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Capacity Requirements Planning

the vital third dimension to your manufacturing resource planning

downloadcrp0You can purchase this 11 page, fully illustrated e-book on capacity requirements planning (CRP) for 4.95 (about US$8 or €7) by clicking the image on the right.

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Capacity Requirements Planning eBook details - capacity planning is the vital third dimension to your manufacturing resource planning. If you do not check to make sure your work centres are not overloaded you cannot know that your master schedule is a realistic and achievable plan. If your plan is not realistic and achievable you do not have a plan, you have a wish list.

Capacity requirements planning is one of the most useful but most often ignored benefits of having an MRPII or ERP system implemented. Once you have set up and understood how to use capacity requirements planning, it requires almost no extra maintenance cost as it uses the information you already have on the system for material planning. Capacity requirements planning gives you a visual picture of the work load on all your work centres so that you can get the most from bottlenecks and balance the load across the business.

Contents :

  1. Introduction
  2. Capacity Planning Requirements
  3. Work Centres
  4. Routing
  5. The Capacity Requirements Calculation
  6. Annualised Hours
  7. Input / Output Control
  8. Finite Capacity Planning
  9. Production Model


One of the biggest differences between MRP (material requirements planning) and MRP II (manufacturing resource planning) or ERP (Enterprise Resource Planning) is the recognition that planning material is not sufficient, a company also needs to plan its other resources so that both material and resources are available at the same time. Problems with material must affect the capacity plans, problems with capacity also have to affect the material plans. Planning of these resources is carried out at three levels in the MRP II process. At the sales and operations planning stage a rough cut capacity plan is used to check on critical resource availability. Rough cut capacity planning looks at just the critical resources used by each product family over a time scale of between 15 months and many years depending on the company.<.p>

crpcogsWhere the mix within a family or the timing within a month affects the usage of a critical resource, it is also necessary to carry out a rough cut capacity check at the master schedule level. At this level you are looking at the critical resource requirement of end items generally up to the cumulative lead time.

Capacity requirements planning, on the other hand, is carried out at the part number level and looks at every work centre. In addition, the resource required is calculated for every planning period, normally a day, rather than by the month only as with the rough cut capacity planning on the sales and operations plan or by week if rough cut capacity planning is used at the master production schedule level.

Rough cut capacity planning makes a number of assumptions. Rough cut at both the family and master schedule item level assumes all the critical resources will be required at the same time as the product is sold or the master schedule part is required. Rough cut also does not take stock of work in progress into consideration and does not take account of batch sizes. Capacity requirements planning, on the other hand, calculates the capacity requirements that will be required to meet the master schedule taking all planning criteria into consideration.

The other major difference between the rough cut planning techniques and capacity requirements planning is that the rough cut processes are tests of the feasibility of the plan. The plans will be modified or decisions taken to change resources available and the promise date for customer orders based on the outcome of the rough cut process. At the capacity requirements planning level, an order may already have been received and a commitment made to the customer or, in a make to stock environment, a commitment made to a marketing plan. If the rough cut process is working correctly, the master production schedule should be achievable. Any adjustments to the plans should be at the detail level or to take account of problems and interruptions, we do not want to have to contact the customer and change the delivery date promised.

The same material requirements planning logic that determine what material we need and when we need it also determines what capacity we need and when we need it. We do, however, need a capacity planning structure in place before we can do this.

You can purchase this e-book by credit card for 4.95 (about US$8 or €7) by clicking the "Buy crp E-Book" image at the top of this page.


This e-book plus 10 more like it can be purchased together in the compendium book "Business Excellence - the integrated solution to manufacturing planning and control" price 24.90, about 45US$ / €37. . . more details