1, Basic concepts and influencing factors of feed rate
Feed rate, also known as feed rate, refers to the speed at which the tool moves relative to the workpiece in the feed direction. In CNC lathe machining, feed rate is usually expressed as the distance the tool moves per minute (mm/min) or the distance the tool moves per second (mm/s). The selection of feed rate is influenced by various factors, including but not limited to the following:
Workpiece material: The physical properties such as hardness, toughness, and thermal conductivity of different materials have a direct impact on tool wear and cutting force, thereby affecting the selection of feed rate.
Tool material and type: The material (such as hard alloy, ceramic, cubic boron nitride, etc.) and geometric shape (such as rake angle, rake angle, rake angle, etc.) of the tool determine its cutting performance and durability, which in turn affects the feed rate.
Cutting parameters: There is a certain relationship and mutual constraint between cutting speed, cutting depth (back cutting amount), and feed rate. Reasonably adjusting these parameters can optimize the machining process while maintaining cutting efficiency and machining quality.
Machine performance: The performance parameters such as stiffness, accuracy, power, and control system of the machine limit the range of feed rate selection.
Processing requirements: The dimensional accuracy, surface smoothness, processing efficiency, and other requirements of the workpiece are also important factors to consider when selecting the feed rate.
2, Selection of feed rate for rough machining
The main purpose of rough machining is to quickly remove a large amount of metal from the surface of the workpiece to approximate the final shape and size. In the rough machining process, larger cutting depths and higher feed rates are usually allowed to improve machining efficiency. However, excessively high feed rates may lead to increased tool wear, increased cutting force, and decreased surface quality of the workpiece.
For most materials, the feed rate for rough machining is typically within the following range:
Soft materials such as cast iron and aluminum alloy: feed rates can reach up to 200-500mm/min, or even higher, depending on the performance of the cutting tool and machine tool.
Hard materials such as steel and stainless steel: The feed rate is relatively low, generally between 100-300mm/min, to avoid rapid tool wear and excessive cutting force.
It should be noted that the selection of feed rate for rough machining also needs to consider the durability of the tool and the load-bearing capacity of the machine tool. When the stiffness of the machine tool allows, the feed rate should be increased as much as possible, but should not exceed the limit values of the tool and machine tool.
3, Selection of feed rate for precision machining
The main purpose of precision machining is to further remove machining allowance on the basis of rough machining, improve the dimensional accuracy and surface smoothness of the workpiece. In the precision machining process, it is necessary to strictly control the cutting depth and feed rate to ensure machining quality and tool life.
For most materials, the feed rate for precision machining is typically within the following range:
Soft materials such as cast iron and aluminum alloy: The feed rate is generally between 50-200mm/min, depending on the machining requirements and tool performance.
Hard materials such as steel and stainless steel: The feed rate is lower, generally between 20-100mm/min, to avoid excessive cutting force and scratches on the surface of the workpiece.
During the precision machining process, the following points should also be noted:
Choose appropriate cutting tools: High precision and durable cutting tools should be selected for precision machining, such as hard alloy cutting tools or cubic boron nitride cutting tools.
Optimize cutting parameters: While maintaining machining quality, minimize cutting depth and feed rate as much as possible to reduce cutting force and cutting heat.
Using cutting fluid: Cutting fluid helps to reduce cutting temperature and friction coefficient, minimize tool wear and workpiece deformation, and improve machining quality and tool life.
