Abstract: Relatively light gauge thermoplastic sheet material is pierced by a hot punch to provide a bearing aperture. The hot punch is held in sheet-penetrating position long enough to cause plastic flow of displaced material and formation of a collar-like hub surrounding the aperture. The hot punch is withdrawn and replaced by a cool punch to retard further plastic flow of the displaced material, thereby fixing the aperture in desired size and shape. There results a bearing aperture having an axial length greater than the starting thickness of the sheet material, and consequently a larger bearing surface integrally formed locally in the sheet material. Apparatus for forming the bearing aperture is also disclosed.