Abstract: Tublar workpieces are formed with perforations of desired size and/or shape by repeatedly piercing selected portions of the workpieces by needles, pins or analogous piercing tools. The tools can be stationary while the workpieces roll therealong, or the workpieces can rotate while coming into repeated engagement with one or more sets of orbiting tools. The frequency and the number of penetrations of tools into selected portions of the workpieces are selected with a view to heat the tools as a result of frictional engagement with the material of the workpieces, i.e., as a result of repeated penetration into and extraction from selected portions of a rotating or rotating and rolling and/or axially moving workpiece. This enhances the making of predictable perforations in tubular workpieces, especially workpieces which consist of a synthetic thermoplastic material, such as bobbins for the storage of textile yarns.