by Doug Carter

Electronics Technology

Background:

During the development of a particular industrial process, an engineering log is carefully kept which records adjustments, corrections, perturbations and decisions made by technical personnel as the experimental process runs are made. When a project engineer compares actual results with expected results, she/he critiques the process and makes changes in the process specifications to move the results in the direction of greater yield. As this occurs, the decisions made by the process engineer are only as good as the integrity of the engineering log.

During the bake phase of the run process, the temperature is to be recorded every 5 minutes. If the temperature drops below 250 degrees, specifications require that the process be stopped, the product cleaned in accordance with an established cleaning procedure, and the bake phase started again from the beginning.

Bill was the shift supervisor and Jon was the technical specialist who kept the log. During the bake phase Jon noticed that the temperature had dropped to 245 degrees. Jon notified Bill that the phase should be restarted. Bill increased the temperature control setting and the process temperature began to increase. Bill explained that the temperature sensor was defective and one must control the temperature manually, that the process would be all right since the specs had a 2% tolerance. Jon asked how to reflect the incident in the log. Bill replied, "Just show it at 250 degrees, it won't make that much difference, if we re-run bake we'll have to stay an hour late and I promised my wife that I would be home by 5:00. We have an important dinner engagement."

Questions:

What problems might occur if Jon does not show the temperature variation in the log?

At the beginning of the next shift the shift supervisor will read the log.

Should the defective temperature sensor be replaced before the next run?

Will the process engineer be able to make a correct analysis of the results and recommended valid specification changes if s/he doesn't know about the temperature deviation?

What problems might occur if Jon does show the temperature variation in the log?

What should Jon do?