Before the newly purchased plastic moulding machine is first used, it may be necessary to clean or disassemble the barrel of the injection moulding machine when there is a need to change products, replace materials, exchange colors or find decomposition in plastics in production.

Heating barrel cleaning method is usually used for cleaning barrel. Cleaning materials generally use plastic materials (or plastic recycling materials). For thermosensitive plastics, such as polyvinyl chloride (PCE), low density polyethylene (LDPE) and polystyrene (PS) can be used to clean the transition materials, and then the new materials processed can be used to replace the transition cleaning materials.

Selection of 1.3.4.4 release agent

The release agent is a material which can make the plastic products easy to release. Zinc stearate is suitable for plastics other than polyamides; liquid white wax is better for plastics of polyamides; silicone oil is expensive, difficult to use and less used.

The proper amount of release agent should be controlled and used as little or no as possible. Excessive spraying will affect the appearance of the product, and will also have a negative impact on the decoration of the product.

1.4 Cautions in Operation of Injection Molding Machine

Developing excellent operation habits of injection moulding machines has great advantages for the longevity and production of trudging machines.

1.4.1 Before startup: (1) Check whether water and oil enter the control box of the electrical appliances. If the electrical appliances are damp, do not turn on. Maintenance personnel shall blow dry the electrical parts before starting the machine. (2) Check whether the supply voltage matches, generally should not exceed (+15%). (3) Check the emergency stop switch and whether the front and rear door switches are normal. Verify that the rolling direction of the motor and the oil pump is the same. (4) Check whether the cooling pipes are dredged, and pass cooling water into the cooling water jacket at the end of the oil cooler and the barrel. (5) Check whether there is any lubricating oil (grease) in the moving parts and add enough lubricating oil. (6) Turn over the electric heating and heat each section of the barrel. When the temperature of each section reaches the requirement, keep it warm for a period of time, so that the machine temperature tends to be stable. The holding time varies according to the requirements of different equipment and plastic materials. (7) The hopper is filled with satisfactory plastics. According to the requirements of different plastics for injection moulding, some materials must be dried first. (8) Cover the heat shield on the barrel, which can save electricity and extend the life of the electric heating coil and current contactor.

1.4.2 During operation: (1) Do not cancel the effect of the door at will for the sake of greed and convenience. (2) Be careful to inquire about the temperature of the pressure oil. The temperature of the oil should not exceed the stipulated plan. The working temperature of hydraulic oil should be maintained between 45 ~50 C, which is generally suitable in the planning of 35 ~60 C. (3) Be careful to adjust the limit switches of each stroke to prevent the machine from bumping in action.

1.4.3 At the end of the operation: (1) Before shutdown, the plastics in the barrel should be cleaned up to prevent oxidation or long-term thermal decomposition of the remaining materials. (2) The die should be turned over so that the elbow bar structure is locked for a long time. (3) There is a need for hoisting equipment in the workshop. When assembling and disassembling bulky parts such as moulds, great care should be taken to ensure production.

1.5 Reasons and Treatment of Injection Molded Product Attack Defects

In the process of injection moulding, some defects such as unsatisfactory injection, depression, flying edge, bubble, crack, warping deformation and standard change often occur because of poor data processing, unreasonable product or mould planning, lack of suitable process and operation conditions by operators, or mechanical reasons.

There are three main aspects in the evaluation of plastic products. The first is the appearance quality, including completeness, color and luster; the second is the accuracy between standards and relative orientation; and the third is the corresponding mechanical, chemical and electrical functions. These quality requirements are different according to the different application occasions of the products and the requirements of the standards are also different.

Production practice has proved that the defects of products lie primarily in the planning of dies, manufacturing accuracy and wear degree. But in fact, the technicians in plastic processing factories often suffer from the difficult situation of ineffectiveness due to the problem of using process methods to compensate for the defects of dies.

The process adjustment during production is the demand way for the quality and output value of trekking products. Because the injection cycle itself is very short, if the process conditions are not well mastered, there will be endless waste products. When adjusting the process, only one condition is changed at a time, and multiple queries are made. If the pressure, temperature and time are unified, it is easy to form disorders and misunderstandings, and if something goes wrong, it is not clear what the reason is. There are many ways to adjust the process. For example, there are more than ten possible ways to deal with the problem of unsatisfactory product annotations. We should select one or two primary plans to deal with the crux of the problem, so that we can really deal with the problem. In addition, attention should be paid to the dialectical contacts in the plan. For example, there are sags in the products, sometimes the material temperature has to be trudged, sometimes the material temperature has to be lowered, sometimes the material quantity has to be added, and sometimes the material quantity has to be reduced. It is necessary to acknowledge the feasibility of the reverse method in dealing with the problem.