Materials Requirements Planning

Transcription

1 Materials Requirements Planning

2 Independent and Dependent Demand Independent Demand A Dependent Demand B(4) C(2) D(2) E(1) D(3) F(2) Independent demand is uncertain. Dependent demand is certain.

3 Dependent Demand Dependent demand: Demand for items that are subassemblies or component parts to be used in production of finished goods. Once the independent demand is known, the dependent demand can be determined.

4 Material Requirements Planning Defined Materials requirements planning (MRP) is a computerized inventory planning and control system for determining when (no earlier and no later) and how many of each of the parts, components, and materials should be ordered or produced. It translates master schedule requirements from end items into time-phased requirements for subassemblies, components and raw materials. Dependent demand drives MRP MRP is a software system

5 Material Requirements Planning System Based on a master production schedule, a material requirements planning system: Creates schedules identifying the specific parts and materials required to produce end items Determines exact unit numbers needed Determines the dates when orders for those materials should be released, based on lead times

6 6 Firm orders from known customers Aggregate production plan Forecasts of demand from random customers Engineering design changes Master production Schedule (MPS) Inventory transactions Bill of material file Primary reports Planned order schedule for inventory and production control (work orders, purchase orders), rescheduling notices Material planning (MRP computer program) Secondary reports Inventory record file Exception reports Planning reports Reports for performance control The McGraw-Hill Companies, Inc., 2004

7 MRP System MRP Inputs MRP Processing MRP Outputs Master schedule Bill of materials MRP computer programs Primary reports Secondary reports Changes Order releases Planned-order schedules Exception reports Planning reports Performancecontrol reports Inventory records Inventory transaction

8 MRP Inputs 1: Master Production Schedule Drives MRP process with a schedule of finished products; states which end items are to be produced, when these are needed, and in what quantities Quantities may consist of a combination of customer orders & demand forecasts Quantities represent what needs to be produced, not what can be produced

9 Master Production Schedule (MPS) Time-phased plan specifying how many and when the firm plans to build each end item Aggregate Plan (Product Groups) MPS (Specific End Items)

10 Master Production Schedule Example: Shows items to be produced Derived from aggregate plan Item / Week Oct 3 Oct. 10 Oct. 17 Oct.24 Oct. 31 Clipboard Lapdesk Lapboard Pencil Case

11 MRP Inputs 2: Bill-of-Materials Bill of materials (BOM): One of the three primary inputs of MRP; 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.

12 Level 0 Product Structure Tree: Example 1 Chair 1 Leg Assembly Seat Back Assembly 2 Legs (2) Cross bar Side Rails (2) Cross bar Back Supports (3) 3

13 Product Structure Tree: Example 2 Bicycle(1) P/N 1000 Handle Bars (1) P/N 1001 Frame Assembly (1) P/N 1002 Wheels (2) P/N 1003 Frame (1) P/N 1004

14 Product Drawing: Example 3 Clipboard Top clip (1) Bottom clip (1) Pivot (1) Spring (1) Finished clipboard Pressboard (1) Rivets (2)

15 Product Structure Tree ( Example 3) Clipboard Level 0 Pressboard (1) Clip Ass y (1) Rivets (2) Level 1 Top Clip (1) Bottom Clip (1) Pivot (1) Spring (1) Level 2

16 13-16 MRP and ERP Gross Requirements: needed during each period. Scheduled Receipts: Existing orders that arrive at beginning of period. On-hand or available balance: (depending on software convention, could be at the beginning of each period or end): Book: Inventory balance at end of each period. Net requirements: What is need to meet requirements and safety stock. Planned order receipt: arrives at beginning of period. Planned order release: Addresses lead time.

17 MRP Inputs 3: Inventory Records File One of the three primary inputs of MRP Includes information on the inventory status of each item by time period Gross requirements Scheduled receipts Amount on hand Lead times Lot sizes And more...

18 MRP Terminology (1 of 3) Gross requirements Scheduled receipts Projected on hand Net requirements Planned-order receipts Planned-order releases

19 MPR Terminology (2 of 3) Gross requirements Total expected demand Scheduled receipts Open orders scheduled to arrive Projected on hand Expected inventory on hand at the beginning of each time period

20 MRP Processing Terminology (3 of 3) Net requirements Actual amount needed in each time period Gross requirements available inventory Planned-order receipts Quantity expected to be received at the beginning of the period Offset by lead time Planned-order releases Planned amount to be ordered in each time period

21 MRP Processing: Example 1-School Mate Products Master Production Schedule Clipboard Lapdesk Item Master File (ınventory record file CLIPBOARD LAPDESK PRESSBOARD On hand On order 175 (Period 1) 0 0 (sch receipt) LLC Lot size L4L Mult 50 Min 100 Lead time 1 1 1

22 School Mate Products Product Structure Record Clipboard Level 0 Pressboard (1) Clip Ass y (1) Rivets (2) Level 1 Lapdesk Level 0 Pressboard (2) Trim (3 ) Beanbag (1) Glue (4 oz) Level 1

23 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Gross Requirements Scheduled Receipts 175 Projected on Hand 25 Net Requirements Planned Order Receipts Planned Order Releases

24 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Gross Requirements Scheduled Receipts 175 Projected on Hand Net Requirements 0 Planned Order Receipts Planned Order Releases ( ) = 200 units available (200-85) = 115 on hand at the end of Period 1

25 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Gross Requirements Scheduled Receipts 175 Projected on Hand Net Requirements 0 0 Planned Order Receipts Planned Order Releases 115 units available (115-85) = 20 on hand at the end of Period 2

26 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Gross Requirements Scheduled Receipts 175 Projected on Hand Net Requirements Planned Order Receipts 100 Planned Order Releases units available (20-120) = additional Clipboards are required Order must be placed in Period 2 to be received in Period 3

27 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Gross Requirements Scheduled Receipts 175 Projected on Hand Net Requirements Planned Order Receipts Planned Order Releases Following the same logic Gross Requirements in Periods 4 and 5 develop Net Requirements, Planned Order Receipts, and Planned Order Releases

28 School Mate Products ITEM: LAPDESK LLC: 0 PERIOD LOT SIZE: MULT 50 LT: Gross Requirements Scheduled Receipts Projected on Hand 20 Net Requirements Planned Order Receipts Planned Order Releases

29 School Mate Products ITEM: LAPDESK LLC: 0 PERIOD LOT SIZE: MULT 50 LT: Gross Requirements Scheduled Receipts Projected on Hand Net Requirements Planned Order Receipts Planned Order Releases Following the same logic, the Lapdesk MRP matrix is completed as shown

30 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Planned Order Releases ITEM: LAPDESK LLC: 0 PERIOD LOT SIZE: MULT 50 LT: Planned Order Releases ITEM: PRESSBOARD LLC: 0 PERIOD LOT SIZE: MIN 100 LT: Gross Requirements Scheduled Receipts Projected on Hand 150 Net Requirements Planned Order Receipts Planned Order Releases

31 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Planned Order Releases ITEM: LAPDESK LLC: 0 PERIOD LOT SIZE: MULT 50 LT: Planned Order Releases ITEM: PRESSBOARD LLC: 0 x2 x1 x2 PERIOD x1 x1 LOT SIZE: MIN 100 LT: Gross Requirements Scheduled Receipts Projected on Hand 150 Net Requirements Planned Order Receipts Planned Order Releases

32 School Mate Products ITEM: CLIPBOARD LLC: 0 PERIOD LOT SIZE: L4L LT: Planned Order Releases ITEM: LAPDESK LLC: 0 PERIOD LOT SIZE: MULT 50 LT: Planned Order Releases ITEM: PRESSBOARD LLC: 0 PERIOD LOT SIZE: MIN 100 LT: Gross Requirements Scheduled Receipts Projected on Hand Net Requirements Planned Order Receipts Planned Order Releases

33 School Mate Products Planned Order Report PERIOD ITEM Clipboard Lapdesk Pressboard

34 Capacity Usually expressed as standard machine hours or labor hours Capacity = (no. machines or workers) x (no. shifts) x (utilization) x (efficiency)