Assessing and Diminishing Work Costs - PowerPoint PPT Presentation

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Assessing and Diminishing Work Costs

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  1. Estimating and Reducing Labor Costs Chapter 4

  2. The Role of Labor Costs in Manufacturing: The Auto Industry Other 100% Overhead 90% Warranty Quality 80% 70% Assembly and other Labor costs 60% Purchasedparts andassemblies Parts andmaterialcosts 50% 40% Logistics costs 30% 20% Material costs 10% 0% Final Assembler’s cost Including Tier 1 Costs Including Tier 2 Costs Rolled-upCosts over ~ 5 Tiers • While labor costs appear small at first, they are important - look relative to value added - role up costs throughout the value chain • Implications • - also hunt for pennies (e.g. line balancing) - spread operational excellence through the value chain

  3. Scooter Mania

  4. Scooters by Xootr, Stafford, PAwww.xootr.com/xootr/tour/nfactorytour.htm Components Finished Xootrs Deck assembly Steer assembly Frame assembly 3 main processes: All labor-paced. 1. Steer and fork assembly 2. Frame wheel assembly 3. Deck assembly

  5. Xootr Roma sold at $200 May July April June March August January October November December September Weekly demand 1400 1200 1000 800 600 400 200 0

  6. Utilizations with demand of 125 units/week

  7. Let us generalize:Cycle Time: Time to process 1 unit • OT: Operating time per week • D: Demand per week • Requested Cycle Time = RCT = OT / D • Designed Cycle Time = DCT = 1 / Process capacity • If RCT > DCT, then we can produce at the requested level. • Design is feasible. • If RCT < DCT, then we canNOT produce at the requested level. • Design is infeasible. Capacity must be expanded. • Example: If a student can answer a multiple choice question in 2 minutes but gets a test with 30 questions and is given only 30 minutes then • OT=30 minutes; D=30 • Desired cycle time = 1 minute < • < 2 minutes = Cycle time from the process (design) capability

  8. Let us generalize: Labor Productivity Measures for a Demand-Constrained System: RCT > DCT Overall Performance Measures =Idle Time RCT • Capacityi = • Utilizationi= DCT=a4 a2 Activity Time a1 Labor Productivity Measures a3 • Direct Labor Content=a1+a2+a3+a4 • If one worker per resource:Direct Idle Time = (RCT-a1) +(RCT-a2) • + (RCT-a3)+(RCT-a4) • Average labor utilization 1 2 3 4

  9. Time to complete X units starting with an empty system Time to make X units = Time through empty system + = Time through empty system + - For continuous flow processes: “(X-1)=X” Example: How many minutes are required to make 100 ? 13+11+8=32 mins required for the first scooter (99)(13)=1287 mins required for the remaining 99 units

  10. Utilizations with demand of 125 units/week • No worker is fully utilized at the demand of 125 units/week. • There is an imbalance in the amount of work done by workers. • Upon balancing the assembly line, the process capacity improves. • But the thruput does not change as the line is demand constrained.

  11. Utilizations with demand of 200 units/week

  12. Labor Productivity Measures for a Capacity-Constrained System: RCT < DCT Bottleneck =Idle Time DCT=a4 a2 Labor Productivity Measures Activity Time • If one worker per resource:Direct Idle Time=(DCT-a4)+(DCT-a1) +(DCT-a2) +(DCT-a3) a1 a3 1 2 3 4 Since the system is capacity-constrained, line balancing can improve the capacity.

  13. Balancing an Assembly Linewithout Resequencing Operations 10 9 8 7 5 4 2 3 1 Cycle Time Before Line Balancing 1: Prepare cable 2: Move cable 3: Assemble washer 4: Apply fork, threading cable end 5: Assemble Socket head screws 6: Steer pin nut 7: Brake shoe, spring, pivot bolt 8: Insert front wheel 9: Insert axle bolt 10: Tighten axle bolt 11: Tighten brake pivot bolt 12: Assemble handle-cap 13: Assemble brake lever + cable 14: Trim and cap cable 15: Place first rib 16: Insert axles and cleats 17: Insert rear wheel 18: Place second rib and deck 19: Apply grip tape 20: Insert deck fasteners 21: Inspect and wipe-off 22: Apply decal and sticker 23: Insert in bag 24: Assemble carton 25: Insert Xootr and manual 26: Seal carton 900 800 12 700 10 11 20 9 600 19 8 18 500 Activity time [seconds] 7 26 400 17 6 25 22 5 300 16 15 24 4 23 200 14 2 3 100 13 1 21 0 Steer Frame Deck Cycle Time After Line Balancing 900 800 700 26 600 17 25 500 24 Activity time [seconds] 16 15 22 23 400 6 14 300 21 13 20 200 12 19 100 18 11 0 Steer Frame Deck

  14. Utilizations after Line Balancing with demand of 200 units/week

  15. Demand of 700 units/week after line balancing • With the rate of 5.41/hour, weekly production in 35 hours is about 189.5 units < 700 units. • Capacity constrained system • Capacity expansion options: • Replicate the assembly line • Selectively add workers to the line • Add generalists • Add specialists

  16. Deck assembly Deck assembly Deck assembly Deck assembly Steer assembly Steer assembly Steer assembly Steer assembly Frame assembly Frame assembly Frame assembly Frame assembly Replicate the assembly line • How many lines do we need? • Roundup(700/189.5)=Roundup(3.69)=4 Components Finished Xootrs

  17. Deck assembly Steer assembly Frame assembly Finished Xootrs Selectively add generalists • How many generalists do we need? • Steer assembly: 1 worker provides 35(5.78)=202.3 units • Roundup(700/202.3)=4 needed for Steer assembly • Frame assembly: 1 worker provides 35(5.98)=209.3 • Roundup(700/209.3)=4 needed for Frame assembly • Deck Assembly: 1 worker provide 35(5.41)=189.5 • Roundup(700/189.5)=4 needed for Deck assembly 4 workers 4 workers 4 workers Components

  18. Selectively add specialists • How many specialists do we need? • Need 700 units in 2100 (=35x60) minutes or 1 unit in 180 secs. • Group tasks so that total task time is less than or equal to 180 secs.

  19. Selectively add specialists • Completing the table, we observe that 12 workers are needed. 200 180 160 10 140 120 9 5 3 100 Activity time [seconds] 7 80 4 60 8 2 40 4 6 1 1 20 0 Worker 1 2 3 4 5 6 7 8 9 10 11 12 7 8 9 10 11 12 1 2 3 4 5 6

  20. Key-points to remember: • Where do process times / cost estimates quoted by production managers come from? • How to make labor related decisions • pricing • hiring • Impact of process design on productivity • Line balance • Idle time • Direct labor content Calculations: Determining resource requirements to support a volume target. Estimating direct labor content. Calculating direct manufacturing cost Adjusting for idle time The Importance of Process DESIGN Mechanics of a worker-paced line Mechanics of a work cell

  21. Summary • Cycle time, requested and designed, Idle time • Capacity-constrained vs. Demand-constrained systems • Line balancing • Line capacity expansion strategies