What Will Affect the Service Life of Plasticized Components of Injection Molding Machine?
The plasticized components of the injection molding machine include screw, barrel, screw tip, screw seat and check ring.
When the injection molding machine is working, the plasticized components are like the wheels of a motor vehicle. As long as it is started, it will be subjected to pressure, impact, friction, and squeeze. For the same tire, driving on a flat road and operating by a skilled driver can often prolong the service life of the tire. When driving on roads that are often bumpy and sandy, coupled with frequent emergency braking actions, the pattern on the tire surface is quickly polished and scrapped.
Therefore, to ensure that the injection molding machine is always in good condition, it is necessary to clarify the performance and quality of the injection molding machine used. And strengthen the management of the use of the injection molding machine. It’s to achieve the purpose of reducing the failure rate, reducing the maintenance cost, and extending the service life.
Generally speaking, the following aspects affect the service life of the plasticizing system of the injection molding machine:
1. The Effect of Mechanical Wear
Some modified plastics are added with minerals, glass fiber, metal powder, etc. The existence of these materials will cause uniform mechanical wear on the screw, screw check ring / seat / tip and the barrel over time during the plasticization and injection processing. It can grind off the nitride layer and plating layer. After abrasion, the gap between the screw and the barrel is increased. That will reduce the plasticizing effect and increase the leakage of the melting plastic. Besides, it will also reduce the injection efficiency and the processing accuracy.
2. Mechanical Fatigue and Overload Work
The machine operator habitually set the machine working at low-temperature, high-speed and high-pressure. And that gradually degrades the performance of the plasticized components.
For example, when processing PC and PA plastics, if the temperature doesn’t meet the requirements, the viscosity of the plastic is very high. If the screw action is forced at this time, the screw pressure and the screw torque must be increased, thus increasing the stress fatigue of the screw.
3. Human Factors (including operating errors or illegal operations, etc.)
1) When metal impurities are mixed in the plastic and enter into the barrel (https://tekwellmachinery.com/injection-molding-machine-barrel/), due to the extrusion effect, the screw edges, grooves, screw check ring and screw check seat will be worn. And it will result in unstable injection molding and easy to occur black dots and black streaks phenomenon.
2) The high temperature plastic resin with low temperature setting. That causes excessive torque of the screw during the plasticization and further causes stress fatigue of the screw.
3) Cold-start is an impatient and irresponsible work attitude. When the temperature of the barrel has not reached the set required temperature or just the moment reached, the residual material in the barrel, its outer layer absorbs the heat from the heating band, so the temperature is relatively high. While the temperature of the inner layer is still very low. Therefore, the rotation of the screw torque is very large during cold start, causing stress fatigue on the screw. In severe cases, the screw will be twisted quickly, and the check ring and check seat will be twisted as well.
Hence, we should check the breakage of the blades of the crusher frequently. If we find the blades are worn, then we should replace them immediately. On the other hand, the magnets in the hopper should be checked and cleaned frequently. When the metal scraps adsorbed on the periphery of the magnet are saturated, the adsorption force for the iron scraps on the outer layer will be weakened, and easily fall into the barrel with the resin.