Unit Time 8/24/04 Paul A. Jensen Operations Research Models and Methods Copyright 2004 - All rights reserved

Operation time depends on processing time and setup time The processing time is the time required to process one unit of product The setup time is the time to setup a machine for a single batch or lot of product

Different times for an operation: The time to process one piece at the operation, the operation time. The time used on the operation to produce one finished good, the unit time. The total time for a production volume V.

Example Operation Unit Flow Time 1 1.929 1.0 2 1.736 2.0 3 3.086 0.5 4 1.389 0.3 5 5.879 0.4 6 5.291 7 4.762 8 1.111 1.2 Unit Time 1.929 3.472 1.543 0.417 2.352 10.582 2.381 1.333

Example: Line with defects and inspection u 1.88 Operation i 1 2 3 4 5 6 Oper. Time t Unit Flow Total Time = 50.76

Repeating an operation is called recycling V C = p ( + ) Recycled amount: Vp  1 -  Total Flow: (1 + ) =

Recycling with Scrap

Example: Line with defects and recycling u 1 Unit Flow Unit Time U 3.33 4.44 5.55 6.66 Total Time = 29.97

Alternative Designs

A complex flow routing

Analysis

Solution

An example with defects routed through the whole line