Advanced Milling Operations
Keyway milling, fly cutters, carbide inserts, tramming, and rough milling strategies for maximum material removal.
- Describe keyway milling procedures and Woodruff key slots
- Explain feed rate calculations for carbide inserts and fly cutters
- Demonstrate tramming and angle milling procedures
Lesson 1
Keyway Milling & Fly Cutters
Keyway Milling
A keyway is a slot cut into a shaft or hub to receive a key that prevents relative rotation between the shaft and a mounted component (gear, pulley, coupling). Keyway milling requires precise alignment and controlled depth.
Types of keyways:
- Square keyway - milled with an end mill, key is rectangular cross-section
- Woodruff keyway - milled with a special Woodruff key cutter (half-moon shaped), creates a semicircular seat for a half-moon key
Square Keyway
Cutter: End mill
Shape: Rectangular slot
Key type: Square or rectangular
Use: Heavy-duty power transmission
Woodruff Keyway
Cutter: Woodruff key cutter
Shape: Semicircular seat
Key type: Half-moon
Use: Tapered shafts, light duty
Fly Cutters
A fly cutter is a single-point cutting tool mounted in an arbor that rotates in the milling spindle. It is used for facing large flat surfaces more economically than a face mill because only one insert or tool bit is required.
Key points:
- Produces excellent surface finish at low RPM with fine feed
- Cover a wider area per pass than end mills
- Must run at lower RPM due to the large cutting diameter
- The cutting radius determines the effective diameter for speed calculations
Fly Cutter Speed
Calculate RPM using the fly cutter's cutting diameter (2x the radius from center to tool tip), not the workpiece width. A 6-inch diameter fly cutter in steel at 100 SFM: RPM = (100 x 4) / 6 = 67 RPM.
A Woodruff keyway uses a half-moon cutter for tapered shafts. A fly cutter faces large areas with a single-point tool. Calculate fly cutter RPM using the cutter's cutting diameter.