1.What are the special requirements for lubricants in galvanized sheet stamping?
No damage to the galvanized layer
Avoid strong acid, strong alkali or highly corrosive ingredients to prevent the zinc layer from dissolving and discoloring.
The lubricant must be compatible with the zinc layer, not chemically react, and not damage the passivation film of the zinc layer. Strong lubricity
The galvanized layer is relatively soft and is easily "strained" due to friction during stamping. Lubricants are required to form a high-strength oil film to reduce the friction coefficient between the mold and the plate.
Easy to clean
If subsequent processes such as painting and welding are required, the lubricant must be easily removed by water or weak alkaline cleaning agents to avoid residues that affect the bonding strength.
Stability
Anti-emulsification and anti-oxidation, not easy to decompose or deteriorate during the stamping process, and can maintain the lubrication effect for a long time.
2.What are the commonly used types of galvanized sheet stamping lubricants?
Mineral oil-based lubricants, emulsified lubricants, synthetic lubricants, solid lubricants
3.What are the advantages of commonly used galvanized sheet stamping lubricant types?
Mineral oil-based lubricants: strong lubricity, low cost, good stability
Emulsified lubricant: moderate lubricity, dilutable with water, easy to clean
Synthetic lubricant: excellent lubricity (strong extreme pressure resistance), easy to wash, good rust resistance
Solid lubricant: good stability at high temperature, no oil film pollution
4.What are the selection suggestions for key process scenarios?
Simple stamping
Preferably choose emulsified lubricants, which are low-cost and easy to clean, can meet basic lubrication needs, and reduce zinc layer scratches.
If there is a requirement for rust prevention, you can choose emulsifiers containing zinc salts and molybdates to take into account short-term rust prevention.
Medium and deep drawing
Synthetic lubricants are recommended, which contain extreme pressure additives and can form a chemical adsorption film under high pressure, effectively preventing zinc layer scratches and mold adhesion, and no residue after washing, which does not affect subsequent painting.
Deep drawing / high-speed stamping
High extreme pressure synthetic lubricants or solid lubricants must be selected:
Deep drawing: Use synthetic oil containing sulfide esters and chlorine-based extreme pressure agents to enhance the oil film strength and avoid zinc layer cracking.
High-speed stamping: Add synthetic lubricants with PTFE micropowder, which have excellent shear resistance and reduce lubricant failure caused by frictional heat generation.
5.What are the considerations for selection?
Compatibility test
Before the first use, apply a small amount of lubricant on the galvanized sheet and observe after standing for 24 hours: if there is no discoloration of the zinc layer, no bubbles or shedding, it is compatible.
Cleaning compatibility
If the subsequent process is electrophoretic coating, it is necessary to ensure that the lubricant can be completely removed by the degreaser before electrophoresis, which can be verified by the "water film continuity after cleaning" test.
Environmental friendliness
Low VOC and biodegradable lubricants are preferred, especially in industries with strict environmental protection requirements.