Performance characteristics and applications of high-speed steel end mills

High-speed steel end mills, as key tools in metal cutting processes, have performance characteristics closely related to their application fields. The following is an analysis from three dimensions: core performance, processing adaptability, and typical application scenarios:

First, core performance characteristics

High hardness and thermal stability

High-speed steel end mills can still maintain a hardness of 55-60HRC at a high temperature of 600℃. This feature enables them to maintain the sharpness of the cutting edge for a long time during high-speed cutting. For instance, when processing 45# steel, even if the cutting speed reaches 30m/min and the tool tip temperature rises to 550℃, stable cutting can still be achieved, avoiding accelerated wear caused by thermal softening.

Toughness and impact resistance

Its internal organizational structure combines high strength and toughness, and can withstand the impact load during the cutting process. For instance, when processing cast iron, the cutting tools need to withstand the impact of hard particles inside the material. The anti-chipping ability of high-speed steel end mills is 30% higher than that of carbide tools, and the chip breakage rate is 25% lower.

Grindability and processing economy

The grinding coefficient of high-speed steel is only one-third that of cemented carbide, the grinding efficiency is increased by 40%, and the surface roughness of the ground surface can reach Ra0.4μm. This feature makes the tool easier to grind in complex contour processing, and the grinding cost of a single tool is 60% lower than that of cemented carbide.

Second, processing adaptability analysis

Advantages of low-speed and heavy-load cutting

When processing viscous materials such as 304 stainless steel, high-speed steel end mills can effectively reduce the formation of built-up edge by lowering the cutting speed (to 15-25m/min). For example, when processing 304 stainless steel plates with a thickness of 8mm, a three-tooth coarse-tooth end mill is used, with a feed rate of 0.1mm per tooth. The surface roughness can reach Ra1.6μm, and the tool life is extended to 1.5 times that of carbide tools.

Multi-edge teeth and chip-holding space design

Fine-toothed end mills (with 5-10 teeth) are suitable for semi-finishing. For instance, when machining the cavities of aluminum alloy molds, by increasing the number of teeth to 8 and combining it with a 35° helix Angle design, the chip removal efficiency can be enhanced by 35%, while the surface quality can reach Ra0.8μm. Coarse-toothed end mills (with 3 to 6 teeth) are more suitable for roughening processes. When processing HT250 gray cast iron, the single-tooth cutting allowance can reach 0.5mm, and the material removal rate is increased by 40%.

Handle structure and clamping stability

Straight shank end mills (with diameters ranging from 2 to 20mm) are suitable for the miniaturization processing of CNC milling machines. For instance, when processing precision electronic components, by keeping the clamping length within three times the diameter, it can ensure that the radial runout is ≤0.01mm. Mohs taper holders (with diameters ranging from 6 to 63mm) and 7:24 taper holders (with diameters ranging from 25 to 80mm) are widely used in large-scale machining centers. When processing aviation aluminum alloy structural components, the clamping repeat positioning accuracy of taper holder tools can reach 0.005mm.

Third, typical application scenarios

The field of mold manufacturing

When processing automotive body panel molds, high-speed steel ball end mills are used for curved surface finishing. Through the combined design of a helix Angle of 40° and a rake Angle of 15°, a surface quality of Ra0.4μm can be achieved, and the cost is reduced by 40% compared with hard alloy tools. For example, when processing the engine hood mold of A certain vehicle model, a single tool can complete 200 hours of continuous processing, and the surface finish meets the requirements of grade A surface.

Repair and fitting of mechanical parts

When repairing broken machine tool guide rails, high-speed steel end mills can quickly remove the damaged layer by combining low speed (5-10m/min) with large cutting depth (0.8-1.2mm). For example, when repairing the X-axis guide rail of a certain CNC milling machine, a coarse-toothed end mill with a diameter of 16mm was used. A single pass could complete a 0.5mm deep repair, and the processing efficiency was three times higher than that of electrical discharge repair.

Teaching and experimental scenarios

In the numerical control processing training of vocational colleges, high-speed steel end mills have become the first choice for entry-level training due to their low cost (the price of a single one is only 1/5 of that of hard alloy) and high safety. For instance, in the practical training of CNC milling machines in a certain vocational college, students can master the influence of tool geometric parameters on processing quality by repeatedly grinding high-speed steel end mills. The practical training cost is 80% lower than that of using carbide tools.