How to maintain and care for preform molds
一. Overview of the structure of preform molds
二. Key points for daily maintenance
(I) Mold cleaning
(II) Lubrication and maintenance
(III) Inspection and tightening
三. Regular maintenance measures
(I) Accuracy detection and adjustment
(II) Hot runner system maintenance
(III) Cooling system maintenance
(IV) Disassembly and maintenance of the mold
四. Troubleshooting and repair
(I) Analysis and treatment of preform molding defects
(II) Repair of mold mechanical failure
五. Maintenance records and management
六. Conclusion
Regular maintenance of preform molds is our basic treatment. You are welcome to consult us about the maintenance and care of preform molds!
一. Overview of the structure of preform molds
Preform molds are mainly composed of cavities, cores, hot runner systems, cooling systems, demolding systems, and mold frames. The cavity and core are responsible for the molding of the preforms, and their accuracy and surface quality are directly related to the appearance and dimensional accuracy of the preforms; the hot runner system is used to evenly transport the plastic melt to the cavity to ensure the stable flow of the melt; the cooling system removes heat through circulating cooling water to promote rapid cooling and shaping of the preforms; the demolding system smoothly removes the preforms from the mold after molding; the mold frame provides support and positioning for other components to ensure the overall strength and stability of the mold. Understanding the structure of the mold is the basis for maintenance. Only by clarifying the functions and relationships of each component can maintenance work be carried out in a targeted manner.
二. Key points for daily maintenance
(I) Mold cleaning
1. After production, the mold surface should be cleaned immediately. Use a clean soft cloth or a special mold cleaner to remove impurities such as plastic melt, oil, dust, etc. that remain on the mold surface. For key parts such as the cavity and core, they must be cleaned carefully to avoid the accumulation of impurities that affect the quality of the next molding.
2. Clean the cooling water channel of the mold regularly. Minerals and impurities in the water may form scale on the inner wall of the water channel, affecting the cooling effect. Chemical cleaning or high-pressure water flushing can be used to remove scale and debris, ensure the unobstructed flow of cooling water, and maintain the normal heat dissipation function of the cooling system.
(II) Lubrication and maintenance
1. Apply an appropriate amount of lubricant to the moving parts of the mold, such as the ejector, slider, guide column, etc. Regularly. Select the appropriate lubricant variety, such as high-temperature grease, lubricating oil, etc., and determine the lubrication cycle according to the working temperature and movement frequency of the mold. Good lubrication can reduce friction between parts, reduce wear, improve the flexibility and reliability of the mold, and also help reduce equipment operation noise.
2. Check the sealing of the nozzle and manifold of the hot runner system. If necessary, add sealing grease for sealing maintenance to prevent plastic melt leakage and ensure the pressure stability and uniformity of melt delivery of the hot runner system.
(III) Inspection and tightening
1. Before starting the machine each time, conduct a comprehensive inspection of the mold. Check whether the mold parts are loose, deformed, damaged, etc. Pay special attention to the tightening of the fixing screws, locating pins and other connectors. If they are loose, they should be tightened in time to ensure the stability and accuracy of the mold during operation.
2. Check whether the ejection mechanism of the demoulding system is normal, and whether the ejector rod and ejector tube are bent or stuck. Ensure that the demoulding action is smooth and unobstructed to avoid damage to the preform or mold due to demoulding problems.
三. Regular maintenance measures
(I) Accuracy detection and adjustment
1. Regularly use high-precision measuring instruments, such as three-coordinate measuring instruments, profilometers, etc., to detect the dimensional accuracy of the mold cavity and core. According to the test results, analyze the wear and dimensional change trend of the mold during use. If the accuracy is found to be beyond the allowable tolerance range, timely repair measures should be taken, such as repair welding, EDM, grinding, etc., to adjust the mold size to the qualified range to ensure the molding accuracy of the preform.
2. Check the fit of the mold parting surface to ensure that the parting surface is flat and tight. If there are gaps or unevenness, it will cause defects such as flash and burrs on the preform, affecting product quality. The parting surface can be repaired by grinding, polishing, etc. to restore it to a good fit.
(II) Hot runner system maintenance
1. Regularly check the working status of the heating elements of the hot runner system, such as heating rods and heating coils. Use tools such as multimeters to measure their resistance values to determine whether there is a circuit break or short circuit. If damaged, it should be replaced in time to ensure that the hot runner system can provide heat stably and keep the plastic melt in a uniform molten state.
2. Calibrate the temperature control system of the hot runner system. Use a standard thermometer to compare and measure with the mold temperature controller, adjust the parameters of the temperature controller so that the displayed temperature matches the actual temperature, and ensure the accuracy of the temperature control of the hot runner system. This is crucial for the stable injection of plastic melt and the consistency of the quality of the preform.
(III) Cooling system maintenance
1. In addition to daily waterway cleaning, regularly inspect and maintain the water pump, pipes, valves and other components of the cooling system. Check the working performance of the water pump, such as whether the flow rate and pressure are normal. If there is any abnormality, it should be repaired or replaced in time. Check whether the pipeline has leakage or rupture, and whether the valve can be opened and closed flexibly to ensure the integrity and reliability of the cooling system.
2. Monitor and treat the water quality of the cooling system. According to the water quality, add water stabilizer or change water in time to prevent rust and corrosion of the cooling water channel, extend the service life of the cooling system, and also help improve the cooling efficiency.
(IV) Disassembly and maintenance of the mold
1. According to a certain period, the mold should be fully disassembled and maintained. During the disassembly process, the components should be marked and recorded for subsequent assembly. Thoroughly clean, rust and degrease the disassembled parts. For worn parts, such as ejector pins and sliders, repair or replace them according to the degree of wear.
2. Polish the cavity and core of the mold to remove the oxide layer and fine scratches on the surface and improve its surface finish. The smooth surface of the cavity and core helps to reduce the flow resistance of the plastic melt and improve the appearance quality of the preform. It can also reduce the adhesion of the plastic on the mold surface and facilitate demolding.
四. Troubleshooting and repair
(I) Analysis and treatment of preform molding defects
1. If the preform has flash, it may be caused by insufficient mold clamping force, loose parting surface, mold wear and other reasons. Check the working status of the clamping mechanism and adjust the clamping force to the appropriate range; check the parting surface and repair it; repair or replace the worn mold parts to eliminate the flash defect.
2. When bubbles appear in the preform, it may be caused by insufficient drying of the plastic raw material, too fast injection speed, too high melt temperature or poor mold exhaust. The drying process of raw materials should be strengthened, the injection speed and melt temperature should be appropriately reduced, and the exhaust system of the mold should be checked, such as opening exhaust grooves, adding exhaust needles, etc., to improve the exhaust effect of the mold, thereby reducing the generation of bubbles.
3. The problem of uneven wall thickness of the bottle embryo may be caused by the concentricity deviation between the mold cavity and the core, uneven melt distribution in the hot runner system, uneven cooling, etc. It is necessary to check the assembly accuracy of the mold, adjust the concentricity of the cavity and the core; check the runner balance of the hot runner system and make necessary adjustments; optimize the layout of the cooling system to ensure uniform cooling of the bottle embryo to solve the problem of uneven wall thickness.
(II) Repair of mold mechanical failure
1. If the ejection mechanism of the mold fails, such as the ejector pin is broken, the ejection is not smooth, etc., you should first check whether the ejection mechanism is assembled correctly and whether there is interference between the ejector pin and the mold parts. For the broken ejector pin, a new ejector pin of the same specification should be replaced, and its material and heat treatment quality should be checked to see if they meet the requirements. For the problem of poor ejection, you can clean the debris in the ejection channel, check whether the working pressure of the ejection cylinder or cylinder is normal, and make corresponding adjustments and repairs.
2. When the slider mechanism of the mold is stuck or inflexible, it may be caused by too small a gap between the slider and the guide rail, impurities entering, poor lubrication, etc. The debris between the slider and the guide rail should be cleaned, the appropriate gap should be adjusted, and lubrication should be re-performed to ensure that the slider mechanism can work normally.
五. Maintenance records and management
It is very necessary to establish a complete maintenance record file for pet bottle molds. The record should include the date, content, inspection results, replaced parts, maintenance personnel and other information of each maintenance. Through the analysis of maintenance records, the use rules and failure occurrence of molds can be summarized, which provides a basis for formulating a reasonable maintenance plan. It also helps to trace the maintenance history of the mold, discover potential problems in time, take preventive measures, and further improve the management level and maintenance effect of the mold.
六. Conclusion
The maintenance and maintenance of pet bottle molds is a systematic and meticulous work, covering daily maintenance, regular maintenance, troubleshooting and repair. By strictly implementing scientific and reasonable maintenance measures, the service life of the mold can be effectively extended, the quality of the preform can be guaranteed, production efficiency can be improved, and production costs can be reduced. Plastic bottle manufacturers should attach great importance to the maintenance of preform molds, establish and improve relevant systems and processes, strengthen the training and management of operators and maintenance personnel, so that the molds are always in the best working condition, and lay a solid foundation for the sustainable development of the enterprise. In the future development, with the continuous advancement of mold manufacturing technology and plastic processing technology, the maintenance methods of preform molds will also continue to innovate and improve to meet the new needs of industry development.
Foshan Heyan Precision Mold Technology Co., Ltd.'s main business is preform molds, blow molds, bottle cap molds and other products. It has a strong engineering, R&D, technology, sales team, advanced processing equipment and rich project experience. If you want to know more or have special needs, please call 13318345050, WeChat ID.pet bottle mold
