Use and maintenance of injection molds
The use and maintenance of injection molds are critical to ensuring smooth injection molding production, extending mold life, and ensuring stable product quality. In actual production, many mold failures and product defects are related to improper use and inadequate maintenance. Therefore, establishing a scientific and reasonable mold use and maintenance system is crucial for improving production efficiency and reducing production costs. The use of injection molds involves multiple steps, including installation and commissioning, parameter setting, and production monitoring, while maintenance includes daily cleaning, regular inspections, and troubleshooting. The two complement each other to ensure the mold is in good working condition.
Correct installation and commissioning of the mold is the first step to ensure its safe operation. Improper operation may cause damage to the mold or personal safety accidents. Before installing the mold, it is necessary to conduct a comprehensive inspection of the mold to check whether there are scratches or rust on the surface of the cavity and core, whether the ejection mechanism is flexible, and whether the cooling water channel is unobstructed. During installation, the fixed platen and movable platen of the injection molding machine should be cleaned, and then the mold should be slowly hoisted into the injection molding machine. The positioning holes should be aligned, and the fixed mold base plate and movable mold base plate should be fixed to the injection molding machine’s platen with bolts. Note that the bolts should be tightened evenly to avoid uneven force on the mold. During the commissioning phase, it is necessary to gradually adjust parameters such as clamping force, injection pressure, and holding pressure. Observe whether the mold opens and closes smoothly and whether the ejection is in place to ensure that all actions are coordinated. When the mold is first tested, low speed and low pressure should be used. After confirming that the mold is working properly, the parameters can be gradually increased to normal production values.
Properly setting injection molding process parameters is an important guarantee for the normal use of molds. Improper parameter settings will not only affect product quality but also increase mold wear. During the production process, appropriate parameters such as melt temperature, mold temperature, injection speed, and holding time should be set based on the structural characteristics of the mold, the properties of the plastic raw material, and the requirements of the product. For example, excessively high mold temperature will extend the cooling time of the product, reduce production efficiency, and increase the risk of thermal deformation of the mold. Excessive injection pressure will place excessive load on the mold cavity, accelerating wear on the cavity surface and deformation of the mold plate. In addition, frequent mold changes or parameter adjustments should be avoided to reduce the impact of alternating hot and cold temperatures on the mold. For molds that are produced for a long time, the stability of the process parameters should be regularly checked to promptly detect and correct abnormal fluctuations.
Daily cleaning and lubrication are the basic work of mold maintenance and can effectively reduce the wear and failure rate of mold components. After each production, plastic residues, oil stains and other debris on the mold surface and in the cavity should be cleaned promptly to prevent the residue from carbonizing at high temperature during the next production, which will affect the quality of the product and the life of the mold. When cleaning, you can use tools such as copper brushes and compressed air to avoid scratching the cavity surface with hard metal tools. For moving parts such as the mold’s guide system (such as guide pillars and guide sleeves) and ejection system (such as ejector pins and ejector plates), grease or lubricating oil should be added regularly to reduce friction and wear between components and ensure flexible movement. In addition, the cooling water channel also needs to be cleaned regularly to prevent scale deposition from clogging the water channel and affecting the cooling effect. Special pipe cleaning agents can be used for flushing to ensure the smooth flow of the cooling system.
Regular inspections and troubleshooting are key measures to prevent major mold damage and extend its service life. After a period of use, molds may develop various faults due to wear and fatigue, such as wear of guide pins and sleeves leading to reduced guiding accuracy, bending and breaking of ejector pins, and scratches on the cavity surface. Therefore, it is necessary to develop a regular inspection plan and conduct a comprehensive inspection of the key components of the mold, including measuring the fit clearance of guide pins and sleeves, checking the verticality and wear of ejector pins, and inspecting the surface quality of the cavity and core. Any problems discovered should be repaired promptly, such as replacing severely worn guide pins and sleeves, repairing scratches on the cavity surface, and straightening or replacing bent ejector pins. For some complex mold failures, such as mold plate deformation and cavity cracking, professional mold maintenance personnel should be consulted to avoid further losses caused by improper maintenance.
Mold storage and care are also crucial components of maintenance. Molds that sit idle for extended periods require proper storage to prevent damage and rust. Before storage, the mold should be thoroughly cleaned and maintained, removing any oil and debris from the cavity and moving parts. All moving parts should be filled with rust-proof oil. The mold should then be closed and the fixed and moving plates secured with bolts. During storage, the mold should be placed in a dry, well-ventilated environment free of corrosive gases, away from direct sunlight and rain. Large molds should be stored in dedicated mold racks to prevent deformation. A mold storage file should also be maintained, documenting mold usage, maintenance history, and storage location to facilitate quick retrieval and inspection upon next use. Regularly inspect stored molds and replace any deteriorated rust-proof oil to ensure they are in good working order.
