Magnesium die casting equipment
Die casting equipment
Due to the active nature of magnesium alloy die-casting, it is flammable and explosive. The requirements for equipment are also high, and inferior equipment is potentially dangerous.
The die-casting operation requires the molten magnesium liquid to be injected into the mold cavity at a speed of 70-100 m/s (at the gate). Because molten magnesium liquid is flammable and explosive, it burns violently when it meets oxygen. Explodes when it meets water. It will react violently when it encounters rust, moisture-containing concrete, silicon-containing refractories, etc., and it is difficult to extinguish the fire. A large fire cannot be extinguished, so the performance, reliability and safety of its die-casting equipment are extremely high. Inferior equipment is very easy to cause disasters and accidents. In the process of exploring the application. There have been many major safety accidents caused by equipment problems both at home and abroad.
Major safety incident of magnesium die casting
- In December 1998, a magnesium furnace crucible ruptured and leaked at a die-casting plant in Hyogo Prefecture, Japan. A large amount of magnesium liquid flowed out to the machine bed and the ground. And then a fire broke out. All the workshops were burnt down and many people were injured.
- In March 1999, a fire accident occurred in a factory in Mie Prefecture, Japan. Due to the leakage of molten magnesium liquid. Magnesium liquid flows out from the corroded hole of the crucible. Reacts with the heat insulating refractory material in the furnace, and ignites, and the workshop is burnt down.
- From 1996 to 2001, Shaanxi Beibei Forest Machinery Factory used old-fashioned ordinary cold-chamber die-casting machines and simple old-method furnaces to produce magnesium alloy shells, and many major safety accidents occurred. A high-temperature magnesium liquid suddenly exploded when it was injected into the mold cavity. Exploding the clamping mechanism, and the fireball rushed out, causing injuries to the chief technologist of the plant and others who were on the scene at that time. Once the furnace crucible was corroded, perforated, leaked and caught fire. The white light was dazzling, and the fire spread rapidly. The factory used trucks to transport fine sand in an emergency. And the machine furnace was completely covered, so that the fire was initially controlled.
Why need high quality magnesium die casting equipment(1)
Under normal circumstances, some measures can be taken to extinguish the initial, small-area fire of magnesium liquid. Once a large fire occurs, spreads, or explodes, it will be impossible to control the fight and rescue, which will cause huge casualties and losses of personnel and property.
In order to ensure safe production and long-term production use and reliability under harsh conditions. The quality requirements for magnesium alloy full die casting equipment are extremely high. Different from ordinary machinery and equipment, inferior equipment produced by manufacturers without strong comprehensive technical strength can easily cause major disasters and accidents.
Inferior crucibles are produced for a long time under high temperature conditions above 6500C (the outer layer is above 7000C), and the outer layer is easy to oxidize quickly. The inner layer will quickly etch deeply due to the corrosion of magnesium liquid and the corrosion of SF6 protective gas. After the perforation, the molten magnesium liquid flows out and catches fire and explodes, which will cause major disasters and accidents, and the protection of covering agents with traditional local methods will aggravate the corrosion process.
The crucible of the high-quality equipment is made of specially developed composite materials. The inner layer is corrosion-resistant, and the outer layer is heat-resistant and high-temperature oxidation resistant, which can avoid serious perforation accidents.
Why need high quality magnesium die casting equipment(2)
- The protective gas control of high-quality die-casting equipment is accurate and stable, and the gas composition and flow are sufficiently guaranteed. It also has special automatic protection devices in case of sudden power outages, sudden accidents, etc., which is extremely safe. The gas composition and flow control of inferior equipment is inaccurate. It is easy to cause the furnace to ignite due to the concentration and flow rate being too low, or to cause rapid corrosion of the furnace due to the concentration and flow rate being too high. Magnesium liquid leaked and ignited and exploded, and lacked reliable automatic protection measures under special circumstances.
- The high-quality equipment adopts specially developed refractory materials and does not react with magnesium liquid. Inferior materials are made of ordinary refractory materials, which are prone to violent reaction and explosion when the magnesium liquid leaks.
Why need high quality magnesium die casting equipment(3)
- High-quality equipment adopts specially developed hot-work steel imported from Germany. It can withstand the corrosion of high-temperature magnesium alloy. And can maintain good high temperature properties such as hardness, tensile strength, yield strength, toughness, creep resistance and tempering resistance at high temperatures of 650~7000C. Inferior equipment uses ordinary hot work steel. Can not withstand the corrosion of high-temperature magnesium alloy liquid and difficult to maintain good high-temperature performance. It is easy to cause splashing of high-temperature magnesium alloy liquid under high pressure (400~800kgf/cm2) and high speed (70~100m/s) after deformation, cracking or leakage. Injury or explosion or fire accident.
- The high-quality equipment controls the injection system accurately, scientifically, and reliably. The inferior equipment design is immature, and the components and materials are low and unreliable. It is prone to safety and die-casting product quality accidents. The high-quality equipment uses high-quality international famous brand hydraulic components, which are extremely reliable and do not leak oil. Inferior equipment uses inferior hydraulic components, which work unreliable and most of the oil leaks. The leaked oil and the water sprayed by the release agent are mixed to form oil and water and accumulate around the machine. Once it comes in contact with high-temperature magnesium liquid, it is prone to explosion.
Generally
In terms of the overall performance and quality of the equipment, there is a significant gap between the two. Poor crucible material and unstable shielding gas composition will affect the composition and performance of the alloy. Cause the inherent quality of die castings to decline. For example, the tendency of cold and hot cracking increases rapidly. The comprehensive mechanical properties decrease, and the corrosion resistance fails to meet the requirements. The unstable performance of the injection system can also cause the internal structure of the casting to be loose.
The mechanical properties of the die-casting product to be unstable, and various other die-casting defects.
