PLASQUIP WORKSHOP TOOL
Plastic Bending Calculator
Estimate the minimum outside bend radius, heated-zone width and suitable Shannon heating profile for acrylic, polycarbonate, polypropylene, PET and polyethylene sheet. This tool is intended for fabricators, sign makers, plastics workshops and buyers selecting strip-heating equipment.
How the plastic bending calculation works
The required heating-zone width is the arc length of the outside bend: 2 × π × outside radius × bend angle ÷ 360. The calculated width is matched to the smallest standard Shannon heating profile that can cover the zone and, where verified, the sheet thickness.
Aligned upper and lower heating profiles improve heat penetration through the sheet. Their widths are not added together. Wider heating zones may require two, three or four heating wires to distribute heat evenly.
Factors that affect plastic bending
Material and grade
Acrylic, polycarbonate, PP, PET/PETG and PE-HD soften differently. Cast and extruded grades can also require different temperatures.
Sheet thickness
Thicker sheet needs more time and often double-sided heating. Shannon's practical polycarbonate capacity is half the equivalent acrylic capacity.
Radius and bend angle
A larger outside radius or greater bend angle creates a wider arc and therefore a wider heated zone.
Temperature and dwell time
Measure sheet temperature—not heater temperature. Hot spots, moisture, coatings or excessive dwell can damage sheet below the nominal upper limit.
Plastic strip heating and bending equipment
Use the result as a starting point when comparing Strip Heaters & Bending Machines and Shannon bending machines. Popular workshop options include the ABM-500S, ABM-700, Shannon HRT series and Shannon HRPi series.
Plastic bending calculator FAQs
How wide should the heated area be for bending acrylic?
PLEXIGLAS and PERSPEX guidance commonly places the heating zone at approximately three to six times sheet thickness. The final width also depends on the required outside radius and bend angle, which this calculator converts into arc length.
Does heating from above and below double the heating width?
No. Aligned upper and lower profiles heat the same zone from both faces, improving penetration and temperature uniformity. Their widths are not added together.
Can I use the acrylic rules for polycarbonate?
No. Shannon's real-world machine capacity for polycarbonate is treated as half the equivalent acrylic thickness. Polycarbonate hot-line bending is typically performed at a sheet temperature of 155–167°C, and the sheet supplier should confirm the bend radius.
What temperature should I use for plastic strip heating?
Use the material-specific sheet-temperature range shown in the result. It is not a wire or heater setting. Measure the sheet near the bend and use trials to establish heater distance, power and dwell time.
Is this the same as plastic bending allowance?
The calculator determines heated arc width and equipment requirements. Fabrication bend allowance and finished flat-pattern dimensions can also depend on neutral-axis movement, shrinkage, springback and tooling, so confirm the developed length with a production trial.