The Difference and Tool Selection of CNC Roughing and Finishing

Introduction
CNC (Computer Numerical Control) machining is a widely used and efficient method of manufacturing complex parts. CNC machining includes roughing and finishing processes, which are essential for producing high-quality parts. Both processes involve the use of cutting tools, but they differ in their cutting strategies, surface finish, and tool selection. This article will discuss the differences between CNC roughing and finishing and the tool selection for each process.

1. CNC Roughing
CNC roughing involves the removal of large amounts of material from a workpiece, typically at high speeds and feeds. The goal of roughing is to remove the bulk of the material and leave a small amount for finishing. Roughing tools are designed to remove material quickly and efficiently, with little regard for surface finish. Carbide roughing end mills, for example, are designed with larger flutes and a higher helix angle to remove material more aggressively. Roughing tools are also designed to be more durable than finishing tools, as they are subjected to higher forces and more wear.

2. CNC Finishing
CNC finishing is the final step in machining a part and involves removing small amounts of material to achieve the desired surface finish and dimensional accuracy. Finishing tools are designed to be very precise and leave a smooth surface finish. Carbide finishing end mills, for example, have sharper edges and smaller flutes to create a smoother surface finish. Finishing tools are also designed to be more delicate than roughing tools, as they are subjected to less force and wear.

3. Tool Selection for Roughing
Roughing requires tools that are capable of removing large amounts of material quickly and efficiently, while also being able to withstand high forces and wear. Carbide roughing end mills are the most common tool used for roughing. They are available with a range of flute geometries and coatings, with larger flutes being ideal for removing large amounts of material quickly, and coatings like AlTiN (Aluminum Titanium Nitride) providing excellent heat and wear resistance.

4. Tool Selection for Finishing
Finishing requires tools that are capable of achieving high precision and smooth surface finishes. Carbide finishing end mills are the most common tool used for finishing. They are available with a range of flute geometries and coatings, with sharper edges and smaller flutes being ideal for creating a smoother surface finish, and coatings like TiSiN (Titanium Silicon Nitride) providing high heat and wear resistance and low coefficient of friction.

In conclusion, CNC roughing and finishing are two essential processes in CNC machining. Each process requires specific cutting strategies and tool selection to produce high-quality parts efficiently. By understanding the differences between roughing and finishing and selecting the appropriate tools for each process, manufacturers can improve their production efficiency and the quality of their finished parts.