Short Answer:

A multi-point cutting tool is a cutting tool that has more than one main cutting edge to remove material from a workpiece. These multiple cutting edges work simultaneously, resulting in higher metal removal rate, smoother operation, and better surface finish. Common examples of multi-point cutting tools include milling cutters, drills, broaches, and grinding wheels.

Multi-point cutting tools distribute the cutting load among several edges, which reduces tool wear, increases tool life, and allows higher cutting speeds. They are commonly used in machining operations where high productivity and precision are required, such as milling, drilling, and grinding.

Detailed Explanation :

Multi-Point Cutting Tool

A multi-point cutting tool is a tool that contains more than one cutting edge and removes material from the workpiece with all cutting edges working at the same time. Each edge removes a small portion of the material, which makes the cutting operation smoother and faster compared to a single point cutting tool. These tools are used in machining operations where high production rate, accuracy, and surface finish are important.

The main function of a multi-point cutting tool is to perform metal removal efficiently and to distribute the cutting forces over several edges. This reduces vibration, heat generation, and tool wear. As a result, it allows the machining of harder materials at higher cutting speeds.

Construction of Multi-Point Cutting Tool

A typical multi-point cutting tool consists of:

1. Body: The main supporting structure that holds the cutting edges.
2. Cutting Teeth or Edges: Multiple sharp edges that perform the cutting action.
3. Shank or Arbor Hole: The part by which the tool is fixed to the machine spindle or holder.
4. Flutes: The grooves or spaces between teeth that allow chip removal and coolant flow.

Each tooth acts as an individual cutting edge and removes a small chip in every rotation or movement of the tool.

Working Principle of Multi-Point Cutting Tool

When the multi-point cutting tool comes in contact with the rotating or moving workpiece, each cutting edge cuts a small portion of material in sequence. The tool rotates or moves at high speed, and the combined action of all the edges removes the material quickly. Since several cutting edges share the cutting load, the operation becomes smoother and more efficient.

The heat generated during cutting is also distributed among all the cutting edges, which prevents overheating of any single edge. This feature increases tool life and allows for better control over the machining process.

Examples of Multi-Point Cutting Tools

1. Milling Cutter:
   Used in milling machines, it has multiple cutting edges arranged on the periphery or end face of the tool. Each tooth cuts a portion of the workpiece during rotation.
2. Drill Bit:
   A drill bit has two or more cutting edges that remove material in the form of chips while rotating to create holes.
3. Broach:
   A broach has a series of teeth arranged in sequence, each tooth removing a small layer of material to achieve the final shape.
4. Grinding Wheel:
   A grinding wheel has a large number of small abrasive particles that act as cutting edges to remove material during grinding operations.

Advantages of Multi-Point Cutting Tool

1. Higher Material Removal Rate:
   Since multiple edges work simultaneously, material is removed quickly, improving productivity.
2. Better Surface Finish:
   Each edge removes a small chip, leading to smoother surfaces.
3. Reduced Tool Wear:
   The load is shared among many edges, reducing wear on individual cutting points.
4. Higher Cutting Speed:
   These tools can work at higher speeds due to reduced heat per edge.
5. Longer Tool Life:
   The distribution of cutting load increases the durability and service life of the tool.

Disadvantages of Multi-Point Cutting Tool

1. Complex Design:
   The tool geometry is more complex compared to single point tools.
2. High Manufacturing Cost:
   These tools are more expensive to produce and maintain.
3. Difficult to Sharpen:
   Resharpening or regrinding all cutting edges equally is challenging.
4. Vibration Issues:
   Improper balancing can cause vibrations during high-speed operations.

Tool Materials Used for Multi-Point Cutting Tools

The tool material should possess high hardness, toughness, and wear resistance. Common materials used are:

• High-Speed Steel (HSS)
• Cemented Carbide
• Ceramic
• Cubic Boron Nitride (CBN)
• Diamond

These materials can withstand high temperatures and provide longer tool life during high-speed cutting operations.

Applications of Multi-Point Cutting Tools

Multi-point cutting tools are widely used in manufacturing industries for:

• Milling of flat or contoured surfaces.
• Drilling holes in metals and non-metals.
• Broaching internal and external profiles.
• Grinding for precision finishing.
• Reaming to improve hole accuracy.

They are essential tools in modern machining centers and CNC machines for mass production and high-accuracy work.

Comparison with Single Point Cutting Tool

• A single point cutting tool has one cutting edge, while a multi-point cutting tool has two or more.
• Multi-point tools can operate at higher speeds and provide better surface finish.
• Tool wear and heat generation are less in multi-point tools because of load sharing.
• However, they are more complex and expensive compared to single point tools.

Conclusion:

A multi-point cutting tool is an advanced and efficient tool that has multiple cutting edges working together to remove material from the workpiece. It provides high productivity, better surface finish, and longer tool life compared to single point cutting tools. Though complex in design, these tools are widely used in modern machining processes like milling, drilling, broaching, and grinding due to their high efficiency and precision.