Factors to consider before purchasing
CNC plasmas are great additions to any shop because they can deliver high-quality cuts at a relatively low operating cost. While CNC machines are large purchases and there are many factors you may want to consider before buying. By doing the appropriate research you can save yourself as well as your company a great deal of time and money.
The quality of the machine
The most important thing you want to ensure before buying is that you are investing in a high-quality machine. There are a few different things to consider when looking at the quality of a machine.
Design of the machine:
Before deciding on the plasma you want, you should look at the design of the table. Even the smallest factor can affect the performance of the table. Check to see if the gantry is too heavy; a heavy gantry can make the plasma torch difficult to control with high speed and accuracy. Also, consider for gauge metal cutting a machines roller hold-down feature as there will inevitably be plasma dust that can hinder some units. This plasma dust can eventually mix with the oil creating a sludge that can damage your parts.
Servo motors are generally considered to be better than stepper motors. A servo motor can move to a virtually infinite amount of positions within its range of motion and tells the operator where it is at every moment. A stepper motor on the other hand, only has a finite number of positions it can move to and does not provide this feedback for the operator. This creates situations where an operator will tell the stepper to move to a certain area, but because it does not provide feedback, the operator will not know if this movement actually occurred. This becomes a problem if the torch comes into difficulty causing the entire cut to be offset from what the operator planned. Although, servo motors are more expensive than stepper motors, they make up for the cost with the added precision and assurance they offer.
The software that comes with your machine
The software coupled with your machine is arguably the most important part. The software allows you to both design what you want cut and control the actual plasma torch. Software such as AutoCad for the CAD portion and EZ G Code for the CAM portion is excellent for creating high-quality designs then outputting the file to the machine. Software used to control the plasma is usually bundled with the machine, but be sure to look for software that is specifically optimized for your table.
How the machine handles dust and smoke
Plasma cutting generates a good amount of dust and smoke, so this is definitely something you will need to take into consideration. Without proper ventilation, the dust and smoke can quickly consume your shop, which is harmful to both employees and other machines. There are features standard in machine packages that will help prevent this from happening.
A downdraft system is a series of skirts around the base of the table along with a fan that sucks the smoke and dust through the table through a filter. This feature effectively eliminates the smoke and dust although can be anywhere from 5-20% of the machine cost.
A water table is another alternative for containing your dust and smoke. It is essentially a shallow table of water under the cutting surface of the plasma that catches sparks and dust as they fall. The one downside of a water table is that the water can splash on the bottom of the cutting table and cause rust to form. This will require your constant attention to ensure this does not happen. Typically customers use a rust inhibitor so that no rust in the table forms.
Once you have considered all of these factors, you will be in a much better position to make an informed buying decision. CNC plasma technology can be a large capital expenditure which requires the appropriate cost-benefit analysis, will ultimately increase a company’s productivity.