Don’t forget
DVT, EVT, PVT, and DFM
Sometimes, you manufacture innovative products that have never been produced
before. It means there is no previous manufacturing experience for that particular
product – you are creating it for the very first time. Usually, 500 to 1000
units you should manufacture in a few test production runs (EVT, DVT, and
PVT). The intention is to test and debug processes and spot problems before you
find yourself with 20,000 defected units that in some cases might be 100% your
fault. For example, in design.
Big companies can afford to have a more extensive test runs of 2000 to 5000
units, or even more. They write them off (read: pay for their destruction) just
to test and optimize the production process and line. With that being said,
never compare yourself with Apple, Sony or Samsung unless you have billions in
a bank account somewhere in Ireland.
For DFM (Design for Manufacturing), there is a simple math formula: (Manufacturing)
– (DFM) = Failure. DFM is a part of product development. Your engineers and
designers must be aware what kind of design and solutions are scalable and
reliable for manufacturing. Their choices and decisions significantly affect
the rate of defective products coming out of a production line.
Hopefully, it’s not hard to see how these two phases relate to the quality
control and quality itself. Now, let’s get back to the list of 10 essential
rules for quality control.
Rule 1: What may go wrong will go wrong
There are no perfect manufacturing processes only because there is no
perfection in the world at all. Therefore, keep yourself on top of everything
or hire someone to help you. There are many factors and sub-factors that can go
wrong. For example, people, equipment, processes, materials, management, and
environment, etc. However, keep in mind that if you choose to dive deep into
quality control of each of these factors, it will increase the price of setting
up manufacturing.
Rule 2: Have someone experienced with your type of product
Rule 1 is the reason why contract manufacturing is
the most common model that companies of all sizes use instead of contracting
factories themselves. Overall, contract manufacturers reduce risks by taking
responsibility on themselves. Factories do not accept too much of risk.
For them, a big defective production is a question of life and death, as well
as for you.
However, you don’t need to choose a CM to manage your production, but at least
a person who has dealt with or accomplished manufacturing operations for a
similar product as yours. It can help you a lot.
Rule 3: Who are your customers?
If you are selling to the wealthiest markets in the world where people
are used to high-quality standards, customers will not forgive functional but
still defective product. In some other countries, to receive poorly packed and
a slightly scratched product is just not that important as people are used to
that. You might also target customers with lower income who don’t expect
high-end products for cheap.
Therefore, do not excessively chase for the highest quality standards for
low-end products – it doesn’t make sense.
Rule 4: Define quality control methods
The choice of quality control methods depends on precise product
requirements and functionalities. For example, mechanical parts might be
inspected with eyes to make sure they are scratch free. You can compare the
color, material, and dimensions. It is checking against specifications.
If you deal with electronics, then you can check the quality of your PCBA by using
visual inspection, x-rays, in-circuit test, and automated optical inspections,
etc. Do that when an assembled PCB is getting out of the production
line.
If your product has a screen, then you will probably need to test these
displays before final product assembly. So you need to define how you are going
to check the screens – you need to power them, and to upload some pictures on
the screens in order to make sure they work as you expected.
So, defining quality control methods depend on your product.
Rule 5: Set your sample size correctly
Imagine you have 10,000 units to check. You won’t go one by one and
check every single piece because it will take forever, and add up costs. On the
other hand, small sample size might result in failing to spot defective
products, disappoint your customers and lose a significant amount of money.
There are no golden rules for sample size. Depending on product requirements,
you will choose the proper sample size, and you can adjust the size over the
process.
Therefore, if you check 200 out of 10,000 units, and there is a high
major-defect-rate of 10%, you will make sure to check another 1200 units. Let’s
say that the rate remains the same. If a factory is ready to give you a 10%
discount on the final bill, that’s fine. If not, you will possibly need to check
the whole batch, piece by piece. Put these defective products on the side and
ask the factory to re-do it (if possible). You can also ask the factory to pay
for extra costs that you had here.
There are tons of other situations and scenarios that depend on urgency,
concrete defect, defect rate itself and other things. At the end, what counts
is how your negotiations with the factory end up.
Rule 6: Quality control checklists
Checklists are almost a synonym for quality control. You are the one who
defines what is acceptable for your product and what is not. You need to
develop procedures and checklists for the quality control of your product.
Either you’re doing QC yourself or sending someone on your behalf. It’s better
to have the lists ready as they will clarify the process and reduce the costs.
If you accidentally drop something from the list – don’t blame anyone else but
yourself.
Rule 7: Check the process
You can capture most of the problems early on the production line. That
means you have an understanding of the manufacturing process and you have a
budget to hire someone who will spend time at the factory overseeing the
manufacturing of your product. Don’t forget to define procedures and
requirements for that, too. Having someone just wander around the factory is
not going to get the work done.
Rule 8: Apply quality control at every step
Apply incoming quality control, which means control of raw materials and
components that are arriving at the factory. Then after manufacturing, apply
outgoing quality control, which means check whatever leaves the factory. You
might be able to do different parts of the production at various locations.
Therefore these incoming and outgoing checks make more sense. Do quality
control of packaging, fulfillment, and everything else if you want to ensure
that your product meets the highest expectations. Of course, this drastically
increases the costs and you must find a financial justification for such
approach.
Rule 9: Never trust factories, or anyone else
Factories might tell you that they have internal quality control methods
and procedures. They might promise 0% defect rate. Although those things are
possible, not many factories can deliver that. They are just searching for
another gig. Define and sign everything you agreed so that you have a written
proof of what has been agreed, and do not trust given promises. Make sure that
you have balanced the invoice only, and only, after you checked the goods
toughly and confirmed everything is in place.
Rule 10: Have respect for your suppliers
Be careful with pressuring your suppliers, especially if they are
factories. For example, if you have a small batch that is not generating a
significant revenue, a factory could make some cuts here and there, or just
drop you. They could also accept your order, but then receive a bigger order
and postpone yours. In fact, if that happens, they’ll probably delay
yours, anyways.
Try to perceive the world from their angles, as they need to pay their bills
and make some profit as well.
The bottom line
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