I. Components Susceptible and causes of wear of plastic hat molding machine during long-term use
plastic cap molding machines will be affected by mechanical friction, high temperature, material impact and so on in the continuous production process, leading to multiple core components wear. These components can be categorized into the following categories:
1.Mold-Related Components: directly exposed to molten plastic, easy to wear and corrode.
Cavity and core: As the core structure of plastic cap molding, they are exposed to molten plastics (such as PP and PE) for long periods of time at temperatures of 150 to250° C. They can also withstand the mechanical shock of opening and closing the die after each molding cycle. This can easily lead to surface scratches and cavity wear (such as thread deformation), leading to glitter and size bias in plastic caps. If the raw material contains impurities (such as particles), the cavity surface will accelerate wear, reducing product precision.
Mold guide pins and guide bushing: These components ensure coaxial properties when opening and closing the die. They are constantly affected by reciprocating friction. Inadequate lubrication or the presence of dust can lead to coarse guide pins and wear of the guide bushings. This can lead to mold jamming and even dislocation of the cavity, affecting the quality of the plastic cover. Mold thimble/ thimble: Be responsible for pushing the plastic cover out of the mold cavity after molding. Each demolding operation involves friction with the plastic cover and the inner wall of the mold cavity. This is especially true in the production of complex plastic caps bottle caps,such as those with sealing rings. Injector force is not uniform, it is easy to cause bending or surface wear, leading to the top cover after the removal of white deformation. In severe cases, pins can damage mold cavity.
2.Heating and temperature control elements: long-term high temperature operation can lead to serious aging and wear.
Heating coils/heating plates: Wrap around the barrel and mold runners, which constantly heats the plastic to melt it. The insulation layer on the surface of the heating coil tends to age and wear out due to the prolonged high temperature (180 to 280 degrees Celsius in the barrel). The internal resistor wire after high temperature oxidation can reduce their power and may even partially burn out. This leads to unstable temperatures in the drums and incomplete plastic melting, which affects the density and strength of the plastic lid. Thermocouples/temperature sensors: used to detect real-time temperature of barrel and die. If sensor probe is exposed to high temperature drums or contaminated with plastic melt for a long time, it is easy to form scale on the surface of the probe and reduce sensitivity. This can lead to a miscalculation of temperature by the temperature control system, which can lead to overheating or overheating. This not only affects the quality of the product but also accelerates the wear and tear of the heating components.
3.Transmission and actuator components: They withstand mechanical loads and experience significant friction losses.
Hydraulic cylinders/cylinder seals: Plastic cap Injection molding machines rely on hydraulic cylinders to close the mold, while compression molding machines rely on cylinders to control mold pressure. Seals (such as O-rings and oil seals) are affected by high pressure and reciprocation over a long period of time. As a result of aging and hydraulic oil contamination, they are prone to malfunction, leading to oil and air leaks in cylinders, reduced clamping force and even equipment downtime. Gear and rack/drive belts: Used to transfer power (e.g. opening, closing and rotating drum screws for driving die). Long-term meshing or frictional transmission it is easy to cause gear tooth surfaces wear and spotting. Drive belts may age and crack due to prolonged stretching and friction, resulting in reduced transmission accuracy, increased equipment noise and unstable molding cycles.
Tubular screw: responsible for the transport and melting of plastic materials. The screw rotates at high speed in the barrel (up to 50-150 rpm), causing constant friction with the inside of the barrel and the plastic material. This can easily cause wear and tear on the flight surface of the screw (especially in the production of fiberglass caps), and reduce the efficiency and uniformity of the melt. the barrel's inner wall will also increase the gap between the screw and the cylinder, causing ``backflow"and reducing production efficiency. Auxiliary and Conveying Components: Due to the impact of materials and dust, it is Frequently easy to wear.
Feeder Hoppers and Screws: In automatic feeding systems, the hopper can hold plastic particles for a long time. If the raw material contains hard impurities, it is easy to wear down the the hopper's inner wall. When feed screws conveys material for a long time, it will wear the fin of the screw, which leads to unstable feeding speed and uneven material flow in the tube. This can lead to a shortage of plastic covers and weight variations.
Conveyor Belts/Rollers: Used to transport the finished plastic caps for subsequent inspection and packing. The plastic cover will rub and hit repeatedly, causing abrasion and cracking on the conveyor belt surface. Dust intrusion will lead to lubrication failure roller bearings of conveyor, interference or abnormal noise, affecting the continuous operation of the production line.
ii. Daily maintenance points for extending the service life of equipment
System maintenance is required to minimize wear and tear of the aforementioned wearable parts. Specific maintenance measures are as follows:
1. Mold Maintenance: Regular maintenance, Precise Protection
Daily cleaning and lubrication: After each production run, use a specialized cleaner (such as plastic mold cleaner) to clean plastic residue on the mold cavity and ejector pin surfaces to prevent carbonization and accelerated wear. High temperature resistant grease (such as lithium base grease) should be applied to the guide pins, guide bushings and nozzle before daily operation to ensure adequate lubrication and reduce friction loss.
Regular inspection and repair: weekly inspection mold cavity and ejector pin for wear. If scratches are found on the cavity surface, polish and repair with fine sandpaper (e.g., 800-1200 grit). Measure the gap between the guide pin and guide sleeve monthly. If the gap exceeds 0.05mm, replace the guide bushing or pin promptly. Complete mold removal is performed quarterly and any aging ejector pins and seals are replaced to ensure mold accuracy. Raw material control: use screening equipment (such as vibrating screen) to remove impurities from raw material and prevent hard particles from entering the mold. For easily degradable plastic raw materials such as PVC (PVC), the molding temperature and residence time are controlled to reduce the adhesion of decomposition products to the surface of
the mold cavity surface, thus reducing corrosion and wear.
2. Heating, temperature control system maintenance: stable temperature control, timely replacement.
Heating Component Inspection: Check the insulation layer of the heating coil for any damage before starting each day. If damage is found, replace it immediately. Check the resistance of the heating coil weekly with a multimeter. If deviations exceed 10% of the rated value, heating coil should be replaced in a timely manner to avoid underpower and production impacts. Wash the surface of temperature sensor probe a month to ensure the accuracy of temperature measurement.
Temperature control System Calibration: calibration of the thermocouple/temperature sensor quarterly using standard thermometers. If the deviation exceeds ±2°C, adjust the temperature control parameters or replace the sensor to ensure that the temperature of the drum and die is stable within the specified range and to reduce excessive wear on the heating components due to temperature fluctuations. Transmission and Actuator System Maintenance: ensure adequate lubrication and regular inspection.
Hydraulic/Pneumatic System Maintenance: check the level and quality of hydraulic oil daily. If the hydraulic fluid is cloudy or contains too much water, replace it promptly (wear-resistant hydraulic fluid number 46 is recommended). Clean hydraulic oil filter once a month to prevent impurity from clogging the pipeline. Cylinders/air seals are inspected every six months. If leakage or deterioration is detected, replace immediately to prevent pressure loss.
Transmission Component Maintenance: once a week, gear oil is applied to gear and rack meshes, and drive belt is sprayed on the belt surface to reduce friction loss. Check tooth surface wear monthly. If you notice a reduction of more than 5% in alveolar or tooth thickness, replace the gear promptly. Adjust drive belt tension quarterly to avoid slippage or tightness caused by excessive excessive looseness and accelerate belt aging. Screw and drum maintenance: every time the replacement of raw materials, the drum and drum should be thoroughly cleaned to prevent mixing of different raw materials, causing decomposition or wear. Check screws weekly for wear and tear. If the fin becomes shallower, adjust screw speed and back pressure to reduce wear and tear. Screening of screw and barrel accuracy every
6 months. Replace screws or barrel if clearance exceeds 0.2mm.
4. Auxiliary System Maintenance: clean protection to ensure delivery
Feed system maintenance: daily cleaning of raw materials left on the feeder hopper to prevent moisture and caking to feed screw wear. Check feed screw weekly for wear and tear. If fin wear causes the feed speed to decrease, the screw should be replaced in time. Wash the feed machine filter core once a month to prevent dust from entering the filter and reduce wear and tear of screw and filter. Conveyor Belt/Roller Maintenance:: daily cleaning of plastic debris on the surface of the conveyor belt to prevent debris from getting stuck on the belt drum bearings. Lubricate conveyor roller bearings weekly to prevent dry abrasion. Check conveyor tension monthly. If there is any looseness or deviation, adjust the tensioner to extend the belt's lifespan.
V. Comprehensive equipment maintenance: Regular Inspections and recording
Daily inspection: Make a daily inspection schedule to record the operation parameters of the equipment (e.g. clamping force, temperature and pressure) and the condition of vulnerable parts. If you notice anything unusual (such as increased noise or temperature fluctuations), stop checking immediately to prevent a glitch from escalating to a major fault.
Regular maintenance plan: Develop monthly, quarterly and annual maintenance plans based on frequency of equipment usage frequency (e.g., 8 hours per day versus 8 hours per day). (24 hours a day). Specify component replacement intervals for components (e.g., heater coils every 1-2 years, seals every 6 months) to ensure orderly maintenance of the equipment and to maximize its overall service life.
