This section provides an overview for internal grinders as well as their applications and principles. Also, please take a look at the list of 10 internal grinder manufacturers and their company rankings.
Table of Contents
Internal Grinders are machines that grind the internal surfaces of workpieces, which are mainly cylindrical in shape.
Grinding is a machining process that uses a grinding wheel.
Grinding wheels are made of hard abrasive grains such as aluminum oxide and silicon carbide, which are hardened with a bonding agent.
Grinding is not suitable for roughing because the depth of cut is smaller than that of cutting.
However, it is an effective machining tool for precision machining because of its high dimensional accuracy and surface finish roughness.
Internal Grinders grind by attaching a small-diameter internal grinding wheel to a spindle called a wheelhead.
The workpiece is held in place by an external jaw chuck or electromagnetic chuck attached to the spindle.
Internal Grinders are broadly classified into two types according to the grinding method: rotary workpiece type and planetary type.
In the workpiece rotary type, the wheel spindle and main axis rotate with respect to each other, and the grinding wheel on the wheel spindle oscillates back and forth while cutting into the workpiece mounted on the main axis.
The planetary grinding method is used when the workpiece is large or difficult to balance during rotation.
While rotating the wheel spindle, the wheel spindle itself is given a planetary motion to grind while moving along the internal surface.
In order to maintain the sharpness, accuracy, and shape of the grinding wheel, dressing is required when the wheel is changed or after each grinding volume.
The grinding wheel is dressed by placing the rotating grinding wheel on the diamond dresser installed on the machine.
In basic workpiece-turned Internal Grinders, the wheel head with the grinding wheel attached has a sliding mechanism in relation to the spindle, and the grinding wheel enters the hole.
Internal Grinders grind the internal surface of cylindrical shapes, but by adjusting the slide position, they can also grind the end face perpendicular to the shaft center of the hole.
Since grinding can be performed simultaneously in a single process, it is possible to achieve high-precision machining.
The diameter and length of the hole that can be ground are determined by the outside diameter of the grinding wheel and the machine stroke.
Various bore diameters can be accommodated by setting up a grinding wheel that matches the bore diameter.
However, since the bore deflection tends to be medium-high due to of the wheel spindle, it is necessary to select a grinding wheel with the largest diameter possible for the bore and set it on the wheel spindle head using a wheel spindle with a short shaft neck.
The machine can also be used for stepped bore diameters, and the coaxiality of the bore diameter can be ground in a single process to achieve high precision. Taper grinding can also be performed by angling the spindle.
When grinding workpieces with a grinding wheel, if the peripheral speed, which represents the surface speed of the wheel, is low, the abrasive grains will fall off together with the bonding agent.
Under typical grinding conditions, the wheel spindle head is rotated at 2000 to 3000 rpm to achieve the aforementioned peripheral velocity because of the small diameter of the grinding wheel.
The spindle workpiece speed is set so that the peripheral speed of the grinding surface is about 35 to 45 m/min.
*Including some distributors, etc.
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