Making Stuff: The Custom Plastic Manufacturer

Microdyne Plastics, Inc. started in 1975 as a custom plastic molding company.  From our small beginnings, this was how we began the company and still continue today. In today’s manufacturing world, the opportunity still exists to produce custom products and containers.  In most cases “custom” means a human must think about, design or touch something to make the custom product to specifications, and of course, humans cost money.

While some products can be cut to a specific length or painted a certain color to make them custom, in the case of plastic injection or blow molding if the shape is different in any way, a new mold may need to be built for the specific product. It could be just a centimeter different, but it still requires a full set of molds or inserts for the shape. Naturally this means lots of personal attention.

Sure, with digital design, an old set of plans can be tweaked a little and saved as a new set. There can be lots of time saved in the design, but an engineer usually is making the changes. Once the design is completed, the mold or tool must be mostly hand built.

What is called a mold or a tool in the plastics industry is really a machine in its own right. It contains a cavity (or multiple cavities) which is how the shape and form of the part is determined. But the tool must also have a way to get the molten plastic into the cavity and a vent where gasses (air) can escape from the voids in the tool. The mold is generally in two halves so it can be pulled apart to get the molded pieces from the tool. These two halves must fit together precisely so the molten plastic does not leak from the tool. To get the cooled molded plastic out of the tool, ejector pins or other methods are needed to move through a cavity pushing the part from the cavity.

Finally, the tool itself must fit onto the machinery that handles the plastic. We have left several other components from this illustration, but the point here is that the tool is a machine itself, usually one of a kind. Each of these parts must be designed to fit with the other parts, and has a high degree of hand work.

The tool-making process requires precision machining of steel or aluminum. CNC machining or electrical discharge machining processes are used to remove solid metal material from a larger block. While some of these processes are automated today, skilled operators are required. Many other smaller operations and other metal machining operations must generally be crafted by hand. And, in many cases, since only one of each tool is made, robots can’t easily be programmed to do this custom work.

As a result, while the per-piece cost of plastic is low, these little “machines” are expensive to build. While they can last for years and be made to make well over a million parts, the initial capital investment can start in the tens of thousands of dollars and go up. Tools can have a wide life span, depending on the mold type and material used.

In considering the cost of the tool, you need to spread out the cost over the tools lifetime. If a tool’s cost is $20,000, then its cost per piece for 500,000 pieces is just 4 cents each. Add the cost of the material, machine time, human setup time, and some profit, and you have the overall cost of your plastic product.

If you have short runs, there are set-up and run time costs so the unit price rises a slight amount per piece. If you need a small quantity only, then your tool cost is spread over a shorter number of total units which effectively increases the cost.

In each case the design and tool costs for custom plastic parts take human time and/or intervention.

If your product is a standard plastic bottle or jar, and you can use a standard shape, the manufacturer of this standard shape has incurred the cost of the tool, so your cost can be less. This same approach can work for other standard or purchased parts if you can find them. These may include plastic bottle tops, clips, connectors or other products.

Custom takes time, and human time is expensive. So custom work will always have a premium on it. Fortunately, having products that are unlike others creates stronger brands that also command higher prices from the ultimate consumer. Redesign and rethinking products and how to manufacture them can create new markets. The partner of innovation is the custom manufacturer. Think of where the iPhone would be without it!

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