Tech Talk
What are the differences between "Single-point/Multi-point Tracing and Dressing"?
Single point diamond dressing and profiling with pantographs and tracers is carried out using a single point diamond, set at an angle to the grinding wheel. The mounted diamond point performs in a similar manner to lathe cutting tool and requires the clearance angles and attack angles in order to perform its function efficiently.
If the diamond were stood upright to dress the grinding wheel it would wear quickly. If the set angle were equal to the facet angle on the diamond point it would generate a great deal of heat. The heat would not only destroy the mount but the thermal growth would also upset the accuracy of the traced form. It is most important therefore to keep a copious flow of cutting fluid during a dressing cycle. The diamond point is moved across the wheel to trace the path of the required shape. The path of the diamond may also be controlled by CNC control in the same manner as the diamond disks.
There are many types of mounted point dressers. The single point is a special case and must be treated with care. The diamond must be rotated during its life to give even wear around the stone. The diamond must not be abused or allowed to heat excessively as the mounting may become distorted and upset the accuracy of the system. Flood cutting fluid must be used when dressing. Less critical are mulitpoint diamonds and impregnated point which obviously have more than one active diamond point in contact with the grinding wheel periphery in a dressing cycle. The multi-point systems however are less accurate, particularly where fine detail is required.
Mounted point dressers are traversed across the grinding wheel, forming the profile and sharpening the wheel periphery. A fast feed will result in a corse helix to be dressed across the wheel an dleave a periphery suited only for rough grinding and poor surface finishes. A slow feed reults in a finer helix which although yields high surface finish, tends to dress flats on the abrasive grain and so prevent high stock removal. The combination of abrasive grain size and fine or coarse dressing will result in an optimum wheel periphery which will give both the surface finish required coupled with a suitable stock removal rate.
Profiling with a diamond point is a relatively inexpensive method, with respect to diamond cost, to create a form on a grinding wheel, however the accuracy and the wheel conditioning does not normally match that of diamond roll dressihng. A diamond roll is very expensive and sometimes prohibitive for the job shop and small batches, therefore the CNC controlled diamond disk system may be more economical depending on the detail and the accuracy of the required form.
