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Welcome to my blog for all things related to business quality (processes, systems and ways of working), products and product quality, manufacturing and operations management.

This blog is a mixture of real-world experience, ideas, comments and observations that I hope you'll find interesting.

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February 2010
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An Inspector Calls

The quality guru W. Edwards Deming once said “you can not inspect quality into the product; it is already there.”

There is a great deal of emphasis within the quality management profession on Quality Assurance (preventive techniques) rather than Quality Control (corrective techniques). Inspection, in most cases, is seen as Quality Control; in other words it is not a way of adding value but rather is a cost to the business.

Well that’s true enough – who am I to doubt Deming – but I’d like to put a little balance into the argument. Whilst Quality Assurance is a great ideal to strive for, there is often merit in doing at least some QC; inspection does still have a valid place in your quality tool-box.

Inspection can act as a safety net. Yes, Quality Assurance should be delivering high quality, Zero Defects products that you shouldn’t need to check. But suppose it doesn’t? Suppose something goes wrong? You don’t want your customers to be the first people to spot a problem, so inspection is your chance to find defects first and to fix them quickly so the faults are corrected at source.

Think of a typical problem you have had with incoming materials or parts, or finished goods produced by your company, or even with something you’ve bought for home from the high street. Did it take sophisticated, expensive, calibrated test equipment to spot a subtle defect or could you see it with just a moment’s glance? In other words, would a simple inspection have found the problem? I believe you’ll find in many cases it would have done. If I think back over my years of experience in industry this would be true for many of the defects that I have encountered – they were obvious, why did nobody find them before me?

This can make the process of inspection very cost-effective as it can be done quickly compared with some other screening techniques, such as HASS testing or soak testing, which can be very effective but can tie up expensive equipment for much longer periods.

So what do you need in order to do inspection effectively?

Well, you ought to know what your inspection criteria are. Do you have cosmetic standards? (I’m talking scratches, discolouration and misalignment, not eye-liner and lipstick!) You need to have something that determines what is visually acceptable and what is not, and this should be agreed with your suppliers to avoid the ‘is it / isn’t it good enough’ argument. You need specifications or drawings if you’re measuring things, and you might be able to use industry-wide workmanship standards such as the electronics industry’s IPC-610.

You may also need measuring and inspection tools including simple magnifiers, optical inspection systems, and so on. Digital cameras are a huge asset as ‘a picture is worth a thousand words’ and you should be keeping records and metrics (Key Performance Indicators) of your inspection results so you can monitor whether quality is getting better or worse over time and do something about it.

Having a defined inspection process is also beneficial. This helps to avoid the problem of people always inspecting their own work (which can suffer from them having consistent blind spots), or missing out key things you want to have inspected, or suffering from inspection fatigue whereby a small number of defects amongst many good parts don’t get spotted at all.

If 100% inspection isn’t desirable, why not use an Acceptable Quality Limit scheme? See the my blog on AQLs from a few weeks ago.

And here’s a thought – why do inspection of incoming goods or materials at all? Get your suppliers to do the inspection and prove to you they’ve done it e.g. with a digital photo records or measurements. Apart from saving you money it shortens their own quality feedback loop and encourages them to improve quality at source.

Preventive QA, as I mentioned at the start of this piece, is usually seen as superior to Corrective QC; back to Deming who wisely said, “You are never better off after the fire department leaves than you would have been if they weren’t needed in the first place.” But that doesn’t mean we should disband the fire service or throw away our smoke detectors and rely solely on fire risk assessment. Inspection has a useful place in ensuring quality and can be highly cost-effective. Are you making the best use of it?

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