How can die-casting mold factories improve the production quality of die-casting parts?

1. Melting process

1) Carbon equivalent. It should have a relatively high carbon equivalent, HT250, and up to 3.95; HT300， And up to 3.82; HT350， And 3.76.

2) Silicon to carbon ratio. Suggest controlling the silicon to carbon ratio between 0.55 and 0.62.

3) Control alloying. Adding alloying elements is beneficial for improving casting performance, typically 0.4-0.6% for Watt (Cu) or 0.2-0.4% for Watt (Cr).

2. Ingredients

The amount of pig iron added should be less than 10%, and high scrap steel and high permeability carbon treatment processes can be used to produce high-quality graphite products.

3. Iron liquid temperature

The high temperature of molten iron can refine graphite, which is the basis of high carbon equivalent and high-strength gray cast iron. When the temperature of molten iron is between 1500-1550 ℃, the liquid iron oxide and silicon dioxide ash will be significantly reduced.

4. Pregnancy

The method of incubation is more important than the inoculant. Based on the actual development situation of the enterprise, we strive to ensure the quality of the social incubation environment by adopting instantaneous incubation treatment methods such as flow inoculation, sprue cup inoculation, floating silicon inoculation, and in mold inoculation. The sample should be triangular in shape. After thermal analysis and testing of the effectiveness of the inoculant before and after the cold inoculation ratio, it is necessary to prevent excessive cooling from causing shrinkage smaller than graphite, and also to prevent shrinkage due to excessive casting.

5. Performance testing

Strengthen the testing of the performance of attached casting test bars and the microstructure through metallographic analysis. At the same time, we should pay special attention to strengthening the inspection of undercooled graphite, carbides, and pearlite in the gold phase, improving the quality of metallurgical products in the production of castings, so that their development maturity is greater than 1, hardening degree is less than 1, and quality correlation coefficient is greater than 1.

6. Thermal aging

1) The heating rate should be slow, generally (30-50) ℃/h.

2) The annealing temperature should be 500-550 ℃, and the holding time should be 25mm per hour until combustion.

3) The furnace temperature difference is controlled by the system to maintain a temperature of ± 20 ℃.

4) The heat-resistant aging sequence should prevent stress relief during rough machining processes.