Ask the Expert

Determining capacity 

Question: I am working at a sheet metal HVAC fabrication plant. The majority of jobs are custom fabrications. The company has no idea what it can produce per day in pounds of metal. What is the best way to determine capacity? There is no historical data available for reference.

In the same plant, jobs are scheduled according to customer due date. What is the best way to approach this issue?

Answer: It may be necessary to observe the output (in terms of tons produced)over randomly chosen intervals of time. You can choose intervals to span different times of day, days of week, and different order types. You should then be able to develop a statistical estimate of mean throughput rate (average number of units produced per unit time) under a variety of conditions.

A more accurate estimate can be obtained by tracking several product specific production lots and observing production plus setup times as the lot works through the plant. This will give you an average product-specific production rate. You can then find the aggregate production rate by estimating the mix of products this plant produces and taking a weighted average. The realized capacity is likely to be a function of product mix.

Diwakar GuPta, Ph.D. 

What's world-class?

Question: I am familiar with lean manufacturing, just-in-time manufacturing, and quick-response manufacturing. Where does world-class manufacturing fit in?

Answer: World-class manufacturing is a term coined by Richard Schonberger from the title of his book. It is generally recognized as lean manufacturing.

John S.W. Fargher, Ph.D.