10/25/2015 IENG 471 Facilities Planning 1 IENG Lecture Schedule Design: The Sequel

10/25/2015IENG 471 Facilities Planning 2 Assignments Assignment (Due Today): HW:(HW 1.5) 5 Criteria for the Strangeglove Facility 5 Quantitative Measures for the Criteria One measure for each Criterion Next Assignment: HW:(HW 3) See Assignment Link required input for each of the workstations equipment necessary for each machine steady state cycle time for each machine ideal machine assignment for each machine compute the idle time unit cost at each workstation total cost per good unit square footage for each workstation and the total space required

10/25/2015IENG 471 Facilities Planning 3 Equipment Requirements Equipment Fractions are the number of machines of one type required to produce the required volume of product(s) Some machines can be used to perform multiple operations… So, if idle time on the machine exists, and there are multiple products scheduled, then fewer total machines may be required! Some machines may not be able to perform the required operation(s) fast enough to reach the required volume with only one machine… So, more copies of the machine may be required!

10/25/2015IENG 471 Facilities Planning 4 Estimating Equipment Fractions The equipment fraction for each req’d machine is based on all of the operations the machine will perform Good thing we got those Operations Process Charts! To find the number of machines of a type for the facility: The number of workstations for a shift ( F ) is: where: S is the standard time to perform the operation, per unit Q is the quota of output units per shift E is the efficiency of production on the machine, expressed as a percentage of the standard operation time H is the hours available for production on the machine during the shift (or whatever unit of time matches parameter S ) R is the availability (reliability*) of the machine, expressed as % of the “up time” that the machine is available to work (% H )

10/25/2015IENG 471 Facilities Planning 5 Reliability Reliability is a measure of how often a system fails: How long (on average) you can run it until it stops working right How do you know that it’s not working right? MTTF (Mean Time To Failure) or MTBF (Mean Time Between Failures)

10/25/2015IENG 471 Facilities Planning 6 Maintainability Maintainability (serviceability) is a measure of how long it takes to return the system to proper operation: Sum of the times required to: diagnose the problem obtain repair parts / tools repair the failed components return the unit to operating conditions MTTR (Mean Time To Repair)

10/25/2015IENG 471 Facilities Planning 7 % Availability = MTTF MTTF + MTTR Availability Availability is a function of Reliability and Maintainability: It is the percentage of time that you can count on using it for production

10/25/2015IENG 471 Facilities Planning 8 Since the number of real machines is an integer The lower bound on the number of machines required is 4 – the sum of the equipment fractions, rounded up … Theoretical Qty for Job Shop The upper bound on the number of machines required is 6 – the sum of the ceiling values for each operation… Theoretical Qty for Mass Prod But … Equipment Fractions - continued Op. No. Equip. Fraction Integer Ceiling Total Req’d 46

10/25/2015IENG 471 Facilities Planning 9 Equipment Fractions - continued We should adjust the required number of machines to also account for: Frequency of changeover (flexibility) Set-up times Preventative maintenance Manufacturing policies… Therefore, both total machines estimates might not really be feasible … it assumes that everything is best case scenario!

10/25/2015IENG 471 Facilities Planning 10 Ex: Injection Mold Rubber Feet Process for juicer is: Mold & trim feet – 2% scrap rate Transport trimmed feet to line – 1% scrap rate Assemble juicer – 0.5% scrap rate 3 grams of rubber needed per foot Find the number of feet to be processed at each workstation! Find the raw rubber needed for this process!

10/25/2015IENG 471 Facilities Planning 11 Ex: Injection Mold Rubber Feet Shift is 8 hr, but reduced by two 15 min breaks, and 35 min machine warm-up (to heat the mold and material). Production schedule requires 2450 sets of feet daily MTTF is 38 hours MTTR comprises 5 min to diagnose, 55 min to obtain spare parts, 7 min to fix, 18 min to re-warm Run one shift per day Obtain one set of four feet per cycle Cycle time is 40 s (steady state) Find the equipment fraction for this process!

10/25/2015IENG 471 Facilities Planning 12 Questions F = Machines (Job Shop)F = 5 Machines (Mass Prod.) What is the machine fraction if, instead: A Manufacturing Engineer suggests using a four unit mold instead of a single unit mold? F = Machines (Job Shop)F = 2 Machines (Mass Prod.) An Industrial Engineer suggests running three shifts, eliminating daily warm-up time? F = Machines (Job Shop)F = 4 Machines (Mass Prod.) An improved facility design reduces the time to get spare parts to 2 min, and the re-warm time to 1 min? F = Machines (Job Shop)F = 4 Machines (Mass Prod.) What if we did all three suggestions? F = Machines (Job Shop)F = 1 Machine (Mass Prod.) What are the reasons we might do some but not other suggestions?