Popular Science on Trochoidal Milling in Machining

What is trochoidal milling? Let’s explore it today.

 

End mills are primarily used for machining flat surfaces, slots, and complex profiles. Unlike turning, the design and selection of the milling path are critical for effectively machining slots and intricate shapes. For instance, conventional slot milling techniques can create a circular contact angle of up to 180°, which can result in poor heat dissipation and a significant increase in temperature during the machining process.

However, by modifying the cutting path to allow the milling cutter to rotate while simultaneously orbiting, the contact angle and the amount of material removed per revolution can be reduced. This adjustment decreases cutting forces and temperatures, which extends tool life and facilitates longer continuous cutting operations. This technique is known as trochoidal milling, as illustrated in Figure 1.

 

The advantages of the trochoidal milling processing method include reducing the difficulty of cutting and ensuring high processing quality. By selecting appropriate cutting parameters, it is possible to enhance efficiency and lower costs. This method is particularly effective when working with difficult materials, such as heat-resistant alloys and high-hardness substances, where it can significantly improve outcomes. This effectiveness may explain the growing attention and preference the industry is showing towards trochoidal milling.

 

Technical Advantages

A trochoid, which can also be referred to as a hypotrochoid or an extended epitrochoid, is the path traced by a point located on or inside a moving circle as it rolls along a straight line without slipping. This shape is sometimes called a long or short amplitude trochoid.

Trochoid machining utilizes an end mill with a diameter smaller than the width of the groove to transform a semicircular groove into a smaller arc. This technique allows for the machining of various grooves, surfaces, and cavities. In theory, a single end mill can produce grooves and surfaces of any size, making it versatile for processing a wide range of products.

 

The advancement and use of computer numerical control (CNC) technology have led to the adoption of controllable milling paths, optimized cutting parameters, and the various advantages of trochoidal milling. This technology is increasingly recognized in industries such as aerospace, transportation equipment, and tool and die manufacturing for its effectiveness in parts processing. In particular, in the aerospace industry, commonly used titanium alloy and nickel-based heat-resistant alloy components present numerous challenging machining characteristics, including:
High hot hardness makes machining challenging for cutting tools and can lead to deformation. The high shear strength can easily damage cutting edges, while low thermal conductivity hinders heat dissipation from the cutting zone, where temperatures often exceed 1000°C, which intensifies tool wear. During metal CNC machining, material often welds to the cutting edge, creating a built-up edge and resulting in poor surface quality. Nickel-based heat-resistant alloys with austenitic matrices are prone to severe work hardening. Additionally, carbides within the microstructure of these alloys can cause abrasive wear on cutting tools. Furthermore, titanium alloys are chemically active, which can worsen damage through chemical reactions.

These challenges can be addressed with trochoidal milling technology, ensuring consistent and smooth machining.

Due to the continuous optimization of tool materials, coatings, geometries, and structures, along with rapid advancements in intelligent control systems, programming technologies, and high-speed, high-efficiency, multifunctional machine tools, high-speed cutting (HSC) and high-performance cutting (HPC) have reached new levels of performance.

High-speed machining mainly aims to increase cutting speed, while high-performance machining focuses not only on higher speeds but also on minimizing idle time. By strategically configuring cutting parameters and paths, complex machining processes can be streamlined. This approach reduces the number of steps involved, increases metal removal rates per unit of time, extends tool life, and ultimately lowers costs.

 

Technical Prospects

The following is data on the application of trochoidal milling in aircraft engines.

 

Machining the titanium alloy Ti6242 can reduce tool costs per unit volume by nearly 50%. For grooves machined in parts made from the nickel-based heat-resistant alloy Inconel 718, labor hours can be decreased by 63%. This process also reduces the overall quantity of tools required by 72% and cuts tool costs by 61%. Additionally, machining X17CrNi16-2 can lead to a reduction in labor hours of approximately 70%. Due to these successful outcomes, advanced trochoidal milling methods are being increasingly applied across various fields and are starting to gain interest in the area of micro-precision machining.

 

 

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At Anebon, we strongly believe in putting the “Customer First” while always maintaining high quality. With over 12 years of industry experience, we have closely collaborated with our clients to deliver efficient and specialized services, including stamped metal parts, CNC machining of aluminum parts, and die-casting components.