Vacuum Forming Blank Size

MANUFACTURING – INJECTION MOULDING & PLATIC CALCULATOR Vacuum Forming Blank Size A precise tool.
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What is the Vacuum Forming Blank Size & How does it work?

Vacuum forming starts with a flat sheet (the blank) that is heated until pliable. The sheet is then draped over a mould and a vacuum pulls it into the cavity, reproducing the part geometry.

The size of the blank must be larger than the final part to accommodate the material’s draw‑in around the mould’s walls and any shrinkage that occurs as the plastic cools.

By knowing the part depth, the draw angle of the mould, and the material’s shrinkage factor, the required blank size can be calculated with a simple geometric formula.

B = Dleft(2tantheta + 1right)left(1 + frac{S}{100}right)
B = required blank size (mm), D = part depth (mm), ΞΈ = draw angle (Β°), S = shrinkage factor (%)
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Parameters
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Frequently Asked Questions
How do I calculate the blank size for vacuum forming?
To calculate the blank size, add extra material around the part’s perimeter to account for the draw-in during forming and any shrinkage as the plastic cools.
What factors affect the required blank size in vacuum forming?
The required blank size is affected by the part depth, the draw angle of the mould, and the material’s shrinkage factor.
Why does the blank need to be larger than the final part?
The blank needs to be larger to accommodate the material’s draw-in around the mould’s walls and any shrinkage that occurs as the plastic cools.
Can you explain the role of draw angle in vacuum forming?
The draw angle affects how much the material stretches over the mould, influencing the required blank size to ensure proper formation.
How does material shrinkage impact the blank size calculation?
Material shrinkage reduces the part’s dimensions as it cools, so the initial blank must be larger to account for this reduction during the forming process.

Results are for informational purposes only and do not constitute professional advice.