PCBN (Polycrystalline Cubic Boron Nitride) is mainly used for machining ferrous materials, such as hard and soft cast iron, hardened steel alloys, sintered iron and superalloys.
PCBN inserts offer higher removal rates and production output, increased tool life, consistent surface finish and excellent dimensional control.
Reconditioning
Fowler Sales and Service also provides reconditioning services for your PCD and PCBN tipped tools and inserts. If your tools have experienced a severe fracture, breakage or deterioration in its cutting ability, we offer relapping, resizing or retipping services, providing an economical way to return the tool to perfect working condition.
When mounting your diamond or CBN grinding wheel, make sure that the wheel is balanced and runs true. Generally, the wheel is machined to tolerances of ISO H6/H7.
Once mounted on the proper arbor, the grinding wheel should not be removed
It is important to choose a flange, spindle and arbor that are of suitable dimensions, with a diameter of at least 33% of the wheel diameter, and the bore no more than 20% of the wheel diameter.
Before assembling, check that the spindle and flange are in good condition, neither dirty nor frayed, and that the spindle taper itself runs very true, within a maximum deviance of 0.002 mm.
When assembling, make sure that the wheel is placed correctly on its surface and that all bolts are fastened and secured (according to the flange manufacturer’s instructions).
After assembling and prior to operation, ensure that the grinding wheel is balanced.
For static balancing of the wheel, move the balancing weights found in the flange into position in order to counteract any imbalances.
After the wheel has been mounted on the spindle, perform an initial manual test to ensure that the wheel’s total run-out is no more than 0.02mm.
Wet grinding is the preferred and generally recommended method to use when working with diamond and CBN grinding wheels.
The use of coolant increases the removal rate, reduces friction, minimizes heat generation and enables free cutting – all of which serve to prevent damage to the work piece and to increase the lifespan of the tool.
A steady coolant supply is an important factor in achieving optimum grinding results and a cost-effective work method.
Synthetic or semi-synthetic solutions, emulsions and grinding oils can all be used as coolants. CBN grinding wheels, however, deliver optimum performance with the use of straight or pure oils.
Dressing gives the grinding wheel its geometrical accuracy and makes it run true, while conditioning opens up the grinding wheel and exposes the abrasive grit by clearing away bond material from around the cutting edges.
Dressing and conditioning are needed if your grinding wheel gets clogged, dirty or suffers any form of deterioration in its grinding ability.
The same is true in the case of replacing grinding edges or straightening the surface of the wheel.
Dressing and truing operations should be performed only after assembling and balancing the grinding wheel on the spindle.
The dressing operation can be performed wet or dry.
Surface speed of diamond wheel 300 rpm.
Surface speed of SiC wheel 15-20 m/s.
For safety and efficiency of use, the device should be held securely by a magnetic table or by bolts where possible. On surface grinders, the spindle of the truing device must be parallel to the wheel axis.
The devise must be placed in such a way that the truing wheel rotation does not unscrew the securing bolts (the correct direction of rotation is indicated by an arrow on the unit).
This truing device can only be used dry.
Turn the wheel spindle to full operating speed and move the grinding wheel into close contact with the truing wheel. Prior to contact, rotate the truing wheel by hand, using the knurled screw, to avoid wearing the truing wheel flat.
Feed by about 0.01 mm per pass using a traverse feed rate of 1-2 m/min, while traversing the diamond or CBN wheel across the full width of the truing wheel.
Dressing CBN wheel is carried out with multi-point metal bond diamond dresser. The dressing traverse feed rate should be at least 500-700 mm/min.
Grinding wheels are composed of thousands of diamond or CBN grains and powered by a tremendous centrifugal force, which causes the wheel to spin at a rate of thousands of revolutions per minute. The particles in the perimeter of the wheel reach speeds of tens of meters per second. Incorrect application not only leads to inferior results, it may also cause an increased safety risk to the user. It is therefore crucial that you adhere to all the safety procedures outlined here.
Please Do
Care for your grinding wheel as you would any fragile material.
Store your grinding wheel in a clean, dry place.
Check your wheel before assembling for damage that may have occurred during shipping. Look it over to make sure that the diamond layer of the wheel is whole and intact.
Make sure that the bore is of suitable dimensions.
Make sure the maximum speed indicated on the wheel is suitable for the machine on which it will be used.
Check that materials to be grinded are in the proper location on your grinding table (at the height of the spindle or a bit above, and no more than 3 mm from the wheel).
Use a security cover that is at least ¾ the size of the grinding wheel.
Always use protective eye gear when grinding.
Do Not
Do not use a wheel that is not balanced, level or straight. You must also make sure that the spindle is straight before usage.
Do not use the wheel before carrying out a visual inspection for cracks, scratches and stains on the wheel body or the abrasive layer.
Do not grind materials that are not specifically intended for your wheel.
Do not operate a grinding machine if the safety devices have been removed.
Do not try to force a wheel onto a spindle for which it is not suited, or place a wheel of a larger diameter on a smaller spindle. Always ensure that the wheel and spindle are of matching size.
Do not use worn out wheels.
Do not exceed the maximum recommended speed for operating your wheel.
Do not use flanges or spindles whose surfaces are not straight, parallel, clean or balanced.
Do not fasten the bolts too tightly.
Do not grind on wheel surfaces that are not intended for use.
Do not force a piece onto the wheel in a manner that will interfere with the wheel’s movement.
