Damage causes and disassembly and maintenance methods of injection molding machine screw!

    Repair and replacement of screw of horizontal injection molding machine.

    1. If there are slight wear or scratch marks on the working surface of the screw of the horizontal injection molding machine, the damaged parts can be ground and polished with oilstone or fine abrasive cloth.

    2. When the working surface of the screw is seriously worn and the scar groove is deep, check and analyze the wear reason of the screw, eliminate the defects, so as to prevent similar phenomena from appearing again, and then stop repair welding for the deep scar groove.

    If the thread of the whole screw is seriously worn, the fit gap between the screw and the barrel increases, the molten material leakage increases during operation, and the injection quantity is unstable, the outer circle of the screw thread shall be thermally sprayed with wear-resistant alloy, and then the screw grinding shall be stopped according to the practical size of the inner diameter of the barrel according to the fit gap of the parts.

    If the barrel is seriously worn, the diameter of the inner hole increases after repair, and the grinding after spraying of the screw can not meet the requirements of the matching gap between the barrel and the screw, the screw shall be stopped for remanufacturing. The thread outer diameter of the screw shall be processed according to the matching clearance requirements of the two parts and the actual inner hole diameter of the barrel.

    Cause of screw damage of vertical injection molding machine.

    1. Low temperature during plasticization of raw materials.

    2. Metal foreign matters are mixed in the raw materials or there are many impurities in the raw materials.

    3. The screw idling time is too long.

    4. The selection of manufacturing screw data is unreasonable.

    ⑤. The screw manufacturing accuracy is low, and the heat treatment hardness of the threaded working face is low.

    Special tools shall be used to disassemble the screw of vertical injection molding machine, and heavy hammer is not allowed. The detailed disassembly steps are as follows.

    1. Remove the nozzle and the connecting piece between the nozzle and the barrel.

    2. Separate the key joint at the rear of the screw from the drive shaft.

    3. Remove the connecting flange and move the screw forward.

    4. When the head of the screw exposes the barrel, immediately remove the connecting thread of the screw (Note: most of the threads here are left-handed).

    5. Remove the check ring and sealing ring on the screw.

    6. The disassembled nozzle, check ring, sealing ring and screw rod shall be immediately cleaned up with copper brush and shovel tools. The sticky materials that are particularly difficult to settle shall be heated in the oven at a low temperature that can soften the materials, and then the residues shall be removed.

    7. Assemble the parts on the screw together, and apply molybdenum disulfide heat-resistant grease on the connection part of each thread to facilitate the next disassembly.

    8. For horizontal injection molding machine, the screw not used for the time being shall be coated with protective oil after the surface is cleaned, wrapped and hung in a ventilated and safe place.