Numerous Original Equipment Manufacturers (OEMs) claim to offer the greatest option available when purchasing CNC plasma cutting systems. Making the appropriate decision is essential to your long-term return on investment because it might be challenging to compare variables in production designs and important components. “Machine quality starts with a solid foundation and is linked with quality components carefully selected depending on a machine’s design and demand,” retired motion specialist Brad Meyers (previously of Hypertherm Inc.) remarked in an interview. To assist consumers in choosing the machine that best suits their application requirements and budget, we have reviewed the structural characteristics of machine designs and important motion system components in this article.
The thickness of the material utilized in the frame, beginning with the foundation, is crucial. Steel makes up a large portion of the cost of manufacturing equipment, and lower-priced machines frequently employ thinner material and less bracing. These designs could be flexible during acceleration and deceleration, which harms part repeatability and machine precision. Brad advises customers to avoid machines with bolted-together frames and instead opt for devices with welded frames in the category of light industrial equipment.
The carriage that spans your machine and supports your cutting torch is called a gantry. Any unintentional movement of the gantry will be sent to the torch, affecting the cut piece. When describing the requirements for a cutting machine using a high-definition plasma system, Brad noted, “I would propose no less than 3/16″ thick square tubing for a gantry.” Each end truck of the gantry is mounted to the rail system. In general, the gantry will be more stable with wider-end trucks. The center of mass calculation for a gantry is one of the most crucial phases, and sadly, Brad has seen many of them designed wrong.
You require motors to move the gantry, and stepper and servo motors are the two most often utilized types with plasma cutting systems. Stepper motors are a less expensive type typically employed in hobby-level and light-duty industrial machinery. Large gantry machines, high-definition machines, and costly light industrial equipment are the most common places to find servo motors. The motor’s purpose is to move the gantry. Hence the motor must be the correct size. The inertia ratio, with a common aim of 10:1 or 8:1, is used by many OEMs to determine motor size. Both the motor and the load have inertia in a servo system. Their relative inertia ratios will impact the effectiveness of the system.
This ratio is one of the most critical—and most ignored—aspects of servo motor sizing. A gearbox will be used in servo-driven systems to assist the motor in achieving the desired inertia ratio and necessary torque. Brad recommends planetary gearboxes over belt-driven systems. The high rigidity of planetary gearboxes, which is crucial for applications involving frequent start-stop cycles, is achieved by distributing the load across multiple gear teeth. Additionally, planetary gearboxes have less backlash, increasing machine accuracy.
The gantry and all of the motion machinery move along a rail system. Rail systems might be built into the side of the machine, mounted on a pedestal, or integrated into the floor. The rail system typically includes a rack and pinion to drive motion along an axis and a linear bearing guide to steer motion. The machine’s accuracy and long-term repeatability depend on the rail system. OEMs must choose the best rail system by considering load mass, external force, beam deflection, friction, and inertia.
Helical rack and pinion gears have various benefits over straight ones, including quieter operation, increased load capacity, and continuous engagement over the tooth length. A well-thought-out rail system should be positioned to reduce cutting-related contamination.
This article was written to provide a general overview of key designs and components in CNC plasma cutting systems manufacturing. The goal was to provide a list of features you should research when looking at purchasing a cutting machine. By comparing the machine frame, gantry and end truck designs along with key components like motors, gearboxes, linear rails, and rack and pinions, you can start to compare and evaluate differences in OEM designs. It is essential to recognize that not all machines are created equal and that repeatable, accurate motion matters.
A broad overview of the basic designs and elements used in the production of CNC plasma cutting systems is provided in this article. The intention was to identify the characteristics you should investigate before buying a cutting machine. You can begin to examine and evaluate differences in OEM designs by contrasting the designs of the machine frame, gantry, and end truck, as well as essential parts such as motors, gearboxes, linear rails, and rack and pinions. It is crucial to understand that not all machines are made equally and that precise, repeatable action is necessary.