Production Planning and Control
Professor JIANG Zhibin
Dr GRANG Na
Department of Industrial Engineering & Management
Shanghai Jiao Tong University
Chapter 7
Contents
•
Introduction
•
Master Production Scheduling (MPS)
•
Material Requirement Planning (MRP)
•
Capacity Planning
Overview of Production Planning Activities
Production Planning:
Given specific process planning, process technologies, and production conditions, production planning predetermine varieties, quantities, quality, and schedules of products to be produced according to market demand of products.
Figure 4.1 Framework of Production Planning Activities Process Planning
Aggregate Planning
Master Production Scheduling (MPS)
Material Requirement Planning (MRP)
Operations Scheduling (Shop floor Scheduling & Control) Demand Forecast Rough-cut capacity Planning Long Range Medium Range Short range
Strategic capacity Planning
Capacity Req. Planning Order
Time Dimensions:
• Long-range planning is done annually and focus on a planning horizon greater than one year;
• Medium-range planning usually covers a period from 6 months to 18 months, with monthly or sometimes quarterly time increments;
• Short-range planning covers a period from one day or less to six months, with weekly time increment usually.
Figure 4.1 Framework of Production Planning Activities Process Planning
Aggregate Planning
Master Production Scheduling (MPS)
Material Requirement Planning (MRP)
Operations Scheduling (Shop floor Scheduling & Control) Demand Forecast Rough-cut capacity Planning Long Range Medium Range Short range
Strategic capacity Planning
Capacity Req. Planning Order
Management
• Process Planning determines the specific technologies and procedures required to produce a product a service.
• Strategic capacity planning determines long-term capabilities (e. g. size and scope)
• Aggregate planning concerns with setting up production rate by product family or other categories for intermediate term (6-18 months).
Figure 4.1 Framework of Production Planning Activities Process Planning
Aggregate Planning
Master Production Scheduling (MPS)
Material Requirement Planning (MRP)
Operations Scheduling (Shop floor Scheduling & Control) Demand Forecast Rough-cut capacity Planning Long Range Medium Range Short range
Strategic capacity Planning
Capacity Req. Planning Order
Management
• Master production scheduling generates the amounts and dates of specific items required by orders.
• The inputs into MPS are arrived orders and AP results.
• Rough-cut capacity planning is used to verify that the production and warehouse facilities, equipment, and labor are available , and the key suppliers have allocated sufficient capacity to provide materials when needed.
Figure 4.1 Framework of Production Planning Activities Process Planning
Aggregate Planning
Master Production Scheduling (MPS)
Material Requirement Planning (MRP)
Operations Scheduling (Shop floor Scheduling & Control) Demand Forecast Rough-cut capacity Planning Long Range Medium Range Short range
Strategic capacity Planning
Capacity Req. Planning Order
Management
• Material requirement planning takes the end product
requirements from MPS and breaks them down into their components and subassemblies to create a material plan
(production orders and purchase order).
• Capacity requirement planning (CAP) allocate production
resources to each production order.
• Operations scheduling allocates jobs to specific
machines, production lines or work centers.
Figure 4.1 Framework of Production Planning Activities Process Planning
Aggregate Planning
Master Production Scheduling (MPS)
Material Requirement Planning (MRP)
Operations Scheduling (Shop floor Scheduling & Control) Demand Forecast Rough-cut capacity Planning Long Range Medium Range Short range
Strategic capacity Planning
Capacity Req. Planning Order
Management
Chapter 7 Production Planning
Contents
•
Introduction
•
Master Production Scheduling (MPS)
•
Material Requirement Planning (MRP)
•
Capacity Planning
Month 1 2 Mattress production 900 950 Week 1 2 3 4 5 6 7 8 Model 327 200 400 200 100 Model 538 100 100 150 100 Model 749 100 200 200
MPS for mattress models
Aggregate production plan for mattress
• Aggregate production plan for mattress specifies the total number of mattress planned per month, without regard of mattress types; • MPS specifies the exact types of mattress and quantities planned
for production by week.
Mater Production Scheduling
•
Aggregate planning specifies product groups, rather than exact items;•
As the next level down in the planning process, MPS is time phased plan that specifies how many and when a firm to build each end item.•
In the case of the furniture company Its AP may specify the total volume of mattress it plan to produce over next month, e. g. 900 for the next 1 month;
Its MPS identifies period by period ( usually weekly)
which mattress styles and how many of these mattress styles are needed, 200 Model 200 for Wk 1, 100 Model 538 for both Wks 2 and 3 respectively, and 100 Model 749 for Wk 3...
Week 1 2 3 4 5 6 7 8
Model 327 200 400 200 100
Model 538 100 100 150 100
Mater Production Scheduling
Could a MPS be changed?-Flexibility of MPS
When updated?
• New order arrives;
• Unfinished orders when the products are delayed; • Some work center becomes bottleneck;
• There are shortage of raw material • Other reasons.
• MPS needs the continuous revisions:
Production lead time;
The cycle of demand forecasting;
Mater Production Scheduling
• MPS needs continuous revisions in order to meet the needs of customers by reducing the inventory, on time delivering, and improving the production efficiency.
• Rolling production plan is used to make MPS.
• Rolling production plan is to update the production plan over a predetermined horizon based on the planned production.
Key problems when making MPS
• The connection with APP
APP considers the production level and workforce level;
Production level in APP is broken down into the demand in every period with respect to each end product;
Combining with the initial inventory, the broken production level is the forecasted demand in MPS.
Key problems when making MPS
• The frozen period of MPS : • MPS is the basis of MRP.
• The revision of MPS, especially that has been implemented, impacts MRP, which leads to the increase of the cost.
• The way to deal with this problem is to set different time fences during which MPS can’t be revised or easily revised: demand frozen time fence and planning frozen time fence.
Key problems when making MPS
• The frozen period of MPS :
• Demand frozen time fence: During the period from now to demand frozen time fence, MPS can’t be revised without the permit of managing executives.
• Planning frozen time fence: it is longer than demand frozen time fence. During the period from demand frozen time fence to planning frozen time fence, the application software can’t revise MPS, but the planner can revise it.
Key problems when making MPS
Figure 4.2 MPS Time Fences
• Each company may have its own time fences and operating rules
• Frozen: absolutely no change could be made in a firm, or the most minor changes may be allowed in another.
• Moderately firm: some changes to specific products within a products group so long as parts are available;
• Flexible: almost an variations in products are allowable, providing that capacity remains about the same and that there are no long lead time items involved.
Alternatives of MPS in different production types
• MPS is to determine the quantity of each end product in every period.
For MTS, end product is the finished product.
For ATO, end products are the components and parts. For MTO, end products are raw materials and basic
