Capability
Vacuum forming
Thin and heavy gauge thermoforming for large covers, trays, and enclosures, where tooling cost is a fraction of a mold.
How this works
A sheet of thermoplastic is heated until pliable, drawn down over a tool by vacuum, cooled, and then trimmed. Because the tool only has to withstand atmospheric pressure rather than injection pressure, it can be cast epoxy or machined aluminum rather than hardened steel.
That single fact is the reason to choose it: tooling typically costs a small fraction of an injection mold, so vacuum forming wins decisively on large parts and modest volumes, exactly where injection molding is uneconomic.
The sheet is clamped, heated until it sags, then drawn down onto the tool by vacuum through small vent holes. It is trimmed after it cools. Tooling is a single half, which is why it is a fraction of the cost of a mold.
When vacuum forming is the right process
The trade against injection molding is almost always about part size and volume. Thermoforming has low tooling cost and a high per-part cost; molding is the reverse.
- Large parts. A machine cover a metre across would need an enormous press and an enormous tool to mold, but is routine to form.
- Modest volumes. Hundreds to low thousands a year, where an injection tool would never amortise.
- Simple, open geometry. Covers, trays, panels, and housings with one open face.
- Fast tooling. A cast epoxy buck can be produced far more quickly than a steel mold, which matters when a launch date is fixed.
- It is the wrong process for small precision parts, fine detail, closed geometry, or anything needing consistent wall thickness throughout.
Processes and tooling
| Type | How it works | Typical use |
|---|---|---|
| Thin gauge | Sheet under roughly 1.5mm, often fed from a roll and formed in a continuous line. | Trays, blister packaging, disposable containers, dunnage. |
| Heavy gauge | Cut sheet from roughly 1.5mm to 12mm, loaded individually. | Machine covers, equipment housings, medical cart panels, vehicle interior parts. |
| Male (positive) tool | Sheet is drawn over the outside of the tool. | Better wall thickness at the top. Interior surface takes the tool detail. |
| Female (negative) tool | Sheet is drawn into a cavity. | Exterior surface takes the tool detail. Deep draws thin the base considerably. |
| Plug assist | A plug pre-stretches the sheet before vacuum is applied. | Deep draws where wall thickness would otherwise be unacceptable. |
| Pressure forming | Adds positive air pressure above the sheet. | Sharper detail, crisper radii, and molded-in texture. Closer to a molded appearance. |
Twin-sheet forming
Where the part has to be hollow, a double-walled panel, a pallet, a tank, a duct, two sheets are formed at once in matched tools and welded together at the flange while both are still hot. It gives a stiff closed section with no assembly operation and no adhesive, at a tooling cost far below the blow mold or rotational tool that would otherwise be needed. It is worth asking about whenever you find yourself planning to bond two formed halves together.
Bucks are commonly cast epoxy for lower volumes and machined aluminum where volume, cycle time, or temperature control justifies it. Aluminum tools can be temperature-controlled, which improves repeatability and shortens cycles.
The sheet thins wherever it stretches furthest. On a male tool the sheet touches the top first and thins down the side walls. On a female tool it reaches the corners last and thins there. Whichever surface touches the tool is the one that holds dimension, so choose the tool by which face has to be accurate.
Materials
| Material | Chosen for |
|---|---|
| ABS | The general-purpose choice. Forms easily, paints and bonds well, good impact strength. Not UV stable without capping. |
| HIPS | Low cost for trays, packaging, and internal parts. Brittle and poor chemical resistance. |
| PETG | Clarity with good impact strength, and food-contact grades available. Forms at lower temperatures. |
| HDPE | Chemical resistance and toughness for industrial trays. Difficult to bond or paint. |
| Polycarbonate | Impact resistance and clarity for guards and machine windows. Must be dried before forming. Where the part is a guard that will be cleaned or handled, specify an abrasion-resistant grade such as Makrolon AR or SR; plain PC scratches easily.Must be dried before forming. |
| ABS/PC alloy | Higher temperature and impact performance for demanding covers. |
| TPO | Automotive interior surfaces with a soft touch and grained finish. |
| Kydex | Flame retardance and chemical resistance for aircraft and rail interiors. |
| Co-extruded capped sheet | A color or UV-resistant cap layer over a cheaper substrate, so no painting is needed. |
Design rules that decide cost
Wall thickness is not controlled directly. The sheet starts uniform and thins wherever it has to stretch, so the deepest and sharpest areas end up thinnest. Every rule below follows from that.
- Keep the draw ratio modest. Depth up to roughly the width of the part is comfortable on a male tool; female tools and deeper draws need plug assist.
- Expect the thinnest section to reach 40 to 70 percent of nominal on a deep draw. Start from a thicker sheet than the finished wall you need.
- Use generous draft, at least 3 degrees on male tools and 5 degrees or more on female tools, or the part will not release.
- Radius every corner. An inside radius at least equal to the sheet thickness is a working minimum, and larger radii both form and release better.
- Avoid undercuts. They need split bucks or manual removal, and both add cost per part.
- Fine detail, sharp edges, and text reproduce poorly under vacuum alone. Pressure forming is the answer where they matter.
- Plan the trim line early. Trim tolerance is looser than molded tolerance, and the trim fixture is part of the tooling cost.
Trimming and finishing
- CNC router or 5-axis trimming for repeatable edges on heavy gauge parts
- Steel rule die trimming for high-volume thin gauge work
- Drilling and machining of mounting holes and apertures
- Edge finishing: sanded, polished, or capped
- Painting, silkscreen, pad printing, and hot stamping
- Bonding, welding, and assembly into multi-part enclosures
- Insert and hardware installation for mounting points
Trimming, machining of openings, hardware installation, and painting are quoted as part of the job rather than subcontracted after the fact.
Also available
Other capabilities
Injection molding
Production molding runs from a tool you already own or one we build for you. Quotes cover the part, the tool, and the lead time separately so you can see what you are paying for.
Injection molds and tooling
Tool design, build, and sampling. The tool type follows the part and the volume, so quotes state which configuration is proposed and why.
CNC machining
Milling and turning from metal and plastic stock, for prototypes through to production quantities.
Let’s get started on your part
Send your CAD files and target volumes. We come back with a price, a lead time, and any design notes that would reduce either.