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Special Tools for Tiny Parts

 

When discussing things like pizza or Hadron particle colliders, bigger is usually better. For medical devices and their components, the trend is to go smaller whenever possible.


Smaller devices take up less space, usually use less energy, are easier to dispose of, and go places where bigger devices are not welcome. Miniaturization is especially desirable for surgical devices, catheters, implantables, and the internal mechanisms of personal products like insulin pumps. In the last five years we have worked on more projects that require tiny components than in the entire 30 years we have been in business. And fabricating miniature parts is not easy! They are specified with tight tolerances, usually less than the width of a human hair. Case in point, one of our ocular implants is so minute that nearly a quarter of a million can be molded from one pound of clear acrylic.

 


The ocular implants above are some of the smallest injection molded parts we have designed.
They were particularly difficult to balance on the tip of Earl’s red pencil.

 

Unique parts and components require special tools.


Designers and engineers who expect to prototype their devices in-house have to consider which resources are available in the “company toolbox”. To this end we have added a  Levin Precision Instrument Lathe to our resource list. It is a manual machine best used for miniature linear shapes like cylinders with or without bored holes. The “micro lathe”, as we call it, gives us a level of control over the design process which directly affects the way we develop prototypes.  The machine allows us to experiment before drafting final part specifications, an activity critical in design for manufacture.

 

We can do the "one-off" jobs other companies will not attempt.


According to Andy Scherer, our senior mechanical engineer, the process of prototyping miniature parts to determine final dimensions is different than simply building production parts. “In many ways, it’s much more difficult. For some of the small parts we work on, they couldn’t be done anywhere else. When we prototype small plastic or metal parts, it’s hard to arrive at a final milled dimension when you’re trying to remove ‘a half a tenth’ (0.00005 inches!) at a time. At that scale materials tend to deform before they cut. They’re tough to measure too. It’s easy to crush them with a micrometer. Outside shops won’t do this kind of prototyping because they want jobs with finalized dimensions, otherwise there’s no money in it for them. If there is going to be testing done on small parts to ensure a final production fit, we have to do it here,” he adds.
 

 

The catheter parts pictured are only a little larger than Abe’s nose. Even so, they are
significant since we were able to fabricate them at our facility with the micro lathe.

 

 

When the micro lathe is booked we still have the ability to fabricate some small parts with our other high-precision machinery. The  Fadal Vertical Machining Center and the Southwestern lathe are big, multi-axis CNC tools. We keep them tuned-up on a rigorous maintenance schedule which assures near extreme accuracy for most close-tolerance jobs. These are the tools of choice when we need to mill formed profiles like slots, threads, or curved shapes. As you might guess, our engineers make the best use of the big CNC machines after they have already agreed on the production part dimensions.

 

Before they are finalized, the real benefit of the micro lathe over the big machines is the “feel” an operator has when milling those tiny morsels that are so easily damaged. For a range of items from miniscule to massive (but much smaller than a particle collider), we can offer a resource our customers would be challenged to find anywhere else.