Active hold-down for heat treating

Abstract

A vacuum hold-down is described, for holding a thin film workpiece while it undergoes large temperature changes and corresponding dimensional changes, which permits creep of the workpiece to avoid damage thereto while still holding it on a support surface. The support surface has a multiplicity of holes arranged in a plurality of zones. The vacuum is repeatedly interrupted at the holes lying at different zones while it continues to be applied at the other zones, to permit creep of the workpiece at a zone when vacuum is not applied thereto.