materials requirements day 3 13/3 10 pg -...

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14 - 1 © 2011 Pearson Education, Inc. publishing as Prentice Hall 8 CHAPTER 2 : MATERIALS REQUIREMENTS PLANNING 2.1 Basics of Materials Requirements Planning (MRP) 2.2 Advantages and disadvantages of MRP 2.3 Bill of materials 2.4 Inventory status file 3 Day 3 13/3 selas a 10 pg - 1ptg Zulk 9 CHAPTER 3 : PRODUCTION ACTIVITY CONTROL 3.1 Shop floor control (Planning, Execution, Control) 3 2 ptg 5 ptg Wan Nazdah 10 CHAPTER 4 : MANUFACTURING RESOURCE PLANNING 4.1 Business Planning 4.2 Production Planning 4.3 Capacity Planning 4.4 Master Production Scheduling 4.5 Resource Requirement Planning 4.6 Material Requirement Planning 4.7 Capacity Requirement Planning 4.8 Production Activity Control 4 Day 4 14/3 Rabu 9 pg 1 ptg Zulk ZULKEPLI B HJ MUHAMAD [email protected] www.fkm.utm.my/~zulkepli/

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Page 1: MATERIALS REQUIREMENTS Day 3 13/3 10 pg - fkm.utm.myzulkepli/userfiles/downloads/kv/heizer_om10_ch14_MRP... · 2.2 Advantages and disadvantages of MRP 2.3 Bill of materials 2.4 Inventory

14 - 1© 2011 Pearson Education, Inc. publishing as Prentice Hall

8 CHAPTER 2 : MATERIALS REQUIREMENTS

PLANNING

2.1 Basics of Materials Requirements Planning

(MRP)

2.2 Advantages and disadvantages of MRP

2.3 Bill of materials

2.4 Inventory status file

3

Day 3

13/3

selas

a

10 pg -

1ptg Zulk

9 CHAPTER 3 : PRODUCTION ACTIVITY

CONTROL

3.1 Shop floor control (Planning, Execution,

Control)

3

2 ptg –

5 ptg

Wan

Nazdah

10 CHAPTER 4 : MANUFACTURING RESOURCE

PLANNING

4.1 Business Planning

4.2 Production Planning

4.3 Capacity Planning

4.4 Master Production Scheduling

4.5 Resource Requirement Planning

4.6 Material Requirement Planning

4.7 Capacity Requirement Planning

4.8 Production Activity Control

4 Day 4

14/3

Rabu

9 pg –

1 ptg

Zulk

ZULKEPLI B HJ [email protected]

www.fkm.utm.my/~zulkepli/

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14 - 2© 2011 Pearson Education, Inc. publishing as Prentice Hall

HASIL PEMBELAJARAN (LEARNING OUTCOMES):

CLO1 Describe the production planning and control

concept in improving the production activities

base on a case study. (C2, PLO1)

CLO2 Apply the knowledge to solve typical problems

related to production activities (C3, PLO3)

CLO3 Practice the team working spirit effectively in a

group to accomplish a case study. (P3, PLO5)

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14 - 3© 2011 Pearson Education, Inc. publishing as Prentice Hall

4 - 6 CHAPTER 2 : MATERIALS REQUIREMENTS PLANNING

2.1 Basics of Materials Requirements Planning (MRP)

2.2 Advantages and disadvantages of MRP

2.3 Bill of materials

2.4 Inventory status file

ASSIGNMENT

7 - 8 CHAPTER 3 : PRODUCTION ACTIVITY CONTROL

3.1 Shop floor control (Planning, Execution, Control) QUIZ

9 - 11 CHAPTER 4 : MANUFACTURING RESOURCE PLANNING

4.1 Business Planning

4.2 Production Planning

4.3 Capacity Planning

4.4 Master Production Scheduling

4.5 Resource Requirement Planning

4.6 Material Requirement Planning

4.7 Capacity Requirement Planning

4.8 Production Activity Control

ASSIGNMENT

Type of Assessment Marks

Pentaksiran Berterusan (PB) : 60%

TheoryQuiz 5%

20%Assignment 15%

PracticalCase Study (Group) 10%

40%Report & Presentation 30%

Penilaian Akhir (PA) : 40%

TheoryPeperiksaan Akhir Teori (Theory

Examination)40%

40%

PracticalPeperiksaan Akhir Amali

(Practical Examination)0%

Jumlah (Total) 100%

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14 - 4© 2011 Pearson Education, Inc. publishing as Prentice Hall

14 Material Requirements Planning (MRP) and ERP

PowerPoint presentation to accompany

Heizer and Render

Operations Management, 10e

Principles of Operations Management, 8e

PowerPoint slides by Jeff Heyl

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14 - 5© 2011 Pearson Education, Inc. publishing as Prentice Hall

Outline Global Company Profile: Wheeled

Coach

Dependent Demand

Dependent Inventory Model Requirements

Master Production Schedule

Bills of Material

Accurate Inventory Records

Purchase Orders Outstanding

Lead Times for Components

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14 - 6© 2011 Pearson Education, Inc. publishing as Prentice Hall

Outline – Continued

MRP Structure

MRP Management

MRP Dynamics

MRP and JIT

Lot-Sizing Techniques

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14 - 7© 2011 Pearson Education, Inc. publishing as Prentice Hall

Outline – Continued

Extensions of MRP

Material Requirements Planning II (MRP II)

Closed-Loop MRP

Capacity Planning

MRP In Services

Distribution Resource Planning (DRP)

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14 - 8© 2011 Pearson Education, Inc. publishing as Prentice Hall

Outline – Continued

Enterprise Resource Planning (ERP)

Advantages and Disadvantages of ERP Systems

ERP in the Service Sector

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14 - 9© 2011 Pearson Education, Inc. publishing as Prentice Hall

Learning Objectives

When you complete this chapter you should be able to:

1. Develop a product structure

2. Build a gross requirements plan

3. Build a net requirements plan

4. Determine lot sizes for lot-for-lot, EOQ, and PPB

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14 - 10© 2011 Pearson Education, Inc. publishing as Prentice Hall

Learning Objectives

When you complete this chapter you should be able to:

5. Describe MRP II

6. Describe closed-loop MRP

7. Describe ERP

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14 - 11© 2011 Pearson Education, Inc. publishing as Prentice Hall

Wheeled Coach

Largest manufacturer of ambulances in the world

International competitor

12 major ambulance designs

18,000 different inventory items

6,000 manufactured parts

12,000 purchased parts

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14 - 12© 2011 Pearson Education, Inc. publishing as Prentice Hall

Wheeled Coach

Four Key Tasks

Material plan must meet both the requirements of the master schedule and the capabilities of the production facility

Plan must be executed as designed

Minimize inventory investment

Maintain excellent record integrity

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14 - 13© 2011 Pearson Education, Inc. publishing as Prentice Hall

Dependent Demand

For any product for which a schedule can be established, dependent

demand techniques should be used

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14 - 14© 2011 Pearson Education, Inc. publishing as Prentice Hall

Dependent Demand

Benefits of MRP

1. Better response to customer orders

2. Faster response to market changes

3. Improved utilization of facilities and labor

4. Reduced inventory levels

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14 - 15© 2011 Pearson Education, Inc. publishing as Prentice Hall

Dependent Demand

The demand for one item is related to the demand for another item

Given a quantity for the end item, the demand for all parts and components can be calculated

In general, used whenever a schedule can be established for an item

MRP is the common technique

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14 - 16© 2011 Pearson Education, Inc. publishing as Prentice Hall

Dependent Demand

1. Master production schedule

2. Specifications or bill of material

3. Inventory availability

4. Purchase orders outstanding

5. Lead times

Effective use of dependent demand inventory models requires the following

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14 - 17© 2011 Pearson Education, Inc. publishing as Prentice Hall

Master Production Schedule (MPS)

Specifies what is to be made and when

Must be in accordance with the aggregate production plan

Inputs from financial plans, customer demand, engineering, supplier performance

As the process moves from planning to execution, each step must be tested for feasibility

The MPS is the result of the production planning process

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14 - 18© 2011 Pearson Education, Inc. publishing as Prentice Hall

Master Production Schedule (MPS)

MPS is established in terms of specific products

Schedule must be followed for a reasonable length of time

The MPS is quite often fixed or frozen in the near term part of the plan

The MPS is a rolling schedule

The MPS is a statement of what is to be produced, not a forecast of demand

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14 - 19© 2011 Pearson Education, Inc. publishing as Prentice HallFigure 14.1

Change production

plan?Master production schedule

ManagementReturn oninvestmentCapital

EngineeringDesigncompletion

Aggregate production

plan

ProcurementSupplierperformance

Human resourcesManpowerplanning

ProductionCapacityInventory

MarketingCustomerdemand

FinanceCash flow

The Planning Process

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14 - 20© 2011 Pearson Education, Inc. publishing as Prentice Hall

The Planning Process

Figure 14.1

Is capacity plan being

met?

Is execution meeting the

plan?

Change master

production schedule?

Change capacity?

Change requirements?

No

Execute material plans

Execute capacity plans

Yes

Realistic?

Capacity requirements plan

Material requirements plan

Master production schedule

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14 - 21© 2011 Pearson Education, Inc. publishing as Prentice Hall

AggregateProduction Plan

Months January February

Aggregate Production Plan 1,500 1,200(Shows the totalquantity of amplifiers)

Weeks 1 2 3 4 5 6 7 8

Master Production Schedule(Shows the specific type andquantity of amplifier to beproduced

240-watt amplifier 100 100 100 100

150-watt amplifier 500 500 450 450

75-watt amplifier 300 100

Figure 14.2

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14 - 22© 2011 Pearson Education, Inc. publishing as Prentice Hall

Master Production Schedule (MPS)

1. A customer order in a job shop (make-to-order) company

2. Modules in a repetitive (assemble-to-order or forecast) company

3. An end item in a continuous (stock-to-forecast) company

Can be expressed in any of the following terms:

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14 - 23© 2011 Pearson Education, Inc. publishing as Prentice Hall

Focus for Different Process Strategies

Stock to Forecast

(Product Focus)

Schedule finished product

Assemble to Order or Forecast(Repetitive)

Schedule modules

Make to Order

(Process Focus)

Schedule orders

Examples: Print shop Motorcycles Steel, Beer, Bread

Machine shop Autos, TVs Lightbulbs

Fine-dining restaurant Fast-food restaurant Paper

Typical focus of the master production

schedule

Number of inputs

Number of end items

Figure 14.3

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14 - 24© 2011 Pearson Education, Inc. publishing as Prentice Hall

MPS Examples

Gross Requirements for Crabmeat Quiche

Gross Requirements for Spinach Quiche

Day 6 7 8 9 10 11 12 13 14 and so on

Amount 50 100 47 60 110 75

Day 7 8 9 10 11 12 13 14 15 16 and so on

Amount 100 200 150 60 75 100

Table 14.1

For Nancy’s Specialty Foods

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14 - 25© 2011 Pearson Education, Inc. publishing as Prentice Hall

Bills of Material

List of components, ingredients, and materials needed to make product

Provides product structure

Items above given level are called parents

Items below given level are called children

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14 - 26© 2011 Pearson Education, Inc. publishing as Prentice Hall

BOM Example

B(2) Std. 12” Speaker kit C(3)Std. 12” Speaker kit w/ amp-booster1

E(2)E(2) F(2)

Packing box and installation kit of wire,

bolts, and screws

Std. 12” Speaker booster assembly

2

D(2)

12” Speaker

D(2)

12” Speaker

G(1)

Amp-booster

3

Product structure for “Awesome” (A)

A

Level

0

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14 - 27© 2011 Pearson Education, Inc. publishing as Prentice Hall

BOM Example

B(2) Std. 12” Speaker kit C(3)Std. 12” Speaker kit w/ amp-booster1

E(2)E(2) F(2)

Packing box and installation kit of wire,

bolts, and screws

Std. 12” Speaker booster assembly

2

D(2)

12” Speaker

D(2)

12” Speaker

G(1)

Amp-booster

3

Product structure for “Awesome” (A)

A

Level

0

Part B: 2 x number of As = (2)(50) = 100

Part C: 3 x number of As = (3)(50) = 150

Part D: 2 x number of Bs

+ 2 x number of Fs = (2)(100) + (2)(300) = 800

Part E: 2 x number of Bs

+ 2 x number of Cs = (2)(100) + (2)(150) = 500

Part F: 2 x number of Cs = (2)(150) = 300

Part G: 1 x number of Fs = (1)(300) = 300

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14 - 28© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 29© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 30

Assignment #1Bill of Material

- Product structure

- Production planning

- Inventory file

- Time phase planning

© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 31© 2011 Pearson Education, Inc. publishing as Prentice Hall

Bills of Material

Modular Bills

Modules are not final products but components that can be assembled into multiple end items

Can significantly simplify planning and scheduling

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14 - 32© 2011 Pearson Education, Inc. publishing as Prentice Hall

Bills of Material

Planning Bills

Also called “pseudo” or super bills

Created to assign an artificial parent to the BOM

Used to group subassemblies to reduce the number of items planned and scheduled

Used to create standard “kits” for production

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14 - 33© 2011 Pearson Education, Inc. publishing as Prentice Hall

Bills of Material

Phantom Bills

Describe subassemblies that exist only temporarily

Are part of another assembly and never go into inventory

Low-Level Coding

Item is coded at the lowest level at which it occurs

BOMs are processed one level at a time

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14 - 34© 2011 Pearson Education, Inc. publishing as Prentice Hall

Accurate Records

Accurate inventory records are absolutely required for MRP (or any dependent demand system) to operate correctly

Generally MRP systems require more than 99% accuracy

Outstanding purchase orders must accurately reflect quantities and scheduled receipts

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14 - 35© 2011 Pearson Education, Inc. publishing as Prentice Hall

Lead Times

The time required to purchase, produce, or assemble an item

For production – the sum of the order, wait, move, setup, store, and run times

For purchased items – the time between the recognition of a need and the availability of the item for production

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14 - 36© 2011 Pearson Education, Inc. publishing as Prentice Hall

Time-Phased Product Structure

| | | | | | | |

1 2 3 4 5 6 7 8Time in weeks

F

2 weeks

3 weeks

1 week

A

2 weeks

1 week

D

E

2 weeks

D

G

1 week

Start production of DMust have D and E completed here so

production can begin on B

Figure 14.4

1 week

2 weeks to produce

B

C

E

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14 - 37© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 38© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 39© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 40© 2011 Pearson Education, Inc. publishing as Prentice Hall

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14 - 41© 2011 Pearson Education, Inc. publishing as Prentice Hall

MRP Structure

Figure 14.5

Output Reports

MRP by period report

MRP by date report

Planned order report

Purchase advice

Exception reports

Order early or late or not needed

Order quantity too small or too large

Data Files

Purchasing data

BOM

Lead times

(Item master file)

Inventory data

Masterproduction schedule

Material requirement

planning programs

(computer and software)

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14 - 42© 2011 Pearson Education, Inc. publishing as Prentice Hall

Determining Gross Requirements

Starts with a production schedule for the end item – 50 units of Item A in week 8

Using the lead time for the item, determine the week in which the order should be released – a 1 week lead time means the order for 50 units should be released in week 7

This step is often called “lead time offset” or “time phasing”

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14 - 43© 2011 Pearson Education, Inc. publishing as Prentice Hall

Determining Gross Requirements

From the BOM, every Item A requires 2 Item Bs – 100 Item Bs are required in week 7 to satisfy the order release for Item A

The lead time for the Item B is 2 weeks –release an order for 100 units of Item B in week 5

The timing and quantity for component requirements are determined by the order release of the parent(s)

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14 - 44© 2011 Pearson Education, Inc. publishing as Prentice Hall

Determining Gross Requirements

The process continues through the entire BOM one level at a time – often called “explosion”

By processing the BOM by level, items with multiple parents are only processed once, saving time and resources and reducing confusion

Low-level coding ensures that each item appears at only one level in the BOM

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14 - 45© 2011 Pearson Education, Inc. publishing as Prentice Hall

Gross Requirements Plan

Table 14.3

Week

1 2 3 4 5 6 7 8 Lead Time

A. Required date 50Order release date 50 1 week

B. Required date 100Order release date 100 2 weeks

C. Required date 150Order release date 150 1 week

E. Required date 200 300Order release date 200 300 2 weeks

F. Required date 300Order release date 300 3 weeks

D. Required date 600 200Order release date 600 200 1 week

G. Required date 300Order release date 300 2 weeks

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14 - 46© 2011 Pearson Education, Inc. publishing as Prentice Hall

Net Requirements Plan

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Net Requirements Plan

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Determining Net Requirements

Starts with a production schedule for the end item – 50 units of Item A in week 8

Because there are 10 Item As on hand, only 40 are actually required – (net requirement) = (gross requirement - on-hand inventory)

The planned order receipt for Item A in week 8 is 40 units – 40 = 50 - 10

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Determining Net Requirements

Following the lead time offset procedure, the planned order release for Item A is now 40 units in week 7

The gross requirement for Item B is now 80 units in week 7

There are 15 units of Item B on hand, so the net requirement is 65 units in week 7

A planned order receipt of 65 units in week 7 generates a planned order release of 65 units in week 5

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Determining Net Requirements

A planned order receipt of 65 units in week 7 generates a planned order release of 65 units in week 5

The on-hand inventory record for Item B is updated to reflect the use of the 15 items in inventory and shows no on-hand inventory in week 8

This is referred to as the Gross-to-Net calculation and is the third basic function of the MRP process

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S

B C

12 138 9 10 11

20 3040

Lead time = 6 for SMaster schedule for S

Gross Requirements Schedule

Figure 14.6

1 2 3

10 10

Master schedulefor B

sold directly

Periods

Therefore, these are the gross requirements for B

Gross requirements: B 10 40 50 2040+10 15+30

=50 =45

1 2 3 4 5 6 7 8Periods

A

B C

Lead time = 4 for AMaster schedule for A

5 6 7 8 9 10 11

40 1550

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Net Requirements Plan

The logic of net requirements

Available inventory

Net requirements

On hand

Scheduled receipts+– =

Total requirements

Gross requirements

Allocations+

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MRP Planning Sheet

Figure 14.7

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Safety Stock

BOMs, inventory records, purchase and production quantities may not be perfect

Consideration of safety stock may be prudent

Should be minimized and ultimately eliminated

Typically built into projected on-hand inventory

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MRP Management

MRP is a dynamic system

Facilitates replanning when changes occur

Regenerating

Net change

System nervousness can result from too many changes

Time fences put limits on replanning

Pegging links each item to its parent allowing effective analysis of changes

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MRP and JIT

MRP is a planning system that does not do detailed scheduling

MRP requires fixed lead times which might actually vary with batch size

JIT excels at rapidly moving small batches of material through the system

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Finite Capacity Scheduling

MRP systems do not consider capacity during normal planning cycles

Finite capacity scheduling (FCS) recognizes actual capacity limits

By merging MRP and FCS, a finite schedule is created with feasible capacities which facilitates rapid material movement

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Small Bucket Approach

1. MRP “buckets” are reduced to daily or hourly

2. Planned receipts are used internally to sequence production

3. Inventory is moved through the plant on a JIT basis

4. Completed products are moved to finished goods inventory which reduces required quantities for subsequent planned orders

5. Back flushing based on the BOM is used to deduct inventory that was used in production

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Balanced Flow

Used in repetitive operations

MRP plans are executed using JIT techniques based on “pull” principles

Flows are carefully balanced with small lot sizes

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Supermarket

Items used by many products are held in a common area often called a supermarket

Items are withdrawn as needed

Inventory is maintained using JIT systems and procedures

Common items are not planned by the MRP system

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Lot-Sizing Techniques

Lot-for-lot techniques order just what is required for production based on net requirements

May not always be feasible

If setup costs are high, lot-for-lot can be expensive

Economic order quantity (EOQ)

EOQ expects a known constant demand and MRP systems often deal with unknown and variable demand

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Lot-Sizing Techniques

Part Period Balancing (PPB) looks at future orders to determine most economic lot size

The Wagner-Whitin algorithm is a complex dynamic programming technique

Assumes a finite time horizon

Effective, but computationally burdensome

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Lot-for-Lot Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35 35 0 0 0 0 0 0 0 0 0

Net requirements

0 30 40 0 10 40 30 0 30 55

Planned order receipts

30 40 10 40 30 30 55

Planned order releases

30 40 10 40 30 30 55

Holding cost = $1/week; Setup cost = $100; Lead time = 1 week

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Lot-for-Lot Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35 35 0 0 0 0 0 0 0 0 0

Net requirements

0 30 40 0 10 40 30 0 30 55

Planned order receipts

30 40 10 40 30 30 55

Planned order releases

30 40 10 40 30 30 55

Holding cost = $1/week; Setup cost = $100; Lead time = 1 week

No on-hand inventory is carried through the systemTotal holding cost = $0

There are seven setups for this item in this planTotal ordering cost = 7 x $100 = $700

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EOQ Lot Size Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35 35 0 43 3 3 66 26 69 69 39

Net requirements

0 30 0 0 7 0 4 0 0 16

Planned order receipts

73 73 73 73

Planned order releases

73 73 73 73

Holding cost = $1/week; Setup cost = $100; Lead time = 1 week

Average weekly gross requirements = 27; EOQ = 73 units

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EOQ Lot Size Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35 35 0 0 0 0 0 0 0 0 0

Net requirements

0 30 0 0 7 0 4 0 0 16

Planned order receipts

73 73 73 73

Planned order releases

73 73 73 73

Holding cost = $1/week; Setup cost = $100; Lead time = 1 week

Average weekly gross requirements = 27; EOQ = 73 units

Annual demand = 1,404Total cost = setup cost + holding costTotal cost = (1,404/73) x $100 + (73/2) x ($1 x 52 weeks)Total cost = $3,798Cost for 10 weeks = $3,798 x (10 weeks/52 weeks) =

$730

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PPB Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35

Net requirements

Planned order receipts

Planned order releases

Holding cost = $1/week; Setup cost = $100; Lead time = 1 week

EPP = 100 units

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PPB Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35

Net requirements

Planned order receipts

Planned order releases

Holding cost = $1/week; Setup cost = $100;

EPP = 100 units

2 30 0

2, 3 70 40 = 40 x 1

2, 3, 4 70 40

2, 3, 4, 5 80 70 = 40 x 1 + 10 x 3 100 70 170

2, 3, 4, 5, 6 120 230 = 40 x 1 + 10 x 3

+ 40 x 4

+ =

Combine periods 2 - 5 as this results in the Part Period closest to the EPP

Combine periods 6 - 9 as this results in the Part Period closest to the EPP

6 40 0

6, 7 70 30 = 30 x 1

6, 7, 8 70 30 = 30 x 1 + 0 x 2

6, 7, 8, 9 100 120 = 30 x 1 + 30 x 3 100 120 220+ =

10 55 0 100 0 100

Total cost 300 190 490

+ =

+ =

Trial Lot Size

Periods (cumulative net Costs

Combined requirements) Part Periods Setup Holding Total

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PPB Example

1 2 3 4 5 6 7 8 9 10

Gross requirements

35 30 40 0 10 40 30 0 30 55

Scheduled receipts

Projected on hand

35 35 0 50 10 10 0 60 30 30 0

Net requirements

0 30 0 0 0 40 0 0 0 55

Planned order receipts

80 100 55

Planned order releases

80 100 55

Holding cost = $1/week; Setup cost = $100; Lead time = 1 week

EPP = 100 units

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Lot-Sizing Summary

For these three examples

Lot-for-lot $700

EOQ $730

PPB $490

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Lot-Sizing Summary

In theory, lot sizes should be recomputed whenever there is a lot size or order quantity change

In practice, this results in system nervousness and instability

Lot-for-lot should be used when low-cost JIT can be achieved

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Lot-Sizing Summary

Lot sizes can be modified to allow for scrap, process constraints, and purchase lots

Use lot-sizing with care as it can cause considerable distortion of requirements at lower levels of the BOM

When setup costs are significant and demand is reasonably smooth, PPB, Wagner-Whitin, or EOQ should give reasonable results

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Extensions of MRP

MRP II

Closed-Loop MRP

MRP system provides input to the capacity plan, MPS, and production planning process

Capacity Planning

MRP system generates a load report which details capacity requirements

This is used to drive the capacity planning process

Changes pass back through the MRP system for rescheduling

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Material Requirements Planning II

Requirement data can be enriched by other resources

Generally called MRP II or Material Resource Planning

Outputs include

Scrap

Packaging waste

Carbon emissions

Data used by purchasing, production scheduling, capacity planning, inventory

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Material Resource PlanningWeeks

LT 5 6 7 8

Computer 1 100

Labor Hrs: .2 each 20

Machine Hrs: .2 each 20

Scrap: 1 ounce fiberglass each 6.25 lbs

Payables: $0 each $0

PC Board (1 each) 2 100

Labor Hrs: .15 each 15

Machine Hrs: .1 each 10

Scrap: .5 ounces copper each 3.125 lb

Payables: raw material at $5 each $500

Processor (5 each) 4 500

Labor Hrs: .2 each 100

Machine Hrs: .2 each 100

Scrap: .01 ounces of acid waste each 0.3125 lb

Payables: processors at $10 each $5,000

Table 14.4

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Closed-Loop MRP System

Figure 14.8

Priority Management

Develop Master Production

Schedule

Prepare Materials

Requirements Pan

Detailed Production

Activity Control

(Shop Scheduling/Dispatching)

Capacity Management

Evaluate Resource Availability

(Rough Cut)

Determine Capacity Availability

Implement Input/Output Control

Aggregate Production Plan

OK?NO

OK?NO OK? YES

OK? YES

Planning

Execution(in repetitive systems JIT techniques are used)

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Capacity Planning

Feedback from the MRP system

Load reports show resource requirements for work centers

Work can be moved between work centers to smooth the load or bring it within capacity

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Smoothing Tactics1. Overlapping

Sends part of the work to following operations before the entire lot is complete

Reduces lead time

2. Operations splitting

Sends the lot to two different machines for the same operation

Shorter throughput time but increased setup costs

3. Order or lot splitting

Breaking up the order into smaller lots and running part earlier (or later) in the schedule

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Order Splitting

Develop a capacity plan for a work cell at Wiz Products

There are 12 hours available each day

Each order requires 1 hour

Day 1 2 3 4 5

Orders 10 14 13 10 14

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Order Splitting

DayUnits

Ordered

Capacity Required (hours)

Capacity Available (hours)

Utilization: Over/

(Under) (hours)

Production Planner’s Action

New Production Schedule

1 10 10 12 (2) 12

2 14 14 12 2 Split order: move 2 units to day 1

12

3 13 13 12 1 Split order: move one unit to day 6 or request overtime

13

4 10 10 12 (2) 12

5 14 14 12 2 Split order: move 2 units to day 4

12

61

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Order Splitting

Figure 14.9

Available

capacity

Capacity exceeded on days 2, 3, and 5

2 orders moved to day 1 from day 2 (a day early)

1 order forced to overtimeor to day 6

2 orders moved to day 4 (a day early)

14 –

12 –

10 –

8 –

6 –

4 –

2 –

0 –1 2 3 4 5

Days

(b)

Sta

nd

ard

la

bo

r-H

ou

rs14 –

12 –

10 –

8 –

6 –

4 –

2 –

0 –1 2 3 4 5

Days

(a)

Sta

nd

ard

la

bo

r-H

ou

rs

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MRP in Services

Some services or service items are directly linked to demand for other services

These can be treated as dependent demand services or items

Restaurants

Hospitals

Hotels

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Uncooked linguini #30004

Sauce #30006

Veal #30005

MRP in Services

Chef;Work

Center #1

Helper one;Work

Center #2

Asst. Chef;Work

Center #3

Cooked linguini #20002

Spinach #20004

Prepared veal and sauce

#20003

(a) PRODUCT STRUCTURE TREE

Veal picante #10001

Figure 14.10

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MRP in Services

(b) BILL OF MATERIALS

Part Number Description Quantity

Unit of Measure

Unit cost

10001 Veal picante 1 Serving —

20002 Cooked linguini 1 Serving —

20003 Prepared veal and sauce 1 Serving —

20004 Spinach 0.1 Bag 0.94

30004 Uncooked linguini 0.5 Pound —

30005 Veal 1 Serving 2.15

30006 Sauce 1 Serving 0.80

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MRP in Services

(c) BILL OF LABOR FOR VEAL PICANTE

Labor Hours

Work Center Operation Labor Type Setup Time Run Time

1 Assemble dish Chef .0069 .0041

2 Cook linguini Helper one .0005 .0022

3 Cook veal and sauce

Assistant Chef.0125 .0500

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Distribution Resource Planning (DRP)

Using dependent demand techniques through the supply chain

Expected demand or sales forecasts become gross requirements

Minimum levels of inventory to meet customer service levels

Accurate lead times

Definition of the distribution structure

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Enterprise Resource Planning (ERP)

An extension of the MRP system to tie in customers and suppliers

Allows automation and integration of many business processes

Shares common data bases and business practices

Produces information in real time

Coordinates business from supplier evaluation to customer invoicing

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Enterprise Resource Planning (ERP)

ERP modules include

Basic MRP

Finance

Human resources

Supply chain management (SCM)

Customer relationship management (CRM)

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ERP and MRP

Figure 14.11

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ERP and MRP

Figure 14.11

Customer Relationship Management

Invoicing

ShippingDistributors,

retailers,and end users

Sales Order(order entry,

product configuration,sales management)

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Table 13.6

Bills of Material

Work Orders

Purchasingand

Lead Times

Routingsand

Lead Times

Master Production Schedule

Inventory Management

ERP and MRP

Figure 14.11

MRP

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ERP and MRP

Figure 14.11

Supply Chain Management

Vendor Communication(schedules, EDI, advanced shipping notice,

e-commerce, etc.)

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ERP and MRP

Figure 14.11Table 13.6

Finance/Accounting

General Ledger

Accounts Receivable

Payroll

Accounts Payable

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Enterprise Resource Planning (ERP)

ERP can be highly customized to meet specific business requirements

Enterprise application integration software (EAI) allows ERP systems to be integrated with

Warehouse management

Logistics

Electronic catalogs

Quality management

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Enterprise Resource Planning (ERP)

ERP systems have the potential to

Reduce transaction costs

Increase the speed and accuracy of information

Facilitates a strategic emphasis on JIT systems and integration

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SAP’s ERP Modules

Figure 14.12

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Advantages of ERP Systems

1. Provides integration of the supply chain, production, and administration

2. Creates commonality of databases

3. Can incorporate improved best processes

4. Increases communication and collaboration between business units and sites

5. Has an off-the-shelf software database

6. May provide a strategic advantage

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Disadvantages of ERP Systems

1. Is very expensive to purchase and even more so to customize

2. Implementation may require major changes in the company and its processes

3. Is so complex that many companies cannot adjust to it

4. Involves an ongoing, possibly never completed, process for implementation

5. Expertise is limited with ongoing staffing problems

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ERP in the Service Sector

ERP systems have been developed for health care, government, retail stores, hotels, and financial services

Also called efficient consumer response (ECR) systems

Objective is to tie sales to buying, inventory, logistics, and production

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Mathematical Approaches

Useful for generating strategies

Transportation Method of Linear Programming

Produces an optimal plan

Management Coefficients Model

Model built around manager’s experience and performance

Other Models

Linear Decision Rule

Simulation

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Transportation Method

Table 13.6

Costs

Regular time $40 per tire

Overtime $50 per tire

Subcontracting $70 per tire

Carrying $ 2 per tire per month

Sales Period

Mar Apr May

Demand 800 1,000 750

Capacity:

Regular 700 700 700

Overtime 50 50 50

Subcontracting 150 150 130

Beginning inventory 100 tires

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Transportation Example

Important points

1. Carrying costs are $2/tire/month. If goods are made in one period and held over to the next, holding costs are incurred

2. Supply must equal demand, so a dummy column called “unused capacity” is added

3. Because back ordering is not viable in this example, cells that might be used to satisfy earlier demand are not available

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Transportation Example

Important points

4. Quantities in each column designate the levels of inventory needed to meet demand requirements

5. In general, production should be allocated to the lowest cost cell available without exceeding unused capacity in the row or demand in the column

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Transportation Example

Table 13.7

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Assignment #2Linear programming-Transportation method

© 2011 Pearson Education, Inc. publishing as Prentice Hall

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