Injection Mold Maintenance

1. Processing enterprises should firstly equip each pair of molds with a resume card to record and count its use, care (lubrication, cleaning, rust prevention) and damage in detail, according to which it can find out which parts and components have been damaged and the degree of wear and tear to provide information materials for finding and solving problems, as well as the molding process parameters of the mold and the materials used for the product to shorten the trial run time of the mold and improve production efficiency.

2. Processing enterprises should test various properties of the mold under the normal operation of the injection molding machine and mold, and measure the size of the final molded plastic parts. Through this information, the existing state of the mold can be determined to find out where the damage to the cavity, core, cooling system and parting surface is located, and according to the information provided by the plastic parts, the damaged state of the mold can be judged as well as maintenance measures.

3. To focus on several important parts of the mold follow-up inspection: the role of ejector and guide parts is to ensure that the mold opening and closing movement and plastic parts ejected, if any part of the damage and stuck, will lead to stop production, so should always keep the mold ejector pin, guide column lubrication (to use the most suitable lubricant), and regularly check whether the ejector pin, guide column, etc. deformation and surface damage, once found, should be replaced in a timely manner; After completing a production cycle, the working surface, moving and guiding parts of the mold should be coated with professional anti-rust oil, and special attention should be paid to the protection of the bearing parts of the mold with gears and racks and the elastic strength of the spring mold to ensure that they are always in the best working condition;

As the production time continues, the cooling channel is easy to deposit scale, rust, silt and algae, etc., so that the cooling channel cross-section becomes smaller and the cooling channel becomes narrower, which greatly reduces the heat exchange rate between the coolant and the mold and increases the production cost of the enterprise, so the cleaning of the channel should be paid attention to; for the hot runner mold, the maintenance of the heating and control system is beneficial to prevent the occurrence of production failure, so it is especially important. Therefore, after the end of each production cycle should be mold on the band heater, bar heater, heating probe and thermocouple measurement with ohmmeter, such as damage, to replace in a timely manner, and comparison with the mold resume, make a record, in order to timely find the problem, take countermeasures.

4. To pay attention to the surface maintenance of the mold, it directly affects the surface quality of the product, the focus is to prevent rust, therefore, it is especially important to choose a suitable, high-quality, professional anti-rust oil. When the mold completes the production task, it should take different methods to carefully remove the injection residues according to different injection molding materials. Copper rods, copper wire and professional mold cleaning agent can be used to remove the residual injection and other deposits in the mold, and then air dry. It is forbidden to use iron wire, steel bar and other hard objects to clean up in order to avoid scratching the surface. If there are rust spots caused by corrosive injection molding, use a grinding machine to grind and polish, and spray with professional anti-rust oil, and then store the mold in a dry, cool, dust-free place.

As the most important molding equipment for injection molding products processing, the quality of injection mold is directly related to the quality of products. Moreover, since the mold occupies a large proportion in the production cost of injection molding processing enterprises, its service life directly affects the cost of injection molding products. Therefore, to improve the quality of injection moulds, and maintain and repair them to prolong their life cycle, is an important issue for injection molding product processing enterprises to reduce costs and increase efficiency.

After completing a production cycle, the molds are generally kept in storage until the next production cycle comes and then used. But some processing enterprises do not pay enough attention to mold preservation, so that the mold in the preservation period rust, surface finish decline, resulting in product quality decline, high scrap rate, some molds are even difficult to use, need to re-invest a lot of money to buy a new mold, resulting in a great waste.

Data show that the use and maintenance in the mold life factors account for 15% to 20%, injection mold life can generally reach 800,000 times, some foreign mold maintenance can even be extended 2 to 3 times. But domestic enterprises due to neglect maintenance, injection mold life is relatively short, only equivalent to foreign 1/5 ~ 1/3. Due to the short life of the mold and the steel processing labor and energy waste, as well as the impact on product quality brought about by the loss of billions of dollars each year.

Therefore, the maintenance of injection molds is very important, as follows.

1. Processing enterprises should firstly equip each pair of molds with a resume card to record and count its use, care (lubrication, cleaning, rust prevention) and damage in detail, according to which it can find out which parts and components have been damaged and the degree of wear and tear, in order to provide information to find and solve problems, as well as the molding process parameters of the mold and the materials used for the product, so as to shorten the trial run time of the mold and improve production efficiency.

2. Processing enterprises should test various properties of the mold under the normal operation of the injection molding machine and mold, and measure the size of the final molded plastic parts. Through this information, the existing state of the mold can be determined to find out where the damage to the cavity, core, cooling system and parting surface is located, and according to the information provided by the plastic parts, the damaged state of the mold can be judged as well as maintenance measures.

3. to focus on several important parts of the mold follow-up inspection: ejector, guide parts are to ensure the mold opening and closing movement and plastic parts ejected, if any part of the damage and stuck, will lead to stop production, so should always keep the mold ejector pin, guide column lubrication (to use the most suitable lubricant), and regularly check whether the ejector pin, guide column, etc. deformation and surface damage, once found, should be replaced in a timely manner.

After completing a production cycle, apply professional anti-rust oil to the working surface, moving and guiding parts of the mold, and pay special attention to the protection of the bearing parts of the mold with gears and racks and the elastic strength of the spring mold to ensure that they are always in the best working condition.

As the production time continues, the cooling channel is easy to deposit scale, rust, silt and algae, etc., so that the cooling channel cross-section becomes smaller and the cooling channel becomes narrower, which greatly reduces the heat exchange rate between the coolant and the mold and increases the production cost of the enterprise, so the cleaning of the channel should be paid attention to; for the hot runner mold, the maintenance of the heating and control system is beneficial to prevent the occurrence of production failure, so it is especially important.

Therefore, after each production cycle should be mold on the band heater, bar heater, heating probe and thermocouple measurement with ohmmeter, if there is damage, to be replaced in a timely manner, and compared with the mold resume, make a record, in order to timely find problems and take countermeasures.

4. To pay attention to the surface maintenance of the mold, it directly affects the surface quality of the product, the focus is to prevent rust, therefore, it is especially important to choose a suitable, high-quality, professional anti-rust oil. When the mold has finished the production task, it should take different methods to remove the residual injection carefully according to different injection, use copper rod, copper wire and professional mold cleaning agent to remove the residual injection and other deposits in the mold, then air dry.

It is forbidden to use iron wire, steel bar and other hard objects to clean up in order to avoid scratching the surface. If there are rust spots caused by corrosive injection molding, use a grinding machine to grind and polish, and spray with professional anti-rust oil, then store the mold in a dry, cool and dust-free place.

A well-maintained and maintained mold can shorten the mold assembly and commissioning time, reduce production failures, make production run smoothly, ensure product quality, reduce scrap loss, and reduce the operating cost and fixed asset investment of the enterprise, so that when the next production cycle starts, the enterprise can smoothly produce products with qualified quality. Therefore, for the injection molding product processing enterprises, in the current market competition is fierce, maintaining a good mold can help the enterprise.

(1) Single parting surface injection mold

When the mold is opened, the movable mold and the fixed mold are separated, so as to take out the plastic parts, which is called single parting surface mold, also called double-plate mold. It is the simplest and most basic form of injection mold, which can be designed as single cavity injection mold or multi-cavity injection mold according to the need, and it is the most widely used injection mold.

(2) Double parting mold

Compared with the single parting surface injection mold, the double parting surface injection mold has an intermediate plate (also called movable gate plate, which is equipped with gates, runners and other parts and components required by the mold) that can be moved partially in the fixed part of the mold, so it is also called three-plate (movable plate, intermediate plate, fixed plate) injection mold.

It is often used in single-cavity or multi-cavity injection molds with point gate feeding. When the mold is opened, the middle plate is separated from the fixed template at a fixed distance on the guide column of the fixed mold, so that the condensed material of the pouring system can be taken out between these two templates. Double parting surface injection mold has complicated structure, high manufacturing cost and difficult parts processing, so it is generally not used for large or extra-large plastic products.

(3) Injection mold with lateral parting and core extraction mechanism

When the plastic part has side holes or side concave, it is necessary to use the core or slider that can move laterally. After injection molding, the movable mold first moves downward for a distance, then the beveled section of the bent pin fixed on the fixed mold plate forces the slider to move outward, while the push rod of the mold release mechanism pushes the push plate to make the molded part come off from the core.

(4) Injection mold with movable molded parts

Due to the special structure of plastic parts, the injection mold is required to have movable molding parts, such as movable convex mold, movable concave mold, movable insert, movable threaded core or ring, etc., which can be moved out of the mold together with the plastic parts and then separated from the plastic parts during mold release.

(5) Automatic thread release injection mold

When a threaded part is required to be automatically unmolded, a threaded core or ring can be set on the mold that can be rotated to release the part by using the opening action of the mold or the rotating mechanism of the injection molding machine, or by setting up a special transmission device to drive the threaded core or ring to rotate.

(6) Runnerless injection mold

Runnerless injection mold refers to the method of adiabatic heating of the runner to keep the plastic between the nozzle and the cavity of the injection molding machine in a molten state, so that there is no condensation of the casting system when the mold is opened and the part is removed. The former is called adiabatic runner injection mold, and the latter is called hot runner injection mold.

(7) Right-angle injection mold

The right angle injection mold is only applicable to the angle injection molding machine, and is very different from other injection molds in that the direction of feeding is perpendicular to the opening and closing direction. The main channel is opened on both sides of the parting surface of the moving and fixed mold, and its cross-sectional area is usually unchanged, which is different from other molds for injection molding machines.

(8) Injection mold with the release mechanism on the fixed mold

In most of the injection molds, the release mechanism is installed on the side of the moving mold, which is conducive to the work of the ejector device in the opening and closing system of the injection molding machine. In actual production, due to the shape of some plastic parts, it is better to leave the plastic parts on the fixed side of the mold, so that the plastic parts can be released from the mold, it is necessary to set the release mechanism on the fixed side of the mold.