Material Requirements Planning The MRPs objective is to

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 schedule delivery

物料需求計劃 (Material Requirements Planning) MRP in American Industry 1960 - IBM 1971 - 150 MRP systems in use 1972 - The American Production and Inventory Control Society (APICS) launched its MRP Crusade to publicize and promote MRP 1982 - 8000 MRP Systems in use 1984 - 16 companies sold $400 million in MRP software 1989 - $1. 2 billion worth of MRP software was sold to American Industry

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

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

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)

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

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

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

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%

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.

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

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

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

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.

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

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

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

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.

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

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.

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

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

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

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”

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)

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

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

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

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

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.

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

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.

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

Capacity Requirement Planning (產能需求規劃) Part Name: Gear Shaft Drawing Number: D 123 X Operation No. 10 20 30 40 50 Work Center 12 14 17 03 Stores Part Number: SG 123 S/U Time (Standard Hours) 1. 50 0. 30 0. 45 Routing Data Run Time/Piece (Standard Hours) 0. 25 0. 05 0. 10 Operation Turn Shaft Mill Slot Drill Hole Grind Inventory

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.

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.

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 0 1. 5 0. 2 Planned Orders 444 555 200 3 2. 5 0. 25 0. 15

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