General purpose end mills are versatile cutting tools used in milling operations to remove material from a workpiece. They are commonly employed in various industries, including manufacturing, automotive, aerospace, and metalworking, due to their adaptability to different materials and applications. These end mills are designed to perform a wide range of milling tasks, such as face milling, profile milling, slotting, and plunging. Typically made from high-speed steel (HSS), carbide, or cobalt, general purpose end mills can handle a variety of materials, including steel, aluminum, brass, and plastics. Their design features include a cylindrical shank, a cutting head with multiple flutes, and a helical or straight flute pattern, which helps in efficient chip removal and smooth cutting action. The primary use of general purpose end mills is to create precise and intricate shapes and features on a workpiece. They are ideal for producing flat surfaces, contours, and complex geometries. Additionally, they are used for drilling operations, although they are not as efficient as dedicated drill bits for this purpose. General purpose end mills are available in various sizes, lengths, and flute configurations, allowing machinists to select the appropriate tool for specific tasks. Their versatility makes them a staple in machine shops, where they are used for both roughing and finishing operations. In summary, general purpose end mills are essential tools in machining, offering flexibility and efficiency in material removal and shaping tasks across a wide range of applications and materials.

Materials that are not suitable for general-purpose end mills include: 1. **Hardened Steels**: Materials with a hardness above 45 HRC are typically not suitable for general-purpose end mills, as they require specialized cutting tools with coatings like TiAlN or CBN to withstand the high wear and heat. 2. **High-Temperature Alloys**: Alloys such as Inconel, Hastelloy, and Waspaloy are difficult to machine due to their toughness and heat resistance. They require end mills with specific geometries and coatings to handle the heat and prevent tool wear. 3. **Titanium Alloys**: These materials are known for their strength and low thermal conductivity, which can lead to rapid tool wear and failure if not machined with specialized end mills designed for titanium. 4. **Ceramics**: Due to their brittleness and hardness, ceramics require diamond-coated or CBN tools rather than general-purpose end mills. 5. **Glass and Composites**: These materials can cause excessive wear and chipping on standard end mills. Specialized tools with diamond coatings or specific geometries are needed to handle the abrasive nature of these materials. 6. **Hard Cast Irons**: While softer cast irons can be machined with general-purpose end mills, hard cast irons require tools with specific coatings and geometries to manage the abrasive nature and hardness. 7. **Reinforced Plastics**: The fibers in reinforced plastics can cause rapid wear on general-purpose end mills. Tools with specific geometries and coatings are needed to handle the abrasiveness and prevent delamination. Using general-purpose end mills on these materials can lead to poor surface finish, rapid tool wear, and potential tool failure, necessitating the use of specialized tools designed for the specific material properties.

Finishing end mills and roughing end mills are both used in milling operations but serve different purposes and have distinct characteristics. Roughing end mills are designed for removing large amounts of material quickly. They have a unique tooth design, often with serrated or "rippled" cutting edges, which helps break up the material into smaller chips, reducing the load on the tool and allowing for faster cutting speeds. This design minimizes vibration and heat generation, making roughing end mills ideal for heavy-duty operations. They typically have a higher helix angle and larger core diameter, providing greater strength and stability. Roughing end mills are used in the initial stages of machining to rapidly remove bulk material and shape the workpiece roughly to the desired form. Finishing end mills, on the other hand, are used for the final pass to achieve a smooth surface finish and precise dimensions. They have a more refined cutting edge with a higher number of flutes, which allows for finer cuts and a smoother finish. The cutting edges are sharper and more precise, and the helix angle is optimized for minimal deflection and vibration. Finishing end mills are used after roughing operations to refine the surface and achieve the final specifications of the part. They are typically used at slower speeds and feeds compared to roughing end mills to ensure accuracy and surface quality. In summary, roughing end mills are used for rapid material removal and shaping, while finishing end mills are used for precision and surface finish. The choice between them depends on the stage of the machining process and the desired outcome.

Carbide corner-radius end mills offer several benefits: 1. **Increased Tool Life**: The corner radius reduces the stress concentration at the tool's edge, minimizing chipping and extending the tool's lifespan. 2. **Improved Surface Finish**: The rounded edges produce a smoother surface finish compared to sharp-cornered end mills, reducing the need for additional finishing processes. 3. **Enhanced Strength and Durability**: The carbide material provides high hardness and wear resistance, making these end mills suitable for high-speed machining and tough materials. 4. **Reduced Vibration and Chatter**: The corner radius helps in stabilizing the cutting process, reducing vibrations and chatter, which can lead to better dimensional accuracy and surface quality. 5. **Versatility**: They can be used for a variety of applications, including slotting, profiling, and contouring, making them a versatile choice for different machining tasks. 6. **Higher Feed Rates**: The robust design allows for higher feed rates and speeds, improving productivity and efficiency in machining operations. 7. **Better Heat Resistance**: Carbide end mills can withstand higher temperatures, reducing the risk of thermal deformation and maintaining cutting performance. 8. **Reduced Tool Changes**: The durability and versatility of carbide corner-radius end mills can lead to fewer tool changes, saving time and reducing downtime in production. 9. **Cost-Effectiveness**: Although initially more expensive, their longer tool life and efficiency can lead to cost savings over time. 10. **Compatibility with Hard Materials**: They are ideal for machining hard materials like stainless steel, titanium, and hardened alloys, where other tools might fail. These benefits make carbide corner-radius end mills a preferred choice in precision machining, aerospace, automotive, and mold-making industries.

The purpose of the rounded corners on corner-radius end mills is to enhance tool performance and extend tool life. The rounded corners, or radii, help in reducing the stress concentration at the cutting edge, which minimizes the risk of chipping and breakage. This is particularly beneficial when machining harder materials or when the tool is subjected to heavy loads. The rounded edges also contribute to a smoother transition between the cutting edge and the tool body, which can improve the surface finish of the machined part by reducing the likelihood of tool marks and burrs. Additionally, corner-radius end mills are more versatile than square end mills, as they can be used for both roughing and finishing operations. The radius allows for better chip evacuation, reducing the chances of chip re-cutting and heat buildup, which can lead to longer tool life and improved machining efficiency. The rounded corners also help in distributing cutting forces more evenly, which can result in less vibration and chatter during the machining process, leading to higher precision and accuracy in the final product. In summary, the rounded corners on corner-radius end mills provide several advantages, including enhanced durability, improved surface finish, better chip evacuation, and reduced vibration, making them suitable for a wide range of applications and materials.