5 Biggest Mistakes When Designing Products for Manufacture
Over the years, I’ve worked closely with many manufacturers. In fact, it’s something I really enjoy. One of the most satisfying parts of the product design process, is seeing a design turn into an actual finished product. Generally, I’ve had great relationships with the manufacturers I’ve worked with. I’ve found they’re usually quick to provide feedback and suggestions if you take the time to ask. Sometimes, it’s not what a designer wants to hear, but it’s usually very beneficial. Most Industrial Designers consider the end-user when designing a product, but good designers consider all stakeholders and all aspects of the product’s lifecycle, including manufacture.
In my experience, I’ve found there are five crucial mistakes that Industrial Designers make.
Not understanding the process
A product is usually designed with a cost target in mind. It’s no good designing a beautiful product that’s too expensive to sell. Cost should be considered right from the start as it influences the design, material choices and method of manufacture. Each process has benefits and limitations, so it’s important to understand the capabilities of each. Some processes, are more suited to high-volume, low-cost manufacture, while others are more suitable for low-volume, high precision parts. Certain processes are more suited to certain materials, so that should also be considered.
Not accounting for tolerances
This is a huge mistake and one that’s surprisingly common. Any manufacturing process has some degree of variation. You can take a hundred seemingly identical parts, and it’s likely that no two will be exactly alike. For instance, a typical injection-moulded plastic part can vary in size by up to 0.4mm. That may not sound like a big deal. But, imagine you have an assembly of ten parts. If each part is 0.2mm on the large side, then your overall size could be up to 2mm over size. This is known as a tolerance stack-up. Several years ago, I was asked to examine a customer’s mechanical syringe to determine why they were having reliability issues (not our design I should point out). Their product had a safety mechanism that was meant to retract the needle after injection, preventing reuse, however, they were encountering frequent failures. As I examined the product, it quickly became apparent that the original designers hadn’t considered the manufacturing variation, and the tolerance stack-up was the cause of the problem. Basically, it was impossible for the product to function at dimensional extremes.
Using too many fasteners
It’s simple really; more labour means more cost. Reducing assembly time saves money, leading to increased profit. And one of the best ways to reduce assembly time is to reduce the numbers of screws and fasteners.
Not using “Poka-Yoke”
“Poka-yoke” is a Japanese term that basically means “mistake-proof”. Essentially, it’s about designing in a way that prevents incorrect assembly. If it’s possible to assemble something the wrong way, then it’ll inevitably happen at some point. Considering poka-yoke principles ensures that a product can only be assembled the right way.
Not providing the right information
Finally, it’s important to ensure that complete and accurate information is provided for production. Nothing frustrates manufacturers more than receiving incorrect and incomplete information. It’s critical that drawings are properly detailed, including specific instructions and allowable tolerances for key dimensions. Allowing room for assumption is never a good idea.
Over to You
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