How do machine-used ST threading taps achieve efficient chip evacuation through their special flute design?
Publish Time: 2025-08-18
In modern machining, tapping is a key process for creating threaded holes and is widely used in industries such as automotive, aerospace, mold manufacturing, and electronic equipment. With increasing automation, machine-used ST threading taps have become core cutting tools in CNC machining centers, drilling and tapping centers, and other equipment. Unlike manual tapping, machine taps operate at high speeds, continuously, and without human intervention, placing extremely high demands on chip evacuation performance. Chip blockage can easily lead to tap breakage, thread surface damage, and even workpiece failure. Through a scientific and specialized flute design, machine-used ST threading taps achieve efficient chip evacuation, becoming a key technology for ensuring machining stability and production efficiency.
The flute design of machine taps directly influences chip formation, curling, breakage, and evacuation. Common flutes include straight flute, spiral flute, and spiral tip (tip) flute. Each configuration optimizes the chip evacuation path for different materials and machining methods.
Straight-flute taps are the most basic tapping structure. Their cutting flutes are arranged linearly along the axial direction, making them simple to manufacture and suitable for both through and blind hole machining. When machining brittle materials (such as cast iron and brass), chips form fragments and are less likely to entangle. Straight flutes effectively guide chips axially. However, when machining plastic materials (such as stainless steel, mild steel, and aluminum alloys), chips tend to form ribbons and clog the flutes. To address this, high-performance straight-flute taps utilize increased chip clearance, optimized rake angles, and land designs to improve chip holding capacity and reduce frictional resistance.
Spiral-flute taps are specifically designed for blind hole tapping. Their cutting flutes are helical, with a helix angle typically between 30° and 45°. This design generates axial thrust during cutting, pushing chips upward and out of the hole, preventing them from accumulating at the bottom. Especially when machining deep holes or highly plastic materials, spiral flutes effectively prevent chip backfill and secondary cutting, significantly reducing torque fluctuation and tap load. The spiral direction is typically right-hand (aligned with the direction of rotation), ensuring smooth chip evacuation.
Spiral point taps (also known as tip taps) are primarily used for through-hole machining. Their front cutting edge features a beveled groove structure similar to a drill bit, enabling rapid engagement at the start of tapping and guiding chips forward. This "front-end chip evacuation" mechanism is particularly suitable for long through-holes or continuous automated machining, as chips are pushed out in the direction of the tap's advance, preventing accumulation within the hole. Spiral point taps offer efficient chip evacuation and smooth cutting, effectively reducing machining vibration and tap wear.
In addition to the flute structure, the flute surface roughness, cutting edge sharpness, and rake angle design also influence chip evacuation performance. Modern high-performance taps utilize precision grinding to achieve mirror-smooth flutes, reducing friction and adhesion between chips and the cutting edge. Furthermore, an optimized rake angle (typically 8° to 15°) enables smoother cutting, facilitates chip curling and breakage, and avoids the formation of long, sliver-like chips.
Internal coolant holes further enhance chip evacuation. Assisted by high-pressure cutting fluid, coolant flows directly into the cutting zone through internal channels within the tap. This not only reduces temperatures and built-up edge, but also powerfully flushes chips, achieving "hydraulic chip evacuation." This synergistic chip evacuation mechanism is particularly suitable for deep holes, difficult-to-machine materials, and high-speed tapping.
In summary, ST threading taps for machine taps achieve efficient and stable chip evacuation through specialized flute designs, including straight, spiral, and spiral-point flutes, combined with optimized chip space, surface treatment, and internal coolant technology. This not only extends tap life and improves thread quality, but also ensures continuous operation on automated production lines. In modern manufacturing, where efficiency and reliability are paramount, scientific flute design has become a core competitive advantage for machine taps to overcome complex machining challenges.
