Maintenance of Injection Mould

The maintenance of injection mould firstly is the maintenance in the producing process. Like car, if long time without use and no maintenance, the mould will be useless. So after every use of mould, there will be comprehensive maintenance, especially the rust-proof of forming parts and movement parts. Because that the mould will touch the water when producing, so must keep the mould dry, and then brush a layer of oil to maintain.

       

The use of injection mould
The mould creates value in use, but also loses the value itself in use. So the operator must pay great attention to the use of the mould, and should pay attention to the following four points：

1. Before use, check whether there are impurities and dirt in each part of the mould, and the remaining plastic and impurities in the mould should be cleaned with cotton gauze, and the strong adhesive should be scraped off with copper knife.
2. Reasonable selection of clamping force, it should take the no flying edge producing as the standard, not the higher the better, which will increase the power consumption, also easy to damage the transmission parts.
3. All transmission parts should be well lubricated.
4. Don’t use hammer and other objects to hit any part of the mould, so as to avoid deformation and even damage to the mould.

The maintenance of injection mould
Maintenance of cooling watercourse: The cooling water channel is used to cool and solidify the plastic parts in the cavity through cooling water, which has a great influence on the moulding process of the plastic parts.

1. The harm of cooling watercourse blockage
   In the process of long-term work, the surface of cooling water channel is easy to deposit scale, dirt and rust etc., which reduce the circulation area of cooling waterway, and greatly reduce heat exchange of the cooling water in mould, the cooling effect is reduced, the harm is great.
2. Check for blocked watercourse
   The increase of sediment on the surface of the cooling watercourse will cause local blockage of the watercourse, which can be used to determine the internal situation of the cooling water channel by measuring the flow velocity of the cooling water. When measuring, a pressure control valve can be installed between the mould and the cooling water channel. In the same condition, the cooling water can be measured through the pressure of mould. Thus, the blockage of cooling channels can be determined. If it is blocked to a certain extent, it should be cleaned in time.
3. The cleaning of the cooling watercourse
   Due to the design of the cooling water channel is associated with cavity shape, and the shape of twists and turns is inconvenient to apart. Therefore, it can‘t be cleaned by mechanical method, can only use detergent to wash. Under the powerful momentum of detergent, cleaning the dirt that adhesion of there. There are many types of cleaning agents can be chosen.

Maintenance of uninstalled injection mould: When injection mould finish production, it needs to be uninstalled from the injection moulding machine. When removing, clean the remaining plastic carefully, and use different cleaning methods according to different properties of different plastics. Soap water is generally used to remove residual plastics and other sediments in the mould and then dry the mould.If there is rust on the surface of the cavity, it should be cleaned and polished, then protected by lubricant and stored in the warehouse.

Malfunction of injection mould and the solution
There will be some malfunction in the working process of the injection mould, which have adverse effects on product quality, productivity, mould and so on.Below is the detailed description:

Deformation of mould and the solution: Deformation of mould refers to the excessive elastic deformation or plastic deformation of the mould during the working process, which makes the mould cannot work properly or the product quality is not qualified. Below is the reason and solution.

1. Lack of rigidity
   During injection moulding, the mould is subjected to a great pressure, which will not be used if the mould is permanently deformed. However, even within the elastic limit, the deformation of the mould can be recovered, but the solidification of the mould will make the mould opening difficult and can't even be opened. In this case, it is impossible to reconstruct the mould from the structure, but can reduce the injection pressure properly, or add the frame to the outside to strengthen the rigidity. Although is not in beauty look, but can be used.
2. Die assembly misalignment
   If the mould is not properly assembled, such as the joints of mould are not accurately correct, which will cause that the melt filling is not balanced, which can easily cause deformation or dislocation of the mould. In this case, the mould should be reassembled, and it can be corrected by modifying the gate.

Mould cavity damage and the solution: Cavity is the location where shaping the plastic parts, its damage will directly affect the quality of products. Cavity damage is the mechanical damage which suffer from the surface of inside cavity, make surface produce defects, such as scratch, pits and cracks etc.

1. Hard object damages cavity
   Sometimes it is difficult to remove the plastic parts after opening the mould, so to get it with the screwdriver and other hard tools, which can easily hurt the cavity. In addition, after opening the mould, accidentally drop the wrench, hammer and other hard objects into the cavity which resulting in cavity damage.
2. Misoperation
   If don't take out the plastic parts and closing the mould, especially in automatically forming, the cavity and mould are easily hurt by solidified plastic parts.
3. Repair of injury
   After cavity damage, it is difficult to continue work if without repair. Below is the repairing methods of cavity damage:

• Welding: Welding is a commonly used repair method. The most commonly used welding method is the gas welding. If electric welding is used, the mould is prone to deformation and even cracking due to high temperature. If repair using electric welding, the mould should be preheated, and do heat treatment after welding.
• Insert: For small area, deep damage, inserts can be added to repair. Generally, inserting after drilling. When drilling, be careful not to drill through the cooling water channels and screw holes. The fitting of the insert and the cavity should be close, make it smoothly after installing.
• Plate: For defects of less than 0.5mm, it can be repaired by electroplating and can be plated with copper and chrome plated.
• Knock: For the cavity with softy material, it can be used to drill a blind hole on the back of the damaged part, and then knock on the bottom of the blind hole to extrude the damage.

Mould rust and solution: The injection mould is made of tool steel. In the work, it will encounter corrosive gases, water and other materials that cause rusting. The moulded parts made of rusty mould will have quality problems, which should be solved.

1. A gas produced by the decomposition of a melt
   Some raw material after heating will produce volatile gas, a lot of raw material when overheating also produce volatile gas, the gas mostly is corrosive, they are around the machine, when the mould is not working, they would have corrosion on the mould. For this, when the machine stops working, use the soft cloth to wipe the mould and close the mould. If it is not used for a long time, the mould cavity should be sprayed with anti-rust agent, and when the mould is closed, it should be coated with butter and plus the gate.
2. Cooling water in the mould
   Moisture in the air can formed drop of water on the surface of the mould, and it is easy to rust if you do not wipe it in time. In particular, after the mould stops working, it will quickly produce condensed water. Therefore, do not stop moulding easily, even if stop, turn off the cooling water and dry the mould.
3. Carbide produced when forming
   After working for a long time, the mould is analyzed and decomposed to produce carbide, which often causes the mould to wear, corrode or rust. In this case, if carbide is found, wipe it off with a dry cloth immediately.

In conclusion, in the injection moulding industry, if want to make the production cost of plastic injection moulding companies reduce, must pay attention to the the injection mould quality and later maintenance, to improve the service life of the whole injection mould, so as to realize the product cost down, enhance overall market competitiveness.