By Jason Vander Griendt

December 25, 2017 at 5:43 am

If you’re reading this article you might be asking yourself “What are the Guidelines and Principles of Injection Molding?”. Well, we’ll tell you!

There are a number of injection molding guidelines and best practices or principles to follow to ensure that you get the best results in your next injection molding project.

Injection Molding Design Guidelines include:

  • Make sure you use uniform wall thicknesses throughout the part to minimize sinking, warping and residual stresses, and to improve the mold fill and cycle times.
  • You are going to want to use generous radius’ at ALL corners. The inside corner radius should be a minimum of one material thickness.
  • Be sure to use the least of the thicknesses compliant with the process material, or product design requirements. This ensures that the cooling process will be faster, the cycle times will be shorter, and the shot weight will be smaller. All of these will result in the least expensive part cost.
  • Design parts to facilitate easy withdrawal from the mold, by providing draft (taper) in the direction that the mold is opening or closing.
  • Use ribs or gussets to improve the stiffness of your part’s bending capabilities. This will help you avoid the use of thick section, but achieve the same strength and durability, and you’ll save on costs for part weight materials and cycle time.

Injection Molding Principles and Rules are as follows:

  • Don’t forget the necessities of the process. There must be a location in the mold and on the part of the base material where material to form the part can be injected. This is referred to as a gate, and it must be removed from the finished part after it is formed, which can be done manually or automatically. The gate’s position is important, as you’ll typically want to position it at a thicker, intersectional area of your part. This is so that you may remove it without concern for its structural integrity.
  • Consider your wall thickness. This is an important principle because some wholesalers/retailers will require a certain uniform wall thickness for your injection mold. And if you don’t meet the requirements, you won’t be able to sell your part or product. You can manage this by designing your part with manufacturability in mind.
  • Incorporate a draft. Drafting your injection mold by adding a taper will result in a smoother removal of your part from the mold. It will also minimize any friction and scraping between the finished, cooled product and the walls of your mold. This makes the process run much more efficiently.
  • Build in texture. Instead of adding a pesky second finishing process after injection molding, you can incorporate the finished pattern or texture right into your mold! You can achieve this by etching or milling the mold to create a finish. This will give you the greatest control over the finished look and feel of your part. Which will save time and money in the long run by reducing double handling.
  • Know your materials. This is pretty self-explanatory. Simply make sure you are familiar with what you’re working with! Selection of your materials is a crucial aspect of the design process. If you choose the wrong materials, even by the slightest miscalculation, you could end up spending WAY more than you need too.

So there you have it, some guidelines and best practices for injection molding.

If all that information that seems like another language to you we’re here to help. Check out our injection molding information or give us a call on 1.888.202.2052 and let’s talk about making sure your next injection molding project is fulfilling the best design practices.

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Learn more:

Where to buy injection molding machines

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Jason Vander Griendt

Jason Vander Griendt is a Mechanical Engineering Technician with years of experience working at major companies such as SNC Lavalin Inc, Hatch Ltd. Siemens and Gerdau Ameristeel. He is the CEO of JCAD – Inc., a company he started in 2006 after seeing a gap in the market for businesses who could assist clients through the entire product design and manufacturing process.

Jason has been featured in Forbes, has had his businesses analyzed and discussed in multiple start-up books, was a previous winner of the Notable8 Digital Innovator of the year award, and is a regular guest on business panels and podcasts. Email Jason at or follow him on LinkedIn.

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