Investment casting is also known as precision casting because of the relatively high dimensional accuracy and surface finish. The medium/low-temperature mold materials are often called "medium-temperature wax" and "low-temperature wax” because the wax is classified by thermal stability (melting point): high/medium/low melting point wax, corresponding to high/medium/low-temperature mold materials. Higher melting point indicates higher thermal stability. The following details the relevant mold materials:
Low-temperature mold materials: These typically have a melting point below 70°C, low strength, poor thermal stability (30°C), significant shrinkage, and varying dimensions with changes in room temperature. The commonly used typical mold material in China is composed of 50% paraffin wax and 50% stearic acid. However, these materials have a simple production process, high mold recovery rate, reusability, and lower cost. They are generally produced through paste pressing, and manual operation, and can be dewaxed with hot water. These mold materials are usually used together with sodium silicate binders.
Medium-temperature mold materials: Mainly include rosin-wax-based mold materials and filler mold materials, with a melting point between 70-100°C. They exhibit higher strength, good thermal stability (35°C), less shrinkage, excellent dimensional stability, smoother surface roughness when produced through liquid pressing, and good replication performance. They can be reused but require more complex production processes and have higher costs. Dewaxing can be done using water, steam, or microwaves. These mold materials are generally used together with silica sol binders. They are often produced using wax injection machines.
High-temperature mold materials: These include rosin-plastic-based, plastic, and salt-based mold materials, with a melting point above 100°C. These mold materials have high strength, good thermal stability, and minimal shrinkage but require complex production processes and cannot be reused. They are usually removed through flash burn, water, or organic solvent methods. They are costlier. It is evident that water-soluble mold materials and 3D printing mold materials belong to this category. In the book "Investment Casting Technology," high-temperature mold materials are described as having a significant thermal expansion, which often causes the shell to crack due to insufficient strength during demolding.
Ningbo Qianhao is a professional precision casting and machining manufacturer. Our silica sol investment casting selects wax with the melting point of 70-100 ℃ to prepare a wax mold, then to adopt the coating with the silica sol as the main component to carry out multiple covering and drying and finally to bake to form a high temperature resistant ceramic mold for pouring and cooling. Whether you are a new partner or an old friend, we will provide you with quality products and services with 100% dedication!