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.
Shrink rates for injection molded plastic parts vary depending on the materials used andwall thickness. Designing uniform wall thickness offers substantial shrink rate control; on the other hand, non-uniform walls can lead to large pressure drops during filling, significant differences in shrink rates, and internal stresses within the injection molded part that could cause warpage or similar defects.
Manufacturers cannot afford to lose any time in getting their products to market. Advances in technology come rapidly, ratcheting up competition for market share. To ensure success, products must be designed and produced with ultimate precision and efficiency. That efficiency depends on eliminating production delays caused by inconsistencies in the manufacturing process.
With careful planning, complex injection molding can reduce costs, optimize functionality and improve aesthetics in medical devices.
When engineering-grade resins were introduced in the 1950s, some auto manufacturers were unfamiliar with the benefits of metal-to-plastic conversion, i.e. how to design plastics into products, and how to manufacture with plastics. Today this practice, also known as “lightweighting,” is becoming increasingly popular with automakers as they race to comply with a federal mandate calling for automobiles to average 54.5 miles per gallon by 2025.
Moving an idea from conception through production can take many paths. However, what initially appears to be the "easy route" can sometimes lead to complications, including certain efficiencies being overlooked or lost. Generally, spending more time and effort up front can simplify the process and provide desired outcomes, especially when you enlist the engineering expertise of your injection molding partner.
Snap-fit designs can be an effective way to replace fasteners/hardware in injection-molded plastic parts or products. For most applications, snap-fit connections are the simplest and most cost-effective way to assemble two parts — making them ideal for high-volume production. The quick and easy connections help reduce the risk of improper assembly, which occurs more frequently in applications that require more components (fasteners) and tools.
For manufacturers that produce complex, critical-use plastic parts and components, making sure that exact specifications and dimensions are met during production is crucial to success. Even a miscalculation of just .005 inches can spell disaster for the product and cost thousands to fix.
Tooling is arguably the most important part of the entire injection molding process. Not only does the tool need to be perfect to ensure all design specifications are met, but it’s also one of the most expensive, time-consuming fixes if something isn’t right—especially if you’re working with a third-party toolmaker. Working with an outside toolmaker for projects requires a lot of back and forth communication, leaving room for misinterpretations and sometimes delayed responses.