What affects the drying of silica sol precision casting shell?

What affects the drying of silica sol precision casting shell?

The shell making process using silica sol as a binder includes several stages: slurry hanging, sanding, drying, dewaxing, calcination, and performance testing. Throughout the process, the precision casting shell of silica sol dries slowly. Today, precision casting manufacturer Yufeng Metal will discuss in detail what factors can affect the drying of silica sol precision casting shell, and what are the actual production parameters?

1、 What is the drying of silica sol shell?

The definition of silica sol is a colloidal solution formed by amorphous silica particles of varying sizes in water. The colloidal particles in the sol can be connected to each other to a certain extent, forming a spatial network structure, thus it has a bonding function.

So the drying of silica sol shell is actually the process of water evaporation in silica sol coating. Generally, 30% of the silica sol used in investment casting is used as silica sol, of which 70% is the medium water. Therefore, the drying of silica sol is actually the process of 70% of the medium water evaporation.

2、 The influencing factors of silica sol shell drying

2.1. The influence of environmental humidity on the drying of silica sol shell

The environmental humidity rises → the drying speed decreases, and the drying time becomes longer

The environmental humidity reaches 80% or exceeds 80% → the drying time will be infinitely extended

Key point: Environmental humidity must be strictly controlled

Surface humidity: 50% -60%

Back layer humidity: 30% -40%

2.2. The effect of wind speed on the drying of silica sol shell

Wind speed increases → drying time shortens

Introduction to "Precision Casting Technology" by Japanese author Yoshiki Kuoya: Wind speed controlled at 2 meters per second

Precision machining