Pressure casting

High temperature resistant release agent technology for metal die-casting

(1) Quality requirements for die casting release agent: The release agent must have excellent lubrication performance at high temperatures, low evaporation point, and can quickly evaporate at temperatures ranging from 100 to 150. It can form a uniform and dense film during spraying, has no corrosive effect on die castings and molds, has stable performance, does not layer, does not break emulsion, and has no irritating odor. The shelf life at room temperature is more than half a year, and does not decompose toxic and harmful gases at high temperatures, Ensure the personal health of industrial workers.

（2） The function of die-casting release agent is to provide an effective isolation and protection layer between die-casting alloy and die-casting mold, prevent metal liquid from directly washing the cavity and core surface, improve the working conditions of die-casting mold, reduce the heat conduction of die-casting mold, protect the flow of metal liquid, improve the formability of metal liquid, and provide excellent lubrication performance at high temperatures, In order to easily push out the die-casting parts and improve the surface quality of the die-casting parts to prevent mold sticking.    

（3） The types and usage of die-casting release agents are water-based coatings, with a milky white viscous liquid appearance and a pH value of about 7. They are non-toxic, green, and environmentally friendly products. Please rest assured of their use. When using release agents, whether brushing or spraying, the thickness should be uniform and should not be too thick. After coating, the water in the coating should evaporate before the mold can be closed and poured to avoid molding difficulties. When selecting release agents, attention should be paid to the model used:

(1) For general products, the appearance requirements for die castings are not very high because they have undergone metal processing such as sandblasting, lathes, milling machines, and finally have spray paint on the surface. We suggest that you choose the inexpensive A-type release agent.

(2) For larger die-casting parts, the requirements for release agents require higher high temperature resistance, higher isolation, and a more attractive appearance. We suggest that you choose B-type die-casting release agents with better release effects.  

(3) For large, visually demanding, and structurally complex die-casting parts, we recommend that you choose C-type die-casting release agent. The BD-257 series has a high temperature resistance of over 360 degrees, high-quality demolding performance, and overcomes the shortcomings of some domestic high-end demolding agents that although demolding effects are good, they cannot spray paint or the surface of the paint peels off in subsequent processing. The surface of the casting is easy to clean with demolding agents, without any traces, and can be easily painted. 

(4) When using, for products that are difficult to demould, the amount of water added is generally 100 times that of the demoulding agent. For small products that are easy to demould, the maximum amount of water added can be 150 times. For specific products, please make the appropriate ratio for each user.  

Aluminum alloy die-casting, including aluminum, magnesium, and zinc alloy series die-casting products, is widely used in industries such as automobiles, telecommunications, motorcycles, and home appliances. Aluminum alloy die-casting release agent is a necessary additive in the production process. Due to the different volume dimensions, structural complexity, and post processing requirements of products, the requirements for release agents also vary.

Zinc alloy material is melted at high temperature (aluminum melting point 660.4 degrees Celsius), injected into the mold cavity under high pressure in liquid state, and the top part of the mold is opened and ejected in a short period of time. To ensure the smooth release of the product, release agent must be sprayed on the surface of the mold cavity before injection.

The aluminum alloy die-casting release agent must meet the following requirements:  

1. Oil. As an effective material for metal to metal isolation, organic silicone oil is an ideal choice. This silicone oil must have the characteristics of high temperature resistance and not affecting post processing performance (such as aluminum product coating).

2. Aqueous. Due to the mold being in a high-temperature state, any solvent based release agent is not suitable. Using water as the dispersing medium, in a high-temperature environment, the water quickly evaporates, and the effective release material is evenly distributed on the surface of the mold cavity. Uniform film formation, strong adhesion, high temperature erosion resistance, and good demolding performance. 

3. Emulsion. Select appropriate emulsifiers to emulsify silicone oil and prevent its carbonization at high temperatures. To maintain the cleanliness of the product and mold cavity surface. 

4. There is no corrosion on castings and mold equipment. The contour of the casting product is clear, and the surface is smooth and seamless, without affecting the coating.  

5. Volatiles are smokeless, non-toxic, non polluting to the environment, and do not harm the health of operators.

Selection of Hydraulic Oil for Die Casting

The use of high-quality and high cleanliness hydraulic oil can ensure long-term operation of the machinery. When hydraulic oil is injected into the oil tank, it needs to pass through a 15um or finer filter screen to reach the upper limit of the liquid level gauge. As the machinery starts to operate, hydraulic oil will be sucked into the piping and hydraulic components, so the oil volume will drop to an appropriate position (between the upper and lower limits of the liquid level gauge), If there is a shortage of oil during operation, add hydraulic oil again. 

Hydraulic oil not only serves as a power transmission medium, but also lubricates metal surfaces to reduce friction and has a rust preventive effect. The viscosity and pH value of hydraulic oil can affect the sealing of valves and oil seals. In order to select the appropriate hydraulic oil, our company specifically lists the characteristics of the following oils as a reference for hydraulic oil selection.

Free flow with a certain viscosity;

1. Form a suitable seal in the moving parts;

2. There should be no physical or chemical changes during use; Rust and corrosion prevention; 

3. It can withstand load appropriately and reduce the wear of moving parts;

4. According to the purpose, it is flame resistant;

5. It is not easy to form foam; 

The temperature of hydraulic oil also has a significant impact on the lifespan of hydraulic oil. It will seriously affect the viscosity of hydraulic oil, and it will cause oil leakage and accelerated aging of oil seals. So it is recommended to use hydraulic oil at a temperature between 15-55 ° C. 

In the past, mineral type hydraulic oils were mainly used on die-casting machines, which were widely used due to their wear resistance, high stability, and good sealing performance. However, due to the risk of combustion or explosion, flame-retardant hydraulic fluids have been increasingly used in recent years. The water ethylene glycol type hydraulic fluid is currently commonly recommended, and its unique performance in safety, easy handling, and environmental protection has also been valued. However, it cannot be compared with mineral type hydraulic fluids in terms of stability, lubrication quality, sealing performance, etc. Therefore, customers should consult the die-casting machine manufacturer before using this type of hydraulic fluid.