10 Rules For Quality Control To Avoid Failure in Manufacturing
Conducting quality control before, during and after the manufacturing process is the way for you to succeed in delivering a defect-free product. To apply the highest quality control standards increases the price of the product, and someone has to pay for that. Logically, it is the end users who pay for the quality, but before they hand over money to you, you’re the one who’s investing in the manufacturing of thousands of high-quality or just defect-free products.
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 do write them off (read: pay for their destruction). The whole thing was just to test and optimize product, production processes 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
Quality control is a broad topic, with a countless number of situations and outcomes. Which of these 10 rules do you think is the most challenging to implement in your case?
