Midterm outline - Classes

IE 368: FACILITY DESIGN AND OPERATIONS MANAGEMENT
WINTER 2012
OUTLINE OF MATERIAL IN LECTURE NOTES #2, #3 AND #4
PRODUCTION SYSTEM DESIGN – PART #1
1. Generalization/Abstraction of Production Systems for IE Design/Analysis
a. Definitions
• Production system
• Workstation
• Discrete parts
b. Production system performance characterization
• How fast
• How long
• How much
c. Basic types of production system flow
• Job shop characteristics
• Production line characteristics
• Group Technology/Batch processing characteristics
d. Production volume vs. variety
2. Determining Resource Requirements
a. Equipment fraction
b. Incorporating the production of scrap in the equipment fraction
c. Modifications to the equipment fraction equation
• Automated machines
d. Rates and times in calculation
e. Machine assignment
• Ideal/real number of machines to assign (n’/m)
• Repeating cycle time (T c )
• Idle operator/machine time (I o /I m )
• Calculating production system’s job rate
• Calculating cost per job
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PRODUCTION SYSTEM DESIGN – PART #2
1. Performance Evaluation
a. Throughput
b. System responsiveness (TIQ, TIS)
c. WIP levels (WIP Q , WIP)
2. Queuing theory
a. Probability and statistics concepts
• Random variable
• Expected value
• Variance
• Coefficient of variation
3. Utilization
a. Needed to evaluate WS performance
b. Need effective process time (t e ) and job interarrival time (t a )
• Both given or calculated from data
c. Classification of CVs
4. Queuing models for performance evaluation
a. WS m = 1 (simplest case)
• Concept of throughput based on WS’s utilization (is u ≤ or equal to 1?)
− See formulation for TIQ & TIS
• Little’s law Throughput (TP) times either WIP Q or WIP
• Examination of queuing model (relationships amongst parameters in queuing model)
PRODUCTION SYSTEM DESIGN – PART #3
1. Queuing models for performance evaluation (continued)
a. Generalizations of queuing model
• WS m = n (multiple parallel machines)
− See formulation
b. Generalizations of utilization formula
• WS m = n (non-identical machines), 1 job type
• WS m = n (identical machines), 2 job types
• WS m = n (non-identical machines), n job types
c. Multiple linked workstations
• Coefficient of variation for the interdeparture times (CV d )
• Formula to calculate CV d is different if:
− WS m = 1
− WS m = n
d. Automated systems
• Need to estimate t e and CV e
• Comparison of t e and CV e vs. changes in MTTR and MTBF
e. Batched arrivals and departures
• Estimate t a and CV a
• Selection of the queuing model to use depends on same conditions as before.
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