PROCESS FOR CERAMICAL COATING TOOL-SURFACES OF PLASTIC CONVERTING MACHINE WITH CERAMIC MATERIALS OF DIFFERENT COMPOSITIONS

• Main Authors: KELEMEN,LAJOS,HU, SZEDOE,FERENC,HU, KENESEI,VIKTOR,HU, TIMAR,FERENC,HU, JAKO,ANDRAS,HU
• Format: Patent
• Language: English
• Published: 28.06.1991
• Edition: 5
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

In a plastics working tool, esp. for extruding or rolling thermoplastics, in which at least the major part of the plastics-contacting surface of the tool is a ceramic surface, the novelty is that the ceramic surface is formed by a 0.3-0.5 mm thick ceramic layer deposited on the rotational face of a metallic tool body. Prodn. of the tool involves (a) preparing a metallic tool body having dimensions, at any place where a ceramic face is to be formed, which differ from the nominal tool dimension by the intended thickness of the ceramic layer; (b) subjecting the tool body to degreasing, conditioning by powder blasting, and preheating; (c) depositing a base layer and an at least 0.7 mm thick ceramic layer by flame or plasma spraying; and (d) grinding the ceramic layer to the final thickness of 0.3-0.5 mm. USE/ADVANTAGE - The tool is useful as an extruder nozzle or foil roller e.g. for processing molten polyolefins such as linear polyethylene. It is resistant to baked-on eg-deposits so that cleaning operations can be eliminated, has a thin ceramic layer so that thermal conductivity of the tool is not significantly affected, and is not significantly more expensive than conventional tools since the expense of usual operations such as polishing and Cr plating is avoided.