It is ... the responsibility of the expert to operate the familiar and that of the leader to transcend it.
- Henry A. Kissinger
Testing the real thing
Obvious as this may sound, the only way to test a plastic injected part is to test a plastic injected part. That means using the mold to make enough sample parts with which to conduct a product test, before you order thousands of parts.
My 3D printer took me a long way. Now was the time to move to the next stage. Even with the incredibly accurate parts I had made on my Stratasys 3D printer, I knew the next testing had to be with real plastic injected parts.
Depending on which materials you decide on, injected parts can be different. They may look similar, and they are certainly impressive, but for many reasons, the injected part will behave differently to the 3D printed equivalent part. The good news is that you have almost infinite control over your injected parts because of the wide range of materials available on the market. The raw materials available for plastic injection, called “resins”, are too many to count; you have control over the strength, color, flexibility, weight and texture of the piece you will make with injection molding. You can use plastic that is so rubbery it will bend 90 degrees and bend right back without damage, or you can use plastic that is almost as hard as steel, or anything in between. During the testing phase of my product, the folks at Cascade Plastics presented me with injected pieces in different materials before we considered the mold creation stage complete. The fact that they took considerable interest in the product meant that they were in a good position to advise me about which materials might best suit the requirements. Mesaros did several short runs, each in a different color, so we could be sure which materials were which, and in the end it was obvious which material would be the best one to use in the production run. As stated earlier, I was amazed the 3D prototypes snapped together with the final plastic injected parts. This alone gave me a good feeling my product was going to be close to what I had designed.
- Test various material choices before you manufacture a batch of product.
One of the requirements of my PondSecure product was for it to be negatively buoyant. That is, I did not want it to float, but rather, be slightly heavier than the water it displaced so it stayed in place below the surface of the pond. Many flexible plastics can be made stiffer or heavier by adding talc. There are also additives to make certain plastics UV-resistant. Colors vary in price. Black and other cold, dark colors are cheaper. Bright colors are more expensive because you have to use a lot of it to turn your piece of plastic, for example, bright yellow. It might be that only some of your parts have to be a bright color, so consider making batches of the same piece in different colors. In addition, each batch can have a different color, so you can make the same part in different colors if that helps manage costs. Talk to your manufacturer about what color, stiffness, texture and density choices you have and allow plenty of time to pore over the test runs of injected parts, even if you have to pay extra for that stage.
- Allow at least two months to process test runs of injected parts, more time if your parts are complicated.
It did not occur to me at the time, but Cascade Plastics had woven the effort to test the injected parts into the cost estimate for the mold creation. They knew the real profit was down the road and not in creating the molds, so it was in their interests that my product worked. The fact that they had something to lose told me they must have understood the value of the product and underscored for me the value of having committed and capable partners.
We made a few minor, but critical adjustments to the molds, involving about 4 iterations, after which I signed off on them, which triggered the remaining 50% of the mold cost, $18,000.
Cost of this stage: $18,000. Costs so far: $66,800
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