Milling Cutters: Types, Applications, and Assembly Techniques
Milling Cutters: An Overview
What is a Milling Cutter?
A milling cutter is a cutting tool used in milling machines to remove material from a workpiece. It has several edges or teeth and rotates about an axis to perform the cutting motion.
Classification of Milling Cutters
Based on Tooth Type:
- Milled Teeth: Characterized by straight boundaries, these teeth cut with ease and provide good performance. They are sharpened by grinding.
- Straight: Teeth are parallel to the axis, with the full edge cutting the workpiece.
- Helical: Provide a smoother and quieter cut as the teeth are engaged continuously along their length.
- Teeth Bead Breaker: These teeth have a curved cutting edge and are used for machining complex shapes and profiles.
- Dentures (Blade Cutters): Consist of a body with one or more blades attached by welding or mechanical means.
Based on Application:
- Face Milling Cutter (Single Cut): Teeth are cut only on the periphery, used for machining flat surfaces.
- Face Milling Cutter (Double Cut): Teeth on both the periphery and front, used for machining flat surfaces and recesses.
- End Mills: Primarily cut with their periphery, featuring helical teeth. They can be conical or cylindrical and are used for various milling operations.
- Two Teeth Milling Cutter: Consists of two straight or helical teeth, used for plunging and combining longitudinal and vertical movements.
- Three Flute End Mill: Teeth on the periphery and sides, used for grooving.
- Straight Teeth: Used for shallow grooves.
- Alternating Teeth: Used for deep grooves.
- Slot Milling Cutters: Primarily used for grooving.
- Circular Saw: A toothed disk used for narrow slots and parting.
- Angle Milling Cutters: Used for internal angle milling, dovetail grooves, and inclined surfaces.
- Face Tooth: Primarily cut with the face, often manufactured at a 60° angle.
- Peripheral Tooth: Cutting edge is on the angle of the cutter.
- T-Slot Cutters: Small diameter cutters with a cylindrical or conical shank, used for machining T-shaped slots and crescent-shaped pin seats.
- Form Milling Cutters: Used to create specific profiles on workpieces.
- Module Cutters: Used for cutting gear wheels, with different cutters for each module size.
- Gear Hobbing Cutters: Used for gear cutting by generation, synchronizing movement with the workpiece rotation.
- Inserted Blade Cutters: Consist of a shank, body, and replaceable blade tips.
Working Conditions and Assembly
Factors Affecting Cutting Conditions:
Besides the material and shape of the workpiece, factors like machine power and condition influence cutting conditions. Key factors include:
- Cutting Speed: Depends on the cutter material, workpiece material, and desired finish.
- Feed Rate: The movement of the workpiece in the direction of the cut.
- Depth of Cut: The thickness of material removed in a single pass.
Mounting Systems for Milling Cutters:
- Arbor: Used for cylindrical cutters, mounted in sockets and secured with a nut.
- Short Arbor: Typically used for mounting face mills.
- Direct Connection: Used for cutters with tapered shanks that fit directly into the machine spindle.
- Collet Chucks: Used for holding cutters with cylindrical shanks.
- Drill Chuck: Used for holding smaller cutters.
Taper Accommodations:
- Morse Tapers: Have a shallow taper and are less common.
- American Standard Tapers: Widely used in milling machines.
- ISO Tapers: Standardized tapers with a 7/24 taper and 16° 30′ angle.
Workpiece Assembly in Milling Machines
Common Workholding Devices:
- Vise: Used for holding small prismatic parts.
- Fixed Clamps: Similar to a vise with a fixed base.
- Swivel Clamps: Allow for rotation of the workpiece.
- Parallels: Used for supporting prismatic workpieces.
- Direct Mounting on the Table: Used for large or irregularly shaped workpieces.
- Universal Dividing Head: Used for equidistant divisions on cylindrical parts.
- Rotary Table: Used for circular indexing and machining.
- Special Fixtures: Used for specific applications or high-volume production.
Key Considerations for Workpiece Assembly:
- Properly support and secure the workpiece to prevent movement or damage.
- Use appropriate clamping devices and techniques.
- Ensure clearance for the cutting tool and machine components.
- Protect finished surfaces from damage.
By understanding the different types of milling cutters, their applications, and proper assembly techniques, machinists can achieve optimal results in their milling operations.