Waterjet cutting - liquid gold

It's difficult to think of another cutting method that can process a wider variety of materials than waterjet. As well as conventional engineering metals such as aluminium, brass, steel, titanium and copper, water jet has little problem dealing with more diverse materials such as ceramics, stone, composites, concrete, glass, plastics, rubber and wood. For cutting metals, the process has enduring appeal, because its inherent use of water means there is no heat-affected zone, leaving the structural and surface integrity of the material intact. When combined with greatly improved speeds, the popularity of water jet is assured among the UK's subcontract profiling fraternity. A case in point is Waterjet Profilers of Basildon, Essex, which has recently installed a new Byjet 4030 Classic L with two cutting heads from Bystronic (02476 585114). As managing director of a relatively young company, Richard Connelly had a lot to think about before investing in the Bystronic Byjet. "The machine in question had to be versatile enough to produce one-off to high volume production runs, with the ability to switch from one material to another with minimum downtime and with lights out capability," he says. "With all these attributes, we would be able to provide 2-3 day turnaround on most jobs." TWO HEADS BETTER THAN ONE Offering a bed size of 4 by 3m on the Byjet 4030 Classic L, most standard sheet sizes can be processed with up to two cutting heads. The heads feature 'CNC head distance' – functionality that allows complex parts to be cut in the same nest moved by the CNC control. The theme is continued at Kingswinford, West Midlands-based CML Alloys, a supplier and processor of nickel alloys, titanium and specialty materials, where a WardJet 100 hp water jet cutter has been supplied by Wightman Stewart (01422 823801). Here, the company's materials are supplied in all wrought forms for corrosion resisting, heat resisting and other applications where performance and properties are essential to the application. CML now has a complete production line for the machining of sheet and plate titanium, in response to customer demand. WardJet, in fact, has been very busy on the development front, not only launching its new Z-series gantry cutting tables, but also its Psy-winder 5-axis cutting head, a tool designed to cut bevels and undertake weld preparations. The major benefit of 5-axis cutting is the ability to cut a profile from a flat or angled piece of material at any pre-defined angle between 0 and 90°. In addition, the cutting head can be programmed to cut a contoured profile, with the head remaining 90° to the material profile/surface. The cutting of contoured surfaces, which are impossible with conventional 3-axis cutting, can also be carried out, while taper compensation of the cutting head results in increased geometric accuracy at faster cutting speeds. Up to 12,700 mm/min is achievable on the WardJet Z-series. PSY-WINDER'S SUPERIOR APPROACH The Psy-Winder is considered a fixed mechanical tool tip cutter, which means that the motion of the additional rotary axes does not affect the spatial position of the cutting point. According to WardJet, this approach is superior to alternative kinematically modelled mechanisms, which must offset X, Y, and Z positions based on the angles of the fourth and fifth axes. This can accumulate additional error, if the positions of the rotary axes are not perfect. Image: The Psy-Winder can cut parts like this Wightman Stewart is also the UK agent for Accustream, and here the new Dialine cutting head is among the latest innovations. Suitable for retrofitting to all major water jet cutting systems, the Dialine features a removable diamond and so confident is AccuStream in its performance that Dialine comes with a 600 hour cutting time warranty, and can provide up to 1,000 hours of trouble-free cutting. The orifice engages the diamond to produce concentric stream alignment to the cutting nozzle. A ruby can also be used with Dialine and, although this will offer the same quality of cut, working life will typically be shorter. Also claiming to boost abrasive water jet operations is the new Paser 4 cutting head from Flow (01455 895300), which, via an innovative metering valve, is able to reduce abrasive clogging and surging for more consistent abrasive flow. According to Flow, abrasive is the single greatest component of operating cost in abrasive water jet cutting applications. The patent-pending Paser 4 metering valve ensures only the correct amount of abrasive is used, thereby eliminating waste. Another US water jet manufacturer, Omax, has also been busy on the development front, with its new 120X the latest machine to be unveiled. Available from UK agent Aquajet (01257 248480), the machine is supplemented by the recent introduction of the Omax DualBridge system, which doubles productivity through an additional cutting head nozzle. As a result, it is possible to cut smaller parts independently or work together to cut large parts more efficiently. The second bridge is controlled through Omax's intuitive Intelli-Max Premium programming and control software, which features automatic collision protection. In terms of new Omax attachments, the A-Jet nozzle is a software-controlled, multi-axis accessory, permitting the flexibility to cut countersunk holes, bevels and severe angles to a maximum of 60° off vertical. It is designed for high flow/high power applications with multiple pumps. On the subject of pumps, the new energy efficient ECUBE 6200 servo-driven intelligent pump has been developed through the Jet Edge and Tecnocut research and development partnership. According to Jet Edge, the completely electro-mechanical system uses 30% less electricity and has 80% fewer components than a hydraulic water jet intensifier pump and is available through UK agent Aquablast (01502 714143). PUMP UP, PUMP UP THE PRESSURE Also new to the market is Bystronic's ByPump Ultra series of high pressure pumps. While the existing Bystronic pump, ByPump Active, is still available and offers a recommended operating pressure of 3,600 bar, the ByPump Ultra goes well above this. "We have subjected the pump to long and intensive tests, and recommend an operating pressure of 5,300 bar," clarifies Michael Merkle, head of Bystronic's Water jet Division. "The pump is good for users who specifically want to process very thick materials; for example, metal sheets with a thickness in excess of 150 mm. "However, anyone who wants to cut as broad a spectrum of parts as possible, should continue to operate with a ByPump Active pump in conjunction with multi-head cutting, as offered with the ByJet Pro and ByJet Classic series of machines." Why? Well, Mr Merkle says that, while an increase in the operating pressure from 3,600 to 5,300 bar increases cutting performance on average by around 40%, if four cutting heads are used with 3,600 bar, cutting performance can be increased by up to 300%. Box item Small talk Bystronic has introduced a water jet cutting system for processing in the micro range. Over a working area of 1,000 by 600 mm, the new Micro water jet can cut metal bars with a width down to 0.2 mm and a reproducible manufacturing tolerance of ±0.01 mm. Image: Bystronic has smaller things in mind at the moment This innovative abrasive water jet has a diameter of less than 0.3 mm, and typical fields of application will be medical engineering, electrical components and watchmaking. According to Bystronic, the machine is seen as a genuine alternative to the application of wire-cut EDM in the micro-machining field. First published in Machinery, May 2011