): PTF is future master schedule period inside towhich chan es to MPS are evaluated to revent costl schedule disru tion. Outside PTFplanned can be freely changes by computer logic.


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Must recognize all sources of the demand

um o saggrega e gures s ou ma cwith aggregate figures of production, inventory

Disaggregation over time should be efficient

(i.e., optimize cost etc.) Avoid overloading or underloading the

production facility so that production capacity

result.

considering environment MTS, ATO, MTO


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Techni ues for Develo inan MS

Cut and Fit Methods: Try out variousallocations of ca acit to roducts in agroup until a satisfactory combination is

determined. Linear Programming: Can write LP model

constraints, factors and relevant costs.


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An Example Master Schedule generated usingCut and Fit Method

Week0 1 2 3 4 5

MonthTotal

Aggregate forecast 100 200 150 150 200 800

Production 150 150 150 150 150 750Aggregate inventory 400 450 400 400 400 450Item AForecast 60 120 90 90 120 480Production (MPS) 150 150 150 450Inventory 300 390 420 480 390 270Item BForecast 40 80 60 60 80 320Production (MPS) 150 150 300Inventory 100 60 -20 -80 10 80

Total Production 150 150 150 150 150

Aggregate plan capacity 150 150 150 150 150Deviation 0 0 0 0 0

Total Inventory 400 450 420 480 400 350

Deviation 0 -20 -80 0 0


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Customer Order Bookin & MPS Interactions between demand management and MPS is frequent.

The projected available balance (PAB) and available-to-promiseATP are two techni ues used b the master scheduler to ro ect

available inventory or capacity and to promise future production

against customer orders. The PAB considers the availability of goods based on consuming

. , ,PAB uses the forecast while in the near future periods, customerorders are used as a statement of demand.

Available to promise (ATP) is found to determine if future customer.people. The ATP uses customer orders alone as a basis of itscomputation. We will consider three methods of calculations of ATPfigures.

scre e Cumulative ATP (without lookahead) Cumulative ATP (with lookahead)


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Available to Promise ATP : DPAB CALCULATIONS: It is based on a concept called

consumption of forecast by actual orders.

PRIOR TO DTF:

PAB = PRIOR PERIOD PAB OR ONHAND INVENTORY + MPS CUSTOMER ORDERS

PAB = PRIOR PERIOD PAB + MPS MAX(CUSTOMER ORDERS,FORECAST)

ATP = ON-HAND INVENTORY APPLICABLE ONLY FOR PERIOD 1 +MPS (TOTAL ORDERS BOOKED UNTIL NEXT MPS).

Production Capacity or Inventory

Firm customerorders (consuming

Available to promise

Time


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ATP: CalculationsLead Time:1 Lot Size: 300 DTF: 2ON Hand:140 PTF: 4

Week 1 2 3 4 5 6

ORDERS 110 80 50 20 0 0-

MPS

ATP

- -


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Week 1 2 3 4 5 6

ORDERS 110 80 50 20 0 0

-

MPS 300

-


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Week 1 2 3 4 5 6

ORDERS 110 80 50 20 0 0

5 5 5 5 5

MPS 300 300

- -


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Week 1 2 3 4 5 6

ORDERS 110 80 50 20 0 0

MPS 300 300

ATP 30 150 300

[140-110] [300-(80+50+20)]-


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Cumulative ATP with and without lookaheadATP from previous period is added while computing next

.

Without lookahead does not take into consideration those

Week

, .

Item AForecast 60 120 90 90 120Production (MPS) 150 150 150 0 0

nven orOrders 60 55 50 40 30ATP(discrete) 120 95 30

ATP(with lookahead) 120 215 245 245 245


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Rou h-Cut Ca acit Plannin As orders are slotted in the MPS, the effects on the

Rough cut capacity planning (RCCP) identifies

resources.

, ,Resources approach and overall factors.

o esource: s gves e num er o oursrequired at each critical resource to build a particular enditem.


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Example: Rough-Cut Capacity

Suppose, work center WC21 is a critical resource. There are twoend items A and B are master scheduled. The bill of resources for

.

Work Center Part A Part BWC21 2.5 h 2.0 h

Week 1 2 3 4 5 6 7 8

Part A 10 10 10 10 20 20 20 10

Part B 5 25 5 15 10 25 15 10

Then RCCP calculations will appear as follows.Week 1 2 3 4 5 6 7 8 Total

Part A (hours) 25 25 25 50 50 50 50 25 300

Part B (hours) 10 50 10 30 20 50 30 10 210Total (hours) 35 75 35 80 70 100 80 35 510

Available 65 65 65 65 65 65 65 65 520

- - - - - -


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Example: Rough-Cut Capacity

annng If we had considered only the sum (as in aggregate

,sufficient capacity (520 hours) versus a requirementof 510 hours. However, after performing RCCP wesee that several eriods have insufficient ca acitwhile others have an excess.

Planners o tions to make MPS feasible: 1 ad ustthe MPS by changing due dates; or (2) adjustcapacity by adding or taking away resources, usingovertime, or subcontracting of the work .

RCCP can be very rough sometime. A more refinedapproach capacity requirement planning (CRP) isdone during material requirement planning (MRP)p ase o p ann ng.


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