Injection Moldmaking and Grinding Wheel Dressers

Despite the fact that a great deal of precision surface grinding has been replaced by Wire EDM, there is still a demand for the skillful use of grinding wheel dressers. This is one of those toolmaking skills that requires considerable time and patience to master.

There are basically two types of grinding wheel dressers: under the wheel dressers and on the side dressers. In the past, most dressers were on the side, but with the introduction of a highly precise under the wheel dresser that is very easy to use, most shops use the same type.

There are also wheel dressers available that use optics and magnification to project the wheel form on a screen. These attachments are in use in many shops today and are highly accurate, though rather expensive.

Most injection mold making shops need a grinding wheel dresser that is accurate, fast, and low maintenance. If the dresser is so complicated to use that only a few individuals are capable, it is not practical. Also, because precision surface grinding is by nature a slow, tedious process, the need for speed is important as well.

Of all the radius/angle dressers that are commonly available, the simple to use under-the-wheel dresser is the most accurate and easy to use. A small magnifying glass is incorporated to aid in picking up the edge of the grinding wheel, which saves a lot of headaches.

The engraved graduations on the fixture are also highly accurate and, for most applications, are satisfactory. In the event that you need exact angles, it is simple to set and check on a magnetic sine plate by indicating with a dial indicator.

Another very useful item for radius and angle dressing on a precision surface grinder is the boron carbide dressing stick. One of the commercial names for this is Norbide, and it is readily available from a supplier.

Very often it is necessary to redress the corner of a grinding wheel to maintain a sharp, 90 degree corner. Instead of disrupting the grinding operation and mounting a wheel dresser, it is possible to simply use the boron carbide stick manually. With some practice this becomes routine and is a real time-saver.

Overall, nearly any radius or angle can be dressed on a typical grinding wheel with a minimum of quality tooling. The basic requirements would be an under-the-wheel radius dresser, precision angle plate, set of diamond nibs, gage blocks, boron carbide stick, granite surface plate, surface gage and dial indicator.


Post time: 12-09-2016