1 / 12

Chapter 18. Materials Requirements Planning

Chapter 18. Materials Requirements Planning. Outline: Material Requirements Planning (MRP) Master Production Schedule (MPS) Bill of Materials (BOM) Time Fences MRP Logic and Product Structure Trees MRP Examples MRP and Lot Sizing MRP & Capacity Requirements Planning (CRP).

uriah-orr
Download Presentation

Chapter 18. Materials Requirements Planning

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 18. Materials Requirements Planning Outline: • Material Requirements Planning (MRP) • Master Production Schedule (MPS) • Bill of Materials (BOM) • Time Fences • MRP Logic and Product Structure Trees • MRP Examples • MRP and Lot Sizing • MRP & Capacity Requirements Planning (CRP)

  2. Materials Requirements Planning • Materials requirements planning (MRP) is a means for determining the number of parts, components, and materials needed to produce a product (end item) • Dependent vs. independent demand • MRP provides time scheduling information specifying when each of the subassemblies, parts, and components should be ordered or produced • What, when, how many? • Dependent demand drives MRP • MRP is an information system

  3. Materials Requirements Planning • Critical input and data requirements: • Master Production Schedule (MPS) • Bill of Materials (BOM) • Inventory database • Many outputs – primary ones are: • Planned orders to be released at a future time. • Order release notices to execute the planned orders. • Changes in due dates of open orders due to rescheduling. • Cancellations or suspensions of open orders due to cancellation or suspension of orders on the master production schedule. • Inventory status data. Planned order releases

  4. MPS (Specific End Items) Master Production Schedule (MPS) • MPS: One of three primary inputs in MRP • Time-phased plan specifying how many and when the firm plans to build each end item • Developed by disaggregating the “aggregate plan” Aggregate Plan (Product Groups) Week

  5. Bill of Materials (BOM) • BOM: a listing of all of the raw materials, parts, subassemblies, and assemblies needed to produce one unit of a product. • Product structure tree: Visual depiction of the requirements in a bill of materials, where all components are listed by levels. • A simple question: For 100 “M”s how many…

  6. BOM - tree format and low level coding Low-level coding requires that when an identical item occur on multiple levels, then it should be “lowered” to its lowest level for computational reasons. The software will complete all level 0 items first, then all level 1 items, etc. In the original diagram (a) since N appears on levels 1 & 2 In the final diagram (b) (after re-classification) it is lowered to level 2. Also, note that S under P was on level 3, which needed to be lowered to level 4

  7. Time Fences • Frozen • No schedule changes allowed within this window • Moderately Firm • Specific changes allowed within product groups as long as parts are available • Flexible • Significant variation allowed as long as overall capacity requirements remain at the same levels

  8. MRP – The System

  9. MRP Example • Solved problem 1. • MPS: 100 units of X for week 10 • Lead times are on the Excel sheet (given in the book) • Excel time!

  10. Lot Sizing in MRP Programs • The default order size is Lot-for-lot (L4L) • However, for purchased items or for technical reasons, there may be minimum or maximum order sizes • Purchased items/subassemblies may require multiples of predetermined amounts (e.g., multiples of 50) • An example: Problem 5. Excel time. • Common lot-sizing methods are: • Economic order quantity (EOQ) • Least total cost (LTC) • Least unit cost (LUC) • Which one to use? • The one that is least costly!

  11. MRP, Capacity Requirements Planning, and MRP II • Consider the expanded logic flow of MRP II. • When utilized cleverly: • It can be used to lower levels of in-process inventories (Lot-sizing?) • Ability to track material requirements • Ability to evaluate capacity requirements • The basic functions of the capacity requirements planning (CRP) system are: • To calculate the capacity needs based on the planned orders from MRP schedules • To compare the capacity required to the capacity available • Routing charts show the specific departments that each part goes through as well as setup and process times in those departments • Means of allocating production time • Ability to Simulate the manufacturing system

  12. A B(2) C(4) C(2) D(5) Capacity Requirements Planning (CRP) • A small scale CRP example. • MPS for item A is: • 30, 24, 37 units for weeks 7, 8, and 10 • Lead times for A, …, D are: • 1, 2, 3, and 1 week, respectively. • Routing chart for item A is: • Dept 4 (only) • Setup time is 2.0 hours • Processing time is 0.25 hours/unit. • The complete routing chart is available on the Excel file. • Group exercise: Complete the MRP schedules and compute work center load profiles • Excel time!

More Related