Page 416 - Design for Six Sigma a Roadmap for Product Development

Design for X 383

as the DFSS team find appropriate for various reasons; however, we
found these assignments accurate in many applications:

1. Activity: machine cycle time
■ Constant for CNC machines
■ Uniform with parameters (min, max)
■ Triangular with parameters (min, mode, max)
*
2. Activity: conveyor [also automated guided vehicle (AGV)] speed
■ Constant since little variation of actual conveyor speeds
■ Uniform with parameters (min, max)
3. Activity: travel time of AGV, forklift truck, etc.
■ Constant with fixed speed and distance as well as little blockage
■ Triangular with parameters (min, mode, max)
■ Lognormal with parameters (mean, )
†
4. Activity: percent down [when repair time and/or time to (between)
failure(s) is (are) unknown]
■ Must assume distributions (see activities 5 and 6, below) for TTR
and TTF (or TBF) and parameters for one or the other. (We need
both distributions, but only one set of parameters.)

Frequency
Direct
Labor

Σ

Material

Total Cost = Direct labor + Material

Figure 10.10 Direct labor simulation example.

* Note: Mean (min mode max)/3.
† The black belt should avoid this unless very long delays are possible.