A high-quality surface grinder is, of course, critical to successfully grinding parts flat. However several basic areas should be addressed before effectively evaluating the quality of the surface grinder. Correct and precise set up procedures are necessary to achieve the best results of the grinding tool.
Set up areas include:
- Magnetic chuck installation and maintenance
- Grinding wheel selection and balancing
- Diamond selection
Steps for high precision flat surface grinding
Magnetic Chuck Installation and Maintenance
- Grind the machine table flat. Grind deep enough to remove all rust.
- Grind the bottom of the magnetic chuck. Grind so there is approximately .0002” of dish per 6” of chuck length.
- Mount the chuck with a light coating of oil between the surfaces. Tighten the right hand bolts first and then just snug the left side bolts.
Important: The ground-in dish and just snugging the bolts on one side allows the chuck to move due to thermal changes – while minimizing changes in flatness.
- Grind the top surface of the chuck
- Set the chuck magnet to “on.” With a properly built chuck this does not matter, it should not matter if the magnet is “on” or “off.” However, to be safe, grind with chuck magnet “on.”
- Always grind with flood coolant (if available) and use an open-structure wheel, in order to minimize heat buildup in the grinding area.
- Use small down feed increments with frequent dressing to minimize distortion.
- Schedule maintenance
- These steps are done yearly in our shop as rust builds up between the chuck and machine bed.
Grinding Wheel Selection and Balancing
- Select a wheel that will not introduce stress or heat into the work piece. Your wheel supplier should be able to assist you in selecting the proper wheel.
- Wheel balancing is an important part of flat grinding. An unbalanced wheel will produce a poor surface finish and shorten the life of you spindle bearings.
- Wheel balance should be checked during the life of the wheel as it will change as the diameter is reduced.
Diamond Selection and Set Up
- As a rule of thumb, the minimum size diamond should be ½ carat per inch of wheel face.
- Large diamonds dissipate heat better, last longer and dress faster due to more contact with the wheel.
- The diamond should be set approximately 10° in the direction of the wheel location.
- Minimize the shank length and mount as rigid as possible.
- Dressing feed depth should be a maximum of .001” per pass. Use flood coolant if possible.
- Rotate the diamond to a sharp surface whenever possible.
Improve the Return on Your Investment
Careful installation of your surface grinding setup is vital to get the precise results that the grinder and the workholding tools are designed to deliver. Following these steps will not only improve your flat grinding, your grinding tools will continue to perform as expected for a longer time.
The return on your investment in Hermann Schmidt tools to support your precision grinding operations will be far greater with careful set up and ongoing maintenance.