In a high pressure die casting machine, the hollow cylindrical sleeve serves as a chamber to hold molten aluminum prior to its injection into the die cavity, while the plunger tip ‘pushes’ the molten aluminum in the sleeve into the die cavity. This activity is performed at speeds of up to 10 m/s , and pressures reaching 10,000 psi.
Plunger tips are made out of nitrided-steel material, or copper, while sleeves are manufactured typically with nitrided-steel. Both are considered wearing materials, expected to wear-out and be replaced at a certain interval, though the sleeves’ lifetime is generally 4-5x longer than tips. Sleeves also cost more than tips.
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Plunger Lubrication therefore is required primarily to reduce the friction and wear at the interface between the tip outer surface and the sleeve inner surface. By reducing friction and wear, tip and sleeve life may be optimized, providing economical returns for the die caster. In addition, by minimizing wear, high pressures required to produce sound castings are maintained, as the diametrical clearance between the tips and sleeves are kept at a minimum.
In the next discussion, we shall present the various plunger lubrication technologies available as options for the die casters. Visit our website https://fluidsolutions.com.ph/ to learn more.