You already have a few pieces of CNC equipment in your shop, and now you have decided to venture beyond the milling machine, lathes, and routers and purchase a CNC plasma cutting system. It’s a relatively significant decision since a CNC plasma cutter requires a substantial up-front investment.
You might be convinced that a plasma cutter will pay off over time by saving you money on outsourcing your profile cutting work and with the speed and low operating costs of the CNC plasma table. However, it can be intimidating for any first-time buyer to consider the many factors in selecting a suitable plasma cutter for your business or home workshop needs. Remember, purchasing a plasma cutter is a lot like buying a welder: you choose one according to the work you do.
This guide will introduce you to the CNC plasma cutting table and some of the primary factors you should consider before purchasing one. But first, here is some background on the CNC plasma cutter.
What is a CNC Plasma Cutter?
A CNC plasma cutter is a computer numerical controlled (CNC) metal cutting machine using a plasma torch to cut through electrically conductive materials and create various profiles and shapes. The computer-controlled plasma system directs a high-speed jet of hot plasma at the material being profiled.
CNC plasma cutters can cut through a range of materials, including stainless steel, aluminum, mild steel, copper, and sheet metal. You’ll find heavy-duty and light industrial CNC plasma cutters in fabrication shops, restoration shops, welding shops, machine shops, and industrial construction sites, to name a few.
CNC plasma cutting machines can move their high-definition plasma torch along the x-axis, y-axis, and z-axis. The plasma cutter forces a gas or compressed air through a nozzle, and an electric arc is then introduced to the gas, creating the plasma responsible for cutting through the metal.
You can buy CNC plasma cutters in different sizes, prices, and functions. They are accurate and can cut through steel plates at speeds of up to 500 inches per minute. Plasma cutters require a plasma gas and an assist gas to operate, and the type of gas will depend on the material being cut. Those gases include oxygen, nitrogen, methane, argon, and hydrogen.
What Should You Look For in a CNC Plasma Cutter?
There are several excellent brands of CNC plasma cutters from which to choose: the Hypertherm Powermax45 XP and SYNC models and Torchmate are well-respected models. Every CNC plasma cutting machine, from the entry-level machine to the heavy-duty industrial CNC plasma cutter, should have the following components:
1. A CNC Control That is Easy to Use
The CNC control system is the brain of the CNC plasma cutter. Programming transforms drawings into electrical signals that manipulate the cutting speed, feed rate, and motion control. It also signals the plasma power supply, torch height control (THC), and the other components what to do and when to do it.
Most entry-level machines are operated from a personal computer instead of a sophisticated control unit. A computer might not be sufficient in a high production environment but typically works well in a small shop. This method helps decrease the costs for hobbyists, the one-person shop, and smaller fab shops without high production demands.
The most important consideration for any CNC control is the ease of use, so be sure to choose a unit that’s easy to learn and operate, or you may end up with regrets.
2. Check Out the Mechanical Components
Every CNC plasma cutting table has moving parts, such as the gantry (X and Y-axis) and torch carriage (Z-axis, up and down) controlling the torch. These components will vary from machine to machine, so you must consider how much use and abuse the plasma cutter will get.
A heavy-duty machine will withstand the stress of constant use and provide a wider cut thickness, better cut quality, and faster cutting speeds, but it might not come at an affordable price for your operation. The mechanical components of a light-duty plasma cutter, sometimes called a DIY CNC plasma cutter, will be lighter, smaller, and have a lower price tag. However, these mechanical components might not hold up under round-the-clock production.
You can save on driver motors, gearing, and electronics on plasma cutters that are not purchased for heavy use. Many entry-level plasma cutters come with stepper motors instead of servo drives, offering substantial savings and reliability when wider cut thickness and a higher range of speeds are not necessary.
3. CAD/CAM Software to Direct the Process
The software for your CNC plasma cutting table is another critical component. CAD (computer-assisted drawing) allows you to draw the part you need digitally and input it into the CAM (computer-assisted machining) software.
The CAM software applies correct tolerances, kerf width, lead-ins, and lead-outs using post-processing. The CAM file is entered into the CNC control, which converts it into signals that control the cutting process.
Some entry-level plasma cutters include combined CAD/CAM software, making the transfer from drawing to cutting part quick and simple. It allows smaller shops to draw and cut parts on the shop floor while they are at the machine.
4. A Fume Control System is Essential
All plasma cutters produce hazardous fumes and smoke, so you should seriously consider a method for extracting them. There are two primary ways to do this, and the water table is the more common since it’s found predominantly on entry-level CNC plasma cutters. The design is more straightforward, and the ongoing costs are reasonable. However, when you retire the machine, the water must be disposed of in accordance with regulations.
The downdraft fume extraction tables with large-capacity filter units are more efficient for production machines. A fan or blower pulls the smoke below the cutting bed slats in the downdraft system. The fume extraction filter removes fume and dust via ductwork built into the cutting table. This method is a safer, more ecological, albeit more expensive, method of extracting dust and fumes.
5. Think About the Consumables for Your Brand New Plasma Cutter
After the initial purchase, the most critical recurring cost will be the cutting tips and electrodes, also known as consumables. Before buying the CNC plasma cutter, determine how quickly your machine will use these items. Damaged tips and the worn-out electrode can affect your machine’s cutting speed or alter the quality of your cuts. Manufacturers usually recommend changing these two consumables together for optimum cutting performance, which can be costly.
6. Consider the Table Size
Most companies meet their requirements with sizes ranging from 2ft x 2ft up to 5ft x 10ft. And with prices under $1,000, hobbyists and small fabrication shops can jump into the game. Of course, if you require an industrial CNC plasma cutter, you can get one of the larger tables with a price tag of $50,000 and up.
7. Confirm the Torch Height Control
Height control controls three modes: pierce height, cut height and the arc voltage setting. The correct pierce height helps extend the life of the cutting torch tip, while the right cut height avoids plate collisions when the tip is too low. It also prevents increased kerf and angular edges that occur when it’s too high. The arc voltage setting controls the ongoing torch to workpiece distance,
8. Choosing Your Plasma Cutter’s Output Power
The output power of a CNC plasma cutter determines what it can cut. For example, getting 12 amps of output power from a 120V machine means you can cut most 1/8” thick metal, while 60 amps from a 230V machine can cut most metals that are 7/8” thick. Some inverter-based plasma cutters provide high cutting output power but weigh far less than regular cutting machines offering that same cutting capacity.
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