Your Reliability Engineering Professional Development Site
If you have ever been involved in manufacturing or quality-related conversations, you may have heard of ‘Statistical Process Control’ or SPC. And if you Google SPC you will find a bunch of ‘textbooky’ definitions which are likely going to make you run away and never think of it again.
But you shouldn’t. [Read more…]
When it is necessary to check 100% of parts for one or more characteristic?
There are situations where 100% of manufactured parts are checked. These include visual inspection, measurements of a part characteristic, and a reaction to low process capability. These may be accomplished manually or an automated process.
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Many companies use SPC to control their manufacturing and assembly processes. Other companies use 100% inspection and some companies do nothing. How can one choose between these three alternatives?
To make a rational choice, some questions need to be answered.
In my prior article, the assumptions behind SPC were discussed in detail except for the analysis. There are two types data that may be analyzed, Counts and Measurement variables. This article focuses on normally distributed measurement variables, and the construction and usage of $-\bar{X}-$ and R charts.
[Read more…]