Steel Shots

• January 2, 2022

What are Steel Shots?

Steel shot is spherical metallic abrasive media produced by the molten steel by means of atomizing process. Metalworking Industries are the main users of Steel Shots such as ferrous and non-ferrous foundries, steel mills, forge shops and the metal fabricators, sand removal and to improve the metal surface preparation etc. since its process is not harmful, hence steel shot produces the least level of dust. Blast cleaning with steel abrasive media is an important operation at various stages of metal production. There are different varieties and sizes of the steel shot which gives extra ordinary results on the metal surface. It produces the most economical abrasive media which has recycling capacity of more than 30 times due to its robustness and high durability. A larger steel shot vigorously cleans a rougher surface. To accelerate steel shot on the surface, both wheel blasting machine and air powdered system is used. Steel shot produces the least dust because its process is not harsh. Steel shots are used to clean heavy parts of metals such as engine turbine blades, crankshafts and heavy-duty spring, etc. Low carbon steel shot has a low hardness in comparison to high carbon steel shot. Because of its microstructure it resists impact, while the moment it suddenly scatters/dissipate and turns into fine powdered dust. It is even used for flash descaling. Since low carbon steel shot is softer in nature, it is not possible to crush it into grits, therefore it is used less. Steel shots are made from steel scrap. The furnace is an electric furnace. Steel scrap is melted in this furnace and then being atomized into the steel shots by water jet.
Steel shots manufacturing process involves following steps:

• Melting of steel scrap + alloy.
• Atomizing is done by high-pressure water jet.
• Drying the object obtained.
• Screening /separation of different sizes of steel shots (separate the small shot size from the oversized shot particles which are used for grit production).
• Spiraling means removing irregular shaped steel shots.
• Quenching is done to produce superior particle integrity with minimum stress cracks.
• Tempering
• Screening is done to check the quality and specification before packaging.
• Packaging of steel shots into bags.

Steel Shot is exceptionally durable, due to its low friability (a abrasive media can have same hardness but different friability similar to that of durability), the impact of blasting actually tempers the steel shots so that its hardness increases over time, allowing the blasting media to give consistency, repeating the same performance for thousands of cycles. It has extremely low breakdown rate, even no dust is produced. Due to high-impact energy and fast cleaning rates, Steel Shot is used for heavy scouring and to produce very bright finishing surface in sand blasting/shot blasting machine. These steel shots reduce maintenance cost of blasting machine many times.

The functions performed by the steel shots blasting are as follows:

• Removal of surface contaminants, giving a complete clean surface that helps in inspection for process defects.
• Surface preparation: Provides a surface profile (etch, smoothen, matte finish) preparatory to further processing like coating, painting, etc.
• Cleaning of metal, glass, wooden, etc. surfaces.
• Descaling
• Debugging

Advantages of Steel Shots:

• It provides excellent result on the metal Surface.
• High Durability.
• Cost-effective & recycle ability is strong.
• Used in both wheel blast systems and air powered blasting machines.
• Remove surface contamination and provide a completely clean, smooth surface.

Features of steel shots are as follows:

• Steel shots have long working life
• Steel shots have uniform size
• Steel shots provide good service

Steel Shot abrasive media is available in all standard sizes for use in wheel blasting and pressure blasting systems for stripping, cleaning, deburring, finishing, smoothening and metal surface-improvement.  

Properties of steel shots:

Mostly steel abrasives are manufactured from high-carbon steel composition, the best compromise between mechanical and chemical properties, efficiency and durability. The most vital properties for steel abrasives are hardness, size and shape, toughness and cleanliness.

• Recyclability and environmental impact of steel abrasives

The recyclability of steel shots ranges between 1000 and 2000 cycles. Due to its high recyclability level, steel shots tend to generate less wastage when compared to other abrasive media.

• Hardness of steel shot abrasives

Steel shot is available at different hardness levels, ranging between 35 and 55 on the scale.

Industrial applications of steel shots abrasives

• Cleaning

Steel shot and grit are used in cleaning applications for removal of loose material, rust, and paint coatings from metal surfaces. This type of cleaning is common in automotive industry (motor blocks, cylinder heads, railway coaches etc.).

• Stone cutting

Steel grit is used in cutting hard stones. The steel grit is used in large multi-blades frames which are used to cut the blocks of granite stone into thin slices.

• Surface preparation

Surface preparation is a multiple operation of cleaning, smoothing and physical modification of a blasting surface. Steel shot and grit are mainly used in surface preparation for cleaning metal surfaces which are covered with mill scale, dirt, rust, and for physically modification the metal surface like creating roughness for better application of paint and coating. The steel shots are generally employed in shot blasters.

• Shot peening

 Shot Peening is the repeated striking or injecting of a metal surface by hard shot particles. These impacts produce deformation or change in the metal surface but also improve the durability or life of the metal surface. The media used in this process is spherical rather than triangular.