1 CHAPTER 12 MRP AND ERP Solutions 2 Given We have the following information Item End B C D E F G H LT (wk) 1 2 3 3 1 2 1 2 Amount on hand 0 10 10 25 12 30 5 0 a If 20 units of the end item are to be[.]
CHAPTER 12 MRP AND ERP Solutions Given: We have the following information: End Item B(2) E(2) Item C F(3) D(3) G(2) E(2) H(4) E(2) End B C D E F G H LT (wk) 3 2 Amount on hand 10 10 25 12 30 a If 20 units of the end item are to be assembled, how many additional units of E are needed? Step 1: Determine the gross requirements and the net requirements for the End Item: Item Gross Requirements – On Hand = Net Requirements End Item 20 – = 20 Step 2: Determine the gross requirements and the net requirements for B, C, & D Multiply the net requirements for the end item by the usage quantities of B, C, & D to determine the gross requirements for B, C, & D Item Gross Requirements – On Hand = Net Requirements B (20 * 2) = 40 – 10 = 30 C (20 * 1) = 20 – 10 = 10 D (20 * 3) = 60 – 25 = 35 Step 3: Determine the gross requirements and net requirements for E Multiply the net requirements for B, C, & D by the usage quantities of E to determine gross requirements for E Item Gross Requirements – On Hand = Net Requirements [(30 B * 2) + (10 C * 2) + (35 D * 2)] = 150 – 12 = E 138 b Given: An order for the end item is to be shipped at the start of week 11 Determine the latest week that the order could be started To solve this, we need to determine the longest sequence through the product structure tree moving from the end item down to the lowest items The lead time for each item is indicated in bold to the left of each item in the product structure tree shown below wk End Item wk B(2) wk E(2) wk C wk F(3) wk G(2) wk wk Total LT = wk wk D(3) wk E(2) wk H(4) wk wk wk wk wk wk E(2) wk wk wk The longest sequence is weeks (Due time – (End Item + D + H)) 11 – weeks = start of week Given: Eighty units of end item E are needed at the beginning of week Three cases (30 units per case) of J have been ordered, and one case is scheduled to arrive in week 3, one in week 4, and one in week Note: J must be ordered by the case, and B must be produced in multiples of 120 units There are 60 units of B and 20 units of J on hand Lead times are weeks each for E and B, and week for J The product structure tree is shown below: E B(2) J(4) J(3) F(2) a Determine a material requirements plan for J We will need to prepare material plans for E, B, and J All given information is highlighted in bold in the tables below POH is the projected on hand inventory at the beginning of each period All MRP problems below will use the following formula to determine POH: POH (Current Period) = [POH + Planned-Order Receipts – Gross Requirements (Prior Period)] + Scheduled Receipts (Current Period) or using subscripts, we have the following: POHt = [POHt-1 + Planned-Order Receiptst-1 – Gross Requirementst-1] + Scheduled Receiptst Net Requirements = Max[(Gross Requirements – POH), 0] Note: This ensures that we have net requirements only when the Gross Requirements > POH Master Schedule for: E Week Quantity E LT = Lot size: Lot-for-Lot Gross requirements 80 Beg Inv 80 Scheduled receipts Projected on hand 0 0 0 Net requirements 80 Planned-order receipts 80 Planned-order releases B(2) LT = Lot size: Multiples of 120 80 Beg Inv Gross requirements 20 20 160 Scheduled receipts Projected on hand 60 60 60 60 60 Net requirements 100 Planned-order receipts 120 Planned-order releases 120 Notes: Gross Requirements (week 4) = Planned-Order Releases of 80 E * = 160 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [60 + – 0] + = 60 POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [60 + 120 – 160] + = 20 J(3) & J(4) LT = Lot size: Multiples of 30 Beg Inv Gross requirements 480 Scheduled receipts Projected on hand 20 20 20 240 30 30 30 50 80 50 Net requirements 460 160 Planned-order receipts 480 180 50 Planned-order releases 480 180 Notes: Gross Requirements (week 2) = Planned-Order Releases of 120 B * = 480 Gross Requirements (week 4) = Planned-Order Releases of 80 E * = 240 POH3 = [POH2 + Planned-Order Receipts2 – Gross Requirements2] + Scheduled Receipts3 POH3 = [20 + 480 – 480] + 30 = 50 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [50 + – 0] + 30 = 80 POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [80 + 180 – 240] + 30 = 50 POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6 POH6 = [50 + – 0] + = 50 Planned-Order Receipts (week 2) = 16 * 30 = 480 (must order in cases of 30) Planned-Order Receipts (week 4) = * 30 = 180 (must order in cases of 30) b Suppose that in week the quantity of E needed is changed from 80 to 70 units The planned-order releases through week have all been executed How many more Bs and Js will be on hand in week 6? Note: We are now at the start of week Step 1: Before we the MRP processing, we list what changes have occurred: All Planned-Order Releases in weeks – have been executed B had Planned-Order Releases in week (120) corresponding to Planned-Order Receipts (120) in week Change the Planned-Order Receipts to Scheduled Receipts in week J had Planned-Order Releases in week (480) corresponding to Planned-Order Receipts (480) in week The Planned-Order Receipts would have been changed to Scheduled Receipts and received in week (this increases inventory) J had Planned-Order Releases in week (180) corresponding to Planned-Order Receipts (180) in week These will show up as Scheduled Receipts in week and will be added to the original amount of Scheduled Receipts (30) in week Scheduled Receipts for J in week (30) would have been received (this increases inventory) Gross requirements for all items in weeks – would have been disbursed (these transactions decrease inventory) Step 2: Determine the ending inventory for each item at the end of week These will become the beginning inventory balances in week Remember: Scheduled receipts increase inventory while gross requirements decrease inventory Ending Inventory = Beginning Inventory + Scheduled Receipts – Gross Requirements Item E Ending Inventory Week 0+0–0=0 Week 0+0–0=0 Week 0+0–0=0 Item B Ending Inventory Week 60 + – = 60 Week 60 + – = 60 Week 60 + – = 60 Item J Ending Inventory Week 20 + – = 20 Week 20 + 480 – 480 = 20 Week 20 + 30 – = 50 Step 3: Fill in all beginning inventory balances and scheduled receipts, and then change E to 70 units in week of the master schedule Our MRP tables are shown for weeks – only Master Schedule for: E Week Quantity E LT = Lot size: Lot-for-Lot Gross requirements 70 Beg Inv 70 Scheduled receipts Projected on hand 0 0 Net requirements 70 Planned-order receipts 70 Planned-order releases B(2) LT = Lot size: Multiples of 120 70 Beg Inv Gross requirements 140 Scheduled receipts 120 Projected on hand 180 60 40 40 Net requirements Planned-order receipts Planned-order releases Notes: POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [60 + – 0] + 120 = 180 POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [180 + – 140] + = 40 J(4) & J(3) LT = Lot size: Multiples of 30 Gross requirements Beg Inv 210 Scheduled receipts Projected on hand 50 210 30 260 80 80 Net requirements Planned-order receipts Planned-order releases Notes: Scheduled Receipts (week 4) = Original amount of 30 + 180 = 210 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [50 + – 0] + 210 = 260 POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [260 + – 210] + 30 = 80 POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6 POH6 = [80 + – 0] + = 80 Original on hand amounts (week 6): B = 20 & J = 50 Revised on hand amounts (week 6): B = 40 & J = 80 There will be an additional 20 units of B & 30 units of J on hand Given: The company that makes a table wants to ship 100 units at the beginning of day 4, 150 units at the beginning of day 5, and 200 units at the beginning of day Receipts of 100 wood sections are scheduled at the beginning of day On hand balances: Braces = 60 and Legs = 120 Lead times (in days) for all items are shown in the table below The product structure tree is shown below also: Quantity Lead Time 1-200 201-550 551-999 Table Wood Sections(2) Braces(3) Legs(4) Prepare a material requirements plan using lot-for-lot ordering for all items: Master Schedule for: Table Day Quantity Table Lot size: Lot-for-Lot Gross requirements Beg Inv 100 150 100 150 0 100 100 150 200 150 200 200 200 Scheduled receipts Projected on hand 0 Net requirements Planned-order receipts 0 Planned-order releases 100 150 200 Notes: POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [0 + 100 – 100] + = POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6 POH6 = [0 + 150 – 150] + = Planned-Order Releases (days 3, 4, & 6) were back-scheduled day from their Planned-Order Receipts because all lead times = day for quantities of 1-200 Wood Sections(2) Lot size: Lot-for-Lot Beg Inv 200 300 100 Net requirements 100 Planned-order receipts 100 300 300 Gross requirements Scheduled receipts Projected on hand 400 100 0 100 0 400 400 Planned-order releases 400 400 Notes: Gross Requirements (day 3) = Planned-Order Releases of 100 Tables * = 200 Gross Requirements (day 4) = Planned-Order Releases of 150 Tables * = 300 Gross Requirements (day 6) = Planned-Order Releases of 200 Tables * = 400 POH3 = [POH2 + Planned-Order Receipts2 – Gross Requirements2] + Scheduled Receipts3 POH3 = [100 + – 0] + = 100 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [100 + 100 – 200] + = Planned-Order Releases (day 2) = 100 from Planned-Order Receipts of 100 in day (lead time = day for quantities of 1-200) + 300 from Planned-Order Receipts of 300 in day (lead time = days for quantities of 201-550) = 400 Planned-Order Releases (day 4) = 400 from Planned-Order Receipts of 400 in day (lead time = days for quantities of 201-550) Braces(3) Lot size: Lot-for-Lot Gross requirements Beg Inv 300 450 60 240 240 450 600 450 600 600 Scheduled receipts Projected on hand 60 60 60 Net requirements Planned-order receipts 0 Planned-order releases 240 450 600 Notes: Gross Requirements (day 3) = Planned-Order Releases of 100 Tables * = 300 Gross Requirements (day 4) = Planned-Order Releases of 150 Tables * = 450 Gross Requirements (day 6) = Planned-Order Releases of 200 Tables * = 600 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [60 + 240 – 300] + = POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [0 + 450 – 450] + = Planned-Order Releases (day 1) = 240 from Planned-Order Receipts of 240 in day (lead time = days for quantities of 201-550) Planned-Order Releases (day 2) = 450 from Planned-Order Receipts of 450 in day (lead time = days for quantities of 201-550) Planned-Order Releases (day 3) = 600 from Planned-Order Receipts of 600 in day (lead time = days for quantities of 551-999) Legs(4) Lot size: Lot-for-Lot Beg Inv Gross requirements 400 600 120 280 280 600 800 600 800 800 Scheduled receipts Projected on hand 120 120 120 Net requirements Planned-order receipts 0 Planned-order releases 880 800 Notes: Gross Requirements (day 3) = Planned-Order Releases of 100 Tables * = 400 Gross Requirements (day 4) = Planned-Order Releases of 150 Tables * = 600 Gross Requirements (day 6) = Planned-Order Releases of 200 Tables * = 800 POH3 = [POH2 + Planned-Order Receipts2 – Gross Requirements2] + Scheduled Receipts3 POH3 = [120 + – 0] + = 120 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [120 + 280 – 400] + = POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [0 + 600 – 600] + = Planned-Order Releases (day 1) = 280 from Planned-Order Receipts of 280 in day (lead time = days for quantities of 201-550) + 600 from Planned-Order Receipts of 600 in day (lead time = days for quantities of 551-999) = 880 Planned-Order Releases (day 3) = 800 from Planned-Order Receipts of 800 in day (lead time = days for quantities of 551-999) Given: Oh No! Inc sells three models: A, B, and C Lead times are week for all items except C (2 weeks) On hand balances: B = 10, C = 10, and D = 25 units Lot-sizing rules are lot-for-lot for all items except D, which must be ordered in multiples of 100 There is a scheduled receipt of 100 units of D in week The master schedule shows that 40 units of A are needed at the beginning of week 4, 60 units of B at the beginning of week 5, and 30 units of C at the beginning of week The product structure tree for each item is shown below: A D B E C D(2) F D(4) G Prepare a material requirements plan for component D and its parents We will need to prepare material plans for A, B, C, and D Master Schedule for: A Week Quantity A LT = Lot size: Lot-for-Lot Gross requirements 6 0 40 Beg Inv 40 Scheduled receipts Projected on hand 0 0 Net requirements 40 Planned-order receipts 40 Planned-order releases Master Schedule for: B 40 Week Quantity B LT = Lot size: Lot-for-Lot Gross requirements 60 Beg Inv 60 Scheduled receipts Projected on hand 10 10 10 10 10 10 Net requirements 50 Planned-order receipts 50 Planned-order releases Master Schedule for: C 50 Week Quantity C LT = Lot size: Lot-for-Lot Gross requirements 30 Beg Inv 30 Scheduled receipts Projected on hand 10 10 10 10 10 10 10 Net requirements 20 Planned-order receipts 20 Planned-order releases D, D(2), & D(4) LT = Lot size: Multiples of 100 Gross requirements 20 Beg Inv Scheduled receipts Projected on hand 40 180 125 85 5 100 25 125 Net requirements 125 95 Planned-order receipts 100 Planned-order releases 100 Notes: Gross Requirements (week 3) = Planned-Order Releases of 40 A * = 40 Gross Requirements (week 4) = (Planned-Order Releases of 50 B * 2) + (Planned-Order Releases of 20 C * 4) = 100 + 80 = 180 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [125 + – 40] + = 85 POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [85 + 100 – 180] + = Planned-Order Receipts (week 5) = * 100 = 100 (must order in multiples of 100) 10 Given: 40 units of an industrial robot are needed at the beginning of week Subassembly G must be ordered in multiples of 80 and all other components are ordered lot-for-lot The inventory information (shown in bold) and the product structure tree are listed below in the problem solution Prepare the material plan for G We will need to prepare material plans for Robot, C, & G Robot C(3) B E Master Schedule for: Robot F G Week G(2) H Quantity Robot LT = Lot size: Lot-for-Lot Gross requirements Scheduled receipts Projected on hand Net requirements Planned-order receipts 40 Beg Inv 40 10 10 10 10 10 Planned-order releases C(3) LT = Lot size: Lot-for-Lot Gross requirements Scheduled receipts Projected on hand Net requirements Planned-order receipts Planned-order releases 10 10 10 30 30 0 30 Beg Inv 90 20 20 20 20 20 70 10 20 70 70 Notes: Gross Requirements (week 5) = Planned-Order Releases of 30 Robots * = 90 G & G(2) LT = Lot size: Multiples of 80 Gross requirements Scheduled receipts Projected on hand Net requirements Planned-order receipts Beg Inv 15 15 15 15 140 30 15 125 160 35 5 Planned-order releases 160 Notes: Gross Requirements (week 4) = Planned-Order Releases of 70 C * = 140 Gross Requirements (week 5) = Planned-Order Releases of 30 Robots * = 30 POH4 = [POH3 + Planned-Order Receipts3 – Gross Requirements3] + Scheduled Receipts4 POH4 = [15 + – 0] + = 15 POH5 = [POH4 + Planned-Order Receipts4 – Gross Requirements4] + Scheduled Receipts5 POH5 = [15 + 160 – 140] + = 35 POH6 = [POH5 + Planned-Order Receipts5 – Gross Requirements5] + Scheduled Receipts6 POH6 = [35 + – 30] + = 11 12 Given: 200 carts must be ready at the beginning of week The product structure tree, assembly time chart, and inventory information are shown in the solutions below: a Product structure tree: Golf Cart Top Supports(4) Base Cover Motor Body Frame Controls Seats(2) Wheels(4) Assembly Time Chart Supports Top b Cover Cart Motor Frame Body Controls Base Wheels Seats week Start of week Start of week 12 c Develop a material requirements plan that will provide 200 golf carts by week assuming lot-for-lot ordering Master Schedule for: Golf Cart Week Quantity Golf Cart LT = Lot size: Lot-for-Lot Gross requirements 200 Beg Inv 200 Scheduled receipts Projected on hand 0 0 0 0 Net requirements 200 Planned-order receipts 200 Planned-order releases Top LT = Lot size: Lot-for-Lot Gross requirements 200 Beg Inv 200 Scheduled receipts Projected on hand 40 40 40 40 40 40 40 40 Net requirements 160 Planned-order receipts 160 Planned-order releases 160 Notes: Gross Requirements (week 7) = Planned-Order Releases of 200 Golf Carts * = 200 Supports(4) LT = Lot size: Lot-for-Lot Gross requirements Beg Inv 0 640 Scheduled receipts Projected on hand 200 200 200 200 200 200 200 Net requirements 440 Planned-order receipts 440 Planned-order releases 440 Notes: Gross Requirements (week 6) = Planned-Order Releases of 160 Tops * = 640 Cover LT = Lot size: Lot-for-Lot Gross requirements Beg Inv 0 160 Scheduled receipts Projected on hand 0 0 0 Net requirements 160 Planned-order receipts 160 Planned-order releases 160 Notes: Gross Requirements (week 6) = Planned-Order Releases of 160 Tops * = 160 13 Base LT = Lot size: Lot-for-Lot Gross requirements Beg Inv 200 Scheduled receipts Projected on hand 20 20 20 20 20 20 20 20 Net requirements 180 Planned-order receipts 180 Planned-order releases 180 Notes: Gross Requirements (week 7) = Planned-Order Releases of 200 Golf Carts * = 200 Motor LT = Lot size: Lot-for-Lot Beg Inv Gross requirements 120 120 180 Scheduled receipts Projected on hand 300 300 300 300 300 300 300 Net requirements Planned-order receipts Planned-order releases Notes: Gross Requirements (week 6) = Planned-Order Releases of 180 Bases * = 180 Body LT = Lot size: Lot-for-Lot Gross requirements Beg Inv 0 180 Scheduled receipts Projected on hand 50 50 50 50 50 50 50 Net requirements 130 Planned-order receipts 130 Planned-order releases 130 Notes: Gross Requirements (week 6) = Planned-Order Releases of 180 Bases * = 180 Seats(2) LT = Lot size: Lot-for-Lot Beg Inv Gross requirements 0 360 Scheduled receipts Projected on hand 120 120 120 120 120 120 120 Net requirements 240 Planned-order receipts 240 Planned-order releases 240 Notes: Gross Requirements (week 6) = Planned-Order Releases of 180 Bases * = 360 14 Frame LT = Lot size: Lot-for-Lot Beg Inv Gross requirements 0 0 130 Scheduled receipts Projected on hand 35 35 35 35 Net requirements 95 Planned-order receipts 95 Planned-order releases 95 Notes: Gross Requirements (week 3) = Planned-Order Releases of 130 Body * = 130 Controls LT = Lot size: Lot-for-Lot Gross requirements Beg Inv 0 0 130 Scheduled receipts Projected on hand 0 0 Net requirements 130 Planned-order receipts 130 Planned-order releases 130 Notes: Gross Requirements (week 3) = Planned-Order Releases of 130 Body * = 130 Wheel Assemblies(4) LT = Lot size: Lot-for-Lot Gross requirements Beg Inv 0 0 520 Scheduled receipts Projected on hand 240 240 240 240 Net requirements 280 Planned-order receipts 280 Planned-order releases 280 Notes: Gross Requirements (week 3) = Planned-Order Releases of 130 Body * = 520 15 ... Scheduled receipts Projected on hand 10 10 10 10 10 10 10 Net requirements 20 Planned-order receipts 20 Planned-order releases D, D(2), & D(4) LT = Lot size: Multiples of 100 Gross requirements 20 Beg... size: Lot-for-Lot Gross requirements 60 Beg Inv 60 Scheduled receipts Projected on hand 10 10 10 10 10 10 Net requirements 50 Planned-order receipts 50 Planned-order releases Master Schedule... 40 10 10 10 10 10 Planned-order releases C(3) LT = Lot size: Lot-for-Lot Gross requirements Scheduled receipts Projected on hand Net requirements Planned-order receipts Planned-order releases 10