In abrasive jet machining (AJM), a high velocity jet of abrasive particles accelerated in pressurized air is made to strike the work surface. When abrasive particle thwacks surface at high velocity, it erodes material. Another similar and age old technique is sand blasting (or grit blasting), where fine sand particles are propelled to the work surface by pressurized air at a very high velocity to remove material. Mechanism of material removal (i.e., impact erosion) is same for both AJM and sand blasting processes.
However, process parameters of sand blasting are not controlled precisely and thus it is less reliable for micro-cutting. On the other hand, process parameters of AJM are controlled at their optimum level in order to harness best performance for micro-machining. Thus sand blasting is suitable for cheap cleaning purposes; while, AJM is preferred for accurate and quality cutting, cleaning and deburring purposes. The following sections elucidate similarities and differences between abrasive jet machining and sand blasting.
Similarities between abrasive jet machining and sand blasting
- Both abrasive jet machining and sand blasting processes utilize high velocity jet of solid abrasives (sand is one type of abrasive).
- Both use gaseous medium (commonly air) as a medium to carry abrasives.
- Impact erosion is main mechanism of material removal for both the processes.
- Both can cause air pollution if used abrasives are not ventilated properly.
- Both can cause health problems if proper protection is not utilized while operation.
Differences between abrasive jet machining and sand blasting
|Abrasive Jet Machining||Sand Blasting|
|Various abrasive particles, such as silicon carbide (SiC), alumina (Al2O3), glass beads, etc. are used to remove material by impact erosion.||Only silica sand grains (SiO2) are used to remove material by erosion.|
|Size of the abrasive particles and its flow rate are more or less uniform.||Sand particles usually have wide range of diameters. Its flow rate is also not uniform in all cases.|
|Process parameters and other influencing factors are regulated properly and precisely.||Process parameters and other influencing factors are not regulated carefully.|
|Quality and finish of the machined surface achieved by AJM are much better.||Quality and finish of the machined surface are not so good.|
|It is costlier but precise, thus beneficial for industrial high quality finishing requirements.||It is cheaper and thus efficient for common civil works.|
|AJM is usually used for removal of coating and rust. It is also used to cut profiles or drill holes on hard metals.||Mainly used to remove rust and coating from solid surfaces.|
|Usually carried out in rooms with proper ventilation. Thus it is less hazardous.||Often it is carried out in open atmosphere, thus causes air pollution. Workers are also exposed to various occupational lung diseases, such as Silicosis.|