Vacuum Forming & Thermoforming Knowledge Hub.

The vacuum forming process begins by clamping a thermoplastic sheet in a frame and heating it with infrared heaters until it reaches forming temperature — typically 150°C to 200°C depending on the material. The heated sheet is then draped over or into a mold, and vacuum pressure (approximately 0.8 to 0.95 bar below atmospheric) draws the sheet tightly against the mold surface. After cooling, the formed part is released and trimmed.

Vacuum forming is widely used because tooling costs range from $2,000 to $30,000 — compared to $10,000 to $500,000+ for injection molding. It can produce parts up to 6 meters in length, with lead times of 2 to 6 weeks from design to production. Machinecraft's PF1-X Series machines use a closed chamber design with pre-blow bubble formation, achieving wall thickness uniformity within ±10% across the formed part.

Key steps in the vacuum forming process

1. Clamp the thermoplastic sheet in the frame
2. Heat the sheet to forming temperature using infrared heaters (ceramic, quartz, or halogen)
3. Pre-stretch the sheet using plug assist or air pressure (optional, improves wall uniformity)
4. Drape the heated sheet over the mold
5. Apply vacuum to pull the sheet against the mold surface
6. Cool the formed part (typical cycle time: 30-120 seconds depending on material and thickness)
7. Release vacuum and remove the part
8. Trim excess material using CNC router or die cutter

Thermoforming is divided into two main categories based on material thickness. Heavy gauge thermoforming processes cut sheets typically 1 to 15mm thick for structural parts such as automotive panels, bathtubs, and equipment covers. Light gauge (thin gauge) thermoforming processes roll-fed film under 2mm for high-volume packaging such as food trays, cups, and blister packs.

Types of thermoforming processes

In a conventional open-frame vacuum forming machine, the heated sheet sags under gravity before forming, which leads to uneven wall thickness — thinner at the top of deep draws and thicker at the base. A closed chamber design solves this by sealing the area above the heated sheet, allowing controlled air pressure to be introduced.

The process works in three stages: first, the chamber seals around the heated sheet. Second, pulsating air pressure is introduced from below to create a controlled "bubble" that pre-stretches the sheet uniformly. Third, the mold rises into the bubble and vacuum is applied to pull the pre-stretched sheet against the mold surface. This pre-blow step ensures the material is evenly distributed before it contacts the mold, resulting in significantly more uniform wall thickness.

All Machinecraft PF1-X Series machines use this European-concept closed chamber design as standard. The pre-blow pressure, timing, and pulsation pattern are programmable via the Siemens HMI touchscreen, allowing operators to fine-tune the process for different materials and part geometries.

The first decision is whether you need a heavy gauge sheet-fed machine or a light gauge roll-fed machine. If your parts are structural (automotive panels, bathtubs, equipment covers) and use sheets thicker than 1mm, you need a sheet-fed machine like the Machinecraft PF1-X Series. If you produce high-volume packaging (food trays, blister packs, containers) from thin film under 2mm, you need a roll-fed machine like the Machinecraft AM Series or FCS Series.

Key selection criteria