When quality issues are found during a pre-shipment inspection, there’s still time to correct them before the product enters the market. However, some quality issues only appear after the product’s been used for a few weeks, or even months, by the consumer.
At this stage, your product may still be covered by a warranty – but don’t expect any replacement units or refunds from your supplier.
For example, chargers explode, and glued parts may start falling off. Or the batteries die out long before they’re supposed to.
Such quality issues are not only hard to prevent, but can also ruin your business – especially if you’re selling on Amazon.com.
In this post, Renaud Anjoran at Sofeast in Shenzhen, explains how you can identify and prevent potential after sales quality issues – using a tried and tested framework for Importers.
Can you give us a few examples of typical quality issues that may show weeks or even months after a product is sold?
Let’s first look at electronic product Failures.
Anything electronics-related inherently has a percentage of failure at some point, and this percentage probability depends on the complexity of the product. A simple switching mechanism driven by some logic control would be more robust than something with a printed circuit board involving thousands of components.
Another major factor is the environment in which the product is used. If the product is submersed in water, used in a harsh environment, or under constant vibration, it might stop working much earlier.
One product comes to mind immediately. A time-delayed fault caused worldwide news headlines, for the wrong reasons. I bet you remember the hoverboards whose lithium-ion battery packs overheated and caught fire.
Note: In Sept. 2016, the CPSC recalled more than 500,000 “hoverboard” scooters from ten manufacturers over fire hazards posed by the devices’ lithium-ion battery backs.
At the time of manufacturing, one can assume that the products were tested for functionality and repeated charge / discharge cycling, as with most products that have rechargeable battery packs. One can also assume that the test results were positive. It was not until the products were in the market for some time that the failure mode appeared.
To get to the bottom of why these hoverboards kept exploding one would have to carry out a root cause analysis. For example, in this case, it could have been an incorrect component on the printed circuit board that limited the voltage when charging the batteries. (I have no insider knowledge on that precise incident.)
Let’s now take a mechanical application.
Gluing two parts together is an extremely common process. And yet, many of the very serious quality issues coming out of China have their origin in the use of an improper glue. Let’s have a look at some of the potential failure modes that only show up after a period of time.
Exposure to the sun, heat, and/or to humidity can have a very strong impact on glue and reduce its ability to hold things together:
a. UV rays break down double bonds and the polymer chain if there are no UV absorbers in it. (Years ago, one could see faded paint on many cars because their paint had no UV absorbers – now it is included in the paint of all cars.)
b. If the glue is made of inferior polymers, its polymer chain can break down quickly due to heat and other factors.
c. Humidity can cause certain chemical reactions, especially in water-based glues (which are very common).
Imagine a shipment that goes across the ocean in a container. There is much heat and humidity. If the products are held together by inferior glue, their quality will quickly degrade during that 2-4 week journey. Or it might take a few months and many customers will complain and return products.
Source: Glue Process Control Q&A
Another product failure that we have come across in the past is gearbox failure on fractional horsepower drive trains (geared motors used in chairlifts, golf carts, wheelchairs etc.). Gear boxes were designed using all the best practices when it comes to gear design, even down to the amount of force each tooth can withstand on the gears. Prototypes were tested for harsh environments, rough terrain, over-speed, etc.
In other words, the prototype products were subjected to all sorts of testing, with a positive outcome. It led to the design being pushed through to mass production.
It was not until several thousand products had been shipped that the first of many failed products were reported. The failure mode was lost drive.
What happened? The products that failed were being used in a more extreme condition than what the product was designed for and tested to. All the failed products exhibited stripped teeth on the plastic gear…
Is this something that could have been identified earlier with the use of a simple design FMEA (Failure Modes and Effects Analysis), design team could have realized the product could be ‘abused’. They could then either make the product stronger, or produced two variations (including a heavy duty one).
Why are these ‘long term’ quality issues worse than defects and damages that are found during a normal quality inspection?
Any issue that is found while the goods are still in the factory (and not entire paid for by the buyer) can be contained. If it is not contained and it reaches the end customer, it can cause very high costs… or worse (some people died in fires caused by hoverboards).
Often, defective goods can be repaired by the factory, especially if the issue comes from poor manufacturing. In the worst case, the buyer decides to sort through the products and take (and pay) only those that are acceptable.
Note that some of the issues I listed above are related to poor design. If, as the buyer, you let the OEM manufacturer start production, it is your fault… You can’t even ask the manufacturer to rework or reproduce the goods in case the issues were found before shipment.
What can Importers do to detect wear and tear related quality issues, before it’s too late?
Some of these potential failure modes may never show up during the development stage or prototype testing – or even throughout production testing – simply because they only appear after an extended period of time.
They can be very difficult to identify in advance unless products are subjected to HALT and HASS (accelerated product reliability testing methods focused on finding potential defects in products).
These acronyms stand for:
- HALT: Highly Accelerated Life Test
- HASS: Highly Accelerated Stress Screen
If you are developing a new product and you want to know if it will keep working as planned after a few years of use, you can send a few samples to a testing laboratory and ask them to perform HALT and/or HASS.
One important aspect of getting the product ‘right’ is to provide a detailed product specification, which should include all the details of your product, including what testing should be carried out.
This way, the factory knows what and how to build the product, as well as how and when to test each unit.
As an importer of products, it is your responsibility to ensure you are importing and selling a safe and reliable product.
If your product is subjected to safety or other regulations, the best way to handle that is through a third party testing laboratory in China. How to choose a good lab for your needs? We asked the question to Dr. Droste from the Hohenstein Institute, who suggested evaluating these factors:
- Is the lab clean and well organized?
- Are the methods I need accredited, e.g. by ISO 17025?
- Are they experienced in the market I want to deliver (US vs. Europe)? References?
- What are the turnaround times?
- Do a blind sampling with failed samples from the past. Do they find the failures? Repeat this after the testing routine has kicked in.
Is it possible to ‘simulate’ wear and tear during a quality inspection?
Testing a product to failure fully through wear and tear takes time. Completing this in a a one-day inspection visit is often very difficult.
However, as part of the inspection criteria, the inspection could include observation and data recording of ongoing tests, such as HALT and HASS.
It is important to understand what test facilities your supplier has, or doesn’t have. How can you be sure they can produce good quality products if they are unable to check it?
The testing facilities will vary for different product types (e.g. castings vs printed circuit boards). Taking this into consideration, you need to understand the manufacturing process and, as I mentioned above, what testing you require your product to go through.
It may be the case where some test equipment is not used and is hidden away, so the inspector needs to ask if certain equipment are available if they are not seen. To reduce that risk, you should list the required equipment in your quality control plan.
How do you suggest that Importers find out how to do stress tests on their products?
Here are two easy steps you can take:
a. Ask your inspection company how they would stress/abuse the product as part of their inspection, and where they could go much more in depth if they had a lot of time.
b. Then, ask a testing laboratory what type of accelerated stress/use tests they can perform. Depending on the type of product, some labs won’t be able to do some of the tests that might be needed.
Ideally, you would also do FMEA analyses as I outlined above – not only on the design but also on the processes. I don’t know many companies in China that can do this well. When it comes to process audits, we can cover many of the common types of productions made in China; however, when it comes to design, our engineers can review electromechanical products but not much more.
If you work with manufacturers that employ good engineers, you can also work with them. You might have to come to China and sit down with them for a discussion on the risks they can envision.
It can be extremely productive. Sometimes we do this on behalf of the buyer, but you should try to lead this if you have the resources. It is your product and you should try to understand it inside out.
Thank you Renaud. How can our readers get in touch with you?
They can contact me at ra(at)sofeast.com, or on Linkedin at www.linkedin.com/in/renaudanjoran.
In addition to product inspections (catching issues before shipment), we work on setting up proper process controls in manufacturing operations. It is the only long-term satisfactory solution to recurring issues that are due to the chemical and/or physical properties of the products and their components, if the factory engineers don’t know how to control the right factors. Readers are welcome to drop me a line!