Tom Beaumont

Product Training Manager

18 years engineering experience, specializing in 3 & 4 axis CNC milling, turning and horizontal boring.

Trochoidal milling is a machining technique used in milling operations to achieve high material removal rates and improve tool life. It involves the use of circular tool paths with a constantly changing radius, which creates a "trochoidal" or spiral-like motion. Machinists utilise this technique to create a slot, or hole, with a size larger than a cutting tool’s diameter.

In this blog we discuss the merits of this machining technique, as well as what to look out for and the best tooling for performing trochoidal milling on a range of materials and machines.

What is trochoidal milling?

In traditional milling, the tool follows a linear or curved path, resulting in continuous contact between the tool and the workpiece. This constant engagement leads to increased wear on the cutting tool and generates significant amounts of heat, which can affect the machining process and reduce tool life.

Trochoidal milling, on the other hand, employs a series of circular arcs with varying radii. The tool path moves in a spiral motion, allowing for intermittent contact between the tool and the material. This intermittent engagement reduces the amount of heat generated and decreases the load on the tool, resulting in improved tool life and increased cutting speeds. Such high speeds are achieved whilst ensuring high axial depths of cut but low radial depths of cut.

What are the benefits of trochoidal milling?

The benefits of trochoidal milling include:

Higher material removal rates: By optimizing the tool path and reducing the amount of time the tool spends in contact with the material, trochoidal milling enables faster cutting speeds and cycle times, whilst increasing productivity.

Extended tool life: The intermittent contact and reduced heat generation help minimize tool wear, leading to longer tool life and reduced tooling costs.

Improved chip evacuation: The spiral-like motion of the tool path facilitates efficient chip evacuation, preventing chip recutting and reducing the likelihood of chip-related issues.

Enhanced surface finish: Trochoidal milling can produce smoother surface finishes due to the reduced contact time between the tool and the workpiece, resulting in improved part quality.

Reduced cutting forces: The intermittent cutting action reduces the cutting forces, enabling the use of smaller and more lightweight machine tools while still achieving high material removal rates.

Cost benefits: As trochoidal milling creates larger diameters than the tool’s cutting diameter, it’s possible to use the same tool to cut various sized holes, reducing the cost to the user of buying multiple tools for different hole diameters.

Used on Low Power Machines: Due to the reduction of cutting forces, created by utilising the whole flute length in milling operations, trochoidal milling allows high metal removal rates on machines with lower total power capacities.

Trochoidal milling is particularly effective in roughing operations, where high metal removal rates are required. It is commonly used in the manufacturing of aerospace components, automotive parts, mould and die applications and other industries where efficient milling is essential.

Can you apply trochoidal milling to any material?

Trochoidal milling can be applied to a wide range of materials, including both metallic and non-metallic materials. However, the suitability and effectiveness of trochoidal milling may vary depending on the specific material properties. Here are some considerations for different material types:

Metals: Trochoidal milling is commonly used in machining various metals, including steel, stainless steel, aluminium, titanium and more. The technique is particularly beneficial for materials that generate high cutting forces or poor chip evacuation. Trochoidal milling helps in reducing cutting forces and facilitating efficient chip evacuation, resulting in improved tool life and higher material removal rates.

Heat-Sensitive Materials: Trochoidal milling can be advantageous for heat-sensitive materials, such as certain aerospace alloys or superalloys. By reducing the contact time between the tool and the workpiece, trochoidal milling minimizes heat generation, which helps in preserving the material's integrity and reducing the risk of thermal damage.

Composites: Trochoidal milling can be applied to composite materials like carbon fibre-reinforced polymers (CFRP) and fiberglass. These materials can present challenges due to their abrasive nature and the potential for delamination. By employing trochoidal milling, intermittent cutting and optimized tool paths can help reduce delamination, improve surface finish and enhance overall machining efficiency.

Hard Materials: Trochoidal milling can be effective for machining hard materials such as hardened steels, cast iron and exotic alloys. The technique's ability to reduce cutting forces and heat generation can help prolong tool life and improve machining performance in these challenging materials.

Non-Ferrous Materials: Trochoidal milling is also applicable to non-metallic materials, including plastics, wood and composites. It helps in minimizing tool wear, reducing heat build-up and achieving better surface finishes.

While trochoidal milling can be applied to a wide range of materials, it is important to consider the specific properties and characteristics of the material being machined. Some materials may require specific cutting tools, coatings, or machining parameters to optimize the trochoidal milling process. If you have any questions or would like a personalised recommendation, don’t hesitate to get in touch with our Technical Team on 01924 869615.

Trochoidal milling tips

Trochoidal milling can be an effective machining technique when properly executed. Here are some tips to consider for successful trochoidal milling:

Tool Selection: Choose the appropriate cutting tool for your trochoidal milling application. Consider factors such as material type, cutting speeds and tool geometry. Solid carbide end mills with high-performance coatings and at least 5 flutes are often recommended for trochoidal milling due to their durability and heat resistance.

Speeds & Feeds: Optimize your feeds and speeds for trochoidal milling. Higher cutting speeds can be achieved due to the reduced tool engagement and intermittent cutting action. However, it is important to maintain appropriate chip load and feed rates for efficient chip evacuation and to prevent excessive tool wear.

Tool Path Strategy: Plan and program the tool path carefully. Trochoidal milling involves circular or spiral-like tool paths with varying radii. Utilize CAM software or programming techniques to generate optimized tool paths that maximize material removal rates and minimize cutting forces.

Chip Evacuation: Trochoidal milling can generate long chips due to the intermittent cutting action. Ensure effective chip evacuation to prevent chip recutting and potential issues. Utilize appropriate chip breakers or special tool geometries to facilitate chip evacuation and maintain good chip flow. YG-1’s V7 Plus’ variable helix is a great example of modern cutting technologies optimised for trochoidal milling at high cutting data.

Rigidity and Stability: Maintain rigidity and stability throughout the machining process. Ensure proper clamping of the workpiece and select a suitable tool holder that offers good vibration damping and rigidity. Minimizing vibrations is crucial for achieving accurate and consistent results in trochoidal milling.

Coolant and Lubrication: Use adequate coolant and lubrication to control heat generation and extend tool life. Proper cooling helps dissipate heat and prevents chip welding or material build-up on the cutting tool. Cutwel stock a variety of high performance semi-synthetic cutting fluids designed specifically for high speed, high feed machining.

Test and Optimize: Trochoidal milling can offer significant benefits, but it may require experimentation and optimization for specific materials and applications. Perform test runs, monitor performance and adjust as needed to achieve the desired results.

Consult with Experts: If you are new to trochoidal milling or facing specific challenges, consult with machining experts or tooling manufacturers. They can provide valuable insights, recommendations and troubleshooting assistance based on their expertise. Our time-served team of technical engineers would be more than happy to assist with any specific queries you have, call 01924 869615 or email sales@cutwel.net.

By following these tips and considering the specific requirements of your trochoidal milling application, you can maximize the benefits of this machining technique and achieve efficient and high-quality results.

What are the best tools for trochoidal milling?

The selection of tools for trochoidal milling depends on various factors such as the material being machined, the desired cutting speeds, the machine capabilities and the specific application requirements. However, in general, milling tools designed for trochoidal milling will have a high number of flutes, usually 6 or 8.

Traditionally, cutters operating at high cutting speeds require deep flute pockets to deal with swarf, meaning less flutes on the cutter were possible. Less flutes created more stress on the cutter, increasing the chances of breakage and faster tool wear. With trochoidal milling, lower tool loads mean deep flute pockets aren’t necessary, allowing for an increased number of shallower flutes. Increased number of flutes relieves stress on each cutting edge, whilst their shallowness increases the size of the tool’s core. Both features create a stronger tool with longer tool life and increased wear resistance.

Cutwel supply a variety of HPC (high performance cutting) milling cutters designed for dynamic milling, profiling, trochoidal milling and finishing applications. The key differentiator between our trochoidal milling cutters will be the material you’re cutting. Our options include:

V7 Plus TRP

Our flagship range of trochoidal milling cutters, YG-1’s V7 Plus TRP range is first choice for machining medium-hard stainless steel, HRSA’s, cast iron & steels up to HRc45.

These 6 flute cutters feature a unique geometry and a variable helix profile designed for exceptional chip evacuation and chatter-free milling, giving excellent surface finish at high cutting speeds and feeds. Furthermore, its unequal flute spacing enables higher feed rates and larger cut depths, both of which are magnified further by utilising trochoidal milling techniques.

Alu Power HPC

Our ultimate milling tool for high metal removal and fast cutting speeds in aluminium, aluminium alloy, die cast aluminium, non-ferrous alloy and plastic.

The Alu Power HPC can be utilised in non-ferrous trochoidal milling applications thanks to its razor-sharp cylindrical land design, coupled with its deep gullet design offering outstanding chip evacuation. Meanwhile, peel milling operations benefit from the cutter's polished, lapped and super-sharp cutting edge and flutes. 

K2 Carbide

Not all trochoidal milling options require high performance tooling. YG-1’s K2 Carbide range is a general-purpose low-cost carbide milling cutter, ideal for medium speed machining of carbon, alloy and pre-hardened steel up to HRc45. Its 6 flute variant is suitable for trochoidal milling, with the 45° helix perfect for chip evacuation at high cutting speeds.

TitaNox

TitaNox cutters are our first choice milling cutter for machining soft or sticky stainless steel, titanium alloys and soft steels up to HRc40. The TitaNox range features 5 flute cutters with chamfer prep or corner radius geometry designed with trochoidal milling in mind.

Machining soft materials can be tricky, as swarf can stick to the cutter’s flute and cause chip build-up, resulting in poor surface finish and potentially damaging the cutter. Despite the high number of flutes, TitaNox cutters offer deeper pockets (whilst retaining a strong core) alongside a variable helix, to help alleviate built-up edge whilst giving excellent chip evacuation. This combination of features makes these cutters superb options for soft material trochoidal milling.

What tool holders are the best for trochoidal milling?

When it comes to tool holders for trochoidal milling, it's essential to consider factors such as rigidity, stability and vibration damping capabilities. As you’re applying high levels of stress to your tool, especially at high cutting speeds and feeds, chatter will be a significant issue. Whilst the milling cutters themselves include vibration-dampening capabilities, tool holding also plays a significant role.

Here are some common tool holder types used for trochoidal milling:

Hydraulic Chucks: Hydraulic chucks use hydraulic pressure to clamp the tool securely. They provide excellent tool holding capabilities, minimizing vibration and ensuring stability during trochoidal milling. Hydraulic chucks are suitable for high-speed machining and demanding applications.

Shrink Fit Tool Holders: Shrink fit tool holders involve heating the tool holder to expand it and then quickly cooling it to shrink it around the tool. This creates a strong and rigid connection. Shrink fit holders provide excellent concentricity, rigidity and vibration damping characteristics, making them suitable for trochoidal milling.

What we wouldn’t recommend is using a standard ER collet chuck or end mill holder. When milling at high speeds and feeds, tool pull-out can occur, as well as vibration. As the tool pulls out, the collet’s grip becomes slacker and wobbles more significantly. This can damage both the tool and the workpiece. In short, ER collet-based tool holding will not be sufficient to realise the many benefits of trochoidal milling effectively.

Choosing between hydraulic chucks and shrink chucks will depend on budget and performance requirements. Hydraulic chucks use oil in the holder’s membrane to provide dampening effects, absorbing vibration and breaking harmonics. Because of this, tools can be pushed harder and lower vibration means a great surface finish. Meanwhile, the heat shrinking process means shrink fit chucks provide strong, reliable clamping. However, the initial set-up cost of purchasing a shrink fit machine and time required to heat shrink tools, makes shrinking the premium option. By comparison, hydraulic chucks provide the far more economical option.

Cutwel supply a wide range of both hydraulic chucks and shrink fit chucks. YG-1’s Power E-Hydro hydraulic chucks can increase your tool life up to 300% more than ER collet chucks, utilising high torque up to 900 Nm for highest volume machining. A permanent run-out accuracy of less than 0.003mm gives high radial rigidity and accuracy in high-speed machining. We stock a range of tapers and sizes, with through coolant capabilities. We also supply a comprehensive range of HPH high performance hydraulic holders from market leaders WTE.

Bilz shrink fit machines deliver expert heat shrinking solutions, beginning at economical entry level models through to starter, professional, premium and heavy duty models. Whatever your size or budget, they’ll have a solution for you! We also supply a comprehensive range of shrink fit chucks, with our WTE chucks 100% made in Germany and used by world leading automotive, aerospace and mould & die manufacturers. YG-1 chucks offer exceptional value on the most popular tapers.

Revolutionary 6 flute design for phenomenal performance and outstanding surface finish in trochoidal milling.

Superior stainless steel and titanium milling for high value workpieces where the highest levels of reliability is required.

Get higher run out accuracy and increased tool life over conventional tool holders, which are unsuitable for trochoidal milling.