Many customers have little idea regarding number of cavities of a plastic mold and how it impacts to the plastic mold cost and the product cost. Here, I would like to give you simple explanation and hope it helps anyone who is looking for a competitive product price.
Many customers are thinking that a plastic mold is making only one piece at a time. In fact, a plastic mold makes more than one piece at a time in many cases. For pen housing, it is pretty common to make 32 cavities, 64 cavities or even higher at 128 cavities in a plastic mold. 128 cavities plastic mold will mold 128 pieces in one shot.
A multi-cavities mold has lots of advantages in cost. Since it molds many pieces at a time, it allows more pieces to share the plastic molding cost. Hence, it helps to bring down the product unit price. The higher output rate also helps in lower the production cost by higher efficiency. However, there are prices for it. Firstly, the plastic mold needs to be bigger to house more cavities. The bigger the plastic mold, the higher the plastic mold cost. It also requires a bigger plastic molding machine for the molding process, which will cost higher than using smaller machines. Secondly, setting up a molding machine is costly. A big plastic molding machine will use up lots of time and plastic resin for the setup. Therefore, a bigger quantity is needed so as to run the plastic molding machine more cost effectively.
It is more cost effective for a plastic mold having more cavities than fewer cavities on condition that the utilization of the machine is high. Otherwise, the high setup cost and amortization of the plastic mold cost will overwhelm the cost benefits from more cavities.
As a guideline, a small order should go for single cavity or fewer multi-cavities plastic mold whereas a bigger order should be better off by making the plastic mold with more cavities.