Preventing Design Challenges in Micro Mold Design


As medical and wearable devices reduce to sizes and weights previously thought to be impossible, engineers and designers are shifting their design chops to micro mold design of complex components. This new direction, however, hasn’t come without a hiccup. These micron tolerance considerations are presenting some common mistakes.

As engineers are asked to fit more functionality into tighter spaces, they are learning new methods to succeed despite increasingly complicated high volume micro mold design challenges. They are shaping the future of product design, without a doubt, but inexperience in this microscopic space has created an alarming trend. Luckily, addressing this knowledge gap early cane stave off massive delays in the manufacturing process and unnecessary product design alterations.

At Accumold we often notice a lack of consideration for gate and ejector pin locations in the industry. As surprising as it sounds, this Achilles Heel of the process can weaken strong manufacturing processes. As engineers cross over from micro machining or even larger molding, it’s best to ensure your team doesn’t overlook this major issue.

micro mold design specs

In micro mold design, gate and ejector pin locations are crucial.

Gate and ejector pin location is a big deal. While this may not greatly impact the design of a small injection molded part the size of a golf ball, consider the surface area committed to an ejector pin when the entire part is 800 x 360 x 380 microns. Luckily, there is an easy fix.

At Accumold, redesign decisions are made through several back-and-forth meetings between designers and our DFM micro mold engineers. When microns determine your typical size considerations, an improperly placed gate can neglect to fill the mold, making a deficient part that lacks a robust structure. And an ejector pin placed in the wrong location? That can change the part geometry significantly. To avoid these snares, there are several rules of thumb to ensure the micro molded design fulfills your goals.

First of all, consider your gate locations. Gate location on every part is recommended to be positioned on the thickest geometry of the part to increase the likelihood the entire mold fills. This can obviously be difficult depending on how complex your component is.

Second, ejector pin locations should always avoid thin areas. This might not sound important, but placing ejector pins on thicker areas prevents ejector pin force from punching through the part or distorting it. But what happens when these considerations simply can’t be implemented? Are you stuck? Absolutely not.

Ejector pin and gate locations shown on this micro mold design.

Ejector pin and gate locations shown on this micro mold design.

When ejector pin or gate locations can’t be accommodated for without compromising the integrity of your micro mold design, our engineers have often turned to a few homegrown workarounds to accommodate part complexity. In the past we have added “gate features” to the end of components.

Essentially, a gate feature is when we create an excess feature on the part that is left connected for the purpose of ejecting it out of the cavity. In order to accommodate customer goals, for obvious reasons, this part then goes through another process developed to remove the gate feature, leaving the original part form factor intact.

Obviously, considering gate and ejector pin locations as your designers create your next project can save time and resources, but in many cases, we’ve assisted with, it saved the entire project. Today’s micro tech has less margin for error than any projects in the past projects, therefore it’s essential to anticipate these micro features that didn’t affect component designers of the yesteryear.

Still, the easiest way to avoid micro mold pitfalls, is to simply share as many details with us in advance, even more so in micro molding. A project you may determine is extremely unique may have challenges already tackled and conquered by our engineers. When you give us a good idea of what your component is, the overall purpose and how it works in the overall product design, breakthroughs are made. Don’t hold back, we can take it.

This piece originally appeared in the June issue of Design World. It has been published here with permission from Design World magazine.

micromolding components next to EU coins.

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