Radiant Furnace Thermal Absorption and Gravity Sag Calibration for Amorphous Polymer Sheet
Calibrating emitter wavelength to polymer absorption bands and setting optical sag triggers prevents core temperature deltas exceeding five degrees Celsius.
Drape Forming
Meaning
Low-pressure sheet shaping methods relying primarily on gravity and light mechanical force shape softened thermoplastic material over positive mold contours. Executing drape forming stretches heated polymer sheets across male tooling with minimal wall thinning or optical distortion. The technique governs large radius bend geometries in acrylic or polycarbonate sheets, stopping where deep cavity draw ratios require positive plug assistance or differential pneumatic pressure.
Heat Softening
Radiant heating panels elevate thermoplastic sheet temperatures until the material passes its glass transition point and hangs flexibly. In drape forming, heat uniformity across sheet width prevents localized stress concentrations during gravity drop over tool curves. Uneven sheet heating causes uneven thinning across contour radii.
Contour Extension
Male mold surfaces guide the sagging sheet while gentle perimeter pressure seals edges for light vacuum assistance. Applying drape forming for aircraft canopy production or architectural glazing avoids mold mark-off on the primary aesthetic side of the sheet. Part depth remains limited to low aspect ratio profiles to avoid web formation between sharp corners.
Surface Integrity
Optical clarity remains preserved because minimal mechanical stretch occurs during sheet placement over polished epoxy or aluminum tooling. Soft felt coverings on drape forming tools eliminate surface scratching during plastic cooling cycles.