Patent ID: 7025108

Claim:
A method for producing heat-resistant casting molds from molding sand containing binder, the method comprising: a) preparing blocks of mold material from molding sand containing binder with a dimension that corresponds to a mold cavity depth of up to about 300 mm to about 400 mm; b) machining out the inner contour of the block by high speed rough milling, oversized with spacing close to the inner wall of the mold cavity, with a high feed rate with a roughing tool that is driven with a high-frequency spindle at high speeds of rotation and comprises a balanced, rotationally symmetrical tool shaft realized as a bending resistant thin-walled tube or sleeve body, that has at the front end a cutting head and is provided at the opposite end of the shaft with a clamping shaft, said cutting head comprising at least one cutting tip, cut out of hard metal plates, that is arranged in a positive-locking or force-fitting manner in a slot provided at the front end of the tool shaft, the effective cutting diameter of said cutting tip being about 12 to about 40 mm, and said tool shaft having a diameter-to-length ratio between about 1:3.5 and about 1:11, thereby providing a mold cavity; c) finish-milling the mold cavity by high speed milling, by removing the oversize material following the contour with a finishing cutter driven at high speeds of rotation by means of the high-frequency spindle and comprising a balanced, rotationally symmetrical tool shaft realized as a bending resistant thin-walled tube or sleeve body, which has at the front end a cutting head and is provided at the opposite end of the shaft with a clamping shaft, said cutting head comprising at least one cutting tip, cut out of hard metal plates, that is arranged in a positive-locking or force-fitting manner in a slot provided at the front end of the tool shaft, the effective cutting diameter of said cutting tip being smaller than that of said roughing tool and said tool shaft having a diameter-to-length ratio between about 1:10 and about 1:30; and d) performing aftertreatment of the surface of the mold material, wherein the aftertreatment step comprises coating and smoothing the mold cavity with mold release compound.