BSCM

Basic of Supply Chain Management

Session 4: Material Requirements Planning 物料需求計劃

Purpose 目標(biāo)

Material requirements planning (MRP) is the bridge between master planning and production in the factory. This session addresses the basic concepts of the MRP process, which relies on the use of planning application software to support a set of business processes for the day-to-day management of the priority plan. MRP has two major business functions:

物料需求計劃(MRP)是工廠主計劃與生產(chǎn)之間的橋梁荷荤。本課討論MRP流程的基本概念鞍帝，該流程依賴于使用規(guī)劃應(yīng)用軟件來支持一組業(yè)務(wù)流程，用于優(yōu)先計劃的日常管理屈呕。MRP有兩個主要的業(yè)務(wù)功能:

• Base on the master production schedule (MPS) quantities and due dates for end items, create a time-phased plan that determines what components are needed to make a product and when. This is called a priority plan for order releases and receipts for materials purchased from suppliers and manufacturers of components, or subassemblies, and end items by the factory.
  根據(jù)主生產(chǎn)計劃(MPS)數(shù)量和成品的交期，制定一個時間階段計劃珠叔，確定生產(chǎn)產(chǎn)品所需的組件以及生產(chǎn)時間蝎宇。這被稱為訂單發(fā)布以及從零部件供應(yīng)商和制造商購買的材料接收的優(yōu)先計劃。

• Maintain and adjust the priority plan to account for changes in customer orders and forecasts, material shortages, and production problems.
  維護和調(diào)整優(yōu)先計劃祷安，以適應(yīng)客戶訂單和預(yù)測的變化姥芥、材料短缺以及生產(chǎn)問題。

Learning Objectives 學(xué)習(xí)目標(biāo)

• Material Requirements Planning Environment 物料需求計劃環(huán)境

  • Explain the role of dependent versus independent demand in MRP.
    解釋依賴需求與獨立需求在MRP中的作用汇鞭。

  • Describe the relationship between MRP and three other functions in the manufacturing planning and control (MPC) hierarchy.
    描述MRP與制造計劃與控制(MPC)層次中其他三個功能之間的關(guān)系凉唐。

• Bill of Material 材料清單

  • Define parent and component in the bill of material (BOM), and explain their relationship.
    在《物料清單》(BOM)中定義母公司和子公司，并解釋它們之間的關(guān)系霍骄。

  • Perform a simple BOM explosion.
    進行一次簡單的BOM爆炸台囱。

  • Explain the use of the planning bill.
    解釋計劃單的用途。

  • Differentiate between where-used reports and pegging reports.
    區(qū)分何處使用報告和跟蹤報告读整。

• Material Requirements Planning Logic 物料需求計劃邏輯

  • List four major inputs to MRP.
    列出MRP的四個主要輸入簿训。

  • Describe the role of lead-time offsetting and exploring in creating the priority plan.
    描述在制定優(yōu)先計劃時，前置時間的逆推和探索的作用绘沉。

  • Explain the origin of the gross requirements in an MRP record.
    在MRP記錄中解釋總需求的來源煎楣。

  • Calculate the net requirements for the end item and components.
    計算成品和組件的凈需求。

  • Offset a planned order release from a planned order receipt.
    從計劃訂單接收（時間）逆推計劃訂單發(fā)出（時間）车伞。

• Using and Managing the Priority Plan 使用和管理優(yōu)先計劃

  • Differentiate between a scheduled receipt and a planned order receipt.
    區(qū)分預(yù)定接收和計劃訂單接收择懂。

  • Differentiate between an open order, a planned order, and a firm planned order.
    區(qū)分公開訂單、計劃訂單和確定計劃訂單另玖。

  • Explain the role of MRP software in the release of planned orders and managing the priority plan.
    說明MRP軟件在計劃訂單發(fā)布和優(yōu)先計劃管理中的作用困曙。

  • List the events of following the release of a planned order.
    列出計劃訂單發(fā)布后的事件。

  • List at least two techniques that can be used to maintain component and end-item due dates in the priority plan.
    列出至少兩種可以在優(yōu)先計劃中維護組件和成品的技術(shù)谦去。

Material Requirements Planning Environment 材料需求計劃環(huán)境

In this section we will address the underlying concepts of MRP:
在本節(jié)中慷丽，我們將討論MRP的基本概念:

• nature of demand 需求的性質(zhì)
• linkages to other manufacturing planning and control functions 與其他生產(chǎn)計劃和控制職能的聯(lián)系
• MRP objectives MRP的目標(biāo)
• inputs to MRP MRP的輸入

Nature of Demand 需求的性質(zhì)

From an MPC standpoint, there are two types of demand: independent demand and dependent demand.
從MPC的觀點來看，有兩種需求:獨立需求和依賴需求鳄哭。

4-6.png

The table shown in Visual 4-6 is an independent demand item, where demand for the item is independent of any other demand. The decision on how many tables to make depends on either a forecast, customer orders, or both. The components of the table, however, are dependent demand items.

在圖4-6中顯示的桌子是一個獨立的需求項要糊，其中對該項目的需求與任何其他需求無關(guān)。決定要制作多少桌子取決于預(yù)測妆丘、客戶訂單或兩者一起锄俄。然而，該桌子的組件是相互依賴的需求項勺拣。

All end items, such as the table, have a BOM -- which we will soon discuss in more detail -- that lists the description and quantity of all of its components. Once the forecast or order quantity is known, MRP calculates the number of all the components required. The demand for components is dependent on the demand for the table.

所有成品(如表)都有一個BOM(我們將很快詳細討論)奶赠，它列出了所有組件的描述和數(shù)量。一旦知道了預(yù)測或訂單數(shù)量药有，MRP就會計算所需的所有組件的數(shù)量毅戈。對組件的需求取決于對該桌子的需求。

Linkages with Other Manufacturing Planning and Control Functions 與其他制造計劃和控制功能的聯(lián)系

MRP is the last of the priority planning levels. It is directly linked to three other MPC functions:
MRP是最后一個優(yōu)先規(guī)劃級別。它與其他三種MPC功能直接相連:

• Master scheduling: The MPS establishes specific end-item due dates and quantities. MRP is the component planner. It calculates a time-phased priority plan. This plan consists of (1) order release and receipt dates for the purchase and manufacture of components and (2) the final assembly operation. MRP determines the materials and quantities needed to make a product and when.

  主計劃:MPS建立特定的成品交期和數(shù)量苇经。MRP是組件計劃者赘理。它計算一個分階段的優(yōu)先計劃。本計劃包括:(1)為采購和制造零部件而發(fā)出的訂單和收貨日期塑陵，以及(2)最后的組裝操作感憾。MRP決定生產(chǎn)產(chǎn)品所需的材料和數(shù)量。

• Capacity requirements planning (CRP): The MRP is valid only if there is sufficient production capacity when it is needed. The check against capacity availability is called CRP.

  產(chǎn)能需求計劃(CRP): MRP只有在有足夠生產(chǎn)能力時才有效令花。對產(chǎn)能可用性的檢查稱為CRP阻桅。

• Production activity control (PAC): MRP is the input to PAC. It plans the release and receipt dates for orders, but it is the responsibility of purchasing and PAC to implement and control the orders.

  生產(chǎn)活動控制(PAC): MRP是PAC的輸入，計劃訂單的發(fā)布和收貨日期兼都，采購和PAC負責(zé)訂單的執(zhí)行和控制嫂沉。

Objectives of MRP MRP的目標(biāo)

What does MRP do? It has two major objectives: determine requirements and keep priorities.
MRP是干什么的?它有兩個主要目標(biāo):確定需求和保持優(yōu)先級。

• Requirements -- MRP determines requirements by addressing the following questions:
  需求——MRP通過解決以下問題確定需求:

  • What components are required to manufacture an end item? Some of these will need to be purchased, some already are in inventory, and some will be made as part of the end-item production process.
    制造最終產(chǎn)品需要哪些部件?其中一些需要采購扮碧，一些已經(jīng)在庫存中趟章，一些將作為最終產(chǎn)品生產(chǎn)過程的一部分。

  • What quantity of each component will be required?
    每個組件需要多少數(shù)量?

  • When will orders be released and received for (1) purchased components from suppliers and (2) for components that will be manufactured or assembled during the production process?
    1)從供應(yīng)商處購買的組件慎王，以及(2)在生產(chǎn)過程中制造或組裝的組件蚓土，何時發(fā)出和接收訂單?

• Priorities -- The order and release dates for purchased and manufactured components listed above constitute the priority plan, but MRP is affected by unplanned events such as changes in the demand, shortages of production capacity, late arrival or completion of components, and excessive scrap. Material planners keep the priority plan current in the face of changing customer sales orders and due dates by actions that include the following:

  優(yōu)先級——上述采購和制造部件的訂單和發(fā)布日期構(gòu)成優(yōu)先級計劃，但MRP受到需求變化赖淤、產(chǎn)能短缺蜀漆、組件遲交或延遲完工、過度報廢等意外事件的影響咱旱。在客戶銷售訂單和到期日不斷變化的情況下确丢，物料計劃員通過以下行動保持優(yōu)先計劃的有效性:

  • Expediting or de-expediting work orders -- also called shop orders or manufacturing orders -- or purchase orders.
    加快或取消加快工作訂單——也稱為車間訂單或制造訂單——或采購訂單。

  • Changing work orders or purchase orders, such as quantities and due dates
    更改工作訂單或采購訂單吐限，例如數(shù)量和到期日

  • Adding or canceling work orders or purchase orders
    增加或取消工作訂單或采購訂單

MRP Process Inputs and Outputs MRP過程的輸入和輸出

Inputs 輸入

There are four major data inputs to the MRP process, as shown in the table below.
MRP過程有四個主要的數(shù)據(jù)輸入鲜侥，如下表所示。

Outputs 輸出

The section on the MRP logic will cover outputs in some detail. MRP creates a priority plan consisting of planned order receipts and releases. Planners, with the support of MRP software, release planned orders that authorize the following:

MRP邏輯部分將詳細介紹輸出诸典。MRP創(chuàng)建一個優(yōu)先計劃描函，包括計劃訂單收據(jù)和交付。計劃人員在MRP軟件的支持下狐粱，發(fā)布計劃訂單赘阀，授權(quán)如下:

• the release of purchase orders to suppliers
  向供應(yīng)商發(fā)出采購訂單

• the release of manufacturing orders, or shop orders, to the factory
  向工廠發(fā)出制造訂單或車間訂單

Planning Software

Because of the volume and complexity of calculations, most companies rely on application software for MRP. Software applications are a lot faster and more accurate in performing MRP calculations needed to create the priority plan. Example of such calculations are:

由于計算量和復(fù)雜性，大多數(shù)公司都依賴于MRP的應(yīng)用軟件脑奠。軟件應(yīng)用程序在執(zhí)行創(chuàng)建優(yōu)先計劃所需的MRP計算時要快得多，也更精確幅慌。這種計算的例子:

• Exploding BOMs for determining an end item's component quantities, down to the component and raw material level
  展開BOM用于確定成品的組件數(shù)量宋欺，直至組件和原材料水平

• Checking inventory records for quantities on hand, on order, or allocated
  檢查庫存記錄，在手數(shù)量、在訂數(shù)量或分配數(shù)量

• Offsetting order release and receipt dates for net component and raw material requirements from the end-item due dates, which will be covered later in this section.
  從成品到期日期對凈部件和原材料需求的訂單發(fā)布和收貨日期進行補償（偏移）齿诞，本節(jié)稍后將對此進行討論酸休。

In addition, MRP software keeps track of due dates in the priority plan and the status of materials and production. It also
此外，MRP軟件在優(yōu)先計劃中跟蹤到期日以及材料和生產(chǎn)的狀態(tài)祷杈。它還

• advises planners on when to release planned orders
  建議計劃人員何時發(fā)出計劃訂單

• advises when to expedite or take other actions on maintain the due dates in the priority plan
  建議何時加快或采取其他行動斑司，以維持優(yōu)先計劃內(nèi)的到期日

• replans MRP on a periodic basic to update material requirements, due dates, and inventory status.
  重新計劃MRP，定期更新物料需求但汞，到期日和庫存狀態(tài)宿刮。

Bill of Material 物料清單

Introduction

bill of material (BOM) -- A listing of all the subassemblies, 
intermediates, parts, and raw materials that go into a parent 
assembly showing the quantity of each required to make an assembly.

    所有組成父組件的部件、中間體私蕾、零件和原材料的清單僵缺，顯示每個組件所需的數(shù)量。

    -- APICS Dictionary 

The authors of Introduction to Materials Management,7th ed. (Arnold et al.), state that the BOM is one of the most important documents in a manufacturing company. They refer to it as the major building block of MRP. BOM data on the raw materials and components needed to produce end items are critical inputs to MRP. Variants of the BOM include recipes for baked goods and formulas for chemicals.

《物料管理導(dǎo)論》(Introduction to Materials Management踩叭，第7版)的作者Arnold等指出磕潮，BOM是制造企業(yè)中最重要的文件之一。他們稱其為MRP的主要組成部分容贝。生產(chǎn)最終產(chǎn)品所需的原材料和部件的BOM數(shù)據(jù)是MRP的關(guān)鍵輸入自脯。BOM的變體包括烘焙食品的配方和化學(xué)配方。

Summarized BOM and the Indented Bill 匯總物料清單和多級物料清單

Summarized Bill of Material

Indented Bill of Material

The BOM usually is presented in list form. Visual 4-12 is an example of a summarized BOM, which is a list of all the components in an assembly. For each component, a bill shows a unique part number, a description, the quantity needed in the assembly of its parent, and the unit of measure.

BOM通常以列表的形式出現(xiàn)斤富。圖4-12是匯總BOM的一個示例膏潮，BOM是配件中所有組件的列表。對于每個組件茂缚，清單顯示了唯一的部件號戏罢、描述、其父組件組裝所需的數(shù)量和度量單位脚囊。

The indented bill in Visual 4-13 is more commonly used and gives an indication of an assembly or end-item product structure. Note the part-number indentation showing that table 100 actually consists of two subassemblies: base 300 and top 025, and a hardware kit 822. The latter is a purchased component because the bill does not show components going into it during production; therefore it is not made by the manufacturer and has to originate with a supplier.

在圖4-13中多級物料清單更常用龟糕，并給出了配件或最終產(chǎn)品結(jié)構(gòu)的指示。注意部分編號縮進顯示表100實際上由兩個組件組成:底座300和頂025和硬件套件822悔耘。后者是購買的組件讲岁，因為賬單上沒有顯示在生產(chǎn)過程中進入的組件;因此，它不是由制造商制造的衬以，必須由供應(yīng)商發(fā)起缓艳。

Base 300 and top 025, as subassemblies, consist of other components. The components of base 300 include legs 306, leg bolts 326, and frame 357. The latter is a subassembly made up of wooden sides 311 and wooden ends 433.

底座300和頂025，作為子件看峻，包括其他組件阶淘。底座300的組件包括底座306、底座螺栓326和骨架357互妓。后者是一個子件溪窒，由木邊311和木端433組成坤塞。

What components in the indented bill, in addition to hardware kit 822, are purchased components?

除了硬件套件822外，在多級清單中有哪些部件是購買的?

How many assemblies/subassemblies are in the bill?

清單里有多少個配件/子件?

With respect to quantities, let's use as an example legs 306 that go into base 300. One unit of base 300 requires four legs 306. Note that the unit of measure is EA(each), so that the quantity required would be 4*1 = 4. If the unit of measure were one dozen, table 100 would be an unconventional 48-legged table.

關(guān)于數(shù)量澈蚌，讓我們以底座300中的腿306為例摹芙。底座300的一個單位需要四條腿306。注意宛瞄，度量單位是EA(每個)浮禾，因此所需的數(shù)量是4*1 = 4。如果以一打為單位份汗，那么桌子100將是一張非常規(guī)的48條腿的桌子盈电。

Note: In practice, glue might often be purchased as an operating supply item and not be included in the BOM. Tracking the specific amount of glue actually used could be impractical. This practice enables the costs to be included as part of the overhead.

注:在實際操作中，膠水可能經(jīng)常作為操作供應(yīng)品購買裸影，而不包括在BOM中挣轨。跟蹤實際使用的膠水的具體數(shù)量可能不切實際。這種做法使成本成為經(jīng)常費用的一部分轩猩。

4-14.png

Single-Level BOM 單級BOM

This visual shows the BOM in what is called a product tree format to facilitate learning and understanding.

這張圖展示了BOM的產(chǎn)品樹格式卷扮，便于學(xué)習(xí)和理解。

We mentioned earlier that the APICS Dictionary definition refers to the BOM as a listing of all components that go into making an assembly. The visual illustrates that a BOM for an end item such as table 100 actually is made up of several single-level bills for its assemblies.

我們在前面提到過均践，APICS詞典定義將BOM作為組成配件的所有組件的列表晤锹。這幅圖說明赠橙，桌子100等成品的BOM實際上是由其配件的幾個單層清單組成的刁赦。

At the top of the visual is a single-level bill for table 100. The bill shows table 100 as the parent and right below it are components needed for its final assembly. We pointed out earlier that two of the components -- base 300 and top 025 -- also are assemblies, but because they are components of another assembly (table 100), they are called subassemblies. The third components is hardware kit 822 consisting of purchased hardware specific to table 100.

在圖的頂部是桌子100的單級清單卜范。該清單顯示了桌子100作為父組件息罗，下面是其最終組裝所需的組件。我們在前面指出鳞绕，其中兩個組件——底座300和桌面025——也是配件京办，但由于它們是另一個配件(桌子100)的組件矛缨，它們被稱為子配件斯辰。第三個組件是硬件工具包822舶担，由購買的特定于桌子100的硬件組成。

Multilevel BOM 多級BOM

If you examine the multilevel BOM for table 100, you should be able to see that it actually is made up of two subassemblies and the final assembly. The point is that end items usually consist of several logical groupings of components, or assemblies, based on the way the product is assembled.

如果您檢查桌子100的多級BOM彬呻，您應(yīng)該能夠看到它實際上是由兩個子件和最終配件組成的衣陶。關(guān)鍵是，成品通常由基于產(chǎn)品組裝方式的幾個邏輯組件組或配件組成闸氮。

The multilevel BOM for an end item such as table 100 is an example of the grouping of single-level BOMs for the subassemblies that go into it.

像桌子100這種成品的多級BOM是加入它的子件的單級BOM的分組示例剪况。

It is important to note that BOM applications software stores information for each assembly and subassembly as a separate and unique single-level bill. When BOM data for table 100 are needed for MRP purposes, the BOM application will assemble the single-level bills for all of the assemblies into a multilevel bill for table 100. The subassembly single-level bills can be used for any end item that requires them.

需要注意的是，BOM應(yīng)用軟件將每個配件和子件的信息存儲為單獨的蒲跨、唯一的單級清單译断。當(dāng)MRP需要桌子100的BOM數(shù)據(jù)時，BOM應(yīng)用程序?qū)⑺信浼膯渭壡鍐谓M裝為桌子100的多級清單或悲。子件單級清單可以用于任何需要它們的成品镐作。

Parent-Component Relationship 父組件關(guān)系

We have alluded to the parent-component relationship is single-level BOMs. The multilevel bill illustrates the fact that subassemblies and purchased components are components of the assemblies that they go into, but they also are parents of the subassemblies and purchased components that go into them.

我們已經(jīng)提到了父組件關(guān)系是單級BOM（組成的）藏姐。多級清單說明了一個事實，即子件和外購件是他們進入的配件的組件该贾，但他們也是子件和外購件的父組件。

BOM: Summary 總結(jié)

These are the key points about the BOM:
BOM要點如下：

• All manufactured end items have a BOM.
  所有制成品都有BOM捌臊。

• An end item usually has a multilevel bill consisting of two or more single-level bills.
  一個成品通常都有一個多級清單杨蛋，由兩個或更多單級清單組成。

• All single-level bills consist of a parent and components below it.
  所有單級清單都包含一個父級和若干下級組件理澎。

• For each subassembly made by the manufacturer and not purchased from a supplier, there also will be a single-level bill.
  每個子件由制造商制成而不是從供應(yīng)商采購逞力，也會有一個單級清單。

• The parent in a subassembly single-level bill also is a component of a final assembly or subassembly.
  子件單級清單中的父級組件也是最終配件或子件的組件糠爬。

• If a part has no other parts going into it on the BOM, then it is assumed to be a purchased part.
  如果一個零件在BOM上沒有其他零件進入寇荧，那么它就被認為是一個外購的零件。

In summary: 總之

• A multilevel BOM is a collection of single-level bills.
  多級BOM是單級清單的集合执隧。

• A subassembly parent also can be a component of an assembly or another subassembly.
  子件的父組件也可以是配件或另一個子件的組件揩抡。

• If a component has no other components going into it, it cannot be a subassembly and therefore is an item purchased from a supplier.
  如果一個組件沒有其他組件進入，它就不能是一個子件镀琉，因此是從供應(yīng)商購得的組件峦嗤。

problem 4.1

planning bill

Planning Bill 計劃單

A BOM lists the components necessary to build an end product. A planning bill, on the other hand, plans material requirements for a family of end products for which there are several variations based on options for one or more components.

BOM列出了構(gòu)建最終產(chǎn)品所必需的組件。另一方面屋摔，計劃單則計劃一系列最終產(chǎn)品的材料需求烁设，這些產(chǎn)品根據(jù)一個或多個組件的選項有多種變化。

Take the example of a bicycle, which has several options for three main components.

以自行車為例钓试，它有三種主要部件可供選擇装黑。

The company takes 18 different variations which these components options (332 = 18), each with its own BOM to maintain. The planning bill simplifies the 18 bills by showing, on one bill, the percentage split -- totaling 100 percent -- for each of the three components based on a forecast or historical usage data.

公司采用18種不同的組件選項(332 = 18)，每個組件都有自己的BOM來維護弓熏。計劃單簡化了18個清單恋谭，在一個清單上顯示了基于預(yù)測或歷史使用數(shù)據(jù)的三個組件的百分比分割(總計100%)。

The planning bill in this case represents the average bicycle. It does not represent a buildable product but is used to simplify forecasting, MPS, and MRP. If 10,000 bicycles were forecasted, you could calculate the number for each of the 18 variations to plan for and ultimately make and ship to distributors. For example, if 10,000 bicycles were forecasted, you would order and stock 2,500 small, 5,000 medium, and 2,500 large-size frames and use the same reasoning for ordering colors and wheels. These the can be assembled when orders come in.

在這種情況下硝烂，計劃單表示的是普通自行車箕别。它并不表示可構(gòu)建的產(chǎn)品，而是用于簡化預(yù)測滞谢、MPS和MRP串稀。如果預(yù)測了10000輛自行車，那么您就可以計算出這18種車型中每一種的計劃數(shù)量狮杨，并最終將它們生產(chǎn)出來并交付給分銷商母截。例如，如果預(yù)測有1萬輛自行車橄教，您將訂購2500輛小型清寇、5000輛中型和2500輛大型車架喘漏，并使用相同的推理來訂購顏色和車輪。當(dāng)訂單進來時即可裝配华烟。

Where-Used and Pegging Data 用途和資料溯源

Where-Used

Where-used data are used in where-used reports. A where-used report is an inversion of a BOM information.
用途數(shù)據(jù)用于用途報告翩迈。用途報告是BOM信息的倒置。

• A BOM lists the components of a parent item.
  BOM列出父項的組件盔夜。

• A where-used report lists all of the items, or parents, in which a component is used whether or not there is a demand for the parent.
  用途報告列出了使用組件的所有項目或父組件负饲，不管是否需要父組件。

• Data may be single level (traced to the immediate parent) or full level (traced to the end-item parent).
  數(shù)據(jù)可以是單個級別(追溯到直接父級)或完整級別(追溯到最終項父級)喂链。

Where-used information has the following uses:
用途信息有以下作用：

• identifying the parent items affected by an engineering change and assessing the impact of the change
  確定受工程變更影響的父項返十，并評估變更的影響

• assessing the aggregate impact of costing changes for a component
  評估組件成本變動的整體影響

• assessing the effects of component scarcity
  評估組件稀缺性的影響

• assessing the benefits and costs of standardizing similar components, preventing storekeeping unit proliferation
  評估標(biāo)準(zhǔn)化類似組件的好處和成本，防止庫存單位的擴散

Pegging 溯源

A pegging report is similar to a where-used report except that it shows only those parents for which there is an existing requirements. These parents are currently in the priority plan and might be affected by a delay in the delivery of a component. The pegging report shows the following:

溯源報告類似于用途報告椭微，只是它只顯示已存在需求的父項洞坑。這些父項目前正處于優(yōu)先計劃中，可能會受到組件交付延遲的影響蝇率。
溯源報告展示如下：

• the parents creating demand for components 父項創(chuàng)建組件的需求

• the quantities required 所需數(shù)量

• when those quantities are required 何時需要這些數(shù)量

• where-used logic to identify current sources of demand 用于確定當(dāng)前需求來源的用途邏輯

• may be single level or multilevel 可為單層或多層

Uses of the BOM

BOM的使用

There are many uses for the BOM, starting as early as the design stage of a product and continuing through the various stages of the product management cycle: engineering change control, MRP, order management, manufacturing, service and repair, and cost accounting. This places a premium on a accuracy and being up-to-date, as errors in the bills can have broad ripple effects.

BOM有許多用途迟杂，從產(chǎn)品的設(shè)計階段開始，一直持續(xù)到產(chǎn)品管理周期的各個階段:工程變更控制瓢剿、MRP逢慌、訂單管理、制造间狂、服務(wù)和維修攻泼，以及成本核算。這就很看重準(zhǔn)確性和最新性鉴象，因為清單上的錯誤可能會產(chǎn)生廣泛的連鎖反應(yīng)忙菠。

Resource : Introduction to Materials Management,7th ed.,Amold et al., p.70

Material Requirements Planning Logic 物料需求計劃邏輯

Approach to this Section

In this section, we are going to learn about the mechanics, or logic, that MRP uses to develop the priority plan.

在本節(jié)中访得，我們將學(xué)習(xí)MRP用于開發(fā)優(yōu)先計劃的機制或邏輯。

We will explain the MRP logic that creates the priority plan through

我們將解釋創(chuàng)建優(yōu)先計劃的MRP邏輯

• exploding and offsetting requirements 需求展開和補償

• calculating gross and net requirements 計算毛需求和凈需求

This will bring us to the point in the planning process where a developed priority shows the time-phased dates and quantities for planned order releases and receipts for both purchased components (or purchase orders) and manufactured components (or manufacturing orders).

這將使我們在計劃過程中到達這樣一個點:一個已開發(fā)的優(yōu)先級顯示計劃訂單發(fā)布的分階段日期和數(shù)量陕凹，以及采購組件(或采購訂單)和制造組件(或制造訂單)的收貨分階段日期和數(shù)量悍抑。

In the next section, we will address the basics of using and putting the material requirements plan into action.

在下一節(jié)中鳄炉，我們將討論使用和將物料需求計劃付諸實施的基礎(chǔ)知識。

MRP Logic Overview

MRP邏輯概述

As discussed earlier and as summarized in Visual 4-23, the MRP process uses key inputs to determine and end item's required components (what); the quantities of those components (how much); and a time-phased plan (when) for the operations that will convert the end item into a finished product.

正如前面所討論的和在圖4-23中總結(jié)的搜骡，MRP過程使用關(guān)鍵輸入來確定和結(jié)束項目所需的組件(什么);這些分量的數(shù)量(多少);以及將最終產(chǎn)品轉(zhuǎn)換為成品的操作的分階段計劃(何時)拂盯。

4-23-Material-Requirements-Planning-Logic.png

This time-phased plan, or priority plan, expresses the necessary actions in the form of planned order releases and receipts. At the appropriate time, the planned orders are released; this authorizes purchase orders to be released to suppliers for materials and manufacturing orders to the factory.

這一分階段計劃或優(yōu)先計劃以計劃訂單發(fā)布和接收的形式表達了必要的行動。在適當(dāng)?shù)臅r間记靡，計劃的訂單被發(fā)布;這就授權(quán)將采購訂單發(fā)放給供應(yīng)商磕仅，提供給工廠的材料和制造訂單。

Lead-Time Offsetting and Exploding 提前期補償和展開

To create a priority plan, MRP uses a process called lead-time offsetting and exploding. Three of the important components are

為了創(chuàng)建一個優(yōu)先計劃簸呈，MRP使用了一個叫做“提前期補償和展開”的過程。它有三個重要的組成部分：

• lead time, or the time it takes to make a subassembly or component or receive delivery of a purchased component. Manufacturing lead-time data are found in the item master record.

提前期店茶，或制造一個子件或組件或接收購買的組件交付所花費的時間蜕便。生產(chǎn)準(zhǔn)備時間數(shù)據(jù)可以在項目主記錄中找到。

• offsetting, which is the process of determining when a planned order release is needed in advance of the planned order receipt date of the item.

提前期補償贩幻，即在計劃訂單收到日期之前確定何時需要計劃訂單發(fā)布的過程轿腺。

• exploding, which is the process of determining the total of each component needed for a parent.

展開需求，這是確定一個父組件所需的每個組件的總數(shù)的過程丛楚。

Below is the procedure for offsetting and exploding the planned order releases for D.

下面是對D的已計劃訂單發(fā)布進行補償和展開的過程族壳。

4-25-lead-time-offsetting-and-exploding.png

Offsetting 補償

Visual 4-25 illustrates the offset procedure for parent B and its purchased component, D.

圖4-25演示了父組件B及其購買組件D的補償過程。

• Parent B has a lead time of 1 week. Its planned order receipt date is the beginning of week 5, so a planned order release for B must be offset to the beginning of week 4.

B的交貨期為一周趣些。它計劃的訂單收貨日期是第5周期初仿荆，所以B的已計劃訂單發(fā)布必須被補償?shù)降?周期初。

• Parent B is an assembly of components C and D. This means planned order receipts for these components need to be available at the beginning of week 4, as they are needed when the planned order release of B occurs.

B是組件C和D的組裝坏平，這意味著這些組件的計劃訂單接收量需要在第4周開始時提供拢操，因為當(dāng)B的已計劃訂單發(fā)布時需要這些接收量。

• Because the lead time for D is 1 week, a planned order release needs to be scheduled for the beginning of week 3 to meet the week 4 due date.

因為D的交貨期是1周舶替，所以計劃的訂單發(fā)布需要安排在第3周的開始令境，以滿足第4周的到期日。

Exploding 展開

Exploding, also called BOM explosion, is the process of multiplying a parent item's need for components based on the BOM. We already have covered this in the section on the BOM in Problem 4.1. We'll briefly illustrate this with the visual.

展開顾瞪，也叫BOM分解舔庶，是一個基于BOM的父項對組件的需求倍增的過程。我們已經(jīng)在問題4.1的BOM部分討論過了陈醒。我們將用圖像簡單地說明這一點惕橙。

• Each parent in the BOM requires one unit of a component. Because the requirement for end-item parent B is 50 units and because D is a component of B, there is a requirement for 50 Ds in order to make 50 units of B. A single B requires 1 C, so the requirement for C = 1 * 50 units = 50 units.

BOM中的每個父組件都需要一個組件的單位。因為父組件要求最終產(chǎn)品B是50單位因為D是B的一個組成部分,就有50個D的需求孵延，為了組成50單位的B吕漂。1個B需要1個C,所以需要50個單位的C。

• The requirement for parent B of 50 units is in week 5. This means the planned order receipt for B is at the beginning of business on the first day of week 5.

B的需求為在第5周需要50個單元尘应。這意味著B計劃的訂單收貨時間是在第5周的第一天業(yè)務(wù)一開始的時候惶凝。

Conclusion 結(jié)論

• A planned order release for D has been offset by one week from a planned order receipt due in week 4 per the lead-time information from the item master record.

D的計劃訂單發(fā)布已被項目主記錄中每個提前期信息從第4周到期的計劃訂單接收中抵消一周吼虎。

• The planned order release quantity was exploded, per the assumed BOM requirement that one unit of parent B requires one unit of D, so 50 units of B require 50 units of D.

計劃的訂單發(fā)布數(shù)量被分解洒疚，根據(jù)假設(shè)的BOM需求，一個單位的父B需要一個單位的D乏德，所以50個單位的B需要50個單位的D。

How many Ds would have to be ordered if the week 5 requirement for B was 100 units and the required quantity of D per parent item B was two units?

如果第5周B的需求量是100個單位吠昭，而每項B的需求量是2個單位矢棚，那么需要訂購多少個D?

Gross and Net Requirements 毛需求和凈需求

The next step in the MRP calculation logic is the determination of gross and net requirements. In previous exercises, we assumed that if a parent B has a component requirement of 50 Ds, you would need to schedule a receipt of 50 units of D, offset by the appropriate lead time.

MRP計算邏輯的下一步是確定毛需求和凈需求。在之前的練習(xí)中肉津，我們假設(shè)如果父組件 B的組件需求是50個D，那么您需要安排50個單位的D的收貨，用適當(dāng)?shù)奶崆捌趤硌a償署照。

If you have items in inventory, they must be taken into account and subtracted from the gross requirement to determine a net requirement. This also is called gross to net, or netting.

如果你有存貨項目翰撑，它們必須被考慮并且從總需求中減去以確定凈需求宪潮。這也被稱為粗到凈溯警，或凈額計算狡相。

Recognizing Available Inventory 識別可用庫存

The convention is that the projected available inventory shown in a period represents the period-ending inventory. This means it is available at the very beginning of the next period.

約定在一個期間內(nèi)所列的預(yù)計可動用存貨就是期末存貨梯轻。這意味著它可以在下一個時期開始時使用。

To relate this to the visual, look at the 20 units of projected available shown for B in week 4. This is the week 4 end-of-period inventory that is available during week 5.

與圖聯(lián)系起來尽棕，看看第4周B的20個單位喳挑。這是第4周期末庫存，在第5周可用。

Note that the inventory available in week 1 for end item B (20) and component C (10) are shown in the cells before week 1 to indicate that they were the on-hand inventory at the end of the period that preceded week 1.

請注意伊诵，第1周結(jié)束項目B(20)和組件C(10)的庫存在第1周之前的單元格中顯示单绑，以表明它們是第1周之前期末的庫存。

What is the inventory available during week 3 for component C?

C的可用庫存在第三周有多少?

Calculation of Net Requirements

The following summarizes the process for determining net requirements. Refer to the visual.

下面總結(jié)了確定凈需求的過程日戈。如圖询张。

• Find the gross requirement for an end item, such as B (50 units), which is determined by the MPS. It is shown in and is available at the beginning of week 5.

  查找最終項目的總需求，例如由MPS決定的B(50個單位)浙炼。它顯示在第5周的開始份氧。

• Refer to the equation for net requirements, which is as follows:
  凈需求公式如下:

    Net requirements = gross requirements - available inventory 
    凈需求=總需求-可用庫存
  

• Based on the MRP record shown in the visual, the net requirement for B in period 5 is 30.
  根據(jù)圖提供的MRP記錄，第5期B的凈需求為30弯屈。

• A receipt of 30 then is planned based on lot-size policy.
  然后根據(jù)批次策略蜗帜，計劃收到30件。

What is the net requirement for component C in week 4?

第4周C組件的凈需求是多少?

Component Availability and Offsetting 組件可用性和偏移量

Gross requirements, net requirements, and planned order receipts are considered to be available at the beginning of the week in which they are displayed.

毛需求资厉、凈需求和計劃訂單收貨被認為是在顯示它們的那一周開始時可用的厅缺。

For example, the gross and net requirements of end item D are shown in week 4, so a planned order receipt for D is shown in week 4 and is expected to be available at the beginning of the week. A planned order release for D is shown in week 3, based on a one-week lead time.

例如，最終項目D的毛需求和凈需求在第4周顯示宴偿，所以D的計劃訂單收貨在第4周顯示湘捎，預(yù)計在本周初可以收到。D的計劃訂單發(fā)出在第3周窄刘，基于一周的交付時間窥妇。

Basic MRP Record 基本的MRP記錄

4-35-Basic-MRP-Record.png

Salient Features 顯著特性

Up until this point, we have not taken the time to discuss the salient features and terminology pertaining to a typical MRP record. There is one for every component of an end item, including the end item itself.

到目前為止，我們還沒有花時間討論與典型MRP記錄相關(guān)的顯著特性和術(shù)語娩践。每個組件都有一個最終產(chǎn)品項活翩，包括最終產(chǎn)品項本身。

• If there were a time stamp on this record, it would be at the beginning of week 1.
  如果這條記錄上有一個時間戳翻伺，那應(yīng)該是在第一周的開始材泄。

• Week 1 is the action bucket, though no actions are necessary because there are no scheduled receipts or planned order releases; however, when week 3 rolls to week 1, there is the need for a planned order release.
  第1周是action bucket，盡管沒有必要進行操作吨岭，因為沒有計劃的接收量或已計劃的訂單發(fā)布;然而拉宗，當(dāng)?shù)?周轉(zhuǎn)到第1周時，就需要一個計劃訂單發(fā)布辣辫。

• The lead time establishes the offset of the planned order release from the planned order receipt.
  交貨期確定計劃訂單發(fā)布與計劃訂單接收之間的偏移量簿废。

• The top row shows time periods, called time buckets -- or weeks, in this example.
  頂部一行顯示了時間段，在本例中稱為時間桶——或星期络它。

• The number of periods in the record is called the planning horizon; it should be as long as the cumulative lead time, which is equal to longest lead time among all the BOM paths below the end item.
  記錄中的周期數(shù)稱為規(guī)劃視界;它應(yīng)該與累積的交付時間一樣長族檬，這等于在最終產(chǎn)品項之下的所有BOM路徑中最長的交付時間。

• An item is available at the beginning of the time bucket in which it is required.
  一個項目在需要它的時間桶的期初即可用化戳。

• The quantity shown in the projected available row is the projected available balance at the end of the period; all other quantities are for the beginning of the period.
  預(yù)計可用行中顯示的數(shù)量是在期末時預(yù)計可用余額;所有其他的量都是期初单料。

Scheduled Receipts 計劃接收量

The example shown above adds yet another row of data called scheduled receipts.

上面的示例添加了另一行數(shù)據(jù)埋凯，稱為計劃接收量。

• Scheduled receipts are planned orders that, before week 1, already have been released or placed with suppliers and the factory and have receipt dates within the planning horizon.
  計劃接收量是指在第1周之前已經(jīng)發(fā)出或與供應(yīng)商和工廠一起下單并在計劃期限內(nèi)收到的計劃訂單扫尖。

• These orders are called open orders.
  這些訂單稱為公開訂單白对。

• In periods in which there are scheduled receipts, their quantities are added to the projected available balance. (See the addition of 20 units of scheduled receipts to projected available in week 2.) Eventually the quantities influence the gross to net requirements calculation.
  在有計劃接收量的期間，其數(shù)量將加到預(yù)計可用量中换怖。(請參閱第2周預(yù)計可獲得的20份計劃接收量甩恼。)最終數(shù)量影響總量和凈需求量的計算。

• The new formula for net requirements = gross requirements - scheduled receipts - projected available.
  凈需求量的新公式 = 總需求量 - 計劃接收量 - 預(yù)計可用量沉颂。

Class Problem 4.5:

Given the following product tree BOM, explode, offset, and calculate the gross and net requirements. All lead times are one week except for K, where the lead time is two weeks. The component quantities per parent are shown in parentheses and the lot-size policy is as required. The MPS calls for completion of 50 Js in week 5. There is a scheduled receipt of 47 Ks in week 2. There are 85 Ls and 135 Ns on hand.

給定以下產(chǎn)品樹BOM条摸，分解，補償铸屉，并計算總需求和凈需求钉蒲。所有的交貨期都是一周，除了K彻坛，交貨期是兩周顷啼。每個父組件的數(shù)量在括號中顯示，并且根據(jù)需要使用批量策略昌屉。MPS要求在第5周完成50個J钙蒙。計劃在第二周收到47個k。目前有85個L和135個N间驮。

problem-4.5.png

Capacity Requirements Planning 能力需求計劃

In master scheduling, rough-cut capacity planning (RCCP) is used to check the MPS against available capacity. In MRP, another capacity check is performed -- this time focusing on resources available to meet due dates in the priority plan at the component level as opposed to the end-item level.

在主調(diào)度中仪搔，粗能力計劃(RCCP)用于根據(jù)可用產(chǎn)能檢查MPS。在MRP中蜻牢，執(zhí)行另一個產(chǎn)能檢查——這次集中于可用于滿足優(yōu)先計劃中組件級別而不是最終項目級別的到期日期的資源。

This will be addressed in Session 5: Capacity Management and Production Activity Control.

這將在第五課上討論:能力管理和生產(chǎn)活動控制偏陪。

Using and Managing the Priority Plan 使用和管理優(yōu)先計劃

Role of MRP Software MRP軟件的角色

MRP software applications are used in most manufacturing companies and also are used in non-manufacturing industries such as retail, distribution, and service. They perform two major functions:

MRP軟件應(yīng)用程序在大多數(shù)制造企業(yè)中都使用抢呆，也在零售、分銷和服務(wù)等非制造行業(yè)中使用笛谦。它們有兩個主要功能:

• Perform gross to net, lead-time offset, and explosion calculations.
  Given an end-item due date from the MPS, MRP software can perform the gross to net, offsetting, and explosion calculations necessary to create the priority plan for end items and their components. It does these fast, accurately, and in very high volumes.

  執(zhí)行總到凈抱虐、前置時間補償和分解計算。
  給定MPS的最終產(chǎn)品項到期日饥脑，MRP軟件可以執(zhí)行為最終產(chǎn)品項及其組件創(chuàng)建優(yōu)先計劃所必需的總到凈恳邀、補償和分解計算。它可以快速灶轰、準(zhǔn)確地且大量地完成這些任務(wù)谣沸。

• Create action and exception messages.
  Action and exception messages are critical to planners in managing the priority plan. MRP software is integrated with inventory and other systems. The software also keeps track of due dates in the priority plan and the status of materials and production. For example, it issues action messages when a planned order becomes due for release, or tools into the action bucket; it issues exception messages when material availability is not sufficient to meet a planned order receipt date for a component or an end item.

  創(chuàng)建操作和異常消息。
  操作和異常消息對于計劃人員管理優(yōu)先計劃至關(guān)重要笋颤。MRP軟件與庫存和其他系統(tǒng)集成乳附。該軟件還在優(yōu)先計劃中跟蹤到期日以及材料和生產(chǎn)狀況。例如，當(dāng)計劃的訂單到期交付時赋除，或者工具進入操作桶時阱缓，它會發(fā)出操作消息;當(dāng)材料可用性不足以滿足組件或最終產(chǎn)品項的計劃訂單接收日期時，它會發(fā)出異常消息举农。

It is important to note that MRP software is not normally programmed to release planned orders. That is the role of the planner. On the basis of action and exception messages, the planner will release planned orders, expedite or de-expedite component schedules, or change order quantities.

需要注意的是荆针，MRP軟件通常不會被編程來發(fā)布計劃好的訂單。那是計劃者的角色颁糟。根據(jù)操作和異常消息航背，計劃員將發(fā)布計劃訂單，加速或減速組件排程滚停，或更改訂單數(shù)量沃粗。

Order Control 訂單控制

4-Order-Control.png

In managing the priority plan, the material planner works with three main types of orders as shown in the MRP record: planned orders, firm planned orders, and released orders -- or scheduled receipts.

在管理優(yōu)先計劃時，物料計劃員要處理MRP記錄中顯示的三種主要訂單類型:計劃訂單键畴、已確認計劃訂單和已發(fā)出訂單——或計劃接收量最盅。

Planned Orders 計劃訂單

Planned orders are created by planning software when it encounters net requirements. The net requirement generates planned order receipts in the system, and planned order releases appear in a prior period based on the lead-time offset. Note the planned order receipt of 5 units in week 3 and the planned order release in week 1.

計劃訂單是由計劃軟件在遇到凈需求時創(chuàng)建的。凈需求在系統(tǒng)中生成計劃訂單接收量起惕，并且計劃訂單發(fā)布出現(xiàn)在前一個周期中涡贱，基于交付時間偏移量。請注意惹想，計劃在第3周收到5個單元的訂單问词，計劃在第1周發(fā)出訂單。

Firm Planned Orders 已確認計劃訂單

A firm planned order is a tool that enables the planner to override the MRP logic. Note the firm planned order release of 35 units in week 2, three weeks instead of two before the planned order receipt. This could be the result of the planner's decision to allow another week of lead time for the receipt due in week 5, possibly because production has a temporary quality problem and requires another week.

已確認計劃訂單是一個工具嘀粱，它使計劃者能夠覆蓋MRP邏輯激挪。請注意，公司計劃在第2周發(fā)布35個單位的產(chǎn)品锋叨，在計劃收到訂單之前的三周而不是兩周垄分。這可能是由于計劃員決定允許在第5周收貨前再給一周的時間，可能是因為生產(chǎn)有暫時的質(zhì)量問題娃磺，需要再給一周的時間薄湿。

Released Orders 已發(fā)出訂單

Planners are responsible for releasing planned orders, aided by action messages from the MRP system. Once released, a planned order becomes on open order to the factory or supplier. It appears as a scheduled receipt of 20 units as in week 2 of the MRP record shown in the visual.

計劃人員負責(zé)在MRP系統(tǒng)的行動信息的幫助下發(fā)布計劃訂單。一旦發(fā)出偷卧，計劃的訂單就會成為工廠或供應(yīng)商的公開訂單豺瘤。它似乎是預(yù)定收到的20個單位，如圖所示在第2周的MRP記錄听诸。

A released order also is under the control of the planner and is subject to expediting, de-expediting, change in order quantities, and even cancellation.

已發(fā)出的訂單也在計劃員的控制下坐求，并可能發(fā)生加速、減速晌梨、變更訂單數(shù)量甚至取消等情況瞻赶。

In what week was the planned order released for the scheduled receipt for week 2?
第2周的計劃接收量的計劃訂單在哪個星期發(fā)出?

What types of orders are under the control of the planner?
計劃員控制哪些類型的訂單?

Releasing Planned Orders 發(fā)出計劃訂單

4-43.png

The release of an order by a planner, with assistance of the MRP application logic, ensures that work is done in time to meet net requirements.

計劃員在MRP應(yīng)用程序邏輯的幫助下發(fā)布訂單赛糟，確保工作及時完成，以滿足凈需求砸逊。

As shown in the visual, the release of the order involves a number of events.

如圖所示璧南，訂單的發(fā)布涉及到許多事件。

• Releasing a planned order 發(fā)布已計劃好的訂單
• Scheduling a receipt 安排接收
• Creating an open order 開單
• Allocating components to the order 分配組件到訂單

Note that the open order is an authorization to:

• purchasing, to buy the necessary material, or to
• manufacturing, to make the component

注意师逸，開單是授權(quán)：

• 采購或購買必要的物料或
• 制造物料以滿足組件的制造

Maintaining Priorities and Replanning 維護優(yōu)先級和重新計劃

Releasing planned orders is only one of several responsibilities of the planner. The planner has the general responsibility of managing the current priority plan, such as planned orders, open orders, and end-item due dates. The planner also deals with the numerous events that might affect order priorities.

發(fā)布計劃訂單只是計劃員的幾個職責(zé)之一司倚。計劃員負責(zé)管理當(dāng)前的優(yōu)先計劃，如計劃訂單篓像、未完成訂單和最終項目到期日动知。計劃員還處理可能影響訂單優(yōu)先級的眾多事件。

These include 這些包括

• external events such as 外部事件如：

  • changes to customer orders 客戶訂單變更
  • supplier shortages 供應(yīng)商短缺
  • late deliveries and lower than required order quantities from suppliers 遲交及供應(yīng)商低于所要求的訂貨數(shù)量

• internal events such as 內(nèi)部事件如：

  • lower yields or higher scrap factors than planned 收益率低于計劃或廢品系數(shù)高于計劃
  • late or early open order completions 延遲或提前完成公開訂單
  • capacity or resource constraints 產(chǎn)能或資源限制
  • material shortages caused by inventory record inaccuracies that hide shortages or surpluses of components or end items and lead to the need to expedite or de-expedite.
    因庫存記錄不準(zhǔn)確而造成的物料短缺员辩，隱藏了零件或最終產(chǎn)品的短缺或過剩盒粮，導(dǎo)致需要加速或減速。

There basically are two sets of actions available to the planner:
計劃員基本上有兩套行動:

• Maintain the priority plan by taking actions to maintain the scheduled due dates for the production of components or the end item. These would include expediting or de-expediting.

通過采取行動維護零件或最終產(chǎn)品生產(chǎn)的預(yù)定到期日來維護優(yōu)先計劃奠滑。這將包括加速或減速丹皱。

• Replan the due date if an event does not enable the maintaining of a due date. Class Problem 4.6 illustrates the options available to the planner when the receipt of a component is less than planned and affects the schedule of not just one but two parent items that use the same component.

如果事件使得不能維護到期日期，則重新計劃到期日期宋税。問題4.6說明了當(dāng)收到的組件比計劃的少摊崭，并且影響了使用相同組件的兩個父產(chǎn)品項（而不止一個）的進度時，計劃員可以使用的選項杰赛。