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Case study - Medical
When they said it could not be done
454 Life Sciences manufactures DNA sequencing equipment. They asked us to achieve what was thought unachievable for a very small, very complex component part.
The part
A DNA mixing tee measuring .58 by .43 inches - smaller than a dime - and weighing two tenths of a gram. Oil flows continuously through tubing while DNA is injected into the stream, creating microscopic droplets. The geometry of the part is what forms the droplets, so the internal channel dimensions are the function, not a detail of it.
The problem
The customer had already been through a molder who could not deliver. The sticking point was reducing the flow channel from .013 to .010 inches while keeping it smooth and consistent. At that scale a channel is not simply drilled smaller - how it is formed determines whether the flow behaves.
On top of that, the injector orifice had to come in at .004 inches in diameter, roughly the width of a human hair, and carry a luer lock detail so it would mate with standard laboratory fittings.
What we did
Rather than treat the channel as a hole to be produced, we formed it with a precisely guided steel core pin. Guiding the pin accurately is what delivers a smooth channel wall; an unsupported pin at that diameter deflects under injection pressure and the channel comes out tapered or off-axis.
The luer lock detail and the .004 inch orifice were then cut into the tooling to our standard .0001 inch tolerance. Quality control focused on the cross sections, where flash or a burr would disturb the droplet formation the whole part exists to produce.
The result
- .004"
- Injector orifice, hair-width, with luer lock detail
- .2 g
- Finished part weight, .58 x .43 inches
- 1st run
- All tolerances met on the first automatic run
Cross sections came out smooth, with no flash and no burrs. Every tolerance was met on the first automatic run, not after a series of tooling revisions. The technology this component supports was subsequently profiled in published DNA sequencing studies.
Why it worked
Nothing here required equipment another shop does not have. It required deciding, before steel was cut, that the channel had to be formed rather than machined - which is a design conversation, and one we would rather have at the quoting stage than after a tool exists.
If you have a small part with an internal feature that will not hold, see small and complex parts.
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