What level of precision do you need?
Most operations are either fabrication or machine shops. Each have different needs when it comes to the level of cutting precision required. In general, machine shops normally need more accuracy than fab shops but some shops have both the precision chip making equipment of a machine shop and cutting, forming, and welding equipment of a fab shop. Waterjets vary in the precision they offer. Ranging from+/-.005” to .012”,it’s important to consider how you might use your system when determining the right fit for you.
Waterjet systems like the ones from Flow are available with different levels of precision capability. A machine tool equipped with a basic waterjet cutting head, sometimes called a conventional waterjet head, can cut a +/- 0.010” to 0.015” (0.254 to 0.381 mm) accurate part out of any material up to approximately 3” (76.2 mm) thick. Beyond that the finished part is less precise. It is possible to cut a part to tighter tolerances with a conventional waterjet, but to cut to +/- 0.005” (0.127 mm) tolerance the machine cut speed must be reduced to approximately 10 to 15% of maximum cut speed. This slow speed is needed to minimize corner washout caused by stream lag, and part taper caused by the V-shaped kerf created by the jet at high speed. Slower cutting reduces these errors, but takes longer so is more expensive.
However, with Dynamic Waterjet®, the head can be tilted while cutting, thus compensating for the V-shaped taper and the stream lag corner washout. This enables cutting at a much higher speed while also increasing the accuracy of the parts from 0.010” (0.254 mm) accuracy to 0.002” (0.0508 mm). The positional accuracy and dynamic motion characteristics of a machine have an impact on part accuracy and precision. Waterjet machines from Flow are built to minimize the effect this motion has on precision via closed loop (velocity and position) digital drives and motors, precision motion technology, and extremely rigid machine tool design.
Most systems Flow provides are equipped with Dynamic Waterjet® with Active Tolerance Control. Dynamic Waterjet is patented technology that automatically tilts the cutting head impingement angle to compensate for stream lag and taper in a behind the scenes operation based on cutting speed and type of material being cut. The result is two to four times faster cutting and finished part precision of +/-1 to 3 thousandths of an inch (+/- 0.03 to 0.08mm).
Here is the key benefits to cutting materials to precision with waterjet
For Fabrication shops, the waterjet provides a number of material utilization advantages. Because waterjet is a cold cutting process, adjacent parts can easily be cut without issue. On a plasma or oxy acetylene cutting system, you have to leave a 1/4 to 3/4” (6.35 to 19.05 mm) gap between parts so the heat of the second cut doesn’t ruin the previous cut edge.
Due to zero mechanical stress, heat distortion or heat-affected zone (HAZ) being imparted into your material, secondary processing can usually be eliminated. Abrasive waterjets typically produce edge finish of 125 Ra – a satin smooth edge that appears to have been finished by a fine-grit sand blaster. There are projects where the surface finish needs to be better than 125 Ra, where required finished part tolerance tighter than two thousandths of an inch is required, or when pocket milling, threading, or other interior work is needed. In those cases, many machine shops find that using the waterjet to rough the part out at high speed and then finish it off on the mill saves considerable time and material.
The thin kerf and cold cutting nature of the waterjet frees the programmer to optimize the nest as tightly as possible. Most waterjet nesting software includes the capability to set common line cutting, where one pass is used as the cut edge of two adjacent parts. The remnant left over after cutting a nest can be used later since the waterjet did not harm, heat, stress, or warp the material in any way.
Machine shops that mill parts find that the size of the cutting tool affects material utilization. Removal of a large amount of material from a stainless steel part, for example, might require a larger diameter end mill and cause material waste. Since the waterjet cutting stream is 0.030” to 0.040” (0.762 mm 1.016 mm) in diameter very little material is wasted. This might mean that more parts can be created from the raw stock.
Advanced machines incorporating Dynamic Waterjet® technology can produce parts up to three inches thick to a few thousandths of an inch accuracy much faster than taking multiple passes with a milling machine. Solid scrap is worth 2x to 10x more than metal scrap in chip form.
Article by: Siam Anankit Co., Ltd. & MEGA Tech
Reference : https://www.siamanankit.com/