There are many different types and working principles of sand making machines, and impact sand making machines and roller sand making machines are two common types.

An impact sand making machine uses the high-speed impact force of materials to crush them by colliding, rubbing, and hitting the inner wall of the crushing chamber. It is suitable for crushing hard materials and rocks of medium hardness, and it has the characteristics of uniform particle size and good discharge shape. Impact sand making machines are mainly used for stone processing in general construction and road engineering. 

A roller sand making machine uses two symmetrically arranged rollers to repeatedly roll and crush materials. It is suitable for crushing hard materials and rocks of medium hardness. The roller sand making machine can finely crush materials and produce good particle shapes, with characteristics such as uniform particle size and low energy consumption. Roller sand making machines are mainly used in highways, railways, and water conservancy projects.

The choice between an impact sand making machine and a roller sand making machine depends on factors such as actual work requirements, material characteristics, scale, and working environment. The decision on which type of sand making machine to use can be made based on requirements for product particle shape, production capacity, equipment price, and maintenance cost.