DE Blister Die-Cutting

The challenge

Thermoluminescent dosimeter elements arrive sealed inside plastic blister packs. Before anything can be done with them, the plastic has to be cut open and the waste taken away, and the element inside has to come through it untouched.

The difficulty is that the cut has to land in exactly the same place on every pack. A blister pack is a thin, flexible piece of plastic that will happily shift under a blade. If the pack moves, the cut wanders, and a wandering cut on a sealed dosimeter is not a scrap part, it is a damaged one.

What we built

We designed the tooling as one system rather than four parts, because the parts only work if they agree with each other.

A hinged carrier machined from 10mm aluminum holds the pack. The pack drops into a recessed pocket that locates it positively, and the top plate closes and clamps it flat, so the pack is held in a known position instead of being held by hand. A steel-rule die blade does the cutting, and a machined acetal cut block sits behind the plastic to back the cut, so the blade meets a firm surface rather than pushing the material away. A magnet plate handles retention.

Because the pack is located by the carrier and not by the operator, the cut lands in the same place on the first pack and the five hundredth. The tooling carries the accuracy, so the operator does not have to.

Tooling at a glance

• Carrier fixture10mm aluminum, hinged clamp
• Die bladeSteel rule die, 0.028" × 0.937"
• Cut blockCNC-machined acetal copolymer
• RetentionMachined magnet plate

From sketch to parts in hand

The work started as concept sketches, went to dimensioned drawings, and then out to fabrication. The die blade, the machined block, the aluminum brackets, and the magnet plate each came from the vendor best suited to make them, and we managed all of it, so the customer received finished tooling rather than a drawing pack and a list of phone calls.

The result

Tooling designed, fabricated, and delivered as a working set.

Capabilities used

Mechanical design, precision tooling and fixture design, CAD and drawing production, and vendor management through fabrication.