Lubricants are critical to the die casting process. Without proper lubrication, you can quickly run into issues with your dies and parts thereby slowing productivity and decreasing part quality. Henkel’s full portfolio of BONDERITE® die casting lubricants provides solutions for a wide range of casting applications.
Why are lubricants used in die casting?
Die lubricants provide a lubricating film on the mold surface during the die casting process to aid in die release. Proper die lubrication results in clean, bright castings and less likelihood of corrosion or pitting on the mold surface. Here are several reasons die lubricants are used:
Die lubricants prevent welding of molten metal to the die, and release the cavity easily without distortion.
Die lubricants aid in die fill and lubricate the moving parts such as ejector pins and cores.
Water-based die lubricants help lower the temperature of the die.
Die lubricants protect the die surface against attack by the molten metal.
Die lubricants can control directional flow, solidification and die fill.
What Problems Can Lubricants Help Solve?
The right die lubricants can solve common problems during die casting which include:
Porosity: during die casting, gas bubbles can become trapped in the metal leaving behind holes in the part. There are several causes of porosity, one of which is excess die lubricant on the mold surface. If there is too much lubricant on the mold, gases cannot evaporate fast enough when the molten metal is injected. Choosing a lubricant that minimizes overspray can combat this issue.
In-Cavity Build-Up: scale can build up on the die cavity, typically from the oxide of the metal being cast and the parting material. A soft-water based lubricant reduces the chances of in-cavity buildup.
Fish Eye: fish eyes are small holes that appear on the surface of the part when painting. Proper lubrication helps keep the part surface clean prior to painting to increase paint adhesion.
Cold Shut: cold shut is when the casting begins solidifying before the mold completely fills, creating dark lines on the casting surface. It is more prevalent in magnesium alloys. Proper lubrication helps transfer heat to prevent cold shut from occurring.
Types of Mold Release Lubricants
There are many different types of mold release lubricants for die casting, depending on the application and the metal being cast. Water-based lubricants are the most popular and typically preferred because they both lubricate and cool the die. Oil-based lubricants are also sometimes used when increased temperature is required for high quality finishes, but do not have the same cooling efficiency as water-based lubricants. Some mold release lubricants act more as release agents, while others provide insulation to the die. Henkel has a wide selection of lubricants to improve your die casting performance. The core lubricants are highlighted below.