Disc gear milling cutter
Disc gear milling cutters are specialized tools used for milling gear teeth. They are disc-shaped with multiple cutting edges with specific tooth profiles distributed around their circumference. They are suitable for machining various gear types, including spur and helical gears. Depending on the gear module and tooth profile, disc gear milling cutters are categorized as modular and diametral cutters. Modular cutters are the most widely used and are available in sizes ranging from 0.3 to 50 mm. Disc gear milling cutters are typically made of high-speed steel or carbide. High-speed steel cutters offer excellent toughness and sharpness, making them suitable for low-speed milling and form milling. Carbide disc gear milling cutters, on the other hand, offer high wear resistance and cutting speed, making them suitable for high-volume gear machining. An automotive gear manufacturer uses carbide disc gear milling cutters to machine 5mm module spur gears, achieving a milling speed of 120 m/min, three times faster than high-speed steel cutters, significantly improving production efficiency.
The tooth profile design of a disc gear milling cutter directly impacts gear machining accuracy. The cutter’s tooth profile must perfectly match the tooth groove shape of the gear being machined, ensuring proper meshing. Because gears of the same module have different tooth counts, the involute curvature of their tooth profiles also varies. To reduce cutter specifications, cutters of the same module are typically divided into sets of eight, each designed to machine gears with different tooth counts. Cutter No. 1 is used for gears with 12-13 teeth, while cutter No. 8 is used for gears or racks with 135 or more teeth. The cutter’s tooth profile accuracy must meet high standards, with profile errors generally controlled within 0.01-0.03mm to ensure smooth transmission of the finished gear. A disc gear milling cutter produced by a precision instrument factory uses precision grinding to ensure tooth profile accuracy, keeping the transmission error of the machined gears within 0.02mm, meeting the requirements for high-precision gearboxes.
The structural parameters of disc gear milling cutters significantly influence milling performance. The cutter diameter is determined by the gear module and the specifications of the machining machine. Larger diameter cutters offer higher linear speeds and greater rigidity, making them suitable for machining large-module gears, but also come with relatively high tool costs. Smaller diameter cutters are suitable for machining small-module gears and those with complex structures. The number of teeth (cutting edges) of the cutter should be selected based on the material being machined and the surface quality requirements. Cutters with a high number of teeth offer smoother cutting and better surface quality, but have poorer chip evacuation. Cutters with a low number of teeth offer smoother chip evacuation and are suitable for roughing. The cutter’s rake and clearance angles must be designed to balance cutting sharpness and blade strength. When machining steel, the rake angle should be 10°-15°, and the clearance angle 6°-10°; when machining cast iron, the rake angle should be 0°-5°, and the clearance angle 5°-8°. A gear processing company has improved the durability of its disc gear milling cutter by 25% by optimizing the structural parameters of the cutter, and reduced the surface roughness of the processed gears from Ra3.2μm to Ra1.6μm.
The milling process parameters for disc gear milling cutters must be set based on the gear material, module, and precision requirements. The choice of cutting speed is related to the tool and workpiece materials. High-speed steel milling cutters typically have a cutting speed of 15-30 m/min for steel gears and 10-20 m/min for cast iron gears. Carbide milling cutters can increase the cutting speed to 80-150 m/min for steel gears and 60-100 m/min for cast iron gears. Feed rate is typically expressed as per-tooth feed, with a range of 0.1-0.3 mm/s for rough milling and 0.05-0.1 mm/s for fine milling to ensure tooth surface quality. The milling depth is determined by the full tooth height of the gear and is completed in one or more passes. For gears with larger modules, a layered milling method is used, with each pass controlled to a depth of 1-3 mm to reduce tool load. When a motorcycle gear factory processes gears with a module of 3mm, it uses a carbide disc milling cutter with a cutting speed of 100m/min and a feed per tooth of 0.15mm/z. The tooth profile is processed in two passes, which not only ensures processing efficiency but also meets the gear precision requirements.
The use and maintenance of disc gear milling cutters are key to extending their lifespan. Before use, inspect the cutter’s cutting edge for sharpness and defects such as chipping and cracks. During installation, ensure the cutter is accurately positioned on the cutter shaft, with radial runout controlled within 0.01-0.03mm. Adequate cutting fluid is required during milling. High-speed steel cutters should use an emulsion, while carbide cutters can use extreme-pressure cutting oil to reduce cutting temperatures and tool wear. After use, if the cutter’s cutting edge wear or tooth profile accuracy deteriorates, it should be sharpened promptly. After sharpening, the cutter must maintain the original tooth profile parameters and angles to ensure accurate gear processing. A gear manufacturer has established a strict maintenance procedure for disc gear milling cutters, regularly inspecting and sharpening the cutters. This has extended the average cutter lifespan by 40%, saving nearly 200,000 yuan in tool costs annually. With the development of CNC technology, the combination of disc gear milling cutters and CNC milling machines is becoming increasingly close. By controlling the motion trajectory of the milling cutter through CNC programs, gears with higher precision and more complex shapes can be processed, providing strong support for the development of gear processing technology.
