As components made from nickel-based alloys become increasingly prevalent across the aerospace industry, demand for optimized cutting tools continues to grow. But, despite their advantages, nickel-based materials exhibit poor machinability due to their low thermal conductivity, potential for adhering to cutting tools, and the presence of abrasive particles within the alloy structure. Due to these issues, productivity with carbide tools tends to be low. In addition, part complexity means that some components demand extended reach. Here, Henri Sevonen – Senior Industry Segment Manager – Aerospace for the metal cutting specialist Sandvik Coromant, explains how new ceramic end mill technology has emerged to help meet these requirements, with the potential
to optimize the machining of aero-engine parts and provide significant competitive gains.

Most aerospace parts are manufactured from heat-resistant super alloys (HRSAs) and nickel-based alloys, which place a particular set of demands on production engineers looking to manufacture components like spools, turbine disks, combustion casings, and blisks. Although many manufacturers use conventional solid-carbide end mills, such tools have

their limitations in terms of performance when it comes to nickel-based alloys. In a highly competitive global arena, aerospace machine shops are looking for next-level technologies that are capable of delivering a step-change in factors such as productivity and/or tool life. Ceramic end mills can provide that very leap, offering up to 20-30 times more machining speed, in comparison with solid-carbide tools for operations such as shoulder and face milling. Such impressive gains can be achieved largely because ceramic cutters retain their hardness at the high temperatures which arise when machining nickel-based alloys.

The brazed ceramic CoroMill® 316 exchangeable-head end mill for roughing operations is a productive solution for aerospace engine applications in ISO S materials. In the first instance, the exchangeable head concept facilitates inherent process flexibility. Also available is a six-flute version with a straight corner radius that delivers highly productive side milling operations, and a four-flute version designed to boost face milling thanks to its high-feed face geometry. The ceramic substrate of the end mills allows for a different cutting process in comparison with traditional solid-carbide tools. Importantly, the unique S1KU SiAlON grade is purpose-designed for the superior machining of nickel alloys and is supported by negative geometry that provides a tough cutting edge. The latter also features a T-land for stable operations.

SiAlON carries a chemical composition of aluminum oxide and silicon nitride (Al203+Si3N4), a combination that promotes high wear resistance, even at elevated temperatures.

Stable machining

A stable set-up is advised in all cases, and always without coolant application; machine shops should use pressurized air instead as coolant would simply burn at the high temperatures involved. In addition, the use of coolant promotes thermal shocks and has a negative effect on tool life. Importantly, high spindle speeds are required, of at least 13000 rpm. Further recommendations include the use of down milling, as well as a programmed tool path that keeps the tool in constant contact with the material.

It is clear that nickel-based alloys will play a vital role in the future of aerospace manufacturing. However, there are many challenges facing those tasked with producing aerospace engine components. It’s only through continued tooling innovations, such as ceramic end mill technology, that aerospace machine shops will be able to optimize the machining process

Cutting tool specialist Sandvik Coromant expands its offer of CoroMill® Plura HD solid-end mills for heavy-duty roughing in steel and stainless steel with two new grades. This new generation of grades features the unique Zertivo 2.0 coating, which combines world-class productivity with exceptional metal removal rate and the highest possible process security.
CoroMill® Plura HD is Sandvik Coromant’s first choice optimized solution for heavy-duty applications up to 2×D in steel and stainless steel (ISO P and ISO M), offering safe and efficient solid end milling. Thanks to the new Zertivo 2.0 coated grades tool life, process security and productivity are improved even further.

“With Zertivo 2.0 we apply our comprehensive knowledge in coating technologies to our solid round tools”, says Antti Wikström, Global Product Manager, Solid end mills at Sandvik Coromant. “This gives us an opportunity to offer unique, custom-made coatings that will handle our customers’ machining challenges with superior performance and tooling efficiency.”

The new grades allow for 30% higher cutting speed recommendations in primary application areas ISO P and ISO M, as well as secondary materials ISO K and ISO S, due to their optimized flute shape, which provides effective chip evacuation. The grades designed for stainless steel machining come in two variants: one with internal coolant for improved temperature control and chip flow, and one without internal coolant.

The standard assortment offers diameters from 2–25 mm, a 2×D depth of cut, 4 to 5 teeth, and a ramping angle at 5° or 7°. Tailor Made® options are available within the Customized solutions range.

According to PwC’s Industrial Manufacturing report, “The only constant in today’s industrial manufacturing environment is disruption.” Disruptions to supply chains and productivity, caused by the pandemic, have driven manufacturers to diversify to new markets to survive. This creates an increased need for error-free precision machining. Here, Sangram Dash, Product Application Manager for Indexable Milling at Sandvik Coromant, explains how the new CoroMill® MH20 high feed milling cutter can support error-free machining.

“To stay competitive,” continues PwC’s report, “organisations must be able to integrate new business models and technologies to accelerate and adapt.” For machine shops, adapting includes diversifying product offerings and being ready to satisfy customer demand in new markets.

They are also under pressure to diagnose and eliminate product defects through error-proofing. This is a growing challenge, because diversifying into new sectors means handling workpieces made from wider a range of materials like aluminium and heat resistant super alloys (HRSAs). The hardness values of these materials differ enormously from one end of the spectrum to the other. Processes and machining conditions will also vary widely from part-to-part. They include everything from roughing to finishing on out-of-round or near-net-shape cast or forged parts.

Certain types of machining also present unique challenges. For instance, when a tool with a long overhang is used to mill deep narrow pockets, the whole setup becomes unstable. This can lead to unpredictable machining and a higher risk of vibrations that, as we’ll explore, can cause tool failures and downtime.

Manufacturers instead need tooling solutions that provide secure and predictable machining, with increased metal removal rates, reduced cycle times and quick changes between production batches. Fortunately, a solution does exist. As PwC’s Industrial Manufacturing puts it, “with disruption comes the opportunity to innovate.”

Bad vibrations
Why are these innovations necessary? One factor that needs to be overcome is machining vibrations, which negatively affect performance in a variety of ways, including displacement of the tool and imperfections in workpieces. They can even cause tool breakage and unplanned downtime. Another problem with vibrations is the effect on chip formation and chip removal, which are the fundamental occurrences inseparably involved with machining that damage the effectiveness of cutting tools.

Another factor in milling tool underperformance is that most inserts have four edges. The reason for having four edges is that, when one edge becomes dulled or chipped, it’s an easy process to rotate or replace the tip. However, the insert’s corners, between the flat edges, are its weakest parts. These radial edges are designed differently to the insert’s flat edges. They are often placed in the cutting zone and, as a consequence, frequently break first.

These are the issues Sandvik Coromant’s specialists kept in mind while designing a next generation tool that would meet the stringent requirements of a variety of sectors. Crucially, the invention needed to reduce the number of tools, changeovers and tool handling required during manufacturing, for reduced cycle times and improved manufacturing economics.

The result was CoroMill® MH20, a new high-feed milling cutter designed for milling cavities, or pockets, in ISO S, M and P materials.

Opportunity to innovate
The design of CoroMill® MH20 has several innovations. They include a new cutter body material, used for the cylindrical shank bodies, that gives levels of stiffness not seen before in this type of tool. The material minimizes wear and tear during machining and also reduces chip rubbing and coining ― when high stress caused by high cutting forces causes plastic deformation on the insert seat. With this feature, the tip seat remains secure and undeformed which provides better tool life.

Next, we have an alternative to the aforementioned four-edge concept: CoroMill® MH20 is designed with a two-edge insert. With the two-edge concept, machining against a corner or wall will not impact the next edge or leading corner, giving an equal performance per edge. The advantages are greater reliability and protection against wear. The edge line of the insert’s main cutting edge and corner radius are also optimized for further process security.

Another area of innovation is CoroMill® MH20’s insert cutting edge geometry. For the first time in high feed concepts, Sandvik Coromant is introducing dedicated insert geometries for different ISO areas to deliver greater optimized process security and productivity. With CoroMill® MH20, a sloped edge design delivers a gradual and light-cutting action, requiring less power consumption suited to the use of smaller machines.

Sandvik Coromant’s CoroMill® MH20 has exhibited substantially-improved tool life over previous-generation tools for its customers — up to 30% in some cases, although this performance will always differ depending on the material.

Precision machining
One Sandvik Coromant customer, a large machine shop in Canada that specialises in mold and die manufacturing, wished to upgrade its existing tooling setup. The customer had been using a competitor’s tool, which had been suffering from vibrations that made machining processes unpredictable and insecure.

To resolve these issues, the machine shop turned to Sandvik Coromant to test the performance of CoroMill® MH20 against its existing tool. Both tools were used to perform rough pocketing on a workpiece made from H13, a popular chromium hot-work steel known for its high toughness and fatigue resistance, to produce a mold.

Each milling tool measured 25.4 mm (1 inch) and was run at a cutting speed (vc) of 168 m/min (550 surface ft/min). CoroMill® MH20 was run at a slightly higher feed rate with two inserts, because this allowed the depth of cut to be increased by 35%. The parameters were: a feed per tooth (fz) of 1 mm/tooth (0.04 inch/tooth), feed speed (vf) of 5,080 mm/min (200 inch/min) and axial depth of cut (ap) of 0.8 mm (0.031 inch).

The competing tool was run at an fz of 0.63 mm/tooth (0.025 inch/tooth), vf of 4572 mm/min (180 inch/mm) and ap of 0.5 mm (0.020 inch). Both tools were run until they showed signs of flank wear.

Despite the higher cutting parameters, CoroMill® MH20 finished a complete component with no indexing, and a superior surface finish. It exhibited at 50% tool life increase by running for 300 mins, with a 50% cycle time reduction. The competing tool, meanwhile, ran for half the amount of time at 150 min. It required additional indexing because of poor tool life, which further increased the cycle times. The competitor’s insert again suffered from vibrations that caused screws to back out during machining.

By upgrading to CoroMill® MH20, the customer has achieved a significantly improved tool life and more secure, vibration-free machining processes. Even if, as PwC observes, disruption is the only constant in today’s industrial manufacturing environment, new tooling innovations like CoroMill® MH20 support improved tool life and process security. This greatly benefits manufacturers’ competitiveness.

The new CoroMill 316 generation of exchangeable-head milling cutters from Sandvik Coromant enhances the company’s established Solid Round Tools portfolio by bringing higher levels of versatility and productivity to machining operations in ISO P (steel) and ISO M (stainless steel) materials. Further benefits include high reliability in almost all applications, along with enhanced tool life and a silent machining process.

CoroMill 316 is suitable for all general milling operations, including high-feed face milling, slot milling, helical interpolation, shoulder milling, profile milling and chamfer milling. The exchangeable heads allow users to easily and accurately switch between various operations, creating end mills with optimised radius variation, teeth frequency, geometry and grade. Beyond steel and stainless steel, the tools can also be used successfully on ISO K (cast iron) and ISO S (heat resistant super alloys) materials.

“The latest generation of CoroMill 316 adds a longer cutting length to its list of attributes, delivering even greater flexibility for machine shops,” says Tiziana Pro, Product Manager Solid End Mills at Sandvik Coromant. “Specific operations to benefit includes those that demand higher axial depth, up to 1.2 x Dc, as well as where high stability and vibration suppression are required. In particular, the combination of the modular Coromant EH system and CoroMill 316 provides a number of solutions for all types of machines and user challenges.”

Manufacturers should choose Coromant EH as the preferred rotating modular interface for applications up to 32 mm (1.256 inch) in diameter. Integrated machine adaptors with EH coupling are recommended for small interfaces where gauge line and swing diameter are critical (BT30, SK40, HSK40/50/63, ER, DTH), as well as different shank types in long overhang applications up to 35 mm (1.38 inch) diameter.

CoroMill 316 is part of the extensive Solid Rounds Tools offer from Sandvik Coromant, which today includes more than 10,000 standard products to cover all applications within the areas of solid carbide drilling, milling, tapping, reaming and threading.

Solid Round Tools are purpose-designed to support workflow, efficiency and productivity, with each cutter positioned within three product categories: versatile, optimised and customised. Versatile solutions are performance-oriented tools based on maximising flexibility and cost efficiency for the customer, while optimised solutions comprise a unique line of refined tools for specific needs where extreme efficiency, reliability and durability are paramount. Customised solutions are designed individually to meet the highest performance demands.

The new CoroMill 316 generation of exchangeable-head milling cutters from Sandvik Coromant enhances the company’s established Solid Round Tools portfolio by bringing higher levels of versatility and productivity to machining operations in ISO P (steel) and ISO M (stainless steel) materials. Further benefits include high reliability in almost all applications, along with enhanced tool life and a silent machining process.

CoroMill 316 is suitable for all general milling operations, including high-feed face milling, slot milling, helical interpolation, shoulder milling, profile milling and chamfer milling. The exchangeable heads allow users to easily and accurately switch between various operations, creating end mills with optimised radius variation, teeth frequency, geometry and grade. Beyond steel and stainless steel, the tools can also be used successfully on ISO K (cast iron) and ISO S (heat resistant super alloys) materials.

“The latest generation of CoroMill 316 adds a longer cutting length to its list of attributes, delivering even greater flexibility for machine shops,” says Tiziana Pro, Product Manager Solid End Mills at Sandvik Coromant. “Specific operations to benefit includes those that demand higher axial depth, up to 1.2 x Dc, as well as where high stability and vibration suppression are required. In particular, the combination of the modular Coromant EH system and CoroMill^® 316 provides a number of solutions for all types of machines and user challenges.”

Manufacturers should choose Coromant EH as the preferred rotating modular interface for applications up to 32 mm (1.256 inch) in diameter. Integrated machine adaptors with EH coupling are recommended for small interfaces where gauge line and swing diameter are critical (BT30, SK40, HSK40/50/63, ER, DTH), as well as different shank types in long overhang applications up to 35 mm (1.38 inch) diameter.

CoroMill 316 is part of the extensive Solid Rounds Tools offer from Sandvik Coromant, which today includes more than 10,000 standard products to cover all applications within the areas of solid carbide drilling, milling, tapping, reaming and threading.

Solid Round Tools are purpose-designed to support workflow, efficiency and productivity, with each cutter positioned within three product categories: versatile, optimised and customised. Versatile solutions are performance-oriented tools based on maximising flexibility and cost efficiency for the customer, while optimised solutions comprise a unique line of refined tools for specific needs where extreme efficiency, reliability and durability are paramount. Customised solutions are designed individually to meet the highest performance demands.

Steel milling grade offers greater security and productivity

Machine shops faced with identifying ways of achieving secure machining with long and predictable insert life in steel milling operations can turn to GC1130, an insert made with the Zertivo, a unique production technology from Sandvik Coromant. GC1130 helps to overcome challenging machining conditions with a clean and intact edge, delivering high metal removal rates and performance levels in both wet and dry machining operations. The grade is offered as the first choice for shoulder milling cutters, CoroMill 390 and CoroMill 490 and chamfer cutter, CoroMill 495.

Flaking, abrupt chipping and thermal cracks are common issues encountered when milling materials in steel applications, especially when faced with unfavourable tool paths and deep cavities or when using coolant. GC1130 has been specifically developed to help production engineers combat the subsequent unwanted effects of short insert tool life and unstable production. Manufactured with Zertivo, a unique production technology that helps amplify the grade’s benefits offering peace-of-mind through greater edge-line security and reduced flaking. Furthermore, a high-Cr content fine-grain substrate delivers high resistance to thermal cracks generated as a result of temperature fluctuations during machining, helping to ensure long and reliable tool life.

According to Mikael Eiritz, product manager for milling grades at Sandvik Coromant, “The choice of insert geometry and grade is just as important as the choice of tool when looking for secure machining. The tool and insert together is what contributes to the overall performance in an operation. Many times, when using grade GC1130, customers can move from one component to the next without having to stop production. That saves them time and money.”

When repeated shoulder milling is required, the combination of GC1130 with CoroMill 490 provides a suitably light cutting action and smooth profile that can efficiently reduce the need for a finishing operation. Also available for the CoroMill 390, this grade is best when multiple component features are required. Bringing an added dimension of security and predictability to machining in challenging conditions, the assortment includes many different types of tools and a wide selection of corner radii. Applications such as shoulder milling, linear and helical ramping, turn-milling, deep shoulder milling, edging and pocketing can be performed.

In applications where trouble-free chamfering in various steel types is required, pairing CG1130 with CoroMill 495 reduces downtime and allows for higher machine utilization. Along with the chamfering of holes and edges, typical applications include back chamfers, welding preparation and deburring.

Product manager for shoulder milling at Sandvik Coromant, Thomas Wikgren, states, “Greater process security, productivity and tool life are all within reach with GC1130. At the end of the day, our customers are looking for a reliable tool and insert combination that will help them achieve a lower cost per component.”

New end mills series from Sandvik Coromant delivers secure and high performance machining of steels and stainless steel components.

Sandvik Coromant launches a new series of end mills designed to deliver high performance and security in side milling and pocketing operations.

The CoroMill Plura HFS (high feed side milling) end mills are developed for steels and stainless steel applications, but they can also enhance productivity in difficult-to-machine materials such as heat-resistant super alloys and titanium.

Today’s modern machine shops utilise the latest milling strategies, for example trochoidal milling, to enhance productivity and process reliability. The tool path is often generated with CAM software for constant maximum chip thickness and a short arc of contact, allowing high feed rates, minimum vibration and longer tool life. CoroMill Plura HFS is designed with these strategies in mind. By utilising the complete cutting length of the end mill, it achieves a higher metal removal rate with smaller diameters, compared to indexable milling and traditional milling strategies. This reduces tool costs and improves overall productivity.

CoroMill Plura HFS features include:

• An unequal helix flute design that assures a variable angular pitch in every axial section to increase the chatter-free material removal rate.
• An asymmetrical chip-breaker profile that improves chip evacuation and minimises the risk of edge chipping and tool breakage.
• A conical core shape with a smaller core diameter at the face to improve chip evacuation capabilities, with a larger core diameter at APMX for maximum stability.

Its tough GC1740 grade is developed to manage large ap/ae combinations and resist the bending forces generated when using a 4xDC length of cut.

Ultimately, the new Tailor Made offered by Sandvik Coromant includes CoroMill® Plura end mills for manufacturers or machine shops needing a 5xDC length of cut.

CoroMill 425 offers easy adjustment and higher performance for the finishing of cast materials

With CoroMill 425, Sandvik Coromant offers an eight-edge finishing tool designed for face milling that greatly improves metal removal rate and tool life in the ISO K application area. Due to its innovative setting system, it is particularly user-friendly.

 ​Sandvik Coromant has introduced CoroMill 425, a finishing tool for the face milling of cast materials. With its eight edges it is ideal for face milling components such as engine and cylinder blocks, axle housings, brake carriers and crankcases made of GCI, NCI and CGI materials. Due to its patented setting system, the tool features highly precise, reliable insert positioning that makes set-up very simple.

On the CoroMill 425, the same inserts can be used as working or as wiper inserts. The wiper inserts are mounted in cassettes on the face of the tool. The insert version with a 25° entry angle and optimised chamfer is designed to reduce breakouts and burr formation on the workpiece. A choice of wear-resistant GC1010 PVD insert grade for dry milling and K20W grade for wet milling enables especially long tool life in CGI materials.

The new CoroMill® QD groove milling concept from Sandvik Coromant features internal coolant and dedicated insert geometries for milling with high process security.

​The main challenge in groove milling is often chip evacuation. Chip issues often harm production efficiency, lower component quality or cause tool breakage, especially when machining narrow and deep grooves. Dedicated for groove milling and parting off operations, CoroMill QD takes care of chip issues with optimized geometries and the unique internal coolant solution. The chips are deformed by the insert geometry to a more narrow shape than the groove and then flushed out by the coolant. Combined with long and predictable tool life, this makes CoroMill QD a reliable solution for secure and trouble-free production processes.

Complementing the new cutters is a wide range of new adaptors. These adaptors enable use of CoroMill QD cutters regardless of whether the preferred machines are small- to medium-sized machining centres, large machining centres or multi-task machines. Silent Tools adaptors are available for long overhang machining.

The internal coolant is based on a four-channel delivery solution from the adaptors to the cutter. By implementing this solution on the new adaptors for CoroMill QD, coolant delivery into the groove is achieved.

Innovative CoroMill® 5B90 milling concept from Sandvik Coromant excels at high-performance machining of aluminium components

Sandvik Coromant, a global leading supplier of cutting tools, tooling solutions and know-how to the metalworking industry, presents the innovative CoroMill® 5B90, a high-performance tool for finishing aluminium components. The state-of-the-art tool with an innovative cutting edge arrangement delivers excellent surface quality, without burr formation and reduces cost-per-part by up to 30 per cent. CoroMill 5B90 is ideally suited for typical automotive industry applications such as machining cylinder heads, gearboxes, valve blocks and motor block crankshaft and deck faces.

​Numerous benefits
The new customer- and application-specific finishing cutter for aluminium allows a controlled, high-feed machining process, resulting in improved part quality. As no cost-intensive insert adjustment is necessary, set-up time can be reduced by up to 66 per cent. While each tool is custom-made for customers, Sandvik Coromant offers PCD inserts from stock.

Superior performance
When machining the cylinder heads of a four cylinder engine made from AlSi9Cu-1 at a cut depth of 0.7 mm the new CoroMill 5B90 (diameter of 160 mm, 9 cutting edges) achieved a tool life of 40,000 parts (at a rotational speed of 7,000 rev/min and a feed rate of 12,500 mm/min).