Insert molding is a process that requires an insert — typically metal — to be pre-placed in the tool for injected plastic to flow around. Encapsulating the insert with plastic creates a single molded plastic piece that’s generally stronger than one created using secondary assembly.
Insert molding can be accomplished through two methods:
- Manual insert loading: The generally more cost-effective way to approach very low-volume applications or extremely complex part geometries
- Automated insert molding: A better choice for part consistency. It minimizes human error, improves efficiencies, and ensures optimal cycle times.
Securing an insert in plastic requires precision and a thorough knowledge of how each individual substrate reacts to conditions during the injection molding process.
Geometric dimensioning and tolerancing (GD&T) is a symbolic language that is used on engineering drawings and computer-generated models. It communicates geometric dimensions and allowable tolerances for various parts. Not only is this a useful exercise for product design, it’s also helpful on the manufacturing floor because engineers and operators can quickly see the degree of tolerance that is required for each part.
Surface finish on plastic composites can vary a great deal, depending on the physical and chemical properties of the polymer blend as well as the parameters of the injection molding process.
The first objective for a custom injection molder is working with the customer to determine how important the surface finish is for the appearance and/or performance of the final product. For example, does the product need to be eye-catching or simply functional? Depending on the answer, the material selected and the desired finish will determine the settings for the injection molding process, and any required secondary finishing operations.
Injection-molded and blow-molded plastic parts are so pervasive in everyday life that the two processes are sometimes thought of as interchangeable. While the two may be used in an individual application — perhaps a blow-molded fluid reservoir is attached to a custom injection-molded medical device — injection molding and blow molding serve different purposes and markets.
There are several prototype tooling options for your designs — the one you choose really depends on what you expect to accomplish with the prototype. For example, will the prototype be subjected to testing? Does it need to be "dressed up" for presentation? Will it need to meet tight tolerance requirements?
The most common prototyping options are SLA/SLS, urethane cast, soft tooling, and hard tooling. But which is right for your component? Read on to discover the advantages and disadvantages of each.
When you approach a custom injection molder to produce complex plastic parts or components, determining if the product is suitable for a streamlined injection molding process is one of the first steps.
It can occur in just about any injection-molded part or product — yet the experienced injection molder knows how to eliminate warpage from the production cycle and maintain a steady throughput of high-quality product that meets all customer specifications, including dimensional accuracy and tight tolerances.
For many OEMs, multi-material injection molding is a smart and versatile solution to producing complex components and parts. The ability to incorporate multiple polymers, metals and other non-plastics into the molding process to accommodate threaded holes, inserts, lenses, etc., simplifies assembly and generally enhances end-product performance.
Not taking the time to properly determine shrink rate can have a big impact on the quality of an injection molded part's geometry, performance, and appearance.
To facilitate this calculation, materials suppliers typically provide shrink rate numbers based on ASTM Standard D955 and a .125-inch thick plaque with a specific gating size and location. Although a good place to start, this value is usually not accurate enough for many products, especially critical, highly complex parts.