Moving from metal to thermoformed

What to consider when replacing metal parts with thermoplastics

For decades, manufacturers have been replacing metal parts with plastic ones. Metals have different properties and are fabricated with different processes. The design challenges involved when switching to plastic require expert assistance.

The design rules for thermoplastics are different from sheet metal bending or CNC machining. In addition, selecting a material with the right properties for the application is paramount.

Profile Plastics is an experienced thermoformer that helps manufacturers move from metal to thermoformed parts. Expert Design For Manufacturing (DFM) assistance provides value, along with material selection services. There are a variety of thermoplastics to choose from.

For a real-life example of Profile’s metal-to-thermoforming expertise, check out our case study about switching medical sinks from stainless steel to thermoformed plastics.

Weight reduction and cost

Weight reduction is the primary reason many companies replace metal with plastics for component parts. Heavy-gauge thermoforming uses extruded thermoplastic sheets that are both lighter and less expensive than metal. They also cost less to transport and handle.

Potential savings don’t end there. The tools or molds for thermoforming cost significantly less than those used with metal parts. Once a production mold is made, it can last for the life of the part– no matter how many units are made.

Many thermoplastics can also be recycled and extruded into new non-virgin sheets. Recycling processes for plastics are simpler than for metals, saving money and providing additional value.

Material properties

Sheet metal is impact-resistant but prone to denting. By contrast, impact-resistant thermoplastics have some ability to deform and recover. In other words, plastics can absorb the impact and “bounce back” to retain their original shape. That’s a key consideration for products that may encounter rough use.

Thermoplastics offer other advantages as well. For example, they’re inherently rust and corrosion resistant. They’re also less likely to break and create sharp edges that pose a safety hazard. Sharp edges on metal parts pose cutting risks in industrial applications as well as consumer products.

It’s important to select the right thermoplastic material for the application. That can include resistance to chemicals or UV light. Specialized additives can provide customized properties. For fire-prone environments, UL 94 V-0 flame rated materials add safety.

Other advantages that thermoplastics have over metals include sound damping properties. They absorb and dissipate vibration energy more efficiently, reducing noise. The thermoforming technique of twin-sheet forming adds even more sound deadening capabilities.

Plastics also provide better thermal and electrical insulation than metals. These and other properties could improve your product design.

Less post-processing

Thermoformed parts require trimming and finishing but less than metal parts.

For example, thermoplastics sheets are available in custom colors, even metallics. Parts with molded-in color don’t require painting. Sheet metal fabrication typically involves bare metal that requires painting afterward. In addition, metals or alloys may need hard coating for added impact resistance.

Impacts on metal parts can cause paint to chip or flake, exposing bare substrate. Thermoformed parts have color throughout the material, not just on the surface. With no paint to fail, there’s no need for touch-ups. Molded-in color provides not just durability, but greater longevity in the field.

Another benefit of thermoforming is molded-in texture. The surface finish is designed into the core production tool, unlike having to stamp a texture into sheet metal before bending.

Design rules and process selection

Every manufacturing process has its own design rules. For sheet metal bending, designers need to consider bend lines, bend allowance, flat blank length, and bend radius.

Thermoforming can achieve highly cosmetic, close-tolerance parts, but it does have its own design rules. Factors like draw ratio have different implications. It’s important to work with an experienced thermoformer who can optimize your part design for effective and cost-saving production.

Download Profile’s Thermoforming Design Guide today to see what factors influence success. The guide even covers topics such as textures and dimensioning.

Conclusion

Now that you’ve decided to move from metals or alloys to thermoformed parts, you need to consider whether your part is suitable for thermoforming. And find out which process is the best choice: pressure forming, vacuum forming, or twin sheet forming?

Profile can help you select the best process and the specific material to create a better part which better meets your business requirements.