A surface grinder is an instrument used for smoothing and finishing metal and plastic surfaces. It can be used to remove burrs, chips and sharp edges from surfaces, and also to polish metals and create a honed or polished look. The basic purpose of a grinder is to perform these functions by applying a rotating abrasive material that is attached to the working end of the wheel. This is done by coiling a wire mesh over the workpiece and rotating the abrasive at high speeds.
Surface grinding is most often used to create a flat, smooth finish on thin flat surfaces. It’s a popular, widely used mechanical abrasive machining technique in which a rotating wheel fitted with small, solid steel disks is spun around a vertical shaft at extremely high speeds. The contact with the workpiece results in tiny cracks that form in the surface of the workpiece.
There are two types of horizontal and vertical grinding machines, with each having its own advantages and disadvantages. The most common type of vertical grinder uses a single vertical shaft that is attached to a vertical machine tooling. This is similar to what is used in table saws, whereby one vertical shaft is connected to a number of horizontal spindles. In these cases, the vertical spindle moves vertically in relation to the workpiece. In the horizontal type, the horizontal spindle and cutting edge move parallel to the edges of the work piece.
Unlike surface grinders, vertical ones have no motor drive. They rely upon the operator to rotate the vertical grinding disk at the desired angle and speed, with little manual effort required. The two main advantages of using these machines are that there is much less wear and tear on the mechanical parts, and the operation can be performed over long or short distances. These are ideal for use in abrasive grinding and other workplaces where wear and tear would damage the machine.
Another type of surface grinder is the chuck-style grinder, which has a fixed, stationary workpiece in its chuck. The workpiece could be preloaded prior to the use of the machine. The chucks are usually made of steel or cast iron, and they are placed on top of the workpiece. The chuck wheel rolls along the workpiece as it is inserted into the chuck, and the workpiece and the grinding components remain in constant contact until the workpiece is removed, at which time the chuck automatically stops and the wheels retract to the ground.
Grinding wheels are generally made from either steel or aluminum and are available with either a coated finish or in a magnetized finish. The coated finish is more durable than the magnetized finish, although both types of finish are highly effective against abrasive wheel marks. Magnetic grinders are designed to use with polishing compounds to bring the brightest and most even finish to the final grinding facets. Although magnetic grinding is highly efficient, it is more expensive to manufacture and requires special machines.