Читать книгу Paint Analysis - Roger Dietrich - Страница 17

Let us assume a paint crater issue appearing in an automotive supplier plant. Someone sampled a failed bezel and presented it. To solve the issue, you would want to know as much as possible about the circumstances of this sudden production failure.

Figure II.4: Visible light microscopy picture of a paint crater

A good method is an interview of all the people involved in the project. The questions to be answered with respect to this case are:

 Where does the sampled part come from? (directly from your process, somewhere from the supply chain, from the customer)

 What is the history of this sample? (which does not mean which way parts of this kind typically go, but what the sample in your hand has “experienced”)

 How many parts are affected? (percentage of the lot/production)

 When did the issue appear?

 When has it been realized?

 Are there still good parts which have been produced in the same process?

 Are there any changes of production parameters that can be correlated to the failure?

 Are there any unusual circumstances around the production line that might have influenced the issue? (e.g. construction works, repair, cleaning procedures)

 Are there any (proven) correlations to certain lots, production shifts, material lots, production tools and so on?

Please note: You can never enquire too much but always too little. Be curious and vigilant during the whole data acquisition process. Each piece of information can be very precious, when it comes to the data evaluation of the analyses. The history of a sample also includes the exact circumstances of the sampling. Interviews of the people on the site that deal with that kind of product every day and know the machines very well are a versatile tool.