Side milling is a machining process in which a rotating cutter removes material from the side of a workpiece, rather than cutting directly into it as in slot milling. This method is used to create flat surfaces, shoulders, contours, and features such as steps or pockets. The primary difference between side milling and slot milling is that in side milling, only a portion of the cutter engages the workpiece, whereas slot milling involves full-width engagement.
Cutting Parameters in Side Milling
Several machining parameters influence the effectiveness of side milling, including radial depth of cut (ae), axial depth of cut (ap), and feed per tooth (Fn).
- Radial Depth of Cut (ae): Determines how much of the cutter’s diameter engages with the workpiece. A smaller ae leads to less cutting force and reduced tool deflection, which is beneficial for thin-walled parts or finishing passes.
- Axial Depth of Cut (ap): Defines how deep the tool cuts along its axis. Deeper cuts improve productivity but require sufficient machine rigidity and tool strength.
- Feed per Tooth (Fn): Affects chip load and tool wear. Optimizing Fn ensures efficient material removal while preventing excessive cutting forces.
The overall material removal rate (MRR) in side milling is given by:
MRR = F × ap × ae
where:
- F = feed rate (mm/min or in/min)
- ap = axial depth of cut (mm or in)
- ae = radial depth of cut (mm or in)
Challenges and Considerations in Side Milling
- Tool Deflection: Long overhangs or excessive radial engagement can cause deflection, reducing accuracy.
- Chip Evacuation: Deep axial cuts require efficient chip evacuation to prevent tool clogging.
- Heat Dissipation: Larger radial engagements generate more heat, requiring coolant or optimized cutting speeds.
- Workpiece Rigidity: Thin walls or unsupported sections may vibrate, affecting dimensional accuracy.
Side milling is widely used in machining shoulders, external contours, and pocket walls. It provides flexibility in controlling engagement and optimizing material removal for various applications.