Custom Molded Part: Silicone Pull Plug, for Slotted Keyway
This plug seems pretty straightforward, as it needed to mask a through-hole in a pulley that has a keyway slot cut into the center bore. But there are some aspects to this design that make it a bit more unique than meets the eye.
To begin, although this is a pull plug type of masking device, it has an oversized handle on the end. The customer wanted to be sure that the masking operators would be able to easily grab and pull the parts through the pulley. So the major diameter dimension of the plug - the larger section, that is - was designed slighlty oversized, per the customer's request, causing quite a bit of additional friction to overcome when inserting the plug into the metal part. This handle accounts for this friction, enabling more "grip" to be realized by masking personnel.
It may not be obvious from the picture, but the length of the handle section is a bit longer than the major diameter plug section as well. This is to ensure that that larger handle knob at the end can go far enough through the part to ensure that better grip of a hand on the other side. And that raised section on one side to mask the keyway? It has a tapered "nose" so that the plug will more easily "self-center" in that keyway, rather than the operator having to spend extra time lining it up exactly. Even the beginning portion of the major diameter section is radiused on the front end - due to the slightly oversized diameter, this makes it easier to get the plug "started" in the part.
Every aspect of this plug was carefully thought out in Viadon's design process, so that the plug would work for the customer as intended.