There’s a lot to factor in when developing an injection-molded part. Working with a plastics manufacturer that offers comprehensive services, from the initial consultation through prototype to production, can streamline part design, ensuring specifications align with manufacturing capabilities and functional requirements. Understanding the most critical factors of the process empowers OEMs to make informed choices from the beginning. We’ve compiled a list of eight essential considerations regarding injection molded part design that can set OEMs—and their manufacturing partners—up for success.
1. Involve your injection molding partner early in the development process.
Involving the manufacturer early in the process means OEMs can leverage their expertise in design, materials, and manufacturing equipment. An experienced contract manufacturer can optimize the manufacturing process, enhancing quality and reducing costs.
“With our knowledge as a full-service manufacturer, we're able to look at the component from multiple angles,” explains Nate Schlauch, Director of Business Development at Elite Precision Plastics. “From an assembly standpoint, manufacturing standpoint, pre-production, as far as design.”
A contract manufacturer can enhance the initial design in several ways, including:
Mold design: an efficient mold reduces waste, improves tolerances, and can include more than one part to streamline production.
Features: revising or eliminating certain features helps prevent warp and molding defects
Combining components: redesigning separate parts into a single product can lead to faster production cycles and reduced inventory to store and manage.
If you want to reproduce an existing part, a manufacturer with design experience can suggest adjustments to maximize value and precision.
2. Establish clear communication channels
Open lines of communication support the entire process, from design to production. Miscommunication can lead to significant issues such as design flaws, quality issues, or manufacturing delays. Clarifying communication channels early on helps guarantee all parties are aligned, reducing the risk of errors that compromise quality and affordability.
To establish clear communication channels, consider the following:
Designate specific points of contact on both sides
Establish preferred contact method and hours
Design an emergency contact protocol
Schedule regular check-ins and progress updates
Ensure mutual access to shared documents and files
Maintaining open lines of communication means the final product is more likely to comply with regulatory requirements, meet delivery deadlines, and align with the OEMs original vision.
3. Set clear goals and expectations
Clear, upfront communication around project goals is vital to the design process and for an efficient project trajectory. Michael Comer, Engineering Team Lead at Elite Precision Plastics, emphasizes the importance of defining clear goals throughout the process. Clear guidance guarantees the design team’s time is used efficiently and unexpected changes don’t cause backstepping.
Comer also says up-front goal setting allows manufacturers to advise on whether the OEM's expectations are realistic. “If they're wanting an injection molded part to hold plus or minus five ten-thousandths of an inch tolerance, we can explain to them the difficulty associated with that and make sure that's a necessary requirement,” he explains, “because it adds lots of cost and complexity. We might be able to guide them in a different direction or tweak their design to give them more freedom, lowering the cost and making it easier for everybody.”
4. Consider manufacturability from the start
An experienced injection molding partner has an in-depth knowledge of multiple manufacturing methods. They understand the requirements, benefits, and restrictions of each. Considering manufacturability as early as possible means the manufacturer can guide the OEM toward the best possible manufacturing methods and processes to achieve their product goals.
Examples of injection molding methods include:
Gas-assisted injection molding: reduces material usage, creates hollow sections within large parts
Two-shot molding process: creates parts with two colors or materials by injecting two different plastics into the same mold.
Insert molding: metal or other components are placed into the mold before injection, embedding them inside the plastic part.
Selecting the correct method and other actions addressing manufacturability provide specific benefits for different plastic part designs.
5. Collaborate on material selection
A collaborative approach to selecting materials allows the OEM and contract partner to select the best plastic resins to reach product goals. Collaboration can ensure the chosen resin matches the requirements for properties like strength and chemical resistance. This joint effort also helps balance cost-effectiveness with performance, ensuring the final product meets technical specifications and budgetary constraints.
"Our engineers have backgrounds that allow us to help select materials based on the part designed,” says Comer. He also says materials recommendations are based on a detailed analysis by the entire design team. “We go back and forth so that if a part needs to have a certain geometry, we can select a material that fits that design and also achieves the strength and chemical resistance requirements."
6. Optimize gate location and type
The small opening through which molten plastic enters the mold cavity is known as the gate. Optimizing the gate type and location ensures proper flow, critical to part integrity and overall product success.
There are various types of gates, each with a unique design. The gate design and its position in the mold location impact the dimensions and shape of the part. Poor gate placement can lead to issues like warping, deformation, voids, and sinks.
Manufacturers can conduct a mold flow analysis to determine the optimal gate location. They may also recommend using a hot runner system which minimizes regrind, reducing material waste. OEMs who prioritize eco-friendliness can benefit by using a hot runner, helping to achieve a zero-waste process.
Discussing gate optimization early on allows manufacturers to customize the gate for maximum performance and sustainability.
7. Address critical tolerances and finishes
Communication regarding tight tolerances ensures the manufacturer has processes in place to achieve them.
Examples of precision processes include:
Mold design that accurately aligns with part design
Materials that maintain consistency without shrinking
Advanced metrology tools for precision measurements
Error-reducing automation and process controls that improve consistency
Finishes, or the texture of the part’s surface, are often requested for cosmetic purposes. Surfaces can be rough, matte, or polished to a smooth, glossy appearance. Surface texture may also be selected to improve grip, reduce glare, or other functional purposes. Discussing finishes in advance means the manufacturer can adjust factors like temperature or injection speed to achieve the desired result and set up quality checks to ensure the finish meets expectations.
8. Discuss prototyping services
OEMs can leverage their partner's in-house prototyping capabilities or existing partnerships to validate the part design. This gives the OEM and the manufacturer confidence before investing in the mold.
Prototyping benefits:
Design flaw identification: prototype testing can reveal design issues before committing to purchasing molds.
Fit validation: 3D models are used to validate the fit and ergonomics of the part.
Aesthetics evaluation: models are used to evaluate color, texture, and overall appearance.
Rapid prototyping: quickly modifying, printing, and testing multiple part versions helps refine the design before full-scale production.
Risk reduction: design validation through prototyping reduces the risk of costly errors, production delays, quality issues, and equipment failure due to product inferiority.
A proactive approach to these considerations helps OEMs navigate the complexities of plastics manufacturing. Working with an experienced, full-service contract manufacturer is more likely to deliver high-quality parts and successful launches, giving OEMs a competitive edge in bringing new products to market.
Elite Precision Plastics is a full-service, ISO 13485-certified injection molding manufacturer with extensive experience in part design and tight-tolerance manufacturing. Contact us to learn more about our U.S.-based manufacturing services.