C-22 is considered “moderate-to-difficult” to machine. During machining it can work harden rapidly, generate high heat, weld to the cutting tool surface, and resist metal removal because of its high shear strength. However, C-22 can be machined using conventional production methods at satisfactory rates.

• Machine should be rigid and overpowered as much
  as possible.
• Work piece and tool should be held rigid and tool overhang should be minimal.
• Tools should be sharp at all times—change to sharpened tools at regular intervals rather than out of necessity.
• Use positive rake angle tools for most machining operations—negative rake angle tools can be used for intermittent cuts and heavy stock removal.
• Carbide-tipped tools are suggested for most applications.
• High speed tools can be used with lower production rates and are often recommended for intermittent cuts.
• Use heavy, constant feeds to maintain positive cutting action.
• Use a lubricant, such as soluble oil, especially when using carbide tooling.

Operations Using Carbide Tools

Operation	Tool Type	Speed	Feed	Cut Depth	Coolant
Roughing, with severe interruptions; Turning or Facing	C-2 or C-3 grade: Negative rake square insert, 45° SCEA,1 1/32" nose radius Tool holder: 5° neg. back rake, 5° neg. side rake	30-50 sfm (surface feet/minute)	0.004-0.008"	0.150"	Dry2, oil3 or water-base4
Normal roughing; Turning or Facing	C-2 or C-3 grade: Negative rake square insert, 45° SCEA, 1/32" nose radius Tool holder: 5° neg. back rake, 5° neg. side rake	90 sfm depending on rigidity of setup	0.010"	0.150"	Dry, oil or water-base
Finishing; Turning or Facing	C-2 or C-3 grade: Positive rake square insert, 45° SCEA, 1/32" nose radius Tool holder: 5° pos. back rake, 5° pos. side rake	95-110 sfm	0.005-0.007"	0.040"	Dry or water-base
Rough Boring	C-2 or C-3 grade: If insert type boring bar, use standard positive rake tools with largest possible SCEA and 1/16" nose radius. If brazed tool bar, grind 0° back rake, 10° pos. side rake, 1/32" nose radius and largest possible SCEA.	70 sfm depending on rigidity of setup	0.005-0.008"	1/8"	Dry, oil or water-base
Finish Boring	C-2 or C-3 grade: Use standard positive rake tools on insert type bars. Grind brazed tools as for finish turning and facing except back rake may be best at 0°.	95-110 sfm	0.002-0.004"		Water-base coolant

Operations Using Carbide Tools

Operation	Tool Type	Speed	Feed	Coolant
Facing Milling	Carbide not generally successful, C-grade may work. Use positive axial and radial rake, 45° corner angle, 10° relief angle.	50-60 sfm	0.005-0.008"	Oil or water-base coolants reduce thermal shock damage to cutter teeth.
End Milling	Not recommended, but C-2 grades may be successful on good setups. Use positive rake.	50-60 sfm	0.002" tooth 1/4" dia. 0.002" tooth 1/2" dia. 0.003" tooth 3/4" dia. 0.004" tooth 1" dia.	Oil or water-base coolants reduce thermal shock damage to cutter teeth.
Drilling	C-2 grade not recommended, but tipped drills may be successful on rigid setup if no great depth. The web must be thinned to reduce thrust. Use 135° included angle on point. Gun drill can be used.	50 sfm	0.001" rev. 1/8". dia. 0.002" rev. 1/4" dia. 0.003" rev. 1/2" dia. 0.005" rev. 3/4" dia. 0.007" rev. 1" dia.	Oil or water-base. Coolant-feed carbide tipped drills may be economical in some setups.
Reaming	C-2 or C-3 grade: Tipped reamers recommended, solid carbide reamers require very good setup. Tool geometry same as high speed steel.	50 sfm	0.003" tooth 1/2" dia. 0.008" tooth 2" dia.	Oil or water-base
Tapping	Not recommended

Operations Using High Speed Steel Tools

Operation	Tool Type	Speed	Feed	Coolant
Facing Milling	M-2, M-7, or M-40 series5: Radial and axial rake 0°-pos. 10°, 45° corner angle, 10° relief angle	20-30 sfm	0.003-0.005"	Oil or water-base
End Milling	M-40 series or T-15: If possible, use short mills with 4 or more flutes for rigidity	20-25 sfm	0.002" tooth 1/4" dia. 0.002" tooth 1/2" dia. 0.003" tooth 3/4" dia. 0.004" tooth 1" dia.	Oil or water-base
Drilling	M-33, M-40 series or T-15: Use short drills, heavy web, 1350 crank-shaft, grind points wherever possible	10-15 sfm.	0.001" rev. 1/8" dia. 0.002" rev. 1/4" dia. 0.003" rev. 1/2" dia. 0.005" rev. 3/4" dia. 0.007" rev. 1" dia.	Oil or water-base coolant—use coolant feed drills if possible
Reaming	M-33, M-40 series or T-15: Use 45° corner angle, narrow primary land and 10° relief angle	10-20 sfm	0.003" tooth 1/2" dia. 0.008" tooth 2" dia.	Oil or water-base
Tapping	M-1, M-7, M-10: 2 flute, spiral point, plug tap 0°-10° hook angle nitrided surface may help increase wear resistance but may cause chipping or breakage. Tap drill for 60-65% thread, if possible, to increase tool life. Use best possible tapping compound	7 sfm (cutting)		Sulfochlorinated oil base preferred

NOTES:

1. SCEA – Side cutting edge angle or lead angle of the tool.
2. At any point where dry cutting is recommended, an air jet directed on the tool may provide substantial tool life increases. A water-base coolant mist may also be effective.
3. Oil coolant should be a premium quality, sulfochlorinated oil with extreme pressure additives, with a viscosity at 100° F from 50 to 125 SSU.
4. Water-base coolant should be premium quality, sulfochlorinated water soluble oil or chemical emulsion with extreme pressure additives. Dilute with water to make 15:1 mix. Water-base coolant may cause chipping and rapid failure of carbide tools in interrupted cuts.
5. M-40 series High Speed Steels include M-41, M-42, M-43, M-44, M-45, and M-46 at the time of writing. Others may be added and should be equally suitable.

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