Plastic Injection Molding Design Guidelines

Plastic Injection Molding Design Guidelines

Design for Plastic Injection Molding: A Guide to Important Considerations

When it comes to plastic injection mold design guidelines, there are several important considerations to keep in mind, such as strength requirements, environment exposure, resin selection and more.

Below, we outline some of the most important aspects to consider when you design for plastic injection molding.


How your part will be used is undoubtedly one of the most important considerations for plastic injection molding design. While this may seem straightforward, there may be some important questions you have missed as part of this identification process, such as:

  • What function(s) will your part serve?
  • Is it a single component or part of an assembly
  • What market(s) is your part intended for?
  • What application(s) will it be used in?
  • Who will be handling your end product?
  • Will the part endure continual use or periodic?


When you design for plastic injection molding, you have to consider the characteristic properties your part will require. It’s important consider variables for:

  • Part Weight
  • Tensile Strength
  • Impact Strength
  • Opacity
  • Rigidity or Flexibility
  • Deflection Temperature
  • Service Temperature
  • High Temp Stability
  • Dimensional Stability


Environment is also a priority when discussing plastic injection molding design guidelines. Moisture, heat, chemicals, UV radiation, flammability and corrosion are all top environment considerations to take into account.

Depending on the environment your part will be exposed to you’ll want to consider:

  • Weatherability
  • UV resistant
  • Water resistant
  • Heat resistant
  • Fire resistant
  • Stress-cracking resistant
  • Corrosion resistant


Aesthetics need to be addressed as part of the plastic injection molding design process. Below are some of the top questions to consider when dealing with aesthetics:

  • What is the size and shape?

The size and shape of a part can have a dramatic effect on how the plastic injection molding process is executed. Aspects like uneven wall thickness, thin walls, sharp corners and complex geometries will all affect how the final part will be produced.

  • Are there brand identity requirements?

Some parts may require brand compliance, which may include color, imprints, logo, labeling, packaging, etc. It’s important to understand any brand identity requirements prior to starting the plastic injection molding process.

  • Does your part require a particular surface finish?

Depending on your parts function and end-use, your part may need to possess a finish that’s smooth, high gloss, matte or textured.


Oftentimes parts must pass certain requirements in order to go to market. These may be private, governmental, national or international regulations.

Does your part need to be compliant with:

  • ASTM
  • ANSI
  • OSHA
  • FDA
  • EPA
  • Others?


When it comes to plastic injection molding design guidelines, proper resin selection is one the absolute most important aspects to consider. Choosing the wrong resin can lead to partial or complete part failure.

Plus since there are over 30,000 “recipes” of engineering resins to choose from, it’s critical to talk with an industry expert – who can confirm you are using the best resin for your part, or recommend a better one.

PMC is a Plastic Injection Molder Specializing in Engineering Grade Resins

Plastic Molded Concepts is one of the very few plastic injection molders in the U.S. (and the world) who uniquely specializes in engineering grade resins. PMC provides plastic injection molding services for mission-critical parts that play vital roles in markets like aerospace, military/defense, medical, automotive, electronics and more. Check out our case studies to learn how we have helped customers overcome complex plastic molding challenges.  

We have been thriving in the plastic molding business for 45 years. We have the experience and certified in-house Master Molders, allowing us to take on projects of any complexity.

Request a quote today for your next project.

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