Recently we had a problem with our web site’s “feedback form” (details later) which got me thinking about quality checks in manufacturing and how they can be done in a way that is economical.
We need to double check the work we do because often the result we produce is not the result we intend to produce. It is true that if we double checked everything we did, we would be very unproductive. I can imagine as I type this out, double checking that I have located the correct key before pressing it, checking that the key I pressed appears on the screen before continuing on. Stopping after every sentence to reconsider my spelling, my punctuation and my grammar. Pausing after each paragraph to consider whether what I just wrote was in fact what I really wanted to say. It is ridiculous.
There was a time when everything was double checked. The first time I typed I was uncertain of what I typed. I had to find the letters… Now my fingers press words without me even needing to think about the letters in those words. I string ideas together and present them with thought to the content, but not much thought to the mechanics of my writing. This is how learning works for us humans we get better at something and our minds are freed from having to concentrate on the details. Amazing how our brains were constructed this way. Our brains can watch for exceptions and ignore the majority of our activity. Most people will observe themselves doing this while driving. They will say “I don’t remember that part of my commute today, I remember getting on the freeway and I remember getting off, but I don’t remember spending 30minutes on the freeway..”. As a driver when the brake lights come on in front of you, that is your brain’s queue to start paying more attention. The thoughts of your planned California vacation fade and thoughts of reacting appropriately in traffic start forming.
The same is true in manufacturing. We can’t afford to quality inspect every widget we produce (unless they are expensive enough). At the same time we must know if there is non-conformance in our products that needs to be addressed. Much like the typing example we may have QA staff shadow a new hire until they start learning what to watch for. After a while the production workers will be performing their own less official but important QA functions.
But how do we balance the cost of increased quality assurance with the attention QA requires? We can start with some best practices based on experience. First-off testing examines the first piece produced for defects and deviations, what better place to catch these than with the first piece. Additionally we can set up a sampling rate that allows us some coverage for the produced product. If the variance on an operation is increasing during the production run, this can be detected and corrected before it becomes unacceptable.
Also, remember to perform QA on your QA. If everything keeps coming up roses, then your diligence with suppliers, production equipment and staff training and quality ownership are paying off. You can be less intense in inspecting. If however a product or operation shows reduced quality you can be more vigilant.
Now for that personal example that started this train of thought. Much like the driver who is convinced everything is fine on the freeway, I was convinced that the feedback form on GreenTree Software’s website was working fine. I had done a first-off test when it was first set up which worked fine. We had been receiving some spam through the form which sent us form submissions with SPAM content (probably sent by automated scripts). So when we started receiving completely blank form submissions (the brake lights on the freeway) we just ignored them. On a whim the other day I retested the form and promptly received a blank email. Whoops. So to everyone who tried sending us a message I apologize. We did not receive it and have no record of who you are (or we would apologize personally). The broken form has been taken out of service (everyone has email these days). Again I’m sorry. If I hadn’t tested the other day we would still be losing your messages and receiving blank emails. If you tried to contact us using the form, drop us a line via email and we’ll try to make it up to you.