JetTalk: Optimal combination of waterjet nozzle, orifice and GMA Garnet™ (PART II)
In the previous edition, we talked about orifice selection. Let’s talk about the nozzle and abrasive selection to optimise your waterjet cutting performance.
Nozzle (focusing tube) selection
As a general rule, the orifice diameter should be approximately three times the size of the water nozzle orifice.
While some users would recommend a smaller ratio of about 2.5 times to produce faster cutting speeds, there are trade-offs. It could cause an increase in nozzle wear and part tolerance which translate to more costs. Moreover, the wrong combination can also affect the cutting quality.
Many waterjet cutting users tend to operate with the standard combinations that are commonly practised or promoted in the industry. It may be worth exploring different combinations that could help reduce your orifice and nozzle wear and tear while obtaining a better cutting quality for your project.
Below are the possible combinations*:
Garnet Abrasive Selection
Garnet has been used for decades as an abrasive in waterjet cutting due to its superior physical properties. When added to high pressure streams of water, garnet abrasive is capable of cutting through tough materials including steel, aluminum, stone and inconel.
Currently, the use of abrasive waterjet cutting in the natural stone industry is increasing. The effectiveness of abrasive waterjet cutting on natural stones is dependent on the properties of the stone and machine operating parameters.
Stone (marble & ceramic and granite) is softer material compared to metal. Using finer garnet particle sizes can help achieve a smoother surface finish on softer materials.
Industry standards denote that garnet sizes ranging from 80 mesh to 120 mesh deliver the optimum performance in most applications in industrial waterjet cutting operations. GMA Garnet™ is well known in the industry as a pure and accurately sized garnet abrasive with no dust or ineffective grains to restrict garnet free flow.
*Note: User discretion is advised when following these recommendations. GMA is not responsible for any performance damages resulting from the use of information presented in this chart.
By Hemanshu Dawda, GMA Middle East