Plastic Molding Processes
At Rebling, we perform several types of plastic molding processes to meet our customers’ diverse needs. We have decades of experience with thermoplastic injection molding, insert molding (including wire overmolding), and thermoset injection, compression and transfer molding. No matter what the process, we feel that we can recommend and manufacture plastic parts out of an appropriate material for almost any project.
Plastic Injection Molding
The most common way to produce plastic parts is the plastic injection molding process. When the process uses materials that can be heated to soften or melt, it is called thermoplastic injection molding. Most plastic parts today are made from thermoplastic materials such as nylon, and ABS. When the process uses materials that permanently solidify by a chemical reaction, it is called thermoset molding. Thermoplastic injection molding, which relies on the rapid cooling of the plastic melt in the mold, typically results in a much faster process cycle than thermoset molding. The principal thermoset materials molded by Rebling are DAP, phenolic polyester and epoxy.
Thermoset materials are typically used in specialized applications where retention of mechanical properties at elevated temperatures is a requirement. Using either type of material, plastic injection molding is the most cost effective method for manufacturing at Rebling, because it can be automated, and it does not require any labor intensive preliminary or secondary operations.
One specialized type of plastic injection molding performed at Rebling is called insert molding. This process involves molding plastic around another part, which could be made of metal or another plastic material. Wire overmolding is a special type of insert molding where plastic can be molded over different sizes of wires to form a plug or strain relief. Rebling has experience with wire overmolding several types of parts using a variety of wire sizes.
Thermoset Transfer Molding and Compression Molding
The thermoset transfer molding process starts with pre-forming a cylindrical “pill” of material at the proper weight. The pill is usually hand loaded into a mold, where a plunger pushes the material into the cavity, and the thermoset material cures under heat and pressure.
Thermoset compression molding uses a loose bulk molding compound that must be weighed before an operator or automated equipment places the material into an open mold cavity. The press applies heat and pressure until the part is cured.
While both of these methods are more labor intensive than plastic injection molding, some thermoset materials are only available in transfer and compression grades. In order to achieve some of the special properties of thermoset materials, compression and transfer molding processes are sometimes necessary. That is why Rebling is committed to offering all types of thermoset molding to our customers.
No matter which molding method is used, processing parameters for each part are documented (or stored in machine memory) to insure lot to lot consistency.
Using modern, state of the art primary and auxiliary processing equipment enables Rebling to provide the highest quality plastic moldings available in the industry today. To ensure part consistency and minimize machine downtime, all processing equipment is serviced using an extensive preventative maintenance program. This includes all the customer owned molds and fixtures, which undergo routine maintenance during and after production runs. Every mold is tracked for number of cycles in our ERP system to ensure maintenance is performed at the proper interval.