Delivering stable and productive threading in aluminum alloys
Yukimasa Takagishi | OSG Corporation Product Development Engineer
Aluminum alloys combine low weight with high strength, making them indispensable materials across a wide range of growing industries, including aerospace, semiconductor manufacturing and robotics. Their excellent machinability has long made them a preferred choice for manufacturers seeking efficient and cost-effective production.
Despite their reputation as easy-to-machine materials, aluminum alloys can present significant challenges during tapping operations. Chips generated during threading often become long and stringy, increasing the likelihood of chip entanglement around the tap. This can disrupt stable machining, reduce productivity and negatively affect thread quality.
To address these issues, OSG developed the A-SFT-AL spiral flute tap for aluminum alloys, a new solution designed to provide stable thread production and improved productivity. The series is available in sizes from M2 to M12 and consists of 16 items with chamfer lengths of 2.5 threads and 1.5 threads. Sales commenced in July 2026.
Challenges in Tapping Aluminum Alloys
Aluminum alloys are generally categorized as either cast alloys or wrought alloys. While chips produced from cast alloys tend to break into small, manageable segments, wrought alloys often generate long, continuous chips that can create a variety of machining issues.
A5000 and A6000 Series
The A5000 and A6000 series, both classified as wrought aluminum alloys, are particularly prone to producing large, curled chips that easily become entangled around the tap (Figure 1). As chips accumulate, they can scratch the machined surface and compromise workpiece quality. In many cases, machine stoppages are required to remove the wrapped chips and prevent further damage.
Figure 1. Chip entanglement during tapping of A5052 aluminum alloy
The high ductility of these materials creates an additional challenge. During tap reversal, chips can become compressed and adhere to the thread surface, resulting in thread damage or dimensional inaccuracies that may cause failure during GO thread plug gauge inspection.
A2000 and A7000 Series
The A2000 and A7000 series wrought alloys are known for their exceptional strength, with mechanical properties comparable to certain steels. As a result, tap breakage can become a significant concern during threading operations.
Figure 2. Internal thread condition after tap breakage
When a tap breaks inside a hole, removal is often difficult and time-consuming. Even if the broken tool can be extracted successfully, the internal thread is typically damaged, rendering the component unusable (Figure 2). These issues can lead to increased scrap rates, machine downtime and higher production costs.
Key Features of the A-SFT-AL
Innovative Flute Geometry for Rigidity and Chip Evacuation
One of the defining features of the A-SFT-AL is its newly developed flute geometry, which successfully combines high tool rigidity with large chip pockets. This design promotes efficient chip evacuation, helping to maintain stable machining conditions while reducing the risk of chip-related problems.
The enlarged chip pockets not only improve chip flow but also help prevent chip adhesion and compaction, both of which are common causes of thread quality issues when machining aluminum alloys.
The tap incorporates a unique flute design that challenges conventional design concepts. Although it utilizes a two-flute configuration, it achieves a core diameter comparable to that of a conventional three-flute tap. This innovative structure provides excellent rigidity while preserving ample space for chip evacuation.
Compared with conventional designs, chip pocket volume has been significantly increased. For M8 × 1.25 taps, pocket volume is approximately 20% larger than conventional two-flute taps and 80% larger than conventional three-flute taps (Table 1), contributing to improved chip control and machining stability.
Table 1. Comparison of flute geometries
Reducing Chip Compaction During Tap Reversal
Chip compaction is a common issue in aluminum tapping operations. In the chamfer section of a tap, relief creates clearance between the internal thread and the heel of the tap. As land width increases, the size of this clearance also increases.
During tap reversal, chips can enter this space and become compressed against the thread surface. The resulting chip compaction may deform the thread and cause the threaded hole to fail GO thread plug gauge inspection (Figure 3).
Figure 3. Chip compaction mechanism during tap reversal
Although the A-SFT-AL features a two-flute design, its land width is equivalent to that of a three-flute tap. Compared with conventional two-flute taps, the narrower land width reduces the clearance available for chips to enter, minimizing the risk of chip compaction and helping to maintain thread accuracy.
Optimized Shank Length
The A-SFT-AL also incorporates an optimized shank length designed to improve chip management. By preventing evacuated chips from contacting the tap holder, the design reduces the likelihood of chip entanglement and accumulation around the tool (Figure 4).
Figure 4. Chip deformation caused by contact with the tap holder
Figure 5. Stable cutting fluid delivery to the cutting edges of the A-SFT-AL (M10 × 1.5, thread depth: 20 mm [2D])
In addition, the optimized geometry provides sufficient clearance between the tap holder and the workpiece surface, allowing cutting fluid to reach the cutting edges more effectively (Figure 5). Consistent coolant supply helps suppress built-up edge formation and material adhesion—common challenges when machining aluminum alloys—thereby improving tool performance and reliability.
Cutting Data
The following examples highlight the performance of the A-SFT-AL in a variety of aluminum alloy machining applications.
Machining on Horizontal Machining Centers
Even in horizontal machining center applications, where chips are especially prone to entanglement, the A-SFT-AL effectively suppresses chip wrapping and supports stable, uninterrupted machining.
Machining A7075
The A-SFT-AL provides stable threading performance even in A7075, one of the highest-strength aluminum alloys available.
Machining ADC12 (Cast Alloy)
The A-SFT-AL also provides stable machining performance in ADC12 cast aluminum alloy, a material widely used in automotive component manufacturing.
Floating-Type Tap Holder
The A-SFT-AL is also compatible with floating-type tap holders, enabling stable threading performance while accommodating minor spindle and hole-position misalignment.
Conclusion
The A-SFT-AL was developed to address the practical challenges manufacturers face when tapping aluminum alloys. By combining an innovative flute geometry with increased chip pocket capacity and an optimized shank design, the tap achieves superior chip evacuation, enhanced thread quality and greater process stability.
These design features work together to minimize chip-related issues, helping to reduce machine stoppages, decrease manual chip-removal operations and lower defect rates caused by chip-induced scratching and chip compaction. The result is a more reliable threading process that supports higher productivity and consistent machining performance.
Whether machining wrought or cast aluminum alloys, manufacturers can rely on the A-SFT-AL to deliver stable, efficient and dependable threading. By improving both process reliability and operational efficiency, the A-SFT-AL offers a practical solution for manufacturers seeking to maximize productivity in aluminum machining applications.
For more information on OSG’s A-SFT-AL spiral flute tap for aluminum alloys