Identifying Organic Contaminants in Sub Tier Castings Using FTIR Fingerprinting
Attenuated total reflectance FTIR identifies organic parting agents on raw castings before expensive coating processes fail on customer lines.
Plunger Lubricant
Meaning
Heavy duty lubricant applied to the injection piston of a die casting machine to reduce friction and wear. The plunger lubricant ensures the smooth movement of the piston as it forces molten metal into the die cavity at high speed. It must maintain its lubricating properties under extreme pressure and temperature without contaminating the cast metal.
Wear Prevention
Reduction of metal-to-metal contact extends the life of both the plunger tip and the shot sleeve. If the lubrication fails, the piston can seize or cause deep scratches on the inner surface of the sleeve. This leads to pressure loss and inconsistent filling of the mold.
Graphite based oils or synthetic greases are used because they form a durable film that resists the scouring action of the molten aluminum.
Casting Integrity
Minimal application is required to avoid the entrainment of lubricant into the metal stream. Excessive oil breaks down into gas during the shot, which becomes trapped in the casting as porosity. This gas pocket weakens the part and can cause it to explode during subsequent heat treatment.
Automated dosing pumps deliver a precise volume of lubricant for each cycle to maintain consistency.
Selection Standard
Choice of lubricant depends on the alloy being cast and the cycle time of the machine. High temperature alloys require more stable formulations to prevent the formation of carbon deposits. The viscosity must be high enough to stay on the plunger during the stroke but low enough to be pumped through the delivery lines.