Four factors affecting water cutting speed (I)

Water jet cutting machines are widely used in the industry for their excellent cutting characteristics such as high precision and zero pollution. However, during the cutting process, some operators found that the cutting precision of the cutting machine would be slightly different. Many people It is mistakenly thought that it is the problem of the equipment itself or the water jet sand. In fact, it is not the case. The cutting accuracy of the CNC cutting machine is determined by many aspects and factors. Generally speaking, it can be summarized into four aspects.

1. Water jet pressure

We know that the principle of water jet is to use the impact force and cutting force of high-speed water-sand mixed flow to process the workpiece. The greater the water flow speed, the stronger the cutting force, and the speed of the water-sand mixed flow mainly comes from the acceleration of the water flow by the high-pressure pump. Therefore, the water jet pressure is one of the main factors affecting the speed. Moreover, it was also found through scientific experiments that the increase of pressure significantly improved the quality of the cut section.

2. The influence of the cutter head part

a. Length of sand pipe

A long enough sand pipe can ensure good mixing of abrasive and compressed air, so as to form a more coherent and orderly cutting flow. Experience has concluded that the ideal sand tube length should be 3-4 inches.

b. The accessories are aligned

Be sure to ensure the precise connection and perfect fit of the gemstone nozzle, sand valve, and sand tube to minimize damage to consumables by high-pressure water jets.

c. Water jet diameter

It is worth noting that as the diameter of the nozzle increases, the cutting depth decreases. However, although the cutting speed and depth both increase with the decrease of the nozzle outlet diameter, it is said that it decreases when the pressure is constant. The diameter of the nozzle, the jet will be atomized due to air entrapment close to the nozzle, making it incapable of cutting. 

Experience has concluded that the diameter of the nozzle outlet for cutting is recommended to be selected within 0.1 to 0.3 mm. Moreover, the sealing work of the water jet of the equipment here should be done well. Although the cutting speed and depth decreased with the increase of the nozzle diameter, the kerf width increased, that is, the amount of material damage per unit time increased. It can also be explained in this way that due to the increase of the nozzle diameter, the contact area of the jet acting on the material to be processed increases, thus increasing the resistance of the material, resulting in a downward trend in both cutting speed and cutting depth. But the total energy relationship that the amount of material crushing increases with the increase of jet power does not change.

Experiments have shown that, under the same pressure conditions, it is also found that with the increase of nozzle diameter, the slits become wider, the chip size becomes larger, and the quality of the slits also becomes worse significantly, comparing the quality of material slits processed by nozzles with a diameter of 0.1mm and 0.4mm.

d. Cutting distance

A suitable distance between the end of the sand tube and the material surface will reduce the loss of the water jet when passing through the air, thereby maximizing the cutting efficiency. In addition, due to the resistance of the air, if the distance of the water jet to pass through the air is too long, the water jet will be hindered from spreading. Increasing the diameter of the water jet can also reduce the cutting accuracy. Generally, the faster the speed, the more serious the water jet diffusion.