Why Engineers Are Replacing Metal Parts with Thermoplastics

Metal was historically the default choice for industrial part design. Strength, durability, and temperature resistance made it the obvious answer for many applications.

But that assumption has started to shift.

Modern thermoplastics are solving challenges that metal often struggles with, especially in environments where corrosion, denting, weight, or chemical exposure become long-term performance concerns.

This does not mean plastic is automatically the right replacement for every metal part. But in the right application, thermoplastics can improve durability, reduce maintenance, simplify manufacturing, and create more design flexibility.

For engineers troubleshooting recurring field failures, the better material is not always the traditional one.

Related Content: Material Substitution Without Redesigning the Entire Part

Where Thermoplastics Can Outperform Metal

1. Corrosion and Chemical Resistance

One of the most common reasons engineers start to evaluate thermoplastics is corrosion in the field.

Outdoor equipment, agricultural applications, industrial environments, and marine conditions expose parts to constant moisture, salt, dirt, fertilizers, chemicals, and other contaminants. Over time, metal parts may rust, chip, or require protective coatings and repainting.

Thermoplastics can eliminate many of those issues. Thermoplastic materials resist corrosion, moisture, and chemicals. Color can also be integrated directly into the material, which helps avoid paint chipping or cosmetic wear over time.

For applications where long-term environmental exposure is unavoidable, thermoplastics can significantly reduce maintenance demands and extend part life.

2. Impact and Dent Resistance

Metal parts often absorb impacts permanently. Shipping, operation, field use, and maintenance all introduce opportunities for a part to become dented. Even when the damage is cosmetic, dented parts can still create quality concerns, replacement costs, or customer complaints.

Many thermoplastics behave differently under impact. Properly designed plastic parts can flex and recover from impacts that would dent metal. This can improve both functional durability and long-term appearance.

For high-contact environments or equipment that sees frequent handling, this flexibility can become a major advantage.

3. Weight Reduction Without Sacrificing Performance

There’s also one major advantage to thermoplastics over metal: they weigh significantly less.

Weight reduction can improve ergonomics, simplify installation, reduce strain on connected components, and improve operational efficiency. In transportation and heavy vehicle applications, lighter components may also contribute to fuel savings and easier handling.

Thermoplastics allow engineers to reduce weight while still maintaining the durability required for demanding environments.

This is especially valuable for large parts, where weight reduction helps reduce the overall weight of the completed product.

Additionally, weight reduction can also reduce assembly complexity and simplify handling during production.

Related Content: How to Cut Weight Without Sacrificing Strength in Heavy Vehicles

4. More Complex Geometry

With metal fabrication, achieving complex geometry often requires secondary metalworking or welding. Complex curves, contours, and integrated features can quickly increase production complexity and cost.

Thermoforming allows many of those features to be created directly during the manufacturing process. Ribs, contours, rounded geometry, integrated styling elements, and formed shapes can often be incorporated into the initial part design rather than added later through secondary operations.

Example Applications Where Engineers Are Moving Away from Metal

Engineers across multiple industries are evaluating thermoplastics for parts that historically defaulted to metal.

Common examples include:

• Doors or interior panels
• Consoles
• Small parts
• Gaskets
• Roofs
• Covers and shields

Many of these material changes begin because of recurring corrosion, cosmetic damage, excess weight, manufacturing complexity, or rising production costs. In other cases, engineers are looking for more design flexibility without triggering a full redesign of the product.

Related Content: When Does It Make Sense to Replace Metal Parts with Plastic?

For certain applications, thermoplastics can improve lifecycle performance, reduce maintenance concerns, simplify manufacturing, and create a better long-term user experience. But successful material substitution depends on understanding the application requirements, production goals, operating conditions, and manufacturing constraints early in the process.

ICP works with engineering teams to evaluate whether a thermoplastic solution makes sense for the application, performance requirements, production volume, and manufacturing process.

If you’re considering a material change, a Design for Manufacturability (DFM) review is a practical place to start. It helps you determine whether the change makes sense, what adjustments may be needed, and where risks can be reduced early.

Industrial Custom Products is a one-stop-shop for custom manufacturing and plastic fabrication, including: prototyping and product development, die cutting and dieless knife cutting, thermoforming and vacuum forming, large part thermoforming, CNC plastic routing, fabrication and assembly and drape forming.