Classification of Extrusion Taps by Manufacturing Materials
1. HSS Extrusion Taps (High-Speed Steel Extrusion Taps)
HSS extrusion taps are made of high-speed steel, a kind of alloy steel containing tungsten, molybdenum, chromium, and vanadium, which endows the taps with basic heat resistance and toughness. As the most common and cost-effective type, they are widely used in general precision machining scenarios.
Key Material Characteristics
- Hardness: HRC 62-65, which can maintain good edge retention during moderate-speed machining and soften when the temperature reaches around 600°C.
- Toughness: High toughness and good shock resistance, not easy to break or chip under slight external impact, and can be resharpened multiple times for repeated use.
- Cost-Effective: Lower production cost compared with other high-performance material taps, suitable for small-batch production and general machining needs.
Applicable Scenarios
Ideal for machining internal threads of low-hardness ductile materials, including low-carbon steel, aluminum alloys, copper, brass, and other non-ferrous metals. It is widely used in general machinery manufacturing, hardware processing, and small-batch production fields where the requirements for thread precision and tool life are not extremely high.
Note: Not suitable for high-speed machining or machining of high-hardness materials (above HRC 30), as it is prone to rapid wear and reduced service life.
2. HSS-E Extrusion Taps (Cobalt High-Speed Steel Extrusion Taps)
HSS-E extrusion taps are upgraded versions of HSS extrusion taps, made of high-speed steel added with 5%-8% cobalt alloy (also known as HSSE), which significantly improves the material’s hot hardness and wear resistance. They are the most widely used high-performance extrusion taps in industrial production, especially in medium and high-precision machining fields.
Key Material Characteristics
- Hot Hardness: Excellent red hardness, which can retain high hardness at elevated temperatures (up to 650-700°C), suitable for high-speed continuous machining without softening or deformation.
- Wear Resistance: 3-5 times higher than that of standard HSS extrusion taps, with longer service life, which can reduce tool change frequency and production downtime.
- Toughness: While improving wear resistance, it still maintains good toughness, resisting chipping and breaking under heavy machining forces, and is compatible with most CNC and automatic lathe machining.
Applicable Scenarios
Widely used in high-volume, medium-precision machining, suitable for a variety of materials, including stainless steel (304/316), carbon steel, alloy steel (up to HRC 45), aluminum alloys, and copper alloys. It is the preferred tool for automotive, hydraulic, pneumatic, and electronic 3C industries, such as machining thread holes of auto engine parts, hydraulic fittings, and 3C product casings.
3. PM-HSS Extrusion Taps (Powder Metallurgy High-Speed Steel Extrusion Taps)
PM-HSS extrusion taps are made of powder metallurgy high-speed steel, which is produced by sintering ultra-fine metal powder under high temperature and pressure. This advanced manufacturing process makes the material structure more uniform, with finer grains and no internal defects, thus achieving better comprehensive performance than traditional HSS and HSS-E materials.
Key Material Characteristics
- Uniform Structure: Ultra-fine grain structure (grain size below 10μm) ensures consistent hardness and toughness, avoiding performance differences caused by uneven structure of traditional cast steel.
- High Hardness & Toughness: Hardness up to HRC 66-68, which is higher than HSS-E, and at the same time maintains excellent toughness, realizing the balance between wear resistance and impact resistance.
- High Wear Resistance & Corrosion Resistance: The uniform structure makes the surface of the tap more smooth, reducing friction during machining, and improving wear resistance and corrosion resistance, which is not easy to produce adhesion with the workpiece material.
Applicable Scenarios
Suitable for high-precision, high-speed, and high-demand machining scenarios, such as machining high-hardness alloy steel, stainless steel, and heat-resistant alloy materials (up to HRC 50). It is widely used in aerospace, precision machinery, medical equipment, and other industries, such as machining thread holes of aircraft structural parts, precision measuring instruments, and medical device components.
Note: The production cost is higher than HSS and HSS-E, which is suitable for high-precision and high-value-added machining needs.
4. Carbide Extrusion Taps (Tungsten Carbide Extrusion Taps)
Carbide extrusion taps are made of tungsten carbide (WC) as the main component, bonded with cobalt (Co) (cobalt content is usually 6%-12%), forming a metal-ceramic composite material with extremely high hardness. They are the top-grade products in extrusion taps, mainly used for ultra-high precision and high-hardness material machining.
Key Material Characteristics
- Extreme Hardness: Hardness up to HRC 70-90, which is much higher than HSS and HSS-E, and can retain hardness at temperatures up to 1000°C, suitable for machining high-hardness materials (above HRC 50).
- Super Wear Resistance: The service life is 5-20 times that of HSS taps and 3-5 times that of HSS-E taps, which can significantly reduce tool change frequency and production cost in high-volume machining.
- High Precision: The material has good dimensional stability, and the tap processed by precision CNC grinding has extremely high dimensional accuracy and thread profile accuracy, which can achieve ISO 1-2 class thread precision.
- Brittleness: High hardness leads to relatively high brittleness, poor shock resistance, and easy breakage under improper operation (such as excessive torque or uneven force), so it requires high machining stability.
Applicable Scenarios
Mainly used for ultra-high precision and high-hardness material machining, such as high-strength alloy steel, titanium alloy, heat-resistant alloy, and hardened steel (HRC 50-65). It is widely used in aerospace, military, and high-end precision machinery industries, such as machining thread holes of aircraft engine turbine blades, titanium alloy structural parts, and high-precision mold components.
Note: It is not suitable for manual machining or machining with poor equipment stability, and requires matching with high-precision CNC machines and stable clamping tools to avoid tap breakage.