Centerless grinder is a type of machining operation that makes use of abrasive cutting wheel to remove material from the workpiece. The process of using this wheel is similar to the use of a sandpaper, which is spun around by an electric motor with a rotation on a horizontal axis. This operation helps to eliminate burrs and at the same time helps to polish the workpiece to get a smooth finish. When using this type of machine, a work piece will be ground to a specification, after which the wheels will spin at extremely high speeds in order to remove any remaining material. The high speed of the grinding operation causes the work piece to be ground at a rate that completely grinds the work piece to a fine finish.
The grinding process is a very complicated one, which is exactly why only very experienced machinists are able to use this type of machine. Using a centerless grinder requires precision and complete understanding of the operation, as well as the accurate anticipation of the end results. This technique used to be widely used in the 1950s but was discontinued due to the difficulty in controlling speeds. However, recently they have gained popularity among machinists due to the ability to control speeds during the grinding process, which significantly improves its quality. This type of machining also has some additional benefits, such as being highly repeatable and produces consistent results.
Centerless Grinder systems require large workpieces in order to work well, and it is because of this factor that they are suitable for cutting larger diameter and heavier workpieces. The ability to work with larger and thicker workpieces has its advantages, such as greater accuracy, finer machined finishes and faster turn times. The larger workpieces, which are cut using the centerless grinding technique, result in a smoother surface finish than the usual type of machining. Using this technique reduces the need to remove the workpieces at various stages of the production process, which can be a lengthy procedure in other methods of machining.
Although the centerless grinding process uses large and heavy wheels, it is still very compact in structure and so it is easy to transport and configure. Large companies have been utilizing them for years due to their compact design, and even smaller companies can now utilize them. They are extremely popular with machine tool suppliers, sheet metal manufacturers, furniture makers and automotive manufacturers. A centerless grinding system consists of a rotating screw or cam attached to a center spindle and to a base unit. These systems have two speed modes, ‘Continuous speed’ and ‘Cycling speed’.
They are normally set up either by rotation of the screw, which is commonly referred to as through-feed or continuous speed, or by sliding movement of the cam attached to the center spindle, which is commonly referred to as in-feed or pulsating speed. There are advantages of using these two types of systems. Through-feed grinding wheels provide a very smooth and consistent production of products because the workpieces come in a single sheet and the distance from the in-feed grinding wheel to the work surface is constant. Pulsating and in-feed grinders, on the other hand, move the work piece from one point in the sheet to another, increasing the amount of material that can be processed per hour. The only disadvantage of having two types of system is that there may be limitations to the sizes of the workpieces that can be handled. Also, these types of systems require the use of two or more pieces of machinery.
Centerless grinding wheels are also known as pulsating or scroll wheels and they consist of numerous ceramic beads located around a rotating hub that has a serrated edge. The ceramic beads are pressed or rolled onto the round edges of the hub in such a way that the radial contact leads the wheels to rotate. The wheels are usually situated on top of an alloy plate and the plate may have several heat shields to protect the working parts from the friction caused by the rotation. Due to the circular nature of the rim, it has the ability to deliver excellent results with high repeatability and reliability and this makes it ideal for abrasive applications where high roundness and consistency are required.