1. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
The MRP’s objective is to determine what components
are needed to meet the master production schedule and,
based on lead time, to calculate the periods when the
components must available.
What to order
How much to order
When to order
When to schedule delivery

2. (Material Requirements Planning) MRP in American Industry
物料需求計劃
(Material Requirements Planning)
MRP in American Industry
IBM
MRP systems in use
The American Production and Inventory Control Society
(APICS) launched its MRP Crusade to publicize and
promote MRP
MRP Systems in use
companies sold $400 million in MRP software
$1.2 billion worth of MRP software was sold to American
Industry

3. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Investment in MRP
LaForge and Sturr 1986

4. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
MPS 工令
MRP
BOM
請購單
Inventory
Records

5. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Bill of Material Structure
1. 彙總式 (Summarized Parts List)
2. 多階式 (Multilevel Bill)
3. 單階式 (Single-Level Bill)
4. 規劃料表 (Planning Bill)

6. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
彙總式 (Summarized Parts List)
項目 A
Product Tree

7. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
多階式 (Multilevel Bill)

8. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
單階式 (Single-Level Bill)

9. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
規劃料表 (Planning Bill) - Used to simplify forecasting (MPS, MRP)
100%
Leg A
40%
Side A
55%
Top A
45%
Leg B
35%
Side B
30%
Top B
30%
Leg C
25%
Side C
15%
Top C
25%

10. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
與 BOM 相關表格
用途表 (Where-Used Report)
Where-used reports give the same information as a BOM, but
the where-used report gives the parents for a component
whereas the BOM gives the components for a parent.
溯源報表 (Pegging Report)
A pegging report is similar to where-used report. However, the
pegging report shows only those parents for which there is an
existing requirement.

11. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
溯源報表 (Pegging Report)
Pegged Requirements
Source of Requirements

12. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Uses for Bill of Material
Product Information
Engineering Change Control
Service Parts
Planning
Order Entry
Manufacturing
Costing

13. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
MRP Process
Exploding and
Offsetting
Gross and Net
Requirements
Releasing Orders

14. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Exploding and Offsetting
Exploding the requirements: This is a process of multiplying the requirements
by the usage quantity and recording the appropriate
requirements throughout the product tree.
Offsetting: This is the process of placing the exploded requirements in their proper
periods based on lead time.
Output
Planned Orders
Note: Lead time is the period from when an order is placed until the part is
available for use.

15. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Exploding and Offsetting - Example
Planned Order

16. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Gross and Net Requirement
Often inventory is available and must be included when
calculating quantities to be produced.
Inventory Information
Planned Order

17. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Gross and Net Requirement - Example

18. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Released Orders
Since the objective of the MRP is to have material available when it
is needed and not before, orders for material should not be released
until the planned order release date arrive. Thus an order is not
normally released until the planned order is in the current week.
Before a manufacturing order is released, component availability must
be checked.
When the authorization to purchase or manufacture is released, the
planned order receipt is canceled, and a scheduled receipt is created in
its place.

19. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Released Order - Scheduled Receipt
The scheduled receipts row shows the quantities ordered and when they
are expected to be completed and available.
Note: Net Requirement = Gross Requirement - Scheduled Receipts - Available Inventory

20. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Released Order - Closed Out
When the goods are received into inventory and available for use,
the order is closed out, and the scheduled receipt disappears to
become part of the on-hand inventory.

21. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
U.S. Manufacturing Inventory Turns
Note: Inventory turns are defined as gross annual sales divided by average
on-hand inventory

22. (Material Requirements Planning) system within two years
物料需求計劃
(Material Requirements Planning)
Trouble with MRP (1)
Be able to recoup the
investment in an MRP
system within two years
Booz, Allen, and Hamilton, from a 1980 survey of over 1100 firms

23. 物料需求計劃 (Material Requirements Planning)
Trouble with MRP (2)
Class A: with fully implemented, effective systems
Class B: Have fully implemented, but less than fully effective system
Class C: Have partially implemented, modestly effective systems.
Class D: Have marginal systems providing little benefit to the company
1982 APICS Survey of 679 APICS members

24. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
“MRP is a $100 billion mistake”
“90 percent of MRP users are unhappy”
“MRP perpetuates such plant inefficiencies as
high inventories”

25. (Material Requirements Planning) APICS Literature (Latham, 1981)
物料需求計劃
(Material Requirements Planning)
The Cause of Most MRP System Failures
Lack of top management commitment.
Lack of education of those who use the system.
An unrealistic master production schedule.
Inaccurate data, including bills of material and
inventory records
APICS Literature (Latham, 1981)

26. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
An MRP system is capacity-insensitive, and properly so,
as its function is to determine what materials and components
will be needed and when, in order to execute a given master
production schedule. There can be only one correct answer
to that, and it cannot therefore vary depending on what
capacity does or does not exist.
Orlicky 1975

27. (Material Requirements Planning) Fundamental Wrong with MRP
物料需求計劃
(Material Requirements Planning)
Fundamental Wrong with MRP
MRP
Flawed Model
Note: Lead times are not affected by the status of the plant

28. (Material Requirements Planning)
物料需求計劃
(Material Requirements Planning)
Plant has finite
Capacity
Fixed Lead Time
Release jobs too late
Destroy the desired coordination
of parts at assembly
Finished products to come out
too late
Inflate the MRP lead times
More work into the plant
Increase the flow time
The Solutions ?

29. MRP II Hierarchy Demand Forecast Long-Range Planning Aggregate
Resource
Planning
Rough-Cut
Capacity Planning
MPS
Intermediate-Range
Planning
BOM
MRP
Inventory
Status
Capacity Requirement
Planning
Job Pool
Job
Release
Routing
Data
Short-Term
Planning
Job
Dispatching

30. Capacity Requirement Planning
(產能需求規劃)
Capacity Requirement Planning
The capacity requirements plan (CRP) occurs at the level of the material requirements plan. Planned orders from the MRP and open shop orders (scheduled receipts) are converted into demand for time in each work center in each time period. This process takes into consideration the lead times for operations and offsets the operations at work centers accordingly. In considering open shop orders, it accounts for work already done on a shop order.

31. Capacity Requirement Planning
(產能需求規劃)
Shop Calendar
Planned Order
Releases
CRP
Work Center
Load Report
Open Orders
Routing Data
Capacity and lead Time
for Process Centers

32. Capacity Requirement Planning
(產能需求規劃)
Terms Definition
Open Order
An open order file appears as a scheduled receipt on the
material requirements plan. It is a released order for a
quantity of a part to be manufactured and completed on a
specific date
Planned Order Releases
Planned orders are determined by the computer’s MRP logic
based upon the gross requirements for a particular part.

33. Capacity Requirement Planning
(產能需求規劃)
Routing File
A routing is the path that work follows from work center to work
center as it is completed. It should exist for every component
manufactured and contain the following information:
Operations to be performed
Sequence of operations
Work centers to be used
Possible alternate work centers
Tooling needed at each operation
Standard times: setup times and run times per piece

34. Capacity Requirement Planning
(產能需求規劃)
Part Name: Gear Shaft Part Number: SG123
Drawing Number: D123X
Operation Work S/U Time Run Time/Piece
No Center (Standard Hours) (Standard Hours) Operation
Turn Shaft
Mill Slot
Drill Hole
Grind
Stores Inventory
Routing Data

35. Capacity Requirement Planning
(產能需求規劃)
Work Center File
A work center is composed of a number of machines or workers capable
of doing the same work.
The machinery will normally be similar so there are no differences in the
kind of work the machines can do or the capacity of each.
A work center file contains information on the capacity and move, wait,
and queue times associated with the center.
Move time: the move time is the time normally taken to move material from
one work station to another.
Wait time: the wait time is the time a job is at a work center after completion
and before being moved.
Queue time: the queue time is the time a job waits at a work center before
being handled.
Lead time is the sum of queue, setup, run, wait, and move times.

36. Capacity Requirement Planning
(產能需求規劃)
Work Center File
Available time : The available time is the number of hours as work
center can be used.
Utilization : The percentage of time that the work center is active
compared to the available time is called work center
utilization. It can be determined from historical records
or by a work sampling study.
Efficiency : The workers might be working at a faster or slower pace
than the standard pace, causing the efficiency of the work
center.

37. Capacity Requirement Planning
(產能需求規劃)
Ex: A work center has the following open orders and planned orders
for week 20. Calculate the total standard time required (load) on
this work center in week 20. Order 222 is already in progress, and
there are 100 remaining to run.
Order
Quantity
Setup
Time
Run
Time
Released Orders
222
333
100
150
1.5
0.2
Planned Orders
444
555
200
300 3
2.5
0.25
0.15

38. Capacity Requirement Planning
(產能需求規劃)
Work Center Load Report