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:
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.
|Grade||Function||Key Benefits||Application Method|
|BONDERITE® L-CA 193||Water-based insulating coating||Also known as DAG 193, functions as an insulator to produce high quality castings. Recommended for large surface area castings where more insulation is needed.||Spray recommended, can also be brushed|
|BONDERITE® L-CA 395||Water-based insulating coating||Also known as DAG 395, functions as an insulator to produce high quality castings. Recommended for small to medium surface area castings where good surface finish is needed.||Spray recommended, can also be brushed|
|BONDERITE® L-CA CG 515||Water-based primer coating||Base coat for a more durable finish coat, extending the time between touch ups.||Spray|
|BONDERITE® L-CA RH 200||Water-based graphite release agent||Provides superior release, improved surface finish, and longer tool life in aluminum permanent mold applications.||Spray|
|BONDERITE® L-FG 137||Water-based graphite release agent||Also known as DAG 137, provides superior lubrication and release film for high temperature applications including aluminum permanent mold, low pressure casting and ingot casting.||Spray|
|BONDERITE® L-GP PRODAG||Water-based graphite release agent||Provides superior release, improved surface finish, and good mold protection in aluminum permanent mold applications.||Spray|