Designing effectively with plastics

Effective Plastic Part Design

What do you need to know to successfully design and produce high-quality, highly-engineered plastic parts? Here are five inter-related variables you need to keep in mind: part design, material selection, mold design, molding presses and production processes. The right combination of them can increase your odds of success with your next plastic injection molding project.

Part design

Many design variables can affect the quality and cost of your finished parts. Because of this, inviting your molder to collaborate with you early in your part design process can pay big dividends.

From consistent wall thicknesses and internal radii to including the proper amount of draft into your design and selecting the correct datum structure, there’s a lot to consider. A savvy injection molder can help you anticipate and solve common problems, identify and optimize cost drivers, and can help you significantly improve the manufacturability of your parts.

Material selection

Selecting the right plastic material for your parts is critical to your success.

One big factor that some design engineers tend to overlook is the working environment where the part will be used. Will it be exposed to environmental stresses? A part that has very desirable characteristics at room temperature may become unsuitable for the application under extreme heat or cold. Another part may be exposed to a corrosive environment, which can shorten the life of certain plastic materials. Another common issue regularly seen during a review of part and mold drawings are tolerances that can’t be supported by the selected material.

On the positive side, continuing advances in resin technology are enabling plastics to be used in more demanding applications. A continuing trend is to switch from metal to plastic. Should you convert some of your metal parts to plastic? Your plastic injection molder can help you identify materials that are the best match with your application needs and cost requirements.

Mold design

Much can be done during mold design to enhance the manufacturability of your parts. For example, data from a flow simulation can be used to optimize cooling and gate locations, which will help prevent deformation and maximize the properties of the material.

Ideally, your molder’s Design for Manufacturing (DFM) process should help to identify potential issues with part and mold designs, material selection and molding processes early in the launch process so it can mitigate or eliminate them.

Molding presses

Modern plastic molding equipment can hold tighter tolerances and produce higher-quality parts faster, and at a more consistent level of quality, than older machines.

New injection molding machines are also more energy-efficient and are easier to incorporate into a manufacturing facility that applies automation and data collection into its processes. This enables the molder to reap optimal performance and to keep the machines operating at their best throughout during each production run.

For best results, look for a molder with state-of-the-art molding equipment and the knowledge and expertise to get the most out of it. If they are using older machines, make sure they’re regularly maintained, calibrated and tested to ensure they’re functioning within the manufacturer’s operating parameters.

Production processes

Scientific Injection Molding (SIM) uses a data-driven, scientifically rigorous procedure to develop a high-quality manufacturing process to produce a part. SIM focuses on polymer behavior rather than machine behavior. Its goal is to create a robust, repeatable process that reduces press set-up times and scrap, and improves part quality and consistency.


If you’re looking for a molding partner that understands how to manage all of these variables and can help you achieve successful project launches, we can help. Contact us today to discuss your needs.

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