Machining Processes: Turning, Milling, and Drilling – Trimantec
Introduction of tool geometry:
Tool geometry refers to the physical shape and characteristics of a cutting tool, such as a drill bit, end mill, or lathe tool, that is used in machining operations to shape, form, and remove material from a workpiece.
The geometry of a cutting tool is critical to its performance, and it affects many aspects of the machining process, including the quality of the surface finish, the amount of material removed per unit time, the tool life, and the power requirements for the operation.
The primary elements of tool geometry include the cutting edge angle, the rake angle, the clearance angle, the point angle, the helix angle, and the relief angle. These angles determine the orientation and shape of the cutting edge, which affects the way the tool interacts with the workpiece.
For example, the cutting edge angle determines the sharpness of the tool, the rake angle controls the amount of chip flow and helps prevent tool wear, and the clearance angle allows the tool to cut without interference from the workpiece.
In summary, tool geometry is a critical aspect of machining operations that affects the performance, quality, and efficiency of the process. Understanding and selecting the appropriate tool geometry for a specific application is essential for achieving optimal results in manufacturing.
Classification of tool geometry:
Tool geometry refers to the physical shape and design of a cutting tool used in machining operations. The following are the common classifications of tool geometry:
2. Helix angle
3. Rake angle.
4. Relief angle
5. Cutting edge geometry.
6. Nose radius.
7. Flute geometry.
8. Shank geometry.
9. Coating.
1. Point angle: This refers to the angle formed by the two cutting edges at the tip of the tool. It is usually measured in degrees and is a critical factor in determining the performance of the tool.
| 2. Helix angle: This is the angle formed by the cutting edge and the axis of the tool. It affects the chip flow, tool life, and surface finish of the workpiece. |
3. Rake angle: This is the angle between the face of the tool and a line perpendicular to the workpiece surface. It affects the cutting forces, chip formation, and tool life.
4. Relief angle: This is the angle between the flank of the tool and a line perpendicular to the workpiece surface. It provides clearance for the cutting edge and helps to prevent tool breakage.
5. Cutting edge geometry: This refers to the shape of the cutting edge, such as straight, curved, or wavy, and affects the chip formation, cutting forces, and surface finish.
6. Nose radius: This is the radius of curvature at the tip of the tool and affects the surface finish and tool life.
7. Flute geometry: This refers to the shape and number of flutes on the tool and affects the chip flow and tool life.
8. Shank geometry: This refers to the shape of the shank of the tool, which can be straight or tapered, and affects the stability and clamping of the tool in the machine.
9. Coating: Tool coating can improve the performance of the tool in terms of wear resistance, friction reduction, and heat dissipation.
These factors all play important roles in determining the performance and suitability of a cutting tool for a particular machining operation.
Tool Material Introduction:
Tool materials refer to the materials used in the production of various cutting tools, molds, and dies that are employed in the manufacturing industry. The selection of a tool material is dependent on the particular application, tool geometry, and the workpiece material. The tool material should possess the necessary physical and mechanical properties such as toughness, hardness, wear resistance, and thermal stability required for a particular application.
The commonly used tool materials are as follows:
2. Carbide.
3. Ceramic.
4. Diamond.
5. Cubic boron nitride (CBN).
1. High-speed steel (HSS) - HSS is an alloy of steel with tungsten, molybdenum, cobalt, and other elements. It is used in the manufacture of drills, taps, milling cutters, and other cutting tools. HSS has excellent toughness, wear resistance, and can withstand high temperatures.
2. Carbide - Carbide is a composite material made of tungsten carbide particles bonded with cobalt. Carbide is widely used in cutting tools, drills, and milling cutters. It has a high hardness, excellent wear resistance, and can withstand high temperatures.
3. Ceramic - Ceramic materials such as alumina and silicon nitride are used in the manufacture of cutting tools for machining ferrous and non-ferrous metals. They possess high hardness, wear resistance, and thermal stability.
4. Diamond - Diamond is used in cutting tools for machining non-ferrous metals, composites, and plastics. It has the highest hardness and wear resistance of any known material.
5. Cubic boron nitride (CBN) - CBN is used in cutting tools for machining ferrous metals. It has a high hardness and excellent thermal stability.
Wear characteristics of tool
The wear characteristics of a tool refer to the changes that occur on the surface of the tool as it is used for cutting, drilling, or other manufacturing processes. These changes can be caused by various factors, such as the material being worked on, the cutting speed, the feed rate, and the tool's geometry and composition.
The following are some of the common wear characteristics of tools:
2. Crater Wear.
3. Built-Up Edge (BUE).
4. Chipping.
5. Notching.
6. Edge rounding.
1. Flank Wear: This occurs on the flank or side of the tool and is caused by the rubbing of the tool against the workpiece. It is one of the most common types of wear and can lead to a decrease in tool life and poor surface finish.
2. Crater Wear: This is caused by the high temperatures and pressures generated during cutting, which can cause the material on the cutting edge to melt and flow away. This type of wear can lead to a loss of tool geometry and poor surface finish.
3. Built-Up Edge (BUE): This is a type of wear that occurs when a thin layer of workpiece material adheres to the cutting edge of the tool. BUE can cause poor surface finish, increased cutting forces, and tool breakage.
4. Chipping: This occurs when small pieces of the tool material break away from the cutting edge due to the high stresses and forces involved in cutting. Chipping can lead to a decrease in tool life and poor surface finish.
5. Notching: This is a type of wear that occurs when small notches or cracks appear on the cutting edge of the tool. Notching can lead to a decrease in tool life and poor surface finish.
6. Edge rounding: This is the gradual rounding of the cutting edge of the tool due to repeated use. Edge rounding can lead to poor surface finish and decreased tool life.
It is important to monitor and manage the wear characteristics of tools to ensure optimal performance, reduce downtime, and extend tool life. Regular maintenance, such as sharpening and re-grinding, can help to restore the tool's geometry and prolong its life. Additionally, using the appropriate cutting conditions and tool coatings can help to minimize wear and improve performance.
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