Cutting speed
What is Cutting Speed?
Cutting speed defines how fast the cutting edge of a tool moves along the surface of the material during machining. The unit for cutting speed is meters per minute (m/min), and it indicates how many meters the tool's cutting edge travels across the workpiece material's surface in one minute. This speed directly affects the efficiency of the machining process, the quality of the finished product, and the lifespan of the tool.
The Importance of Cutting Speed in Machining
Cutting speed is one of the most critical machining parameters in machining. Optimizing it is essential, as it determines how quickly material is removed from the workpiece. If the cutting speed is too high, the tool can overheat and wear out more quickly, which may lower the achieved surface quality. On the other hand, if the cutting speed is too low, it can reduce process efficiency and increase production time.
Factors Affecting Cutting Speed
Workpiece material: Different materials require different cutting speeds. For example, softer materials like aluminum can withstand higher speeds, while harder materials such as steel or titanium require lower speeds to avoid overheating.
- Tool material and geometry: The tool's material is one of the most significant factors affecting cutting speed. Tools can be made from materials such as carbide, high-speed steel (HSS), HSCo, CBN, PCD, or cermet. Carbide tools can handle higher speeds compared to those made from high-speed steel. HSCo tools are also very popular due to their hardness and wear resistance, and they can withstand much higher temperatures than standard HSS. CBN and PCD tools are suitable for machining very hard and abrasive materials, allowing even higher cutting speeds. Cermet tools, which combine the properties of ceramics and metals, are extremely durable and precise.
- Coatings: Tool coatings have a significant influence on cutting speed. The most common coatings are CVD (Chemical Vapor Deposition) and PVD (Physical Vapor Deposition). CVD coatings, such as titanium nitride (TiN), titanium aluminum nitride (TiAlN), and titanium carbonitride (TiCN), provide good adhesion and wear resistance, enabling higher cutting speeds. PVD coatings enhance tool hardness and temperature resistance, which allows for faster machining of harder materials.
- Machine tool characteristics: The rigidity, power, and speed capacity of a machine also affect the choice of cutting speed. More rigid and powerful machines enable higher cutting speeds without compromising machine performance.
- Cooling and lubrication: Cutting fluids (coolants and lubricants) have a major impact on cutting speed. Good cooling helps keep the tool temperature low and extends its lifespan, enabling the use of higher cutting speeds.
Optimizing Cutting Speed
Optimizing cutting speed often relies on experiments and recommendations from tool manufacturers. Tool manufacturers usually provide guidelines and calculators to help determine the correct machining parameters for different materials and conditions. It's also important to take into account the characteristics of the machine and consider the entire process to ensure that the selected values are optimal.
Optimizing cutting speed not only improves surface quality and process efficiency, but also saves costs by reducing tool wear and extending tool life. This means lower tool and downtime costs, which is especially important in serial production and long-term projects.
Summary
Cutting speed is an essential factor for the quality and efficiency of machining. It directly affects surface finish, tool durability, and process speed. The optimal cutting speed can be achieved by considering the properties of the material being machined, the tool's material and geometric factors, as well as tool coatings like CVD and PVD. Machine tool characteristics, along with effective cooling and lubrication, are also crucial in enabling higher cutting speeds. By utilizing the recommendations and calculators provided by tool manufacturers, you can ensure that the selected machining parameters are as efficient and cost-effective as possible.
