What Factors May Affect the Water Jet Focusing Nozzles

The right abrasive type and size for a water jet cutting application can make a significant difference in the performance and profitability of your water jet cutting nozzles.

So the key abrasive factors which will determine how consistently and efficiently the waterjet focus tubes are include:

1. Hardness and density

Waterjet cutters need to balance cutting speed and component wear. Using a soft abrasive extends water jet nozzle life but slows down the cut. And soft abrasives fragment and break down on impact with the workpiece. Using an abrasive that is very hard offers fast cutting but erodes the water jet carbide nozzle too quickly. Efficient water jet cutting action requires tough, durable abrasives.

Therefore, the ideal abrasive has the heaviest particles that the water flow can accelerate to the maximum speed and generate the maximum cutting force. An abrasive that is too light won’t pack much of a punch, and an abrasive that is too heavy won’t accelerate to maximum velocity, sapping the water jet stream of its power. As with hardness, the key is to find an abrasive that hits the sweet spot. Garnet has a specific gravity of 4.0 (four times the weight of water) and falls right into the ideal range for punch and acceleration.

2. Particle shape and size

The material cut and edge-finished requires an abrasive particle shape. Grains with sharp, angular edges have been proven to cut more quickly and offer superior edge finishes. Sub-rounded grains are used in more general-purpose, standard cutting applications.

Coarse or oversized particles pose a real risk of clogging the water jet tube and damaging the workpiece. Conversely, excessive fines can collect in the feed line or the cutting head, causing irregular feed or sputtering in the cutting stream. Inconsistent particle size distribution can create a nightmare for adjusting the abrasive feed rate to maintain cutting speeds.

3. Purity and cleanliness

High-purity materials typically involve added processing stages and call for greater attention to detail during the refining process when compared to low-purity products. Low-purity products may contain materials other than garnet that rob a water jet cutting machine of its ability to cut well.

Cleanliness refers to the amount of super-fines present in the abrasive product. These fines are so small that they often adhere to larger particles. Dust causes problems with the flow characteristics of the abrasive, and fines are particles that are too small to serve any useful cutting action.