A Guide to Understanding Steel Grit and Steel Shot

Steel grit and Steel Shot are two of the most common sandblast medias used today. They can be used for a variety of applications to meet a variety of goals. In this article we will cover applications where each is ideal and things to consider about each type of media. We will also learn the differences between steel grit and steel shot and when each is right for an application.

Steel Grit

Steel grit comes in a variety of shapes and sizes which will allow for a variety of blast profiles to be obtained. Steel grit is angular in nature and is created.  Steel grit is ideal for removal of contaminants from a products surface as well as creating a blast profile for new coatings to adhere to. Common uses for steel grit include removing mill scale, removing varying degrees of coatings from a products surface, typical steel grit sizes that are commonly used range from G25 to G80. The larger the number the smaller the size of the actual particles of blast media.

Smaller particles will create a smaller blast profile on the product while large particles (smaller G numbers) will create a deeper profile. Additionally, larger particles will tend to be more effective at removal of heavy amounts of paint while smaller particles will be best suited at removing lighter amounts of surface contaminant. With smaller larger particles like a G80 grit will leave a 1- 2 Mil profile, while larger particles like a G25 will leave deeper profiles between 4 – 6 mils (assuming all other blast equipment settings are the same).

An additional benefit to steel grit is that it can be used multiple times before needing to be replaced. You can use mechanical blast media recovery equipment if you are looking to be able to recover and use the media. This will allow the media to be used about 150 – 200 times before it would need to be replaced with new fresh blast media.

Steel Shot

Steel shot is offered in a variety of sizes but is always a round shape. It is a hard abrasive with a mohls scale of around 8.0, which is similar to the hardness of steel grit.

Steel shot is used for a variety of processes with a primary use being for an application called shot peening. Shot peening hardens a surface by repeated striking of the surface by the steel shot. The repeated striking compresses the metal which increases its strength. Common applications for shot peening include manufacturing gear parts, springs, cam shafts, and turbine blades.

In addition to shot peening. Other applications that use steel shot include those that require maximum energy transfer to effectively create a surface profile. This includes applications like concrete surface preparation, epoxy and adhesive removal, and rubber build up removal.

Like steel grit, steel shot offers a lot of uses prior to needing replacement usually allowing for 150 – 200 cycles depending on the application you are using it for and assuming your using appropriate blast media recovery equipment. Sizing for steel shot comes in a variety of sizes depending on the application. Sizes range with common sizes ranging between s 110 and s 330. In contrast to steel grit, the larger the number of the shot, the larger the steel shot is (s-330 is larger than an s-110). Larger shot will remove thicker coatings as well as result in heavier peening.

Final Thoughts

When selecting a blast media it is always important to understand the product your blasting and the goal of why you are blasting. Depending on these factors you will select both a blast media and blast equipment to properly execute the project.  If you have questions regarding equipment for a project your working on we can often help.

Photo Courtesy Creative Commons Steel Shot Abrasive by Stephen Woolverton CC 3.0