Plunger Lubricant

Types of Plunger Lubricants
Several common types include:

• Mineral or Synthetic Oil-Based: Neat oil or crude oil with EP (Extreme Pressure) or anti-wear additives.

• Water-Based Lubricants (Water-Soluble or Emulsion): Water/oil emulsions or aqueous lubricants used to reduce flames or smoke when in contact with molten metal.

• Dry or Granular/Pellet Lubricants: For example, wax or graphite granules, with or without graphite, used for large plunger gaps.

• Graphite or Non-Graphite Lubricants: Adding graphite or boron nitride to improve sliding properties; may cause smoke or residue.

Key Points for Selection and Use
To ensure optimal performance of plunger lubricants:

• Uniform coverage and good adhesion to the plunger and sleeve surface, so the lubricant is not washed away or displaced when molten metal enters.

• High flash point and low smoke or particulate generation in the work environment.

• High lubricity with appropriate film thickness; excessive thickness may lead to contamination of the molten metal.

• Compatibility with the molten metal (aluminum, magnesium, zinc, etc.) and with the plunger/sleeve surface, e.g., selecting lubricant for high plunger and sleeve temperatures.

• Optimal consumption: Avoid excessive use as residues may cause smoke, deposits, or fire.

• Correct application method: spraying, brushing, injection, or proper pellet placement in the sleeve.