Page 258 - Fanar

i Technical Information

8.2. Cooling and Lubrication Conditions

Application of Coolant:

— It is recommended when the drilling depth is at least twice greater than the diameter

— It is a must with depths five times greater than the drill diameter
— With application of external cooling, the coolant should be fed not only with the appropriate pressure, but
also in the proper manner.

Methods of Coolant Supply:
Internal:

— Should be applied always, when the depth of the hole is at least three times greater than the diameter.
—
— Internal cooling is always recommended to avoid blocking of chips.

External:
— To improve chip evacuation, at least one coolant nozzle (two, if the drill bit is fixed) should be directed close
to the axis of the tool.
—
— External cooling helps to avoid the formation of buildup on the edges, due to lowering the edges'
temperature.
—
— External cooling is allowed for materials, which give short chips.

8.3. Problems and Troubleshooting

Problem: Buildup on edges
Too low cutting speed Increase cutting speed
Too high temperature of tool’s edges Apply cooling
Too great negative rake angle Sharpen the cutting edge
Wear of coating Coating on the edge

Too little oil in coolant Increase amount of oil in coolant
Problem: Chipping off corners
Excessive runout. Use grip with better mounting precision
Excessive feed. Decrease feed.

Insufficient amount of coolant (thermal cracking) Check coolant pressure
Low rigidity of tool holding system Check rigidity of tool’s mount in the grip
Problem: Chipping off corners
Excessive runout. Use grip with better mounting precision
Excessive feed. Decrease feed.
Discontinuous cutting process Check coolant pressure

Low rigidity of tool holding system Check rigidity of tool’s mount in the grip

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