1. Introduction
1.1 The importance of cutting speed
In milling processing, cutting speed is one of the core parameters that determine machining efficiency, workpiece quality, and production cost. Excessive cutting speed can lead to rapid tool wear, excessive surface roughness of the workpiece, and even machining vibration. Too low will greatly reduce production efficiency and increase the time cost per workpiece. A practical case of an auto parts processing plant showed that reasonable matching of cutting speed can extend tool life by 30% and increase machining efficiency by 25%, fully confirming its key role.
1.2 Overview of the purpose
This article aims to sort out the six core factors affecting milling cutting speed for senior machining practitioners and process engineers, and help everyone establish systematic cognition. This article will start from the basic definition of cutting speed, analyze the mechanism of each influencing factor one by one, and finally introduce the use of cutting speed calculator milling, and attach practical FAQs to provide guidance for parameter optimization in actual machining.
2. Definition of cutting speed
2.1 Basic concepts of cutting speed
Cutting speed refers to the linear speed of a certain point on the cutting edge of the milling cutter relative to the machined surface of the workpiece, usually in m/min (meters/min). The core calculation formula is: v = π×D×n/1000 (where v is the cutting speed, D is the tool diameter mm, and n is the tool speed r/min), which is the theoretical basis for the subsequent use of cutting speed calculator milling.
2.2 The role of cutting speed in milling
The cutting speed directly determines the cutting temperature, cutting force distribution, and material removal efficiency during the milling process. The appropriate cutting speed can allow the tool and the workpiece to form a stable cutting state, which not only ensures the rapid removal of materials, but also controls the cutting heat within a reasonable range to avoid thermal deformation of the workpiece material.
3. Tool material
3.1 Types of tool materials
Common milling cutter materials are mainly divided into 4 categories: high-speed steel (HSS), carbide, ceramic, and PCD (polycrystalline diamond). The physical properties of different materials vary significantly, as follows:
| Tool material | Hardness (HRC) | Heat resistance temperature (°C) | Applicable scenarios |
|---|---|---|---|
| High-speed steel | 62-65 | 550-650 | Low-speed milling of ordinary steel and aluminum |
| Carbide | 85-90 | 800-1000 | Medium to high-speed milling, difficult-to-machine materials |
| Ceramics | 90-95 | 1200-1400 | High-speed milling of hardened steels and superalloys |
| PCD | 95 or higher | 700-800 | High-speed finishing of non-ferrous metals and non-metals |
3.2 The influence of different materials on cutting speed
The heat resistance of the tool material directly determines the maximum cutting speed. For example, when machining 45 steel, the recommended cutting speed for high-speed steel tools is only 20-40m/min, while carbide tools can be increased to 100-150m/min. When a precision machinery factory processes stainless steel 304, after replacing the high-speed steel milling cutter with a carbide milling cutter, the cutting speed is increased from 35m/min to 90m/min, the machining efficiency is increased by 157%, and the tool wear is reduced by 40%.
4. Tool geometry
4.1 Basic elements of tool geometry
The geometric elements of the tool that affect the cutting speed mainly include: rake angle, back angle, helix angle, and number of teeth. The rake angle determines the sharpness of the cutting edge, the rural angle affects the friction between the tool and the workpiece, the helix angle is related to the distribution of cutting force, and the number of teeth is directly related to the material removal efficiency.
4.2 The relationship between tool geometry and cutting speed
Sharp positive rake tools can reduce cutting resistance and appropriately increase cutting speed; When processing hard materials, negative rake angle tools are used to enhance the edge strength and reduce the cutting speed. Taking milling aluminum alloy as an example, the cutting speed can reach 300-500m/min with a milling cutter with a large rake angle of 30° and a helix angle of 45°. If a negative rake angle milling cutter is used, the cutting speed needs to be reduced to 150-250m/min under the same working conditions, otherwise it is easy to cause tool chipping.
5. Workpiece material
5.1 Classification of workpiece materials
According to the processing difficulty, it can be divided into three categories: easy-to-cut materials (such as aluminum alloy, mild steel), medium-difficult materials (such as medium carbon steel, cast iron), and difficult-to-cut materials (such as stainless steel, superalloys).
5.2 The effect of workpiece material on cutting speed
The hardness, strength, and thermal conductivity of the workpiece material are the core indicators affecting the cutting speed. The higher the hardness and the worse the thermal conductivity, the lower the cutting speed. For example: processing 6061 aluminum alloy (hardness HB60-80), the cutting speed can reach 200-400m/min; Processing No. 45 steel (hardness HB170-210), the cutting speed is reduced to 100-150m/min; Machining Inconel 718 superalloy (hardness HB300-350), the cutting speed can only be maintained at 20-50 m/min.
6. Use of cutting fluid
6.1 Type of cutting fluid
Common cutting fluids are divided into two categories: oil-based cutting fluids (good lubricity) and water-based cutting fluids (good cooling, including emulsions, semi-synthetic fluids, and fully synthetic fluids).
6.2 Effect of cutting fluid on cutting speed
High-quality cutting fluids can reduce cutting temperatures and reduce tool wear through cooling, lubrication, and chip evacuation, thereby increasing the upper limit of cutting speed. When milling 40Cr steel in a mechanical processing plant, the cutting speed can only reach 80m/min without cutting fluid, and after using fully synthetic water-based cutting fluid, the cutting speed can be increased to 120m/min, and the tool life is extended by 50%. Note: When processing aluminum alloys, special cutting fluid should be selected to avoid sticking knives affecting the cutting speed.
7. Feed rate
7.1 Definition of Feed Rate
The feed rate refers to the moving speed of the workpiece relative to the tool per unit time, in mm/min, which together with the cutting speed determines the machining efficiency.
7.2 The relationship between feed rate and cutting speed
The two are mutually restrictive: under the same power machine, increasing the feed rate requires an appropriate reduction in the cutting speed, and vice versa. For example, when using a φ10mm carbide milling cutter to process No. 45 steel, the cutting speed can be set to 150m/min when the feed rate is 100mm/min; If the feed rate is increased to 200mm/min, the cutting speed needs to be reduced to 100m/min, otherwise the machine will be overloaded due to excessive cutting force.
8. Depth of cut
8.1 The concept of depth of cutting
Cutting depth refers to the depth at which the tool cuts into the workpiece, which is divided into back cut (radial cutting depth) and side cutting (axial cutting depth), which directly affects the cutting force.
8.2 Effect of cutting depth on cutting speed
The larger the cutting depth, the greater the cutting force and the more cutting heat, and the cutting speed needs to be reduced. For example, when milling No. 45 steel, the cutting speed can be set to 120m/min when the cutting depth is 2mm; If the cutting depth is increased to 5mm, the cutting speed needs to be reduced to 80m/min to avoid overheating and wear of the tool.
9. Use of a cutting speed calculator
9.1 Functions of the Cutting Speed Calculator
The cutting speed calculator milling can quickly and accurately calculate the reasonable cutting speed according to the tool diameter, rotation speed, workpiece material, tool material and other parameters, and can calculate the required tool speed in reverse, avoid manual calculation errors, and improve the parameter matching efficiency.
9.2 How to Mill with the Cutting Speed Calculator
The steps to use are simple and easy to understand, as follows:
- Input tool parameters: select the tool type, fill in the tool diameter (mm) and the number of teeth;
- Select material parameters: check the workpiece material (such as No. 45 steel, aluminum alloy) and tool material (such as carbide and high-speed steel) respectively;
- Input machining parameters: fill in feed rate (mm/min), depth of cutting (mm);
- Click Calculate to get the recommended cutting speed and corresponding tool speed, and if the result shows "too high load", you can adjust the feed rate or cutting depth according to the prompts.
10. Conclusion
The milling cutting speed is affected by six factors: tool material, tool geometry, workpiece material, cutting fluid, feed rate, and cutting depth, which are interrelated and mutually restricted. In actual machining, it is necessary to accurately match parameters based on specific working conditions, and cutting speed calculator milling is a practical tool to improve the efficiency and accuracy of parameter matching. Reasonable control of cutting speed can achieve the optimal balance between processing efficiency, workpiece quality and production cost.
Yigu Technology Perspective
Yigu Technology believes that optimizing cutting speed in milling is one of the fundamental aspects of achieving intelligent manufacturing. With the upgrading of machining technology, the intelligent level of cutting speed calculator milling will continue to improve, and it is expected that dynamic parameter adjustment will be achieved in combination with real-time machining data in the future. Enterprises should pay attention to the matching law of cutting speed and various influencing factors, improve the process level with the help of professional computing tools, and pay attention to the innovation of supporting technologies such as tool materials and cutting fluids, so as to further tap the potential for improving processing efficiency.
FAQ
Q1: When using the cutting speed calculator milling, will the missing parameters affect the results?
Yes. Tool diameter, workpiece material, and tool material are the core required parameters, and the lack of these parameters will lead to excessive deviation of the calculation results or even failure. If the feed rate and cutting depth are unknown, you can refer to the built-in default recommended value in the calculator and fine-tune it according to the actual machining effect.
Q2: When machining difficult-to-cut materials, in addition to reducing the cutting speed, what other ways can it be optimized and optimized?
It can be combined with cemented carbide or ceramic tools, and a special cutting fluid with excellent cooling and lubrication performance can be selected to appropriately reduce the feed rate and cutting depth, while ensuring that the machine tool is rigid enough to avoid vibration affecting machining stability.
Q3: How can I quickly switch parameters with the cutting speed calculator when processing different materials with the same milling cutter?
Most cutting speed calculators support parameter saving and quick switching functions, you can save the current tool parameters first, and after switching the workpiece material, you only need to re-select the workpiece material type, and the calculator will automatically match the cutting speed reference value corresponding to the material, and then combine the feed and cutting depth fine-tuning.
