Resin Bond Info
Safe operation practices must be part of every grinding wheel user’s operation. Super abrasive wheels are expensive, but performance justifies the cost. To obtain maximum performance from the super abrasive wheel, the procedures for the user’s operation must extend to what is done with the wheel both before and after it’s actual use. The greatest efficiency and lowest overall abrasive cost can be realized only if proven care and use techniques become standard procedure.
FOR DIAMOND WHEELS
MOUNTING: The following
recommendations are given so that the best results may be obtained in
using diamond wheels: Care should be taken in mounting a diamond wheel.
Flanges; back plates; spindles should be clean, free of burrs, and run
true. By using an indicator and tapping lightly on a wood block held
against the wheel, indicate the wheel within .0005” of the true rotation.
Tighten the flanges securely and recheck with an indicator before using.
When mounting a cup type wheel, use shims inserted between the back plate
and the wheel to obtain a true running face. The use of permanent
mounting should be practiced where convenient.
DRESSING & TRUING: Due to the exceptionally free cutting properties of the diamond wheels, frequent dressing is not necessary. They may be dressed with a soft bonded aluminum oxide or silicon carbide dressing stick. When a beveled or gouged condition has occurred in a face type wheel, the wheel may be removed from the machine and rotated in a figure 8 motion on a cast iron plate sprinkled with 80 to 100 grit silicon carbide dust. To true a peripheral type wheel which has become beveled at the corners, a brake truing device can be used, or let the diamond wheel revolve at a slow speed mounted on a mandrel between lathe centers and true at right angles with a small silicon carbide wheel mounted on a post grinder.
SPEEDS & FEEDS: The best speeds
for diamond wheels for grinding carbide is between 4,000 to 6,000 surface
feet per minute. Slightly higher speeds are not detrimental, particularly
if a flood of coolant is applied and grinding pressure minimized. Table
traverse rates of 100” to 500” per minute with cross feeds of .030” to
.060” may be used. For general surface grinding operations, down feeds
should not exceed .001” per pass for rougher grits up to 120, .0005” for
grits 120 to 220, and .00025” should be used for finish grinding or with
fine grit wheels.
COOLANTS: It has been found that
a generous flow of coolant increases diamond wheel efficiency. The proper
placement of coolant is also important. The coolant must be applied in
the proper place or it will not cool the wheel or the material being
ground, properly. Coolant should always be directed so that the full flow
is at the point of contact between the same directions as the rotation of
the wheel. Note: When ordering always specify wet or dry
grinding. Some resin-bonded wheels are made for dry grinding only for
better life when coolant is not used.
FOR BORAZON WHEELS
MOUNTING: Unless correctly mounted, BORAZON (CBN) wheels cannot perform well. After mounting, all BORAZON (CBN) wheels, except electroplated wheels, must be correctly trued and conditioned to insure good grinding performance. For the correct mounting of a BORAZON (CBN) wheel, the mounting flanges and faces must be in good condition. To reduce the amount of wheel rim material that has to be removed in truing, the wheel should be mounted as true as possible. With the aid of a dial indicator, it is possible to position the wheel so as to minimize runout. Paper washers, blotters, and metal shims should not be used when mounting a BORAZON (CBN) wheel. They make it difficult for the wheel to be held securely on the mount. Ensure the correct wheel guard is in place before starting the wheel. Allow the wheel to come up to full operating speed before starting to grind.
TRUING & CONDITIONING: In truing, the wheel rim is cut or abraded with a tool to develop perfect roundness, concentricity with the spindle and the desired profile. In conditioning, bond material is removed to expose the sharp cutting edges of the BORAZON (CBN) abrasive crystals. The following guidelines are general. DO NOT OVER-TRUE THE WHEEL. Accurate truing is important, an out-of-round wheel will pound the work piece, wear fast and produce poor finishes. Excessive truing simply wastes wheel material and shortens wheel life. BORAZON (CBN) wheels are always trued wet, with a flood of coolant applied as directly as possible to the tool/wheel interface. Single-point and cluster type diamond dressing tools should not be used for truing BORAZON (CBN) wheels. They may damage the wheel. One recommended truing tool for BORAZON (CBN) wheels is a metal-bonded nib containing 40-150 mesh diamond abrasive. With this type of tool, truing increments should be in the .0005” to .001” (0,013 - 0,025mm) range. An alternate to using a diamond nib for truing, is to use a 40/60 grit silicon carbide wheel in a brake-type truing device. Vitrified-bonded wheels with bond hardness in the “J” through “M” range give the best results.
DRESSING & CONDITIONING: Truing glazes BORAZON (CBN)
wheels. They will not grind when glazed. Before grinding, they must be
conditioned to make them free cutting. BORAZON (CBN) wheels can be
effectively conditioned by abrading the wheel surface with a dressing
stick containing fine (220 grit) aluminum oxide abrasive in a “G” to “K”
grade vitrified bond. The dressing stick is forced into the wheel quite
hard. Usually this is done by hand, but a holding device can be used. A
small amount of coolant is used to create a paste or slurry that rolls
like grains of sand between the wheel and the dressing stick. This
abrades out bonding materials which otherwise prevents the wheel from
cutting freely. Before dressing, the wheel will feel smooth, while a
properly dressed wheel will have a rough texture. Rapid loss of the
dressing stick is a good indication that the wheel is being opened.
SPEEDS: BORAZON (CBN) wheels should be used at
6,000 to 7,000 surface feet per minute.
Flood coolant should be used whenever possible. The use of enriched
solutions (5 to 10%) of “heavy-duty” water-soluble oils is effective in
extending BORAZON (CBN) wheel life.
MATERIALS THAT ARE EFFECTIVELY GROUND WITH BORAZON (CBN) WHEELS: HIGH SPEED STEELS, TOOL & DIE STEELS, CARBURIZED STEELS, NITRIDED STEELS, CAST IRON, BEARING STEELS (52100,M – 50 etc.), MARTENSITIC STAINLESS STEELS, COBALT BASED ALLOYS (STELITES), UDIMET HASTELLOY, RENE “71” & “77”, NICKLE BASED SUPERALLOYS (INCONEL 718), WASPALOY, Etc…
Type (1A1, 11A2, 6A2C, Etc.)
Size - Physical Dimensions (Diameter, Thickness, Hole Size, Etc.)
Specifications - As Outlines Below
Specify Type of Material Grinding (Carbide, Steel, Glass, Etc.)
6. Specify Wet or Dry Grinding
Example: 2pc. 1A1 6 x 1/2 x 1 1/4 NCD220R100B-1/8
Diamond And Borazon Wheel
use this chart to find the wheel specifications
needed. The top line in Blue is an example.
Use this chart to Find size of diamond grit and finish left after grinding.
National Diamond Lab wheels are manufactured to the following diamond content specifcations:
National Diamond Lab guarantees that in the manufacture of our diamond wheels not less than the above concentration has been used.
RPM & SFPM Charts in General Info
Use this formula to find Required RPM
Use this formula to find SFPM at known grinding RPM
The following formula may be used to quickly calculate wheel speed
SFPM = wheel speed in RPM x wheel diameter in inches x .262
SFPM = Recommended surface feet per minute
RPM = Revolutions per minute
D = Diameter of Wheel
π = 3.1416 (Pi)
Never exceed the maximum operating speed marked on the super abrasive wheel being used, typical maximum operating speed by bond types are as follows:
The proceeding wheel speeds are the recommended speed and not necessarily the most efficient. Super abrasive diamond wheels operate most effectively at speeds lower then the maximum. The following are general recommendations. CBN Wheels in many cases are used effectively on steels at higher speeds.