Grinding: Centered Design Rules

Centered Grinding Part Design: External

Undercuts should be avoided.
For inside corners, the best practice is to machine a relief at the corner prior to grinding so that a sharp ninety-degree male object can be placed in the corner. This is illustrated below.
For internal holes with sharp corners, the figure below illustrates recommended practice.
Plunge grinding is a centered form of grinding in which the wheel "plunges" radially into the part. The four figures below illustrate good plunge-grinding design practices.
1. The figure below shows how inside radii merging with cylindrical surfaces are to be avoided.
2. The illustration below shows how tapers and angular surfaces should be replaced by straight surfaces if possible.
3. The illustration below shows how deep, narrow grooves are to be avoided. The tool required has a thin, tall protrusion that breaks and wears easily and is not rigid.
4. The illustration below shows how complex surfaces are best avoided for plunge-ground parts.

Centered Grinding Part Design: Internal

Undercuts should be avoided.
Radii should be the same in order to simplify wheel dressing and minimize tool changes.
Hole depth to diameter aspect ratio should be minimized. This is for the same reasons that bored holes are not too deep. Avoiding length to diameter ratios of more than six is a good practice.
If possible, blind holes should be avoided. Blind holes restrict the flow of coolant.
Circumferential interruptions should be avoided. Even axial interruptions should be avoided.
An option to consider is a hardened and ground liner. This option must be weighed against the tolerance build up and extra logistics involved.
Adequate access for coolant flow should be provided. This can be difficult since the coolant shed by the rotating grinding wheel provides an effective "curtain" which prevents coolant exchange.

Glossary

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