When it comes to cutting metal, there are many available processes and choosing the best option varies based on your specific application. The most common processes for cutting metal on a CNC machine are plasma. laser, oxy-fuel, and water jet. Each process has its own advantages and disadvantages, so understanding these will help you select the best one for your operation.
CNC plasma cutting can be separated into two main categories, air plasma and high definition plasma. Maverick CNC machines utilize Hypertherm’s Powermax air plasma systems, which are lower cost than high definition systems. Because Powermax systems run on compressed air and have a low usage of consumables and electricity, they offer the best cost per foot cut return. High definition (Hy-Def) plasma utilizes gases such as O2, N2, F5, and AR to produce very good cut quality. Hy-Def plasma systems require a sophisticated motion platform and software to maximize their capabilities. Hy-Def systems low operating cost and fast cut speeds make them more productive and efficient than laser and waterjet systems in most applications.
Laser systems provide very accurate tolerances and very good cut quality on thinner material. They perform especially well when cutting thin stainless steel. When part tolerance is the key priority, the very thin kerf width and minimal bevel angle allow for very detailed and accurate cutting. Laser is really a precision sheet metal machine and can provide accuracy not possible with plasma on thinner material. There are lasers that will cut thicker material (up to 1”), but the capital cost, operating expense, and minimal cut quality benefit over Hy-Def plasma make it a less favorable option for many applications.
Water jet systems utilize a very fine, highly pressurized (up to 90,000 psi.) water stream to cut material. An abrasive called garnet is injected into the stream and the high velocity flow of the garnet is what cuts the material. Water jets offer tremendous flexibility as they can cut almost anything including metal, plastic, wood, rubber, glass, and more. They provide very tight tolerances and there is no heat affected zone as with all the other processes. When cutting metal though, they have very slow process speeds and high cost of operation due to the amount of garnet used.
Oxy fuel has been in use for many years and is still found on many new CNC cutting machines today. Oxy fuel can cut very thick material and really starts to show its advantage over plasma when you get to 2” thick steel and above. It is common to see several oxy fuel torches on one machine gantry, allowing you to cut multiple parts at the same time. Oxy fuel will not cut stainless steel or aluminum, and high gas consumption must be part of the consideration when evaluating. A common option is plasma and oxy fuel combination, which allows plasma cutting up to 1.5 – 2” and oxy fuel for thicker materials.