3-BSCM-Master Planning

BSCM

Basic of Supply Chain Management

Session 3: Master Planning 主生产计划

Purpose 目标

In Session 2, Demand Management, we addressed the role of marketing and customer relationship management and demand planning in determining customer demand.

在第2课《需求管理》中,我们讨论了市场营销、客户关系管理和需求计划在确定客户需求中的作用。

This session examines the phase of MPC called master planning. Master planning includes sales and operations planning (S&OP), which produces the production plan, and master scheduling, which produces the MPS. The latter is a priority plan consisting of due dates for the production of end items. It then becomes a major input to material requirements planning (MRP), which takes priority planning down to the component level.

本节课考察MPC的阶段,称为主排程。主排程包括销售和运营计划(S&OP),它产出生产计划,以及主排程(Master scheduling),它产出MPS。后者是一项优先计划,包括生产最终项目的截止日期。然后,它成为材料需求计划(MRP)的主要输入,该计划将优先级计划下沉到组件级别。

Learning Objectives 学习目标

  • Purpose and Scope of Master Planning 主排程的目的和范围

    • Explain the elements and importance of the priority plan.
      解释优先计划的要素和重要性。

    • Differentiate between the planning horizons and levels of detail of business planning, S&OP, and master scheduling.
      区分计划范围和业务计划、S&OP和主排程的详细程度。

  • Sales and Operations Planning and Production Planning 销售运营计划和生产计划

    • Describe the purpose of, and key inputs to, S&OP.
      描述S&OP的目的和关键输入。

    • Explain the advantages of production planning at the product family level.
      解释产品族层面的生产计划的优势。

    • List four production strategies and their differences with respect to inventory.
      列出四种生产策略及其在库存方面的差异。

    • Calculate a level production plan and ending inventories for all periods.
      计算所有生产周期的水平生产计划和期末库存。

  • Master Scheduling and the Master Production Schedule 主排程和主生产计划

    • Differentiate between the production plan and the master production schedule (MPS).
      区分生产计划和主生产计划(MPS)。

    • Explain the significance of the MPS planning horizon, time fences, and zones.
      解释MPS计划范围、时间间隔和区域的重要性。

    • Calculate the projected available balance and the MPS in a master schedule.
      在主排程中计算预计的可用余额和MPS。

    • Describe the purpose of the final assembly schedule.
      描述最终组装计划的目的。

  • Resource Planning and Rough-Cut Capacity Planning
    资源计划和粗能力计划

    • Differentiate between resource planning and rough-cut capacity planning (RCCP).
      区分资源计划和粗能力计划(RCCP)。

    • Describe the differences in the bill of resources data requirements between resource planning and RCCP.
      描述资源计划和RCCP之间资源数据需求的差异。

  • Master Production Schedule and Sales 主生产计划和销售

    • Explain the use of the MPS in available-to-promise (ATP).
      解释在可承诺量(ATP)中使用MPS。

    • Perform a simple ATP calculation.
      执行简单的ATP计算。

Purpose and Scope of Master Planning 主排程的目的和范围

In the previous session, we addressed demand management's role in shaping and recognizing independent demand. The role of MPC is to synchronize and translate independent demand into dependent demand.

在上一课中,我们讨论了需求管理在形成和识别独立需求方面的作用。MPC的作用是同步并将独立需求转化为依赖需求。

Two of the MPC processes, as shown in Visual 3-6, are S&OP and master scheduling. These are known collectively as master planning. Note that they also are known as priority planning activities.

如图3-6所示,两种MPC进程是S&OP和主调度。这些统称为总体计划。注意,它们也被称为优先计划活动。

manufacturing-planning-control
Priority Planning 优先计划

In conventional manufacturing, planning the material transformation process requires a sequence of due dates for the start and finish of the purchasing and subassembly operations, some of which might be parallel, leading up to the final product.

在传统制造中,计划材料转化过程需要一系列的开始和结束采购和组装操作的截止日期,其中一些可能是并行的,直到最终产品。

due date -- The date when purchased material or production material is due to be available for use.
-- APICS Dictionary
交期 —— 采购材料或生产材料的到期日。

"Available for use" means that the material or component has been completed and is ready for use by the next operation, or is available as an end item to be delivered or stocked.

“可供使用”是指材料或组件已经完成,并已准备好供下一个操作使用,或作为可交付或库存的成品。

The setting and maintaining of time-phased due dates is called priority planning. Priority planning of due dates for end items is the domain of master planning:

确定和保持时间阶段的到期日期被称为优先计划。成品交期的优先计划是总体计划的领域:

  • S&OP develops plans for products at the family level.
    S&OP为产品系列层级制定计划。

  • Master scheduling develops due dates and quantities at the end-item level.
    主排程在最终项目级别制定适当的日期和数量。

  • Once end-item due dates are established by the master schedule, MRP determines the priority plan and due dates for purchased and manufactured components.
    一旦成品交期由主排程确定,MRP决定购买和制造组件的优先计划和截止日期。

    priority planning -- The function of determining what material is needed and when. Master scheduling and MRP are the elements used for the planning and replanning process to maintain proper due dates on required materials.
    -- APICS Dictionary

    优先计划 —— 决定什么时候需要什么材料的功能。主调度和MRP是计划和重新计划过程中用于在所需材料上维护适当交期的元素。

The focus of this session is on master planning's role in priority planning.

本节课的重点是主排程在优先计划中的作用。

Planning Horizon and Level of Detail 计划的范围和详细程度

In Session 2, we pointed out the importance of how forecasts support the three different levels of planning. A visual from Session 2 is repeated here in Visual 3-8 to emphasize the differences in the planning horizons for the planning processes within MPC, including the business plan. We will discuss the role of master planning in translating the business plan into an MPS shortly. Note the differences in time horizons and the priority planning activities' level of detail. This reflects the top-down approach to translating aggregate business-level plans into plans for products at the family level (S&OP), the end-item level (master schedule), and the component level (MRP).

在第二课中,我们指出了预测如何支持三个不同层次的计划。图3-8中与第二课中的一张图在这里重复了,以强调MPC中计划过程(包括业务计划)的计划范围的差异。我们将很快讨论主排程在将业务计划转换为MPS中的作用。请注意在时间范围和优先计划活动的细节级别上的差异。这反映了自上向下的方法,将聚合的业务级计划转换为产品系列级(S&OP)、成品级(master schedule)和组件级(MRP)的产品计划。

S&OP and Production Planning 销售运营和生产计划

Sales and Operations Planning 销售和运营计划

S&OP translates the strategic business plan into production rates that meet company financial, customer service, and other business goals. Properly performed S&OP is characterized by the following:

S&OP将战略业务计划转化为满足公司财务、客户服务和其他业务目标的生产效率。正确执行S&OP的特点是:

  • Continual updating of the operations, sales, and finance plans in order to meet annual strategic business plan objectives based on the latest market conditions and company capabilities

持续更新操作、销售和财务计划,以满足基于最新市场条件和公司能力的年度战略商业计划目标

  • A formal process for obtaining inputs from and updating the plans of various functions within the organization, especially sales, operations, product development, and finance

在组织内获取和更新各种职能计划的正式程序,特别是销售、运营、产品开发和财务等方面

  • A regular schedule for meeting with senior executives to review the updated plans, usually monthly but as often as weekly in some companies
    期安排与高级管理人员会面,以审查更新后的计划,通常是每月一次,但在某些公司则是每周一次

  • A check to see if resources will be adequate, leading to realistic and coordinated sales, operations, and finance plans
    检查资源是否足够,以实现实际和协调的销售、运营和财务计划

  • Better management of the production rate, sales activities, inventory, and backlog
    更好地管理生产速度、销售活动、库存和积压

Production Planning 生产计划

Purpose and Scope 目的和范围

The production plan is a major output of S&OP and should reflect the resolution of decisions and tradeoffs made during the S&OP process. It is a major input to the end-item priority planning that takes place in master scheduling.

生产计划是S&OP的主要产出,应该反映在S&OP过程中做出的决策和权衡的解决方案。它是在主调度中发生的末端优先级计划的主要输入。

production planning -- A process to develop tactical plans based on setting the overall level of manufacturing output and other activities to best satisfy the current planned levels of sales, while meeting general business objectives of profitability, productivity .. and so on, as expressed in the overall business plan.

生产计划——一种制定战术计划的过程,该计划的基础是制定总体水平的生产产出和其他活动,以最好地满足当前计划的销售水平,同时满足盈利能力和生产率的一般业务目标。等等,就像整个商业计划所表达的那样。

-- APICS Dictionary 

Production planning is concerned with the following:
生产计划涉及下列事项:

  • The quantities demanded of each product family or product line in each period -- Because not much detail is needed, planning is done by product families.

    每个时期每个产品系列或产品线的需求量——因为不需要太多的细节,计划是由产品系列完成的。

  • Desired inventory levels -- Inventory usually is a major asset, and companies will want to control inventory levels. If an item is already in stock, the company does not need the resources to make it.

    理想的库存水平——库存通常是主要资产,公司将希望控制库存水平。如果一个项目已经有库存,公司不需要资源来生产它。

  • The resources of equipment, labor, and material needed in each period -- The purpose of the production plan is to be able to meet demand; to do so, manufacturing must find out what resources are needed.

    每个阶段所需的设备、人力和材料资源——生产计划的目的是满足需求;要做到这一点,制造业必须找到所需的资源。

  • The availability of needed resources -- Once the required resources are decided, the next step is to compare required resources with available resources.
    所需资源的可用性--一旦确定所需资源,下一步是将所需资源与现有资源进行比较。

Typical Production Planning Situation 典型的生产计划情况

Production planning faces the following typical situation:
生产计划面临以下典型情况:

  • The time horizon may be more or less than 12 months and even up to 36 months depending on the manufacturing cycle.
    根据生产周期的不同,时间跨度可能大于或小于12个月,甚至多达36个月。

  • The plan usually is stated as a monthly rate.
    这个计划通常是按月费率计算的。

  • Demand fluctuates or is seasonal for many products.
    许多产品的需求是波动的或者是季节性的。

  • A plan is made for product families or groups.
    为产品系列或产品组制定计划。

  • Plant and equipment usually are fixed within the time horizon.
    工厂和设备通常在时间范围内固定。

  • Management will have a variety of objectives.
    管理将有各种目标。

Production Strategies 生产策略

Four different strategies can be used to develop a production plan.

可以使用四种不同的策略来制定生产计划。

  • Chase, or demand matching, strategy: Production level matches the quantity demanded by period.
    追赶或需求匹配策略:生产水平与周期需求的数量相匹配。

  • Level production strategy, or production leveling: Production level is equal to the average demand.
    均衡生产策略或生产均衡化:生产水平等于平均需求。

  • Subcontracting: Production level is equal to the level of the minimum demand and the rest is fulfilled through subcontracting.
    分包:生产水平等于最低需求水平,其余通过分包完成。

  • Hybrid, or combination, strategy: In addition to the above individual strategies, a hybrid strategy may be used to balance customer service, inventory, and stable labor force objectives.

    混合(或组合)策略:除了上述的个别策略外,还可以使用混合策略来平衡客户服务、库存和稳定的劳动力目标。

Chase (demand matching) strategy 追赶(需求匹配)策略
chase-strategy

The goal of the chase strategy is to produce the quantity demanded at any time. Because the inventory level is stable, the cost of the inventory will not vary significantly from period to period. Production is adjusted to match sales requirements. However, this strategy also has disadvantages:

追赶策略的目标是在任何时候生产需求量。由于库存水平是稳定的,所以库存的成本在不同时期不会有明显的变化。调整生产以满足销售需求。然而,这种策略也有缺点:

  • As production increases, workers must be hired and trained. Extra shifts may be needed, and overtime may be necessary. These requirements all increase cost.
    随着产量的增加,必须雇用和培训工人。可能需要额外的轮班,也可能需要加班。这些要求都增加了成本。

  • As production decreases, people are laid off and employee morale suffers.
    随着生产的减少,员工被解雇,员工士气低落。

  • When production starts to increase again, the best workers may have other jobs and their skills will not be available.
    当生产再次开始增长时,最优秀的员工可能会有其他的工作,他们的技能也无法施展。

  • Manufacturing must have enough plant capacity to produce at the highest capacity level needed, but that capacity might be underutilized during periods of low demand.
    制造业必须有足够的工厂产能,以达到所需的最高产能水平,但在需求较低的时期,产能可能得不到充分利用。

Level Strategy 均衡策略
level-strategy

The basic approach of the level strategy is to make an accurate forecast of average demand for a period, such as one year, and then set a level production rate to match the average. As seen in Visual 3-16, this shows a buildup of inventory during the first part of the year, followed by a drawdown to match demand during the latter half.

均衡策略的基本方法是对一段时期(如一年)的平均需求进行准确的预测,然后设定一个与平均产量相匹配的水平产量。如图3-16所示,这显示了上半年库存的增加,然后是下半年需求的减少。

The advantages are 优势是

  • level production avoids the costs of workforce and capacity adjustments of the chase strategy
    均衡生产避免了劳动力成本和对战略的能力调整。

  • level production avoids changeover costs and enables long runs that reduce per-item production costs.
    均衡生产可以避免转换成本,并能长期运行降低每件产品的生产成本。

The disadvantages are

  • a buildup of inventory and inventory carrying costs
    库存和库存持有成本的增长

  • it requires a more accurate forecast.
    需要更准确的预测。

Subcontracting 分包
subcontracting

Another approach is to level production at a rate equal to the minimum demand level and to meet all additional demand through subcontracting.

另一种办法是以相当于最低需求水平的产量水平生产,并通过分包满足所有额外需求。

Its advantages are as follows:
其优势如下:

  • It prevents the buildup of inventory that occurs in the level production strategy.
    它阻止了在均衡生产策略中出现的库存积压。

  • In a repetitive flow environment, this strategy avoids excess capacity costs and reduces the costs of changeovers and workforce adjustments.
    在重复的流程环境中,该策略避免了过剩的运力成本,并降低了换班和劳动力调整的成本。

  • It can be a means of quickly acquiring additional capacity.
    这可以是一种迅速获得额外能力的方法。

Its disadvantages are as follows:
其劣势如下:

  • Companies do not want to subcontract items for which they have developed propriety production methods that provide a competitive advantage.
    公司不希望转包他们已经开发出适当的生产方法以提供竞争优势的项目。

  • The costs of subcontracting might exceed the cost of in-house production.
    分包成本可能超过内部生产成本。

Hybrid strategy 混合策略

Anold et al., in Introduction to Materials Management, 7th ed. chap.2, refers to chase, level, and subcontracting as pure production strategies. They have their own sets of cost characteristics and tradeoffs.

Anold等,在《物料管理导论》(第7版)第2章,指出追赶,均衡,和分包是纯粹的生产策略。他们有自己的成本特征和权衡。

The hybrid strategy as shown in Visual 3-19 attempts to combine the above elements to balance inventory and production costs by minimizing changeovers during the planning cycle in order to satisfy customers. The diagram shows two changeovers during the cycle, and the production rate tracks fairly closely with demand.

hybrid-strategy

如图3-19所示的混合策略试图通过最小化计划周期内的变更来结合上述要素来平衡库存和生产成本,以满足客户的需求。该图表显示了两个在周期内的变化,并且生产速率与需求密切相关。

The characteristics of the hybrid strategy are as follows:
混合策略的特点如下:

  • Production is at or close to full capacity for at least part of the planning cycle.
    至少在计划周期的一部分,生产处于或接近全部产能。

  • Production is at a lower rate during the other part of the cycle.
    在周期的另一部分,生产速度较低。

  • Production is level during both parts of the cycle.
    生产在周期的两个部分都是均衡的。

  • Workforce adjustment costs are less than they are in a chase strategy.
    员工调整成本低于追赶策略。

  • Inventory buildup is less than it is in a level strategy.
    库存积累少于均衡策略。

  • Hybrid strategy requires a more accurate forecast as in the level strategy.
    混合策略需要更准确的预测,就像均衡策略一样。

As with the level strategy, an accurate forecast is a big advantage. For example, if the forecasted average demand during the low demand period is too low, the buildup of inventory during this period might not suffice during the period of high demand.

与均衡策略一样,准确的预测是一个很大的优势。例如,如果低需求时期的预测平均需求过低,这一时期的库存积累可能不足以满足高需求时期的需求。

Note the example of the hybrid strategy is a simplified one. There are numerous variations of such strategies, each with its own costs and benefits. It is management's job to find the best strategy.

注意,混合策略的示例是一个简化的示例。这种策略有很多不同的变体,每个都有自己的成本和收益。找到最佳策略是管理层面的工作。

Make-to-Stock Production

Developing a Make-to-Stock Production Plan 制定一个生产计划

In MTS production, finished goods are put into and sold from inventory. It is used when
在MTS生产中,成品从库存进入和销售。使用它时

  • demand is fairly constant and predictable
    需求是相当稳定和可预测的

  • only a few product options exist
    只有少数产品可供选择

  • the required delivery times are shorter than the manufacturing lead time.
    所需的交货时间比制造提前期短。

Information needed for a MTS production plan includes
MTS生产计划所需的信息包括

  • a forecast by time period for the planning horizon
    按时段预测规划周期
  • opening inventory
    期初库存
  • desired ending inventory.
    期望的期末库存。

Resource Planning 资源计划

We mentioned earlier that the production plan is a major output of S&OP and that its validity is not just a concern for the manufacturing function but also for the following functions:

我们之前提到,生产计划是S&OP的主要产出,它的有效性不仅是对生产功能的关注,也是对以下功能的关注:

  • Finance: Revenue projections only are as good as sales.
    财务:收入预期仅与销售额持平。

  • Sales and marketing: Sales only are as good as production schedules.
    销售和市场推广:销售仅与生产计划相同。

  • Operations: Production schedules only are as good as the availability of resources.
    运营:生产计划只与资源的可用性一样好。

The production plan must be compared with the availability of resources. Two questions must be answered:

生产计划必须与资源的可用性进行比较。必须回答两个问题:

  • Are the required resources available when needed? The resources of concern at this point are critical resources such as materials, labor, and other operations constraints and especially those that take a long time to acquire.

所需资源是否在需要时可用?目前关注的资源是关键资源,如材料、劳动力和其他操作限制,特别是那些需要很长时间才能获得的资源。

  • If not, how will the difference between planned load and available resources be reconciled? Choices are changing resources or altering load.

如果没有,计划负载和可用资源之间的差异将如何协调?选择是改变资源或改变负载。

Bill of Resources 资源清单
bill of resources

At this stage in the MPC process, resource planning is driven by the production plan and the bill of resources. An example of a bill of resources, sometimes called a resource bill, is shown in Visual 3-32. It lists the resources required to make one average unit in each of three product families for cycles: unicycle, bicycle, and tricycle.

在MPC过程的这个阶段,资源计划是由生产计划和资源清单驱动的。bill of resources子,有时也被叫作resource bill。这里有个例子如图3-32所示。它列出了在三个产品系列中制造一个平均单位所需的资源:独轮车、自行车和三轮车。

Note the following characteristics and implications of the bill of resources shown.

请注意所示的资源清单的下列特点和含义。

  • The three product families, which all are types of cycles, share the same manufacturing resources, such as the plant facility.
    这三个产品系列都属于循环类型,它们拥有相同的生产资源,比如工厂设施。

  • The resource requirements shown for each of the three product families are based on the average unit of each type.
    三种产品系列中每一种的资源需求是基于每种产品类型的平均单位。

  • The product families require two critical resources: steel tons and assembly time labor hours.
    产品系列需要两个关键资源:钢量吨数和装配工时。

  • In multiplying the planned production quantities by the amount of steel and assembly hours needed for each item, total resources required by the three product families can be calculated and then campared with available resources.

    将计划生产数量乘以每项所需的钢量和装配小时数,就可以计算出三个产品系列所需的总资源,然后用现有资源进行转换。

Master Scheduling and Master Production Schedule 主排程与主生产计划

Purpose 目的

In the S&OP process, the production plan determines a feasible rate of production at the product family level over a planning horizon of one to three years. The development of the master schedule is the next step of master planning. It has the following purposes:

在S&OP的过程中,生产计划决定了在产品家族层面上,在1到3年的规划范围内,一个可行的生产速度。总体规划的发展是总体规划的下一步。它有以下目的:

  • Link, or disaggregate, production planning at the product family level (in this case, unicycles, bicycles, and tricycles) to the end-item level (specific models of each family).

将产品家族级别(本例中,独轮车,自行车和三轮车)的生产计划与最终项目级别(每个家族的特定模型)联系在一起。

  • Create the priority plan, including due dates and quantities, for end item manufacturing.
    为最终产品制造制定优先计划,包括截止日期和数量。

  • Provide end-item due dates and quantities used for calculating the rough-cut capacity plan.
    提供成品交期和用于计算粗能力计划的数量。

  • Drive the material requirements plan, which takes the priority plan to the component due date and quantity level.
    驱动物料需求计划,优先计划到组件交期和数量水平。

Master planning seeks to plan and control the impact of independent demand on material and capacity. The master schedule is a vital link between sales and production.

主排程旨在计划和控制独立需求对物料和产能的影响。主调度是销售和生产之间的一个重要环节。

  • It makes valid order promises possible.
    它使有效的订单承诺成为可能。

  • It represents an agreed-upon plan between sales and production.
    它代表销售和生产之间商定的计划。

Objectives 目标

The objectives of master scheduling are to
主调度的目标是

  • maintain the desired level of customer service 维持客户服务的理想水平
  • make the best use of resources 充分利用资源
  • keep inventories at the desired level. 保持所需的库存水平。
Inputs 输入

Inputs to the master scheduling process include
主调度过程的输入包括

  • the production plan 生产计划
  • forecasts for individual end items 单个成品的预测
  • orders from customers 客户订单
  • additional independent demand 额外的独立需求
  • inventory levels 库存水平
  • capacity constraints 产能约束
Relationship to the Production Plan 生产计划关系
Relationship to the Production Plan

Visual 3-39 is a simplified example of the use of input data from the production plan and data from the item forecast to develop a master schedule.

图3-39是使用生产计划中的输入数据和项目预测中的数据来开发主排程的简化示例。

  • The production plan data is aggregate data for product family W by month.
    生产计划数据为产品系列W月汇总数据。

  • The MPS data have been disaggregated on a weekly basis to the end-item level by forecasts for products X and Y, which are in product family W.
    MPS数据已按产品系列W的产品X和Y的预测每周分类到成品水平。

Production plans usually are started in months, and the master schedule usually is stated in weeks.

生产计划通常在几个月内开始,主排程通常在几周内公布。

Why, if this is a level production plan, does the production plan vary from 19,000 to 23,000 units per months?

为什么,如果这是一个均衡生产计划,那么生产计划每个月有19,000到23,000个单位的差异呢?

Developing a Master Schedule 制订主排程

The steps in developing a master schedule are as follows:
制订主排程的步骤如下:

  1. Create a preliminary master schedule for each end item with demand.
    根据需求为每个成品创建一个初步的主排程。

  2. Aggregate the master schedule for all end items if the products use the same resources and take the same amount of time.
    如果产品使用相同的资源并占用相同的时间,则聚合所有成品的主排程。

  3. Perform RCCP.
    执行RCCP。

  4. Resolve differences and publish the MPS.
    解决差异并发布MPS。

Master Schedule Versus MPS 主排程与MPS

The master schedule is represented by a time-phased planning chart that includes the forecast, customer orders, projected available balance of inventory, available-to-promise (ATP), and a line called the MPS. It is this line that we refer to when we develop an MPS. Note that customer orders and ATP are not included in the simplified example of the master schedule shown in Visual 3-41.

主排程表由一个时间阶段规划图表表示,该图表包括预测、客户订单、预计的库存可用余额、可用到承诺(ATP)和称为MPS的线。当我们开发MPS时,我们指的就是这条线。请注意,在图3-41中显示的主排程的简化示例中不包含客户订单和ATP。

3-41
Projected Available Balance (PAB) 预计可用库存

The projected available balance in any period tells you if you need to schedule an MPS. Visual 3-41 shows a forecast and projected available balance at the beginning of a six-period master schedule. If the balance is high enough to cover forecasted demand during all six periods, no MPS receipts are necessary.

任何时期的预计可用库存告诉您是否需要安排一个MPS。图3-41显示了在6个周期的主排程开始时的预测和预测的可用库存余额。如果余额足够高,足以覆盖所有6个周期的预测需求,则不需要MPS收据。

At first glance, it appears that the projected available balance at the beginning of the six-period schedule is not enough to cover the forecasted demand for the entire schedule.

乍一看,在六个期间计划开始时预计的可用余额似乎不足以满足对整个计划的预测需求。

Visual 3-42 shows the calculation of the PAB at the end of period 1. The PAB for period 2 is 10 units while the forecast for period 2 is 30 units. There is a projected shortfall of 20 units of inventory in period 2.

3-42

图3-42显示了周期1结束时PAB的计算。第2期的PAB为10个单位,第2期的预测为30个单位。预计在第2期将短缺20个单位的库存。

When you encounter negative PAB numbers, what should be done?

当你遇到负数时,应该怎么做?

Preliminary MPS 初步的MPS

The first step in creating a master schedule and MPS, or the bottom row in the master scheduling grid in this case, is to develop a preliminary MPS for all end items during the six-period master schedule.

创建主排程和MPS(在本例中是主排程网格中的最底层)的第一步是在六周期主排程期间为所有成品制订一个初步的MPS。

The procedure for calculating the MPS receipt for a single period is as follows:
单期MPS接收量的计算方法如下:

  • Determine if the projected end of period PAB is negative or positive:
    确定期末PAB是正还是负:

    Ending PAB = beginning PAB + scheduled MPS receipt - forecast

  • If it's negative, schedule the MPS receipt according to lot-size policy.
    若为负数,则根据批量策略安排MPS接收量。

  • Recalculate the PAB for the period using the formula above.
    使用上述公式重新计算该周期的PAB。

Planning Horizon 计划展望期

Visual 3-48 illustrates the product structure of end item A. It shows the lead time in weeks for each step of the assembly process, plus the time required to acquire and receive purchase components.

图3-48演示了最终项目A的产品结构,它显示了装配过程中每个步骤的交付时间(以周为单位),以及获取和接收购买组件所需的时间。

3-48

What is the longest cumulative lead time in weeks in this example?

在本例中,几周内最长的累计前置时间是多少?


The number of weeks in the cumulative lead time represents the time required to place and order for and receive the lowest-level component, E, assemble D, and assemble the end item,A. The longest cumulative lead time in the product structure is important because it determines the minimum planning horizon for the item's MPS.

累积交货时间中的周数表示放置和订购并接收最低级组件E、组装D和组装结束项A所需的时间。产品结构中最长的累计交付时间是很重要的,因为它决定了项目的MPS的最小计划范围。

Note, however, that by convention, the receipt of a component or end item is due at the very beginning of the period after the end of the lead time period. In other words, "due" means being available for the next operation or for delivery to the customer on the first day of the next period.

但是,请注意,按照惯例,收到一个组成部分或结束项目应在交期结束后一段时期的开始。换句话说,“due”意味着在下一个周期的第一天可以为下一个操作或交付给客户。

In this example, what is the minimum planning horizon in weeks?

在这个例子中,几周内的最小计划展望期是多少?


Actually, companies will add one or more periods to the planning horizon on top of the cumulative lead time. This gives better visibility in their application software to demand and supply issues just beyond the cumulative lead time that might affect the validity of the MPS.

实际上,公司将在累积的交付时间之上,在计划范围内增加一个或多个周期。这使得他们的应用软件在需求和供应问题上有了更好的可见性,超过了可能影响MPS有效性的累积交付时间。

Final Assembly Schedule 总装计划

The example of the planning horizon above applies mainly to MTS production environments that we introduced in Session 1. The MPS is for the end time that is sold to customers.

上面的计划展望期示例主要适用于我们在第1课中介绍的MTS生产环境。MPS是最后一段时间卖给客户。

In a typical assemble-to-order environment, however, separate MPSs are developed and maintained for the MTS components. A final assembly schedule is used for the assembly or configuration of the end item -- of which there might be numerous options -- when the customer order arrives.

然而,在典型的按订单装配环境中,针对MTS组件开发和维护单独的MPS。当客户订单到达时,最终的组装计划用于最终项的组装或配置(其中可能有许多选项)。

An example would be coverings, or paints, which consist of a base color -- of which there are several -- in different volumes or container sizes to which various tints are added to achieve the final color. All of these are made to stock and sit on the paint store shelf until final assembly, when base and tints are mixed to complete the actual customer order. This model also could apply in a factory where large custom orders from distributors and commercial contractors are fulfilled.

例如,覆盖层或油漆,它由不同体积或容器大小的底色(其中有几个底色)组成,在这些底色中加入不同的色调以达到最终的颜色。所有这些都是为了库存和坐在油漆商店的架子上,直到最后的组装,当基础和色调混合完成实际的客户订单。这个模型也适用于一个工厂,那里有来自分销商和商业承包商的大量定制订单。

Time Fences and Zones 时栅和区域

Time fences and zones are used to manage the master schedule and to deal with changes that occur in customer demand and internal priorities, and problems that arise from supplier delays, machine breakdowns, or higher-than-expected scrap rates. A detailed discussion of time fences and zones would go beyond the basics of master scheduling taught in this course. Here are some important points to consider.

时栅和区域用于管理主排程,并处理客户需求和内部优先级发生的更改,以及供应商延迟、机器故障或高于预期的报废率导致的问题。详细地讨论时间间隔和区域将超出本课程所教授的主调度的基础。以下是一些需要考虑的要点。

  • Liquid zone: Beyond the planning time fence, changes to the MPS for the manufacture or purchase of components are easy to make as long as they are consistent with the production plan. Demand at this time usually consists mainly of forecasts and not actual orders. Planning software often will make routine changes. The planning horizon for master scheduling must extend beyond the planning time fence.

    可变区:在计划时间范围之外,只要与生产计划相一致,对于制造或购买部件的MPS进行更改是很容易的。此时的需求通常主要由预测而非实际订单组成。计划软件常常会做出常规的改变。主调度的计划范围必须超出计划时间范围。

  • Slushy zone: Between the demand time fence and the planning time fence, priorities are not as easy to change as in the liquid zone. Demand consists of orders and forecasts, so tradeoffs are possible -- unlike in the frozen zone. Materials have been ordered and some capacity might have been allocated to the assembly of low-level components. Planning software will not make the changes.

    宽松区:在需求时间栏和计划时间栏之间,优先级不像在可变区那样容易改变。需求包括订单和预测,所以权衡是可能的——不像在冻结区。已经订购了材料,一些能力可能已经分配给低层次组件的组装。计划软件不会做出改变。

  • Frozen zone: Inside the demand time fence, demand is based on customer orders, and capacity and materials have been committed to specific orders. Changes would have ripple effects and cause other orders to be late. Approval to change requires senior management approval. Extra costs will be incurred to reroute, reschedule, and perform additional setups.

    冻结区:在需求时间栏内,需求是基于客户订单,产能和物料已经提交给特定的订单。改变将产生连锁反应,并导致其他订单延迟。变更需要高级管理层的批准。重新安排、重新安排和执行额外的计划将会产生额外的成本。

Aggregating the Master Schedules 聚合主排程

We mentioned earlier that the there are four steps in developing a master schedule. We have reviewed the first step, creating a preliminary master schedule for individual end items.

我们之前提到过,开发一个主排程有四个步骤。我们回顾了第一步,为每个成品创建了一个初步的主排程。

The second step requires the aggregation of MPSs -- as in the six-week planning period shown in Visual 3-51. Aggregation is needed only if the products use the same resources and take the same amount of time. This provides the total order quantity for all items in each week. This information then can be used in RCCP to determine if production resources will be adequate during the planning period.

3-51

第二步需要MPS的聚合——就像图3-51所示的六周计划周期一样。只有当产品使用相同的资源并占用相同的时间时,才需要聚合。这提供了每周所有项目的总订购数量。然后可以在RCCP中使用这些信息来确定在规划期间生产资源是否足够。

Rough-Cut Capacity Planning 粗能力计划

RCCP is the third step in the master scheduling process. It is the second check on the availability of critical resources in the MPC process. The first check is called resource planning, which should have validated the production plan at an earlier date. Resource planning was covered earlier in this session.

RCCP是主排程流程的第三步。这是对MPC进程中关键资源可用性的第二次检查。第一个检查称为资源规划,它应该在较早的时候验证生产计划。本课早些时候讨论过。

The major differences between resource planning and RCCP can be summarized as follows:
资源计划与RCCP之间的主要差异可以总结为:

Resource Planning Rough-cut capacity planning
Validates and plans resource availability for the production plan and for the business plan
验证和计划生产计划和业务计划的资源可用性
Validates resource availability for the MPS
验证MPS的资源可用性
Based on the quantity of a resource required to make one average unit of a product family
基于一个产品系列的一个平均单位所需的资源数量
Based on the quantity of a resource required to make one unit of the specific models or types of end items in a product family
基于产品系列中特定型号或成品类型的一个单元所需的资源数量
Resolving Differences and Publishing the MPS 解决差异并发布MPS

The fourth step in developing an MPS is to resolve any differences between the end-item priority plan and available capacity. Available capacity must be equal to or greater than required capacity.

制订MPS的第四个步骤是解决成品优先计划和可用产能之间的任何差异。可用产能必须等于或大于所需产能。

If required capacity exceeds available capacity
如果所需产能超过可用产能

  • the capacity must be increased, or 必须增加产能,或
  • the plan must be altered. 计划必须修改。

Once capacity issues are resolved, the MPS summary establishes the gross requirements for MRP of component, which we will cover in Session 4.

一旦产能问题得到解决,MPS摘要将建立组件的MRP的总需求,我们将在第4课中介绍。

How can capacity be increased or demand be decreased?

如何提高产能或降低需求?

Master Scheduling and Sales 主排程与销售

It is important to understand the relationship between manufacturing, sales, and the MPS. Here are some important points to consider:

理解制造、销售和MPS之间的关系是很重要的。以下是一些需要考虑的要点:

  • The MPS is manufacturing's anticipated build schedule for end items.
    MPS是制造成品的预期构建计划。

  • It is based on end-item demand forecasts and customer orders provided by sales.
    是基于销售提供的成品需求预测和客户订单。

  • The master scheduler relies on the production plan to make sure that the priority plan -- including end-item quantities and due dates -- established by the MPS is realistic and achievable, and that materials and operational resources will be available and sufficient.
    主调度器依赖于生产计划,以确保由MPS建立的优先计划(包括成品数量和到期日期)是现实可行的,并且将提供足够的物料和运营资源。

  • Manufacturing does not build directly to the forecast; the MPS factors in available inventory and safety stock requirements.
    制造业并不直接按照预测建造;MPS影响了可用库存和安全库存的需求。

  • The master schedule, of which the MPS is a major component, must be flexible enough to accommodate changes in demand, production delays, and material shortages.
    主排程(MPS是主要组成部分)必须足够灵活以适应需求的变化、生产延迟和材料短缺。

MPS and Delivery Promises MPS和交付承诺

In the management of real customer orders, the interests of manufacturing and sales again intersect in the master schedule. Customers are placing orders for both

在实际客户订单的管理中,生产和销售的利益再次交织在主计划中。顾客们都在订购这两种产品

  • items that are in stock 库存商品

  • items that are in production or are planned. 正在生产或计划的商品。

The MPS is the basis for making delivery promises.
MPS是做出交付承诺的基础。

In this short section, we will address the basics of the ATP process.
在这一小节中,我们将讨论ATP过程的基础。

Available-to-Promise 可用承诺

available-to-promise (ATP) -- The uncommitted portion of a company's inventory and planned production, maintained in the master schedule to support customer order promising. The ATP quantity is the uncommitted inventory balance in the first period and is normally calculated for each period in which an MPS receipt is scheduled.

可用承诺(ATP)——公司库存和计划生产的未交付部分,在主排程中维护,以支持客户订单承诺。ATP的数量是第一个时期未提交的库存余额,通常是为计划一个MPS收据的每个时期计算的。

-- APICS Dictionary

Sales, customer service, and distribution use the master schedule to determine the ATP.
销售、客户服务和分销使用主排程来确定ATP。

Visual 3-57 demonstrates a basic approach to ATP for a specific end item.
图 3-57演示了针对特定成品的ATP的基本方法。

3-57
  • Scenario 场景

    • It is period 1, at the start of business on the fist day.
      第一阶段,在第一天开始营业。

    • Customer orders on hand are as shown in the Visual 3-57.
      客户手头的订单如图3-57所示。

    • MPS receipts have been scheduled by the master scheduler.
      主排程已经安排了MPS收据。

  • Procedures 过程

    • Use inventory on hand (200 units) to determine what is uncommitted or ATP in the current plan period of period 1.
      使用在手库存(200个单位)来确定在第1期当前计划期间未提交的或ATP。

    • Calculate ATP for each period in which an MPS receipt has been scheduled.
      计算每一个排程有MPS接收的时期的ATP。

    • Assume in your calculation that the entire ATP will be sold before the next scheduled receipt.
      在你的计算中假设整个ATP将在下次排程收据前售出。

    • When calculating ATP, subtract all orders until the next scheduled receipt.
      计算ATP时,减去所有订单直到下一个计划接收。

  • Calculation 计算
    ATP for period 1 = On hand + MPS scheduled receipt in period 1 - customer orders due before next MPS scheduled receipt
    1期的ATP = 在手库存 + 1期的MPS计划接收 - 客户订单在下一个MPS计划接收之前到期

    ATP for period 2, 4, and 6 (periods with MPS scheduled receipts) = MPS scheduled receipt - customer orders due before next MPS scheduled receipt
    第2、4和6期的ATP(有MPS计划接收的时期) = MPS计划接收 - 客户订单在下一个MPS计划接收之前到期

With the instructor, work through the solution.
与讲师一起,完成解决方案。

How many uncommitted units are expected to be promised to orders in week 1, and later in weeks 4 and 5?
在第1周,以及第4周和第5周,预计会有多少未交付的单元得到订单?


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