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Ask the Engineer: Micro-Molding – Four Case Studies

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Pushing the limits is by design a creative endeavor driving new innovation every day. When working on cutting edge design and products, there can be many roadblocks to side track your efforts but hopefully after working through the first four topics, you might find hope in meeting your goals. 
Below are four case studies or challenging parts that we have produced for our clients. There are a few examples were pushing the limits have made these projects very successful and hopefully at the same time spark your imagination as you work on your own. 
Case 1: 

This tiny part, made of Ultem (PEI) needed to consolidate several functions into a small package. It has a 100μm aspheric lens with a 125μm base radius on one side and a small turning mirror on the opposite side. It also has a tri-lobed press-fit slot at the bottom to receive a 125μm diameter fiber. 
This fiber holder not only requires very high tolerances on its very small features, it also requires an optical surface finish and clarity for the light path to be successful. The Ultem provides the stability and transmissive properties needed for the project. The challenge came in building the tool and managing the processing to fill out the micro features with this difficult material. 
Case 2: 

In this case, a delicate fabric mesh needed to be overmolded into a 2mm diameter cap without crushing the mesh or  allowing the plastic to wick past the shut off. 
Other than the delicate shut-off around the mesh, the other complication with this program was the system to build these parts – this didn’t exist. Here’s a case where not only was the part complex, but so was the custom molding unit that was built to handle the process. It’s a case where the customers ideal was an integrated component and the solution was a custom built injection unit to make it happen. 
Case 3: 

Here’s an example of pushing the limit with insert molding. The larger part, about 1.5″ long, is an extremely complex molded part with three independent metal inserts. The smaller part on the top as five discreet inserts. 
The challenge especially with the larger part, was combining the mold design with all of the different core-pulls, side-actions, and shut-offs so the customer would have one integrated component instead of two or three separate parts. It was a case where their ideal took great collaboration to accomplish.  
Case 4: 

This part is approximately a 4mm diameter PEEK lead frame part. The part is overmolded on the lead strip, then post-mold singulated and die-formed to its final shape. 
As we discussed, PEEK isn’t the friendliest when it comes to thin wall sections. The challenge here was processing this part in a lead frame environment to achieve the 0.25mm thin center. This delicate part then is loaded in custom trays to protect it while in transport to our customer’s assembly location. 
Hopefully keeping these five aspects in mind when approaching your next micro-molded project will help you push the limits and make your next design a success. There can be many roadblocks along the way, but seek out your experts, and who knows, may be the sky’s the limit.
 
Later this month, we will wrap up this series with some interviews with experts in the field of micro-molding. Stay tuned! 
About the Author: 
This is a White Paper by Accumold. For more information, click here or contact Micromolding@Accu-Mold.com or call 1.515.964.5741.

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