Centerless Grinding Wheels
Centerless Grinding Wheels: Specifically Engineered For The Job
Centerless grinding is the called-for solution in many applications because it totally eliminates the need for supporting the work between centers or holding it in some other type of fixture. The two most common forms of centerless grinding are throughfeed and infeed (plunge). The centerless grinding process is used to create round parts by rotating a work wheel in conjunction with a regulating wheel. The work wheel performs the actual grinding, operating in tandem with the regulating wheel which acts as both a frictional driving and braking component.
Centerless grinding is a high-precision operation and is generally utilized for high-production grinding because of its superior size, shape and finish control. But, this high-precision process is only as exacting as the wheel that does the work. Radiac centerless grinding wheels are a specifically engineered combination of grain, bond and structure, providing excellent versatility and freedom of cut.
Radiac centerless grinding wheels also mean ...
Our Centerless grindind wheels-the superhard resin bond centerless grinding wheel mainly to use in the hard alloy, the ceramics, the compound piece, the magnetic material unintentionally and so on each kind of rods and bars grinding, has the grinding efficiency to be high, the working accuracy uniformity good characteristic, the transient equilibrium performance surpasses the international rating above 30%.
Centerless grinding is similar to centered grinding except that there is no spindle. This allows high through-put since parts can be quickly inserted and removed from the process. There are three main types of centerless grinding:
1.Through-feed grinding.
IIn through-feed grinding, the part rotates between the grinding wheel and a regulating wheel as shown below.
For through-feed grinding, one or both wheels of the centerless grinding machine are canted out of the horizontal plane, as shown below. This imparts a horizontal velocity component to the work piece, so that outside feed mechanisms are not necessary.
The grinding wheel is canted with respect to the other two axes so that a component of its surface velocity pushes the part in the direction shown below. This auto feeding characteristic is useful for rapidly processing many parts in quick sequence.
Because of the axial movement, through-feed parts can only have right circular cylindrical ground surfaces. The wheel cannot be dressed to grind more complex shapes.
Below are parts produced with the through-feed centerless grinding process. As can be seen from the quantities produced, through-feed grinding is primarily a mass-production process because of its high throughput.
2.In-Feed Grinding
In-feed grinding differs from through-feed grinding in that the part is not fed axially so that the ground surface does not need to be a right circular cylinder. The grinding wheel can be dressed to accomodate the part. Once the work piece part is in place, the grinding wheel is fed in radially.
Because of the set up time involved for each part, in-feed griding does not have the high throughput of through-feed grinding. In-feed grinding is illustrated below.
3. End-Feed Grinding
In end-feed grinding, the part moves in axially between the grinding wheels, stops for grinding, and then moves out again. The wheel can be dressed to form more complex shapes, but the part can only get progressively smaller in diameter. End-feed grinding is illustrated below.
Centerless Grinding Guidelines
The largest diameter of the workpiece should have the ground surface, if possible. This
allows through-feed grinding.
The axial length of a centerless-ground workpiece should be at least equal to the diameter.
Short workpieces are more susceptible to surfaces that deviate from right circular
cylindricity.
Radii should be as uniform as possible in order to simplify wheel dressing and/or set up changes.
For a flat at the end of a shaft, it is preferable to incorporate a matching flat on the opposite side of the shaft. This will prevent a high spot from forming opposite the flat. Alternatively, the flat can be brought inboard so that the end is a complete cylinder, as shown below in the right-hand view.
Holes with diameter to depth ratios of over four should be avoided unless widening of the mouth of the hole can be accomodated, as illustrated below.
As the following diagram shows, internal grinding should allow for as large a diameter tool support as possible. This illustration shows a hole with an entrance that is smaller than that of the ground area.
When face-grinding turned surfaces, ground undercuts should be avoided. As the figure below shows, face undercuts require specially-dressed grinding wheels that are expensive to maintain and replace.
If at all possible, blind holes should be avoided. If a blind hole must be implemented, the middle two geometries of the following diagram can help with grinding.
The figure below illustrates how ends of in-feed ground parts need to be terminated for satisfactory results. The included angle of the pointy end should be less than 120 degrees. If in-feed grinding is not used, ends of cylindrical parts should not be ground.
