Vacuum Forming / Thermoforming
Vacuum Forming or Thermoforming, is the process of uniformly heating a thermoplastic material and shaping it in a mould or tool. Thermoforming is extremely cost-effective and ideal for a wide range of applications:
- Food Safe Packaging
- POS / Retail Displays
SOWOW are proud to offer a complete in-house vac-forming service:
- CAD development support
- Tool making
1. CAD and material selection form the early stages of a vacuum thermo forming project. Whilst a product may look great as a CAD model, the form may not lend itself well to thermo forming. Two main considerations are:
a) draft angle - when designing a part for vacuum thermo forming, draft angles must be added to the side walls of the part to assist with the removal of the tool, once the part has been formed.
b) contraction - material contraction occurs once the formed material begins to cool following the forming process. Material contraction rates can be calculated and a scale factor applied to the form tool. Essentially the tool is over sized to compensate for any contraction.
2. At SOWOW we are able to fabricate forming tools from a variety of materials, each with their own benefits and specific applications.
- Resin forms
- Metal forms
- Tooling polymer
The material used for tooling, will be largely determined by the part surface finish requirements. Well manufactured and finished tools tend to have a longer production life with more consistent results. Resin and Alloy tooling tend to make the best tools.
Rest assured, we will guide you through the process and fully consider your requirements, budget and lead time.
3. Materials and tools must be prepared prior to forming.
All material and tool surfaces must be thoroughly cleaned to remove debris, adhesive residue and fingerprints. Remember, any imperfections will be replicated in the part. Additional tool preparations to be considered as as follows:
a) Venting - this is essentially adding venting holes in the tool so that the vacuum can be controlled. Particular attention should be paid to tight detailed regions of the tool.
b) Webbing - webbing occurs when the forming material stretching is not equalised. This can be overcome with the addition of strategically placed tool blocks.
Once the necessary preparations are complete and material blanks have been cut, we are ready to form.
Blanks are usually cut oversize so that they can be clamped into position. The tool is lowered beneath the material, and the heat source is positioned and turned on. The duration of heat application depends on material type and thickness. Typically, material suppliers are able to provide calculations and guidance for their product.
Once the material is at forming temperature, the heat source is removed. The tool is then raised and the vacuum is applied. At this point, the material surface should come into full contact with the tooling surface, inheriting the tool form.
The formed sheet should be allowed to cool, but removed from the tool whilst still warm.
Please contact us to discuss how vacuum forming might help you with your project.