What to do with broken parts?

Imagine You do run a production company. Such a real one, not an imaginary one. And this company do produce something.

And, of course, from time to time as we do live in a real world, the product comes out a piece of crap.

What to do with such a crap?

ISO 9000 says…

(…)prevent bad outputs from entering production again(…)

Which is good. If You detected a broken part or a broken product it must not be used or sold.

The easiest way to achieve that it is to scrap it and throw it away.

Store them for investigation

Sometimes however bad parts should not be thrown away. There are plenty of modes of failure. Some of them are random, some are statistically important. For an example You may observe that one of each 100 pieces of Your MP3Players do turn-on when plugged to USB port while 99 pieces do not. This is not a critical failure, but it may turn critical after some time. So it would be best to know why does it happen.

Of course Your Research&Development department is under a full load and it may not be able to react in timely manner to each single failure. And even if they would, they also need some statistics. For an example they must break a piece to see what is inside. And of course such an operation renders that piece inoperable, so no more work can be done.

This means, that if You are observing a repeating, statistically significant failures of unknown origin then You must collect samples.

Prepare some warehouse storage, mark each broken part sample with clear description:

• when it was discovered it is broken?
• when it was manufactured?
• add tracking data so You may pin point all components tracking data;
• who tested it and found out the problem?
• what the problem exactly is?

Describe the problem

And no, “it doesn’t work” is not a good description. Describe step-by-step how to reproduce error. Describe all numeric value and measurements You made. Describe what You have seen. And, equally important, what You think You should have been seen.

Only then Your Research&Development department will be able to do the job.

Be prepared for long-term storage

This depends on the load which is put on Your Research&Development department and failure criticality. I think that for non-critical errors You need to be prepared for 3…9 months long storage. Remember, this is not only due to Research&Development department delay, but also due to the fact that You must collect a reasonable (5…10 pieces at least) number of samples. This also may take some time.

So prepare Your broken product for long term storage. Remove batteries or be prepared to charge them from time to time. Keep them in proper air-conditions and temperatures.

And do not mix them. Remember, they must be tracked piece-by-piece and have their matching description. Piling them up on the shelf is not right.

Store them for training

Now imagine You do manufacture not a 15$ per piece MP3 player, but 5’000$ in-cost worth gizmo for some techno-fetishists.

If You think about quality and safety, then You must continuously train Your employees. Train, re-train, allow them to try out their skills in safe and inexpensive manner.

For that You need training samples. Teaching a guy on assembly line how to put together 5’000$ worth modules using a pneumatic press tool on almost ready 5’000$ worth part is… well… at least stressful for both teacher and pupil.

But what if You would collect some broken parts, spray them with a red paint or drill some holes in them? They will be clearly distinct from regular parts, so chance that someone will re-enter them into production is almost zero, so we are ISO9000 safe. And with such parts You main train Your employees.

Even more, You can let them try by themselves how much force the part can withstand before it is destroyed. Or that if they will stick their fingers there then they will break something. The training with broken parts may be efficient, highly educational and inexpensive

“How not to” examples

Different people do have different minds. Different operations may require different quality criteria. And there is always some shadow zone between “it is good” and “it is bad”. Having a manual which shows “good part” and “bad part” is good.

But having also an example of “bad part” is even better. The employee may then self-control the job confronting it with “good” and “no-good” example.

Note: In mechanics in 1980-ties there were popular “pass”-“no pass” “test rods” for holes. The “pass” side of rod was slightly smaller than the hole should be, the “no pass” side was slightly bigger. All the employee had to it was to try to ram-in both of them. If both could enter the hole, it was too large. If none could enter, it was too small. Why not to use this concept for electronics and other production?

Summary

After reading this blog entry You should be at least partially aware that sometimes it is good to retain broken products. Of course after marking them in some impossible to miss and impossible to remove way.