DETROIT - Managers at Security Plastics Inc., a Miami Lakes, Fla., custom molder, say they've developed a new technique for custom injection molding that allows Security Plastics customers to share machine time, technology and resources. The technique is called heterocavity custom injection molding and amounts to gang molding with a variety of tool inserts in a common mold base. The process involves the use of small, interchangeable custom tools, owned by different customers who share the same mold base and the cost of each production run, said David J. Lucas, Security Plastics project engineer based in Sterling Heights, Mich. He explained the system during the SAE International Congress & Exposition, held Feb. 27-March 2 in Detroit.
``The cost to the customer is a small percentage of the cost of conventional molding,'' Lucas said. ``There's no excess inventory or expensive production set-ups.''
For heterocavity molding, parts must weigh about 1 ounce and use standard engineering resins. Tools can be added or removed in a few minutes, Lucas said. Security Plastics builds heterocavity tools using a laminating process that makes tooling modification simple and fast.
``Because of that, heterocavity tools are good for prototyping. The customer saves weeks of product cycle time and can see prototypes run under production conditions,'' he said.
In heterocavity molding, Security Plastics uses standard tool sizes and an automated quick-release system that allows a tool change in just two minutes, the company said. A molding machine using heterocavity molds has a generally conventional appearance but includes an automated parts removal system of tubes running to boxes for just-in-time shipment.
Flexibility is a major advantage. As production requirements increase, heterocavity tools can be added. Design improvements can be incorporated with minimal disruption of production because all of a customer's tools run independently.