Plastic material selection is where many mechanical design issues are created before the first prototype is built.

Select the best plastic is about finding the one that answers the real requirements of the part.

·        You need a good appearance and easy processing?

ABS may be enough at a low cost.

·        Need better impact resistance or toughness?

PC may be a better direction, if the added cost and processing requirements make sense.

·        Need a balance of appearance, toughness, and manufacturability?

PC+ABS is often a practical compromise.

·        Need more strength and stiffness for a functional component?

PA66, especially glass-filled PA66, may be a strong candidate.

·        But if the part is exposed to humidity, PA66 also brings an important consideration:

Moisture absorption. That can affect dimensions, stiffness, and mechanical properties.

·        Need good chemical resistance and flexibility, and stiffness is not the main driver?

PP may be the smarter choice.

·        Need dimensional stability, electrical performance, and tighter tolerance control?

PBT can become very attractive, especially around connectors and electronic components.

And then come the fillers.

Glass fiber can increase stiffness, strength, and heat performance, but it can also affect:

• Warpage• Mold flow direction• Surface appearance• Weld line behavior• Tool wear• Dimensional variation

Talc can improve stiffness and dimensional stability, but it can also reduce impact performance and change how the part behaves during assembly.

That is why material selection cannot be separated from part design.

Wall thickness, ribs, bosses, snap fits, tolerances, surface finish, tooling strategy, gating

and molding process all interact with the material choice.

Very Important:

Do not leave the final material decision until late in the program.

Injection molds are usually designed around the expected material behavior, including shrinkage, flow, warpage, cooling, and dimensional targets.

Changing from one plastic family to another after tooling has started can create expensive problems.

Sometimes it means tool rework.

Sometimes it means dimensional issues.

Sometimes it means sink marks, warpage, weak snap fits, poor appearance, or parts that simply do not meet the original requirements.

A plastic part is not designed first and material-selected later.

The material is part of the design from the beginning.

If your team needs US-based support with production-ready mechanical design, packaging, or interface-driven components, that is exactly the kind of work we help with at ABAL Mechanical Design.