The set of particles to which a metal is reduced is called shot.
The Royal Spanish Academy ( RAE ) indicates that granalla is a term that comes from a derogatory allusion to grain . The notion of grain , for its part, has several uses: in this case we are interested in its meaning as a portion or reduced amount of something .
Shot is called the set of small particles to which metals are reduced in order to make their casting easier. The process that involves the reduction of these materials is called shot blasting .
Shot characteristics
Before analyzing the concept of shot, it is important to mention that a metal is a chemical element that is characterized by its shine and for being a good conductor of electricity and heat.
Metals usually occur in a solid state , with the exception of mercury. When you want the metal to become liquid , it is subjected to the procedure known as casting , common in metallurgy .
The action of shot blasting , in this framework, is generally carried out to facilitate casting. The shot obtained, however, can be used in different ways.
There are different types of shot: in fact, shot can be made of various materials . Grain sizes and hardness can also vary.
The generation of shot is a process that is part of metallurgy.
How to obtain
The shot is generated through a process that takes place in melting furnaces. In the first instance, spherical (i.e. rounded) particles are produced.
This shot, given its diameter, can fragment. This is how angular grit appears. Both grits (spherical and angular) have particular characteristics, so each one is used according to need .
Uses and applications of grit
Once the grit is obtained, and depending on its properties, it can be used in multiple ways. Steel shot , for example, is used to increase the roughness of a material, strip welds or paint, remove rust or prepare a surface for subsequent treatment.
It can be said, therefore, that this grit is an abrasive . It is usually ejected by a shot blasting machine in an operation known as shot blasting .
The turbines of a shot blasting machine cause the shot to be projected against the surface to be treated. The grit allows it to be smoothed or contributes to the elimination of certain materials or particles found in it.
In addition to cleaning , grit is used to texture a surface and give it a decorative finish. Another possibility is to use it to make engravings on acrylics, glass and other materials.
It should be noted that, if we focus on angular shot, it has points and edges. Therefore, when it is projected by the shot blasting machine, it sticks into the surface and drags particles .
The peening shot
Shot peening is a special shot peening process that consists of the ejection of a jet of spherical shot at high speed and within pre-established parameters. This resource achieves the induction of compressive stresses in the treated surface.
Thus, shot peening offers cleaning like conventional shot blasting, but adding an increase in fatigue resistance from the plastic deformation of the material. As the grains on the surface are crushed, they compress each other and cover the intergranular spaces.