The Importance of DFM and Good Engineering Practices in Injection Molding


Wherever you are right now, take a look around and notice all the engineering that has gone behind every single thing you are able to see within a hundred feet radius. Engineering is all around us, from the chair we sit to the screen wipes we use to un-smudge the fingertips of our coworkers who like to touch our screen. Let’s not even get started on the amount of engineering that has gone behind the device you’re using to read this article.

One thing we can probably all agree on: the field of engineering is broad — mechanical, electrical, software, environmental, chemical (and all the other sciences in between). But regardless of the field, the fundamentals of most engineering disciplines are quite similar. And they are what makes these fields part of the engineering branch.

Engineering has evolved into what it is today due to its direct impact on how a business performs. For example, better functionality achieved through good engineering practices can lead to more satisfied customers, which can lead to more repeat customers, and consequently to higher revenue. Ensuring good engineering can lead a more cohesive design, better usability, lower production costs, and higher customer satisfaction, all of which are crucial to the success of a business.

Design for Manufacturability

At Jaycon Systems, we are big believers of DFM — aka Design For Manufacturability. The implementation of DFM practices varies by engineering discipline and manufacturing process, but here at Jaycon, they relate mostly to plastic injection molding to bring plastic product concepts to life.

The main goal of DFM is to ensure products are not only functional to their original purpose but also optimally designed to the machinery or process in which it will be manufactured. Ensuring a product follows DFM practices means that the part you see on the computer screen will be able to be manufactured and its production will run smoothly and cost-effectively.

In the injection molding world, the cost of manufacturing is often driven by complexity of the features designed into a part, such as undercuts and metal inserts. Size is also one of the most distinct drivers of pricing since mold tooling is ultimately CNC machined in order to serve as a die to mold the plastic — so the larger the part, the larger the mold and the more time and resources will be needed in order to create it.

When designing a part for injection molding, there are three initial aspects we look into: tolerance, draft angles, and undercuts. Tolerance enables multiple parts to fit together without exerting too much force on one another. Draft angles enable the plastic part to be pulled apart from the mold tooling with limited friction. Undercuts are features that prevent a plastic part from exiting the injection mold tooling. Undercuts can get quite complicated, and for cost-effectiveness, designers and engineers are encouraged to design out undercuts when possible to minimize the complexity of the injection mold tooling.

We encourage you to read our previous article, Engineering Guidelines to Designing Plastic Parts for Injection Molding. We explain the design aspects we take into consideration when designing parts for injection molding. These tips and tricks help save our clients time and money in the long run.

Sure, the engineer could make all possible modifications to ensure the product is as cost-effective as possible, but the reality is that there is a balance between what features the client has requested and best engineering practices. The more features there are, the more expensive the product will turn out to be. Here are some of the features that may drive the overall cost of the project, in no particular order:

  • Product material

  • Aesthetics and overall shape

  • Product weight

  • Molded-in inserts

  • Novelty colors

  • Painting, pad printing

  • Ultrasonic welding

  • Textures

  • Other types of post-processing methods

These are just some of the features clients may request that will have a direct effect on the design and cost of manufacturing a part. Every project is different and engineers are constantly being pushed to be creative on how to meet customer requirements and enabling hassle-free manufacturing while driving production costs down.

The beauty of engineering is that with every new client comes a new challenge to overcome and knowledge to gain.

Good DFM as it relates to injection molding goes beyond checking for tolerances, undercuts and draft angles. Throughout the design process, engineers should keep in mind to constantly communicate and document project changes in a version control document or software. Product design is a collection of iterative changes, so keeping track of revisions makes it easier for engineers and clients to refer back to past designs. A good engineer not only meets all of the client’s specifications, but they aid in cutting costs, simplifying design while keeping the product’s purpose and minimizing production time — all of which will lead to a smooth and hassle-free manufacturing process.

This article was published by the Jaycon team. Learn more about how we can take your product design and hardware idea to the next level here.