Gravity casting mold daily maintenance and defect prevention directly lower scrap rate and extend tool life. Improper daily operation increases gravity casting mold premature damage rate by 32% in mass production. This industrial manual explains common mold damage modes, maintenance cycles and preventive measures based on Xinfeng mould field data.
Riser and gating system erosion is the most common gravity mold damage. High-speed aluminum melt scours the mold surface, causing local wear and soldering. Ceramic coating on gating surface can reduce erosion by 35%.
Core vent blockage is mainly caused by aluminum oxide residue. Vent cleaning cycle set at 110–130 cycles to keep gas exhaust smooth.
Thermal crack initiation usually starts at sharp corners and fillet radius below R2.8. Optimizing fillet to R3.0 and nitriding treatment can delay thermal crack formation.
Mold parting line flash is caused by insufficient clamping force or mold base deformation. Mold base flatness should be inspected every 3000 cycles.
Mold coating peeling occurs when coating thickness exceeds 0.34 mm or mold surface is not fully cleaned before coating spraying.
Sand core sticking defects are related to insufficient core coating and improper sand core expansion clearance of 0.8%.
Mold preheating below 300℃ increases thermal shock and accelerates mold surface fatigue cracking. Recommended preheating range 300–370℃.
Mold welding repair must use matching H13 welding wire, followed by post-weld tempering to relieve welding residual stress. Without tempering, re-cracking risk rises by 50%.
Idle mold maintenance: clean cavity and remove aluminum residue, apply anti-rust oil and seal package for long-term storage.
Regular mold dimensional calibration every 4000 casting cycles to check cavity deformation and core position tolerance.
Q1: What is the main cause of thermal cracks on gravity casting molds? A1: Sharp corners, insufficient fillet radius and repeated thermal shock lead to thermal crack initiation. Q2: How often should gravity mold vents be cleaned? A2: Vents should be cleaned every 110–130 casting cycles to prevent oxide residue blockage. Q3: What treatment is required after mold cavity welding repair? A3: Post-weld tempering is mandatory to reduce welding residual stress and avoid re-cracking.
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