Aluminum and Aluminum Alloys
Aluminum is the most commonly used metal in high-pressure die casting†. Aluminum alloys commonly contain silicon, copper, magnesium, zinc, manganese and iron. Molten aluminum is corrosive to steel and the reaction is accelerated at high temperatures and pressure, both of which are commonly found in high-pressure die casting. Silicon improves the fluidity and also forms a low-melting eutectic with aluminum. The most commonly used aluminum alloy has a nominal composition of 8.5% silicon and 3.5% copper and a melting range of 540-595°C (1000 – 1100°F). Some alloys have significantly higher melting temperatures and thus pose greater challenges to die lubrication.
In the early days, hydrocarbon oils were used as release agents for aluminum die casting. However, the higher die temperatures presented a great risk of fire and the industry has now almost completely shifted to water-based products. Dry powder lubricants have been used in a few limited applications, and there have been some recent developments involving waterless liquids. Chem-Trend served as a pioneer in the die casting industry back in the 1960’s with the development of the first commercially successful water-based die lubricants, and today we continue to advance die lubricant technology by developing waterless release agents.
A common problem in aluminum die casting is soldering†. Molten aluminum has the ability to dissolve iron. The product of this reaction forms a weak intermetallic compound that is commonly referred to as solder. Alloys that have low levels of iron are particularly aggressive.