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Kingred uses HT250 gray cast iron as the base material for its wire electrical discharge machining (EDM) machines. "HT250" is a Chinese GB/T standard grade designation based on its minimum tensile strength.

For HT250 cast iron and the components produced from it, key considerations include chemical composition, mechanical properties, micro-structural characteristics, and dimensional tolerances. Kingred castings are manufactured to strict standards, incorporating specific proportions of rare metal additions refined through nearly two decades of production experience.

Mechanical Properties: The Ideal Balance  

Tensile Strength (250 MPa): Represents an ideal load-bearing threshold. HT250 offers greater rigidity than HT200, while avoiding the increased brittleness risk associated with HT300.

Hardness: Occupies an optimal range. Surface hardness provides resistance to cutting wear, while core hardness ensures damping capacity and vibration absorption without compromising toughness.

Micro-structure: Performance-Oriented  

The combination of a pearlitic matrix and fine graphite flakes provides a wear-resistant base.

The size of the prevalent type-A graphite flakes is optimal: neither as coarse as in HT200 (reducing strength) nor as fine as in HT300 (increasing brittleness).

This specific graphite morphology delivers superior damping capacity, significantly enhancing machine stability and vibration resistance during operation.

Manufacturing & Cost Advantages  

HT250 exhibits a higher yield rate and lower dimensional control risk compared to HT300 during casting production. It causes less rapid tool wear during machining operations than HT300, translating into significant cost savings.

The Fundamental Choice  

The selection of HT250 stems from its exceptional balance of performance and cost-effectiveness. It delivers the crucial combination of strength, wear resistance, damping capacity, and productivity required for the demanding environment of molybdenum wire EDM machines, making it the foundational material for Kingred's robust and reliable EDM equipment.