One of the greatest benefits of plastic thermoforming is the ability to economically make large parts.  At STM Plastics, we can thermoform parts up to 8′ x 10′.

Why large parts get thermoformed instead of injection molded

Tooling cost is the key driver when choosing thermoforming over other manufacturing processes for large parts.  The tooling cost gap widens as parts get bigger.

Vacuum forming shapes plastic sheet over an aluminum-cast tool with atmospheric pressure, about 15 psi. By contrast, injection molding pushes molten resin into a closed mold at 10,000 to 20,000 psi. A tool that holds that pressure needs hardened steel in matched halves, cooling channels, and an ejection system. That complexity is what drives up the tooling cost.

Injection molding clamping force also scales with the projected area of the part, so a large part needs a much bigger press, which can be difficult to find. For a thermoformed large part, expect lower tooling cost and a shorter wait for first parts.

Where large thermoformed parts show up

We can serve any industry and we’ve made large parts for equipment enclosures, machine guarding, agricultural components, vehicle and transportation panels, water features, recreational products, process tubs and trays, material handling, and more.

We also ship nationwide and internationally.

What we run

• Part size up to 8′ x 10′
• Gauge from .020″ through .400″ and heavier (heavier is better for large parts)
• Materials HMWPE, HDPE, ABS, HIPS, PETG, polypropylene, PVC, and Kydex
• In-house finishing trimming, deburring, drilling, and assembly

Large Part Design Considerations

Draw ratio, draft angles, corner radii, and material selection work the same on a 10-foot part as on a 6-inch part. Draw ratio, for example, is a proportion, not a dimension: a shallow 10-foot panel and a shallow 6-inch tray present the same forming condition (more or less).

Large shallow parts (panels, covers, trays, enclosure faces) are what thermoforming does best. See our thermoforming design guide for draw ratio, draft angles, and radii.

Is your part a fit?

Send us a drawing, a sketch, or just dimensions and a description. We’ll tell you whether thermoforming is the right process for your part.

For our full range of capabilities, see our custom thermoforming page.