Get the most out of your vitrified-bonded superabrasive grinding wheels by learning to fine tune your dressing process
Your local Meister Engineer may not show up in his Sunday best, but thanks to years of study along with trial and error experimentation, he is one smart dresser. Now the applications specialists of Meister Abrasives USA are prepared to reveal this hard-won dressing knowledge to users of Meister’s superabrasive grinding wheels.
This article provides an overview of the dressing process and why knowledge of it is essential to fine tuning grinding operations for optimal performance and productivity. This wide ranging topic could easily fill a book with useful information on dressing techniques, so this issue can only scratch the surface (so to speak).
Not A Black Art
Contrary to popular belief, the dressing of vitrified-bonded superabrasive grinding wheels is not a black art. It is actually a well known scientific process, much like the grinding process itself. Dressing is also a powerful tool that engineers can use for solving grinding problems. However before you can use this tool effectively, you have to have a basic understanding of various constituents of dressing processes.
Dressing is actually a combination of two processes, truing and sharpening. Truing is the procedure used to ensure that the wheel, once it has been installed on the spindle, is optimally round. it may also refer to the methods used to create shapes on grinding wheel surfaces. Sharpening involves removing bonding material from between the abrasive grains to expose them so that they are ready to cut. For vitrified-bonded wheels these two processes occur simultaneously.
Numerous tools may be used to dress grinding wheels. They include simple handheld abrasive sticks; conventional abrasive rotary wheels used on driven or brake- controlled dressing spindles; single and multipoint stationery diamond tools; and a wide variety of rotary diamond tool configurations (cups, discs, and form rollers). Rotary tools are preferred for dressing superabrasive wheels, in particular vitrified-bonded CBN and diamond wheels. See table below for recommended dressing tools by grinding wheel type.
Once the dressing tool has been selected there are six variables that are most frequently adjusted to yield an optimal dressing and grinding process, opening up a whole new world of process improvement possibilities:
- Wheel and dresser surface speeds: Linear speed at the periphery of the wheel or dresser.
- Direction at point of contact: Unidirectional (wheel/dresser turning with each other), or counter-directional (wheel/dresser turning against each other).
- Speed ratio: The ratio of dresser surface speed divided by wheel surface speed.
- Infeed amount: The depth of cut taken per pass by the dresser on the grinding
- Traverse speed: The linear speed that the dresser travels across the wheel surface.
- Overlap ratio: The number of wheel revolutions for the dresser to traverse a distance equal to its contact width.
Example: Speed Ratio
Increasing the speed ratio, especially with a uni- directional dress, increases the crushing action on the wheel surface, freeing more abrasive crystals for sharper cutting. However dressing forces are higher, requiring a stiffer setup.
Decreasing the speed ratio or running a counter- directional dress makes the wheel duller for better surface finish, with lower dressing forces.
Always More To Learn
Once you have grasped the importance of improving your dressing skills, you can learn more by downloading the Meister Abrasives Dressing Tutorial PDF.
You can also own your own free copy of the Meister Abrasives’ Dressing Calculation Tool, by visiting our Tools/Calculations page.
In addition, Meisterʼs experienced sales force routinely conducts in-plant training at our customerʼs facilities. If you are looking for a way to achieve consistently better grinding results, or training your staff to become smart dressers themselves, this would be a good way to start. Contact your Meister sales representative for more information.