There are several renowned types of grinding machines, even those the industry are not familiar with. For example, cylindrical grinder, surface grinder, roller grinder, etc. However, today we will discuss another grinding machine that is popular but with ambiguous concept. In the metalworking industry, this type of grinding machine is called centerless grinding.
Regarding centerless grinding, this is a machining process that uses abrasive cutting to remove material from the workpiece. The main difference between the CNC centerless grinding and traditional centered grinding is in how the workpiece is positioned. On the CNC centerless grinder, there is no spindle or fixture attached to the workpiece. Instead, the two rotating grinding wheels provide a space for aligning the workpiece without other accessories.
This special design also determines the different operation method on the machine with the centerless form. For instance, the rotational speed of the abrasive wheels is relative to the rate at which they remove material from the workpiece. In grinding the corresponding processes, the PLC vertical grinding method is the most common of all other options. This method makes the process that the rotating wheels create smooth surface on metallic or non-metallic materials programmable and attains the optimal results.
When a large volume of parts has to be machined in a short cycle, centerless grinding is preferred over others. As we discussed earlier, CNC centerless grinding differs from traditional centered grinding, since it doesn’t involve the positioning devices. The workpiece on the centerless form of grinder is fixed by means of the existing components.
Grinding is a process that offers surface quality for the workpieces after removing materials from them. It is the very last procedure following the machining processes like milling, drilling, turning, boring, etc. In addition to the metal working industry, the wood processing, plastics, and rubber industries would all apply this method. The materials made of metals, wood, plastics, or rubber is placed between the grinding wheel and the regulating wheel, and the two wheels rotate relatively to each other. As the abrasive materials contact the workpieces, the wheels would reveal the new sharp surfaces of the workpieces.
When it comes to the grinding wheels, they are not made of general materials like that on a car, for example. In fact, the material of the grinding wheels is usually the composite of different substances. The material is composed of coarse-grained aggregate, which is pressed and bonded together by a cemented matrix to form a solid, round shape under normal circumstances. The design of the wheels contains the various profiles and cross-sections, which is used for achieving different tasks.
They can also be made of metals like solid steel or aluminum discs, and binds their particles to the surface.
The composite materials can be artificial or natural, which can be derived from the development from the past until now. In the past, the natural composite stone was the most common composite materials for the grinding wheels. In contrast, the grinding wheels now utilize the artificial aggregates more to make the grinding wheels.
In the centerless grinding process, the workpiece is fixed between two rotating wheels. These two wheels, including the grinding wheel and the regulating wheel, rotate in the dame direction but at different speeds. The grinding wheel rotates on a fixed shaft, and exerts force downwards to the workpiece fixing platform. The grinding wheel usually performs a grinding action on the contact point to the workpiece at a tangential speed. The regulating wheel is movable, which applies lateral pressure to the workpiece with the rough or rubber-bonded abrasives.
With these premises, in the field of grinding, sometimes people also call centerless grinders as other grinders. There are basically three main types of centerless grinders, namely straight feed, end feed and centerless grinder feed types. For the linear feed mode, the workpiece is completely fed by the grinding wheel, which enters on one side and exits on the other. Therefore, the regulating wheel will deviate from the plane of the grinding wheel and provide an axial force to feed the workpiece between the two grinding wheels. The other two methods are different methods, and we may have the opportunity to discuss them further in the future.
Due to the design of workpieces in engineering drawings, centerless grinding has become increasingly common in industrial applications. It is expectable that in the future, centerless grinding may also be fully developed like surface grinding and cylindrical grinding.
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