Designing For Moldability & Manufacturability

Designing For Moldability & Manufacturability

What’s The Difference Between Moldability and Manufacturability?

Though subtle, the differences between moldability and manufacturability can have an impact when designing parts for the plastic injection molding process. In this post we will explain the differences and provide resources for following injection molding best practices.

What is Moldability?

moldabilityMoldability refers to how well the mold of your part will conform to being injected with molten plastic. Once your mold has been created from your design, a good injection molding process needs to account for how well plastic can fill that mold cavity.  From material selection to mold complexity, there are many factors that will determine whether the part you designed is capable of accepting this process.  Certain features in your part design like undercuts and threading, can be tricky to mold correctly and consistently.   These can cause problems like knit lines, warp and flash.
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Material Selection – A Primer for Injection Molding

Material Selection – A Primer for Injection Molding

Material Selection for Injection Molding

Your choice of material becomes more critical the closer you are to production.
The same material used in each of the manufacturing process will produce different results. For instance, a part 3D printed in ABS will have very different strength and finish properties compared to a part machined via CNC. This is due to the process being used: additive (building a part layer by layer) vs. subtractive (cutting away a shape from a solid block of material).
Because additive manufacturing is typically best used for prototypes where many of the qualities of a chosen material will matter less, we have put together a material guide for injection molding.
We cover some of the most common materials and include a general overview of things like tensile strength, impact strength and chemical resistance. Below are downloadable charts that lists materials in order of best to worst for each.
We hope this will help guide you to selecting the most appropriate material for your project.
Plastics-Charts-tensileStrength Plastics-Charts-maxTemp Plastics-Charts-impactStrength Plastics-Charts-flexuralModulus Plastics-Charts-chemicalResistance
Materials

The Importance of Design for Manufacturability

Design for Manufacturability (DFM) is the proactive process of designing a part to meet the specifications of the chosen manufacturing process used to produce that part. No longer can a product engineer design a part for fit and function only. Product Engineers are also expected to understand the manufacturing process and incorporate those parameters into their design to ensure good part production.
Ignoring design for manufacturability can have disastrous consequences. By the time a product concept gets through the design phase and into the testing/prototyping phase, up to 80% of the budget for that product has been committed. The material costs have been identified, the tooling costs are known and any assembly costs are also worked into the budget by then. And once it has been committed, it is very expensive to turn back to change the design.
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