A CNC grinding machine is a computerised tool that produces very fine finishes or make light cuts. It is worth noting that this machine uses an abrasive wheel as the cutting device. Since CNC machines remove material from a work piece by abrasion, they typically generate a lot of heat. As such, they require a coolant to reduce friction and ultimately prevent the machines from overheating. Here is some more information about these machines:
An overview of CNC grinding machine
The term CNC stands for computer numerical control. Therefore, CNC machines typically come with computer-aided manufacturing (CAM) and computer-aided design (CAD) programs. These programs are essentially computer codes used to command CNC machines to perform certain tasks. A computer programmer writes and alters the code required to run various machining tasks. This aspect makes these machines quite efficient because they do not require humans to operate various levers and wheels manually. In addition, they can make precise cuts and finishes unlike human hands that are susceptible to trembling.
The grinding machine consists of a power-driven wheel that spins at a speed set by the operator or programmer. However, other factors such as the diameter of the wheel and the manufacturer’s rating also determine the spin speed. Additionally, these machines have beds with fixtures or clamps to hold and guide work pieces during the grinding process. Another important feature of CNC machines is the grinding head. There are two ways of manipulating this head. Firstly, an operator can control it to move across a work piece during grinding. Secondly, the operator can move a work piece while the grinding head remains stationary.
How it works
To initiate the grinding process, a programmer or an operator feeds the CNC machine’s computer with commands required to carry out a particular task. The machine then uses these commands to move parts such as the grinding head onto the work piece. At this point, it is important to note that there are various ways of removing material from a work piece. One option is advancing the grinding head through or across a work piece slowly. Alternatively, the grinding head spins at high speed as it advances across the surface of a work piece.
During this process, the machine sprays a coolant on the grinding head and work piece to prevent overheating. Coolants vary widely and include oils, pastes, oil-water emulsions, gels, gases such as air, or aerosols. Besides cooling the work piece and grinding head, coolants maximize the lifetime of the working tip as well as prevent rusting of machine parts. It is advisable to wear protective gear to ensure your skin and eyes are not exposed to lubricants/coolants. This is particularly important because some coolants contain toxic chemicals, biocides, and corrosion inhibitors that could irritate the skin or cause respiratory problems. According to guidelines provided by the National Institute for Occupational Safety and Health (NIOSH), operators should wear protective gear such as safety goggles, respirator masks, and gloves. In addition, the room where one is working should be well ventilated and the CNC machine should have splashguards.
A word of caution
Although CNC machines are highly precise, they may fail to work as expected and “crash.” This happens when a CNC cylindrical grinding machine moves in an unexpected manner causing bending or breakage of the working tip, work piece, or accessories like clamps that hold a work piece firmly. Remember these machine shave no sense of direction and a coding error or bug could lead to unusual movements. Moreover, advanced CNC machines have more than three axes (XYZCQ), which means the working tip can make asymmetric rotations. Some cnc grinding machines have load-sensing systems while others do not have these systems. For this reason, it is up to the operator or programmer to debug and go through his/her code before loading it into the CNC machine’s computer.
If this does not work, one has to stop the grinding process manually to prevent the machine from causing or sustaining more damage. Manufacturers of these machines employ certain techniques to prevent crashes from happening. For example, commercial CNC machines operate on a closed loop system, which means they are aware of their current axis at all times. You will also come across grinding machines that have sensors to detect abnormal movements. However, these safety measures are usually incorporated in commercial CNC cylindrical grinding machines. CNC machines for hobbyists rely on the accuracy of stepper motors that rotate based on magnetic field changes.
In summary, a CNC grinding machine uses abrasive techniques to remove material from the surface of a work piece. Examples of common abrasives include silicon carbide and aluminum oxide. Nevertheless, a person who operates such a machine must have the skills and expertise required to write and debug the relevant computer code.