Medical Device Link.

MATERIALS

An ambulance AED unit requires a suitcase-style handle. The handle has dual functions: carrying the unit and setting it up at an angle (see inset). Therefore, the handle must have a soft touch, but it must also be sturdy enough to hold the weight of the device. The material requirements are the same as those for the AED unit discussed earlier.

The processes selected to manufacture the handle, which is molded of polycarbonate resin, include both gas-assisted injection molding and overmolding. Gas-assisted injection molding produces the hollow substrate part. In a subsequent step, the substrate is put into a second tool to overmold it with a TPU to provide both comfort and grip to the emergency medical technician handling the product. There are three sections in the final molded part: the hollow core, a layer of substrate resin, and, on the outside, the soft-touch TPU.

Return to Article: Material Selection: The Right Resin for Your Design

It is critical to mold the substrate rigid enough that it doesn’t crush under injection pressure in the second molding operation. Another important aspect is creation of a strong chemical bond between the substrate and overmold. In addition, the part should be aesthetic, cleanable, have a soft touch, and be impact resistant. The unit also has to pass a drop test from a certain height without damage.