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What Is It Like To Be A Plastic Injection Mold Maker?
Dec 25, 2017

      Raise your hand if you personally know a plastic injection mold maker, hmmm... I don't see any hands up! Well, who knows what a mold maker does? This doesn't look good, so I will try to give you a little insight into this unknown world.

      I have one of those "invisible jobs" that is seldom recognized, but universally valued. You see, almost everyone likes using their cell phone, computer, driving their car, playing CD's, and generally enjoying the fruit of all our hard work.

      Yet, almost nobody ever thinks about where all this stuff comes from. In fact, I've been asked some very strange questions over the years about what I do, such as when my own mother asked me how many molds I made a day! I told her it takes anywhere from 4-12 weeks to make a typical mold and she just sort of cocked her head and replied, 'Oh."

      Let's just take your computer mouse for example. It is entirely made of plastic, and it took a mold maker to make the mold to make the mouse components. I am guessing that there are 10 pieces altogether in the mouse, so that means 10 different molds had to be made. Here is a little view into a typical day of an American plastic injection mold maker. It doesn't really vary too much around the world either, just in the details and amount of overtime and specialization.

      He, (I've never seen a she, though I heard about one once) starts work at either 6 or 7 a.m. I also have never known a mold maker who started later on a regular basis. He typically works a 9 or 10 hour day and often 5 hours on Saturday. Before Asia became a mold making force to be reckoned with, there was basically unlimited overtime for everyone.

      He has likely been in plastic injection mold making for over 25 years, had two years of technical school, and worked as an apprentice for 4 years. That is a lot of training and experience, which is quite necessary because there is so much to know and master.

      Here is the process in a nutshell, a small nutshell

      Once somebody comes up with the idea to make the computer mouse, he gets a preliminary product design made, then a mold making company is contracted to build the mold, a mold designer comes up with a "blueprint" (nobody uses blueprints anymore, it is called CAD because it is done on a computer), and finally the mouse gets molded into the plastic part.

      So, the mold maker gets the plan from the mold designer and together they come up with a "how to" procedure. The entire mold is gone over in every minute detail because, in the end, a mold a really a million little details that fit together.

       So, for the next month or two, the mold maker works together with machinists, apprentices, and other mold maker to fabricate all the shapes and pieces that comprise a finished mold. They need to cut steel with special cutters on very sophisticated machinery that can easily cost $150,000.00 each.

        Then there is the very mysterious machine called an electrical discharge machine that is truly strange to the initiated. This machine, which goes by the name of EDM, is the main way that all these shapes are produced in the plastic parts you use, such as the curvy mouse.

        The EDM is a bit like sinking your fist into a ball of dough and leaving the imprint of you fist in the dough. Only the dough is hardened steel and your fist would be some graphite, (like pencil lead) made in the shape of the mouse. The EDM produces whatever shape you can make in the graphite into the steel.

        So, the mold maker gets the steel with the shapes, and puts them in a holder (mold base), and makes everything fit perfectly so the plastic part comes out nice and clean. If he does a poor job, you will see the little ugly lines on the part, or little fins of plastic sticking out, like you might see on a cheap Chinese toy.