Green Tap GRT

High-performance and low-carbon forming tap

Tetsuya Mizoguchi | OSG Corporation Applications Engineer (Tap Development Division)

In November 2024, OSG Corporation introduced “Green Tap” at the Japan International Machine Tool Fair (JIMTOF) and released it on November 20 the same year. Green Tap (hereafter referred to as “GRT”) is a revolutionary forming tap designed for high-performance machining with enhanced durability and efficiency. As a forming tap, which creates internal threads by plastic deformation of the material, GRT does not generate cutting chips. In other words, machining troubles caused by cutting chips can be completely eliminated. Furthermore, GRT is a low-carbon product that reduces CO₂ emissions by decreasing power consumption during manufacturing through the adoption of a new and original manufacturing method. By selecting high-performance and low-carbon products, tap users can contribute to the reduction of carbon footprint and the realization of a sustainable society. This article provides an in-depth introduction to the GRT high-performance and low-carbon forming tap, a game-changer for sustainable manufacturing.

Features of GRT

The innovative design and construction of GRT are at the heart of its advancements. Below are its main features.

1. Increased Web Diameter

Conventional taps have oil grooves for supplying coolant during machining as depicted in figure 1. In contrast, GRT eliminated oil grooves entirely in its tool geometry. By removing these oil grooves, the web diameter (cross-sectional area) has increased, making the tool more resistant to breakage. For example, in the case of M6 x 1, the core diameter is increased by 11 percent and the cross-sectional area is enlarged by 24 percent compared to the conventional product as illustrated in figure 2. This tool design significantly enhances tool rigidity.

Figure 1. Comparison of tool geometry between a conventional forming tap (left) and GRT (right).

Figure 2. Comparison of web diameter size between a conventional forming tap (left) and GRT (right).

2. Enhanced Torsional Strength

Taps are subjected to large torsional moments during machining, and have a high risk of breakage. If a broken tap remains inside the workpiece, removal can be extremely difficult. To address this, GRT increases the web diameter, which significantly reduces stress concentration as depicted in figure 3. Finite element method (FEM) analysis shows that the maximum stress has decreased from 3,088 MPa in the conventional forming tap to 1,551 MPa in GRT. Additionally, the rounded edges ensure stable strength.

Figure 3. Comparison of von Mises stress distribution between a conventional forming tap (left) and GRT (right).

3. Lubrication and Cooling Performance

While eliminating oil grooves might seem to lower lubrication and cooling performance, GRT maintains and even improves them through the following three innovations:

3.1. Coolant Flow Design

GRT is designed to allow coolant to flow smoothly to the cutting edges as depicted in figure 4. Computational fluid dynamics analysis confirms that coolant reaches the cutting edges more effectively than in the conventional product, enhancing lubrication and cooling performance in heated areas.

Figure 4. Comparison of coolant flow between a conventional forming tap (left) and GRT (right) by computational fluid dynamics analysis. Size: M6 x 1; cutting speed: 30 m/min.

3.2. Tap Surface Roughness

Due to improvements in the manufacturing method, the surface of GRT is smoother than that of the conventional product as illustrated in figure 5, which reduces frictional heat and extends tool life.

Figure 5. Comparison of surface roughness and machining performance between a conventional product and GRT.

3.3. Plastic Deformation Mechanism

Breaking away from the traditional fixed “60° thread angle” design, GRT employs a new plastic deformation mechanism with variable thread angles as depicted in figure 6. This enhances cutting edge strength while achieving a gap design that allows coolant to reach the cutting edge more easily.

Figure 6. Comparison of plastic deformation mechanism between a conventional forming tap and GRT.

4. Reduced Machining Resistance

In an actual cutting test, GRT reduced torque by 10 percent and thrust force by 55 percent compared to the conventional product as depicted in figure 7. This not only reduces the risk of tool breakage, but also suppresses heat generation, contributing to extending tool life.

Figure 7. Comparison of torque and thrust force between a conventional forming tap and GRT.

Cutting Data

Cutting results of GRT have proven its high durability. When machining SUS304, the tool life of GRT was longer than that of the conventional product for both M1 x 0.25 and M6 x 1 sizes as illustrated in figure 8. GRT also demonstrated high durability in a variety of work materials, including steel and aluminum alloys. Since it can use the same pre-drill hole diameter as conventional taps, the GRT can be easily implemented on the shop floor without having to alter machining conditions.

Figure 8. Durability comparison between a conventional forming tap and GRT. GRT demonstrates stable machining even in difficult-to-machine stainless steel.

Environmental Considerations

While conventional environmentally friendly tools focused on reducing waste through longer tool life and higher efficiency, their effectiveness often depended on how the user uses them. In contrast, GRT reduces CO₂ emissions at the manufacturing stage. For instance, CO₂ emissions during the manufacturing of M6 x 1 size tap can be reduced by 35 percent compared to conventional products. By simply switching to GRT, tap users can easily and cost-effectively lower their CO₂ emissions.

GRT is a forming tap engineered with sustainability in mind. It is highly recommended for users facing challenges such as “frequent tap breakage,” “short tool life,” or “seeking efficient CO₂ emission reductions.”

For more information on OSG’s Green Tap GRT high-performance and low-carbon forming tap