Shaft parts are the core transmission components of mechanical equipment, and their processing quality directly determines the operating accuracy and service life of the equipment. For machining practitioners, choosing the right machining shafts technology is the key to improving machining efficiency and ensuring product quality. This article will start from basic cognition, systematically sort out the core technologies of shaft machining, analyze the core points such as material selection and key influencing factors, and compare real cases and data to help you clearly grasp the applicable scenarios and advantages and disadvantages of various processing technologies, and accurately match production needs.
1. Introduction
1.1 Definition of machining
Machining refers to the process of changing the shape, size, and surface quality of the workpiece through various processing equipment (such as lathes, milling machines, grinding machines, etc.) to meet the design requirements. The core logic is to remove excess material or achieve material shaping through the relative movement of the tool to the workpiece. As an important branch of machining, shaft processing focuses more on accurately controlling key indicators such as rotary accuracy and shape tolerance because most of the shaft parts are rotary body structures.
1.2 Application and importance of axes
Shaft parts are widely used in core fields such as automobiles, motors, machine tools, and aerospace, and undertake the core functions of transmitting torque and supporting rotating parts. According to industry data, in precision machinery and equipment, the failure of shaft parts accounts for more than 30%, and its insufficient processing accuracy will directly lead to equipment vibration, increased noise, and even cause downtime failure. For example, if the machining accuracy of an automobile transmission axle exceeds 0.01mm, it will lead to poor gear meshing and shorten the service life of the gearbox by more than 40%, fully highlighting the importance of shaft machining.
2. Material selection of shaft
2.1 Common material types
The selection of materials for shaft processing needs to take into account strength, toughness and machinability, and the mainstream materials and characteristics in the industrial field are shown in the table below:
| Material type | Core features | Applicable scenarios |
| No. 45 steel | Medium carbon structural steel, moderate strength, good machinability, low cost | ordinary mechanical drive shafts, gear shafts |
| 40Cr | Alloy structural steel, excellent strength and toughness after quenching and quenching | Automobile gearbox shaft, machine tool spindle |
| 20CrMnTi | Carburized steel has high surface hardness and strong core toughness | High-speed precision motor shafts, construction machinery transmission shafts |
| Stainless steel 304 | Corrosion resistance, good toughness, and slightly poor machinability | Food machinery, chemical equipment shafts |
2.2 The influence of materials on processing technology
Material properties directly determine the selection and parameter setting of processing technology. For example, No. 45 steel has good machinability and is suitable for high-speed processing using conventional techniques such as turning and milling; However, stainless steel 304 is easy to stick to the knife and has a high cutting temperature, so it is necessary to choose laser processing or turning technology equipped with special coating tools. Case: When a machine factory processes 304 stainless steel shafts, ordinary turning technology is used in the early stage, and the tool wear rate reaches 80%/100 pieces, and after replacing it with laser cutting + precision grinding combination technology, the wear rate drops to 5%/100 pieces, and the processing efficiency is increased by 35%.
2.3 Considerations for material selection
The selection of shaft processing materials needs to combine three core factors: first, the demand for working conditions (such as high-speed operation and corrosive environments, high-strength and corrosion-resistant materials need to be selected); second, processing costs (low-cost materials such as No. 45 steel are preferred under ordinary working conditions); The third is the difficulty of processing (mass production needs to avoid materials with poor machinability and reduce process complexity).
3. Overview of machining technology
3.1 Turning
Turning is the most basic and commonly used technology for shaft machining, which realizes the processing of outer circles, inner holes, threads and other features through workpiece rotation and tool fixed feed. Its advantages are high processing efficiency and low cost, suitable for batch processing of rotary body shafts; The disadvantage is that the finishing accuracy is limited, and it needs to be combined with grinding technology to improve the accuracy. Applicable scenarios: rough machining and semi-finishing of ordinary drive shafts and gear shafts, mainly carbon steel and alloy steel.
3.2 Milling
Milling can process non-rotary features such as keyways, planes, and splines of shafts through tool rotation and workpiece movement. The core advantage is that the processing flexibility is strong and can realize multi-feature integrated processing; The disadvantage is that the processing speed is slow, suitable for small and medium-sized production. Example: When machining motor shafts with keyways, milling technology is used to directly machine the keyway on the turned shaft, without the need for secondary clamping, and the positioning accuracy is increased by 20%.
3.3 Grinding
Grinding is the core technology of shaft finishing, which can control the surface roughness below Ra0.8 and the roundness error within 0.005mm by rotating the workpiece at high speed through the grinding wheel. The advantage is that the processing accuracy is extremely high, which is suitable for the final processing of precision shafts; The disadvantages are low efficiency and high cost. Applicable scenarios: finishing of precision shafts such as machine tool spindles and high-speed motor shafts.
3.4 EDM
EDM uses EDM corrosive materials, which are suitable for processing difficult-to-machine materials with high hardness and strong toughness (such as mold steel, carbide shafts). The advantage is that complex shapes can be processed, and there is no limit to the hardness of the material; The disadvantage is extremely low processing efficiency and poor surface roughness. Applicable scenarios: local processing of special materials or complex structural shafts (such as special-shaped holes on the shaft).
3.5 Laser processing
Laser processing realizes material cutting, punching, and surface modification through high-energy laser beams, which has the advantages of high processing accuracy, small thermal deformation, and non-contact processing. The disadvantage is that the equipment cost is high, suitable for high-precision, thin-walled shaft machining. Applicable scenarios: machining of precision electronic equipment shafts and thin-walled stainless steel shafts.
4. Key factors in the processing process
4.1 Tool selection and maintenance
Tools are the core element that affects the quality of machining: carbide tools (such as CCMT09T304) are used for turning carbon steel, high-speed steel end mills are used for milling, and CBN grinding wheels are used for grinding. At the same time, it is necessary to establish a maintenance mechanism, replace the tool runout immediately when it exceeds 0.005mm, and store it daily to avoid collision damage to the cutting edge.
4.2 Optimization of processing parameters
The core parameters include cutting speed, feed rate, and depth of cut, which need to be set according to the material and technology. For example, the recommended parameters for No. 45 steel turning (diameter 50mm): cutting speed 120-150m/min, feed rate 0.15-0.2mm/r; Recommended parameters for grinding processing: grinding wheel speed 3000r/min, feed rate 0.01-0.02mm/r. Blindly increasing the cutting speed will lead to increased tool wear and reduced machining accuracy.
4.3 Cooling and lubrication technology
Cooling lubrication reduces cutting temperatures and reduces tool wear. emulsion is selected for turning and milling processing, and the cooling and lubrication are balanced; Cutting oil is selected for grinding to improve lubricity; Extreme pressure cutting oil is used for stainless steel processing to avoid sticking knives. A processing plant has increased the service life of tools by 50% by optimizing the cooling system.
4.4 Machining accuracy and surface quality control
The control accuracy needs to start from three aspects: first, equipment calibration, regular calibration of the machine tool coordinate system, and the error is controlled within 0.001mm; the second is clamping optimization, the long shaft adopts the "three-jaw chuck + top" combination clamping to reduce deformation; The third is process monitoring, using infrared thermometers and vibration monitors to monitor the processing status in real time.
5. Conclusion
Different shaft machining technologies have their own advantages and disadvantages, and need to be accurately matched according to production needs: turning is suitable for batch conventional shaft processing, and the advantage is high efficiency and low cost; Milling is suitable for multi-feature shaft machining, and the advantage is strong flexibility; Grinding is suitable for precision shaft finishing, and the advantage is extremely high precision; EDM is suitable for the processing of complex features of difficult-to-machine materials, and the advantage is that it has a wide range of applicability; Laser processing is suitable for high-precision thin-walled shaft machining, and the advantage is that the deformation is small. In actual production, the combination process of "turning roughing + milling feature processing + grinding finishing" is mostly adopted, taking into account efficiency and precision.
As an enterprise focusing on precision machining technology, we believe that the core of shaft machining technology selection is "working condition adaptation + efficiency cost balance". Conventional turning + grinding combination is preferred under ordinary working conditions to control costs; Advanced technologies such as lasers and electrical sparks can be introduced under precise or special working conditions. In the future, intelligent processing technology will become the mainstream, and optimizing the machining process through digital twins, real-time monitoring and other technologies can further improve accuracy and efficiency. Enterprises need to combine their own product positioning, reasonably match traditional and advanced technology, and build an efficient processing system.
FAQ
1. Batch processing of ordinary drive shafts, which processing technology is the most cost-effective? Priority is given to the technical solution of "turning roughing + semi-finishing", which has high turning efficiency and low equipment cost, which can meet the accuracy requirements of ordinary drive shafts (±0.01mm), and the unit cost can be reduced by more than 40% during batch processing. If you need to improve the accuracy, you can add a grinding finish.
2. Which technology is most suitable for machining carbide shafts? The combined EDM + grinding technique is recommended. Carbide has high hardness, conventional turning and milling tools wear too quickly, EDM can achieve non-contact corrosion processing, and improve surface quality with grinding finishing, which can effectively ensure machining accuracy and efficiency.
3. How to improve the surface roughness of shaft machining? There are three core measures: first, grinding and finishing, and CBN grinding wheels; second, optimize cooling lubrication, select high-quality cutting oil to ensure full lubrication; The third is to control the processing parameters, reduce the grinding feed rate, and increase the grinding wheel speed.
4. Thin-walled shaft machining is prone to deformation, which technology should I choose? Preferential choice is given to the combination technology of laser processing + precision grinding. laser processing is non-contact processing, with low thermal deformation; When combined with grinding finishing, small cutting depth, slow feed rate, and elastic clamping are used to control the deformation within 0.005mm.
