Reducing Burn-On and Metal Penetration with Gilsonite

Burn-on and metal penetration create rough casting surfaces that need costly grinding and shot blasting.

Causes

• High metal temperature and pressure
• Coarse or highly permeable sand
• Insufficient carbon additive
• Poor mould compaction

How gilsonite helps

Gilsonite releases hydrocarbons that form a lustrous carbon film. This barrier stops liquid metal from entering sand pores and reacting with silica.

Other measures

• Use finer sand or add fines
• Improve compaction
• Use mould coatings on heavy sections

Results

Foundries switching to or increasing gilsonite often see cleaner surfaces and less fettling time.

Types of penetration

Carbon additives mainly reduce mechanical and chemical penetration by forming a reducing, non-wetting barrier.

Diagnosis checklist

• Is penetration localized near heavy sections or hot spots?
• Is mould hardness low in those areas?
• Has LOI or volatile content dropped?

Solution path

Restore carbon additive level, improve compaction, adjust sand fineness and use coatings on critical areas.

See foundry grade gilsonite. Related: lustrous carbon explained.