1. Mechanics of Bore Wear in High-Cycle Production
In high-speed mold operation running over 1 million cycles per year, thermal expansion and high ejection forces cause severe micro-fretting between core pins and plate bores. Without protection, bore enlargement leads to flash generation and pin binding.
2. Fits & Tolerances: Precision H7/g6 Alignment
To eliminate bore degradation, mold plates must feature precision-machined H7 bores mated with g6 ground shanks. Proper radial clearance (0.008–0.012 mm) maintains axial alignment while allowing thermal growth during hot runner operation.
3. Hardened Bushings & Core Sleeves
Inserting hardened guide bushings (SKD61/H13 or Bronze-Graphite) into the main mold plate isolates structural plates from direct wear. Bushings are readily replaceable during routine maintenance, protecting expensive mold plates from permanent damage.
4. Surface Coatings: DLC, TiN & Nitriding
Applying Diamond-Like Carbon (DLC) or Titanium Nitride (TiN) coatings to core pin contact surfaces lowers the coefficient of friction below 0.1, eliminating galling even in dry-cleanroom molding environments.
5. Preventive Maintenance & Wear Inspection Protocols
Establish strict PM intervals for checking bore dimensions using plug gauges. Replace guide bushings or worn core pins when radial play exceeds 0.005 mm to maintain zero-defect molded parts.