The stainless steel shots

The products
There are 2 families in this type of shot:
- the casting shots, made through the atomization of liquid metal, which are presented in a more or less spherical form whose features are:
- hardness ranging between 35 and 45 Rc
- apparent density is about 4,7 kg/dm3
- granulometry ranging between 0.1 and 2 mm.
- the cut shots, made from cut stainless steel wires with hardness from 35 to 45 Rc.
The use of these shots, because of a high cost, is limited to the specific applications: the blast wheel projection for the decarbonisation or the cleaning of the casting or laminated surfaces in stainless steel, bronze or aluminium. They are used wherever a pollution risk by ferrous particles might cause an oxidation even superficial.

Use
They are used for applications on not ferrous metals, special alloys, aluminium, or moulded zinc, everywhere it is necessary to obtain a surface free from iron oxide. They have the advantage of making the treated parts brighter.

The cut steel wires

Manufacturing
This cylindrical shot which length is equal to its diameter, is made through an automatic cut on machines, from wiredrawn and graded steel wires which features are:
- resistance of the wire, 160 to 180 kg/mm2
- hardness of about 45-50 Rc. (457-533 HV)
- calibre from 0.2 to 2.2 mm

Use
This shot is used with blast wheel machines, sometimes with compressed air machines, for some delicate or difficult applications, such as the decarbonisation of a part with a high calamine. With use, the cylindrical grain tends toward a round shape and acts as a round casting steel grain. It will be possible then to use the cut wire for some shot-peening operations when this wire will have been ran in and rounded beforehand in order to avoid the notch effect caused by the sharp edges of the cylinder as new.

The cast iron shots

Manufacturing
The cast iron shots are made of salvage scrap iron selected and free from alloyed elements. They are melted and recarburized with a furnace with hot wind. The liquid metal obtained is atomized in grains of spherical shape and quenched through a high pressure water jet.
The grains obtained, dried and sifted, form the spherical shot.
The angular shot, the most used, is obtained through the crushing of round grains.

Structure
With a mainly cement structure with the presence of carbide obtained without any heat treatment, these shots are characterized by a high level of hardness ranging between 55-65 Rc.
They are adapted for the compressed air projection in cabs with recycling. They can be projected in a blast wheel machine but their high abrasive power generates a quick wear of the equipments..

Use
Used especially under the angular form, their strong stripping power and the stability of the operating mix, make them particularly adapted to the surface preparation before coating. Different heat treatments can increase the resistance of these shots (superior to 65 Rc) for hard stripping operations or for the granite sawing.

The aluminium shots

The products
There are 2 families in this type of shot:
- the casting shots, made through the atomization of liquid aluminium, which are presented in a more or less spherical form whose features are:
- density 2.6
- hardness 60-80 HBJ/ 250
- granulometry from 0.2 to 1.8 mm.
- the cut shots, made from cut aluminium wires of cylindrical form, even cubic.

Use
They are used for the cleaning or improvement of the aspect of aluminium or light metals parts. The low mass of these grains and their low density allow creating satin-like surfaces whose colour is not altered with time because of the presence of oxidizing ferrous particles (see chart uses). Used with blast wheel or compressed air machines, these shots require the implementation of particular precautions concerning the dust removal and the filtration in order to avoid the fire risks.