Operations Management Classroom Presentation
- 1. Operations Management MBA 1st Year Term-II Department of Management Studies Nalsar University of Law, Hyderabad Session 16 Asish Kumar Panda
- 2. 2 Problem 8 • A company makes bicycles. It produces 450 bicycles a month. It buys the tyres for bicycles from a supplier at a cost of Rs. 200 per tyre. The company’s inventory carrying cost is estimated to be 15% of cost and the ordering is Rs.500 per order. • Calculate the EOQ • What is the number of orders per year • What is the average annual ordering cost • What is the average inventory • What is the average annual carrying cost • Compute the total annual cost
- 3. Benefits of MRP 1. Better response to customer orders 2. Faster response to market changes 3. Improved utilization of facilities and labor 4. Reduced inventory levels
- 4. Dependent Demand The demand for one item is related to the demand for another item Given a quantity for the end item, the demand for all parts and components can be calculated In general, used whenever a schedule can be established for an item MRP is the common technique
- 5. Dependent Demand 1. Master production schedule 2. Specifications or bill of material 3. Inventory availability 4. Purchase orders outstanding 5. Lead times Effective use of dependent demand inventory models requires the following
- 6. Master Production Schedule (MPS) Specifies what is to be made and when Must be in accordance with the aggregate production plan Inputs from financial plans, customer demand, engineering, supplier performance As the process moves from planning to execution, each step must be tested for feasibility The MPS is the result of the production planning process
- 7. Master Production Schedule (MPS) MPS is established in terms of specific products Schedule must be followed for a reasonable length of time The MPS is quite often fixed or frozen in the near term part of the plan The MPS is a rolling schedule The MPS is a statement of what is to be produced, not a forecast of demand
- 8. Master Production Schedule (MPS) A customer order in a job shop (make-to- order) company Modules in a repetitive (assemble-to-order or forecast) company An end item in a continuous (stock-to- forecast) company Can be expressed in any of the following terms:
- 9. BOM Example B(2) Std. 12” Speaker kit C(3) Std. 12” Speaker kit w/ amp-booster 1 E(2) E(2) F(2) Packing box and installation kit of wire, bolts, and screws Std. 12” Speaker booster assembly 2 D(2) 12” Speaker D(2) 12” Speaker G(1) Amp-booster 3 Product structure for “Awesome” (A) A Level 0
- 10. BOM Example B(2) Std. 12” Speaker kit C(3) Std. 12” Speaker kit w/ amp-booster 1 E(2) E(2) F(2) Packing box and installation kit of wire, bolts, and screws Std. 12” Speaker booster assembly 2 D(2) 12” Speaker D(2) 12” Speaker G(1) Amp-booster 3 Product structure for “Awesome” (A) A Level 0 Part B: 2 x number of As = (2)(50) = 100 Part C: 3 x number of As = (3)(50) = 150 Part D: 2 x number of Bs + 2 x number of Fs = (2)(100) + (2)(300) = 800 Part E: 2 x number of Bs + 2 x number of Cs = (2)(100) + (2)(150) = 500 Part F: 2 x number of Cs = (2)(150) = 300 Part G: 1 x number of Fs = (1)(300) = 300
- 11. Bills of Material Modular Bills Modules are not final products but components that can be assembled into multiple end items Can significantly simplify planning and scheduling
- 12. Accurate Records Accurate inventory records are absolutely required for MRP (or any dependent demand system) to operate correctly Generally MRP systems require 99% accuracy Outstanding purchase orders must accurately reflect quantities and scheduled receipts
- 13. Lead Times The time required to purchase, produce, or assemble an item For production – the sum of the order, wait, move, setup, store, and run times For purchased items – the time between the recognition of a need and the availability of the item for production
- 14. Time-Phased Product Structure | | | | | | | | 1 2 3 4 5 6 7 8 Time in weeks F 2 weeks 3 weeks 1 week A 2 weeks 1 week D E 2 weeks D G 1 week 1 week 2 weeks to produce B C E Start production of D Must have D and E completed here so production can begin on B Figure 14.4
- 15. Determining Gross Requirements Starts with a production schedule for the end item – 50 units of Item A in week 8 Using the lead time for the item, determine the week in which the order should be released – a 1 week lead time means the order for 50 units should be released in week 7 This step is often called “lead time offset” or “time phasing”
- 16. Determining Gross Requirements From the BOM, every Item A requires 2 Item Bs – 100 Item Bs are required in week 7 to satisfy the order release for Item A The lead time for the Item B is 2 weeks – release an order for 100 units of Item B in week 5 The timing and quantity for component requirements are determined by the order release of the parent(s)
- 17. Determining Gross Requirements The process continues through the entire BOM one level at a time – often called “explosion” By processing the BOM by level, items with multiple parents are only processed once, saving time and resources and reducing confusion Low-level coding ensures that each item appears at only one level in the BOM
- 18. Gross Requirements Plan Table 14.3 Week 1 2 3 4 5 6 7 8 Lead Time equired date 50 rder release date 50 1 week equired date 100 rder release date 100 2 weeks equired date 150 rder release date 150 1 week equired date 200 300 rder release date 200 300 2 weeks equired date 300 rder release date 300 3 weeks equired date 600 200 rder release date 600 200 1 week equired date 300 rder release date 300 2 weeks
- 21. Determining Net Requirements Starts with a production schedule for the end item – 50 units of Item A in week 8 Because there are 10 Item As on hand, only 40 are actually required – (net requirement) = (gross requirement - on- hand inventory) The planned order receipt for Item A in week 8 is 40 units – 40 = 50 - 10
- 22. Determining Net Requirements Following the lead time offset procedure, the planned order release for Item A is now 40 units in week 7 The gross requirement for Item B is now 80 units in week 7 There are 15 units of Item B on hand, so the net requirement is 65 units in week 7 A planned order receipt of 65 units in week 7 generates a planned order release of 65 units in week 5
- 23. Determining Net Requirements A planned order receipt of 65 units in week 7 generates a planned order release of 65 units in week 5 The on-hand inventory record for Item B is updated to reflect the use of the 15 items in inventory and shows no on-hand inventory in week 8 This is referred to as the Gross-to-Net calculation and is the third basic function of the MRP process
- 24. Net Requirements Plan The logic of net requirements Available inventory Net requirements On hand Scheduled receipts + – = Total requirements Gross requirements Allocations +
- 25. Gross Requirements Schedule Figure 14.6 A B C 5 6 7 8 9 10 11 40 50 15 Lead time = 4 for A Master schedule for A S B C 12 13 8 9 10 11 20 30 40 Lead time = 6 for S Master schedule for S 1 2 3 10 10 Master schedule for B sold directly Periods Therefore, these are the gross requirements for B Gross requirements: B 10 40 50 20 40+10 15+30 =50 =45 1 2 3 4 5 6 7 8 Periods
- 26. MRP Planning Sheet Figure 14.7
- 27. Safety Stock BOMs, inventory records, purchase and production quantities may not be perfect Consideration of safety stock may be prudent Should be minimized and ultimately eliminated Typically built into projected on-hand inventory
- 28. MRP Management MRP is a dynamic system Facilitates replanning when changes occur System nervousness can result from too many changes Time fences put limits on replanning Pegging links each item to its parent allowing effective analysis of changes
- 29. MRP and JIT MRP is a planning system that does not do detailed scheduling MRP requires fixed lead times which might actually vary with batch size JIT excels at rapidly moving small batches of material through the system
- 30. • is a computer system that integrates application programs in accounting, sales, manufacturing, and other functions in the firm • This integration is accomplished through a database shared by all the application programs ERP Systems
- 32. Major ERP Providers Firm HQ Acquisitions 2004 Share of $23.6B Market SAP Germany 40% Oracle US People Soft JD Edwards 22% Sage Group UK 7% Microsoft US 3% Infor US SSA Baan Source: AMR Research
- 33. • Desire to standardize and improve processes • To improve the level of systems integration • To improve information quality Reasons to Implement ERP
- 34. ERP Drawbacks • Cost – $250M+ for a Fortune 100 company • Transition pain –Implementation resources –Training –Resistance to change
- 35. Summary and Conclusions… • Master Production Schedule (MPS) converts aggregate plan to a detailed schedule • Primary inputs to MRP are MPS, BOM’s (for part relationships) and Inventory Records (for lead times and inventory position) • MRP is a push system but can be used in conjunction with pull systems • MRP grew and evolved to include closed-loop, Manufacturing Resource Planning (MRP II), and eventually ERP
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