Tips for the maintenance of injection molds

Injection molds are divided into the following types.

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 a single cavity injection mold or multi-cavity injection mold according to the need, and is the most widely used type of injection mold.

2 Double parting surface injection 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 locally in the fixed part of the mold, so it is also called three-plate (moving template, intermediate plate, fixed template) 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 structure is complicated, the manufacturing cost is high, parts processing is difficult, generally not used for large or very large plastic products molding.

3 Injection mold with lateral parting and core extraction mechanism
When the plastic part has side holes or sides concave, it needs to use the core or slider that can be moved laterally. After injection molding, the moving mold first moves downward for a distance, and 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 pushing plate to make the molded part come off from the core.

4 Injection mold with moving 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
For molded parts with threads, when automatic unmolding is required, a threaded core or ring that can be rotated can be set on the mold, and the threaded core or ring can be rotated by the opening act of the mold or the rotating mechanism of the injection molding machine, or a special transmission device can be set to drive the threaded core or ring to rotate, so as to unmold the parts.

6 Runnerless injection mold
Runners 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, which is very different from other injection molds in that the direction of the feeding material 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 limitation of some plastic parts, it is better to leave the plastic parts on the fixed mold side for molding, which makes the plastic parts come out from the mold, so it is necessary to set the release mechanism on the fixed mold side.

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

After completing a production cycle, the molds are generally kept in storage until the next production cycle comes. However, some processing enterprises do not pay attention to the preservation of the mold, so that the mold in the preservation period rust and corrosion, 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 make new molds, resulting in great waste.

A well-maintained and maintained mold can shorten the time of mold assembly and trial run, reduce production failure, make the 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 produce qualified products smoothly. Therefore, for the injection molding products processing enterprises, in the current market competition is fierce, the maintenance of good mold can help enterprises.

The information shows 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 extend 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 caused by 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, for the injection mold to take the following measures to ensure the extension of the service life of the injection mold.

1, Processing enterprises should firstly equip each pair of molds with a resume card, detailed records, statistics of its use, care (lubrication, cleaning, rust prevention), and damage, according to which you can find out which parts, components have been damaged, the degree of wear and tear to provide information to find and solve the problem, as well as the molding process parameters of the mold, the materials used in the product, in order to shorten the test 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 the size of the last molded plastic parts measured out, through this information can determine the existing state of the mold, find out where the damage to the cavity, core, cooling system, and parting surface, etc., according to the information provided by the plastic parts, you can determine the damage state of the mold and maintenance measures.

3, To focus on several important parts of the mold tracking test: ejector, guide parts to ensure that the mold open and close movement and plastic parts ejected, if any part of the damage and stuck, will lead to stop production, so you should always keep the mold ejector, guide column lubrication (to use the most suitable lubricant), and regularly check whether the ejector, guide column, etc. deformation and surface damage, once found, to promptly replace 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 gear racks and the elastic strength of the spring mold to ensure that it is 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 an 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, 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 carefully remove the injection residues according to different injection molding materials. Copper rods, copper wire, and a 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 the corrosive injection, use a grinding machine to grind and polish, and spray with professional anti-rust oil, then put the mold in a dry, cool, and dust-free place for storage.