You need to make a distinctively large quantity of plastic molds in your next robotics project. Should you simplify the design to save your self the trouble? There are several options available to you. Many of these fall into the categories of hand forming, vacuum forming, conventional milling, CNC milling, injection molding, and sls stereo lithography categories.
The order these options is presented is not coincidental. Generally this is directly tied to the dollar value associated with each of the processes. But when and where are these monetary lines drawn? There are several factors to consider. Of coarse, money is a driving force, but how often do we undervalue our own time spent in manufacturing a piece for our robots. Another consideration is that of repeatability. Will one piece be exactly the same as the next, or will I have to make special considerations for each piece in my product design. The proceeding ideas represent decisions that we as robotics enthusiasts make normally in a subconscious manner. I present the following based on my recent decision to choose one of the fabrication techniques, which, aided by modern technology proved to be rather painless.
In choosing to injection mold the tractor tread pieces for my robot I was taking a large step towards reducing my overall project cost. Specifically, when accounting for my time in machining complex 3-D pieces, even worse, one hundred and forty four of them, one begins to look for other options. The argument proceeds that this is why we have CNC machining. The problem becomes more evident when you take into account the actual part geometry. The piece I dreamed of would require four separate setups in CNC machining and as further investigation proved require producing four separate sets of custom machined complex tooling fixtures to hold onto the part while machining it. So I decided that an injection mold would be the preferred method of part production.
Upon choosing this method of production tooling, advice will flow in. `That technology is for large companies making tens of thousands of parts, they’ll say. Not to discount this wonderful advice, in large part this is true, but not in the sense that it applies to the common robotics hobbyist. There are many small shops that are more than willing to do small production runs in molding that are willing and friendly enough to stop and help the little guys.