Water glass casting products are widely used in the production of mechanical casting, but sometimes hardening solutions are encountered during use. The commonly used hardening methods currently have two key points:
1. General CO2 gas hardening method
This method is applied to many steel casting factories, with simple equipment, convenient operation, more flexibility, and low cost.
Advantages: Fast hardening speed and high strength. After hardening, the accuracy of the product will also be very high.
Defect: The strength of sand or core sand is low, and a large amount of water glass must be added; High moisture content and susceptibility to moisture; The water glass casting furnace plate has poor air permeability in winter, which directly affects the characteristics of the casting; Poor collapse, difficulty in regenerating old sand, resulting in the direct loss of a large amount of old sand and affecting the environment.
2. Organic ester self hardening method
The hardening agent for CO water glass is gas.
The shape (core) sand has high strength, and the amount of water glass added can be reduced to 3, which is the characteristic of this hardening process. Below 5%; The strength of the water glass casting bucket teeth is good in winter, and the hardening speed can be adjusted (5%) to 150 minutes according to the production environment conditions and changes in the types of adhesives and curing agents; The collapse of molding (core) sand is strong, casting sand is easy to clean, old sand is easy to dry and regenerate, and the recovery rate is high, ≥ 80%. This reduces the pollution of water glass alkaline waste sand on the ecological environment, saves transportation and land costs of waste sand, and saves high-quality silica sand resources. Calcium stearate sand is prone to defects such as cracks and pores in the production of steel castings, and has good sand thermal plasticity and low gas content. It can overcome bottleneck problems such as poor surface stability and easy blowing of CO2 sodium silicate sand molds., Resin sand casting can match the quality and specification accuracy of castings. All self hardening sand processes have low costs and good working conditions.
The main drawbacks of this hardening process are slow hardening speed and poor flowability of core sand.
