ICMCTF 2026 Session IA3-ThM: Innovative Surface Engineering for Advanced Cutting and Forming Tool Applications

The automotive industry faces major challenges amid the shift from combustion engines to electromobility. Customers now demand higher productivity through shorter coating cycles and increased machining speeds for difficult-to-machine ferrous and non-ferrous alloys. These trends require advanced coatings.

Cathode Arc Evaporation (CAE) is widely used in the tooling industry, as it produces coatings with high density, hardness, and deposition rate. However, it generates macroparticles that increases surface roughness. In contrast, HiPIMS can achieve comparable coating properties with significantly lower roughness, albeit at a reduced deposition rate. Surface quality may deteriorate due to micro-arcing and discharge instability when less conductive nitride compound form on the target. To reduces micro-arcing and enhances coating density and hardness, bipolar-HiPIMS was developed, introducing a positive pulse immediately after the negative one to discharge target and accelerate positive ions toward the substrate. Nevertheless, the anode disappearance when depositing low-conductive coatings has not been solved.

This contribution presents PLATIT's recently developed TRM® (Twin Rotating Magnetron) technology installed in the Pi111 coater. The TRM® consists of dual rotating cylindrical magnetron with a Closed Unbalanced Magnetic Field (CUMF), powered by Bi-Pulse HiPIMS operated in asymmetric mode. In this mode, one magnetron operates at high power (up to 13 kW) while the other serves as a low power (0.5 kW) self-cleaning anode. The TRM® operates in “bipolar” mode where each magnetron alternates its polarities, each sequentially acts as a cathode and as a positively biased anode (since the anode is not grounded) during consecutive half-cycles of the pulse period. Owing to the combined effect of high average target power density, the CUMF, and the dense Me⁺ plasma generated during short HiPIMS pulses, the TRM® process achieves a high Ion Current Density to the Substrate (ICDS). The high ICDS, together with process stability and high target power density, are important factors for fast deposition of high-performance coating without the need for high substrate bias. To evaluate the coating performance between CAE and TRM®, AlTiN, AlCrN and TiSiN coatings were sputter-deposited from alloy cylindrical targets in an Ar+N₂ atmosphere. Coating growth was controlled by synchronized pulse substrate biasing, selectively utilizing the Me⁺ rich portion of the sputtered flux. To evaluate the coating performance, the following tests were conducted: adhesion, structure and microstructure (TEM), nanoindentation, and cutting tests (side milling and micro milling).

The minting industry is responsible for the design, production, and distribution of coins and medals both for national currencies and for commemorative purposes. The design and fabrication of coin dies combine expert craftsmanship with state-of-the-art technology which preserves value and celebrates heritage by producing coins of beauty and enduring worth.

The coin dies typically comprise of both highly-polished and frosted areas to create distinct visual contrasts and intricate images. The surface of dies needs to be coated with hard, wear resistant coatings for the die to withstand the force and repeated impact exerted on it during coin production. Physical vapour deposition (PVD) is an environmentally-friendly method used for the deposition of coatings on dies. Some of the processes, such as laser engraving, used in the minting industry during the production of dies have created new challenges for the PVD coatings.

Currently, Teer coatings PVD systems used in the minting Industry are capable of producing coatings for numismatic, proof or circulation coin dies using the PVD magnetron sputtering technique. To overcome the new challenges, an in-situ linear ion source device has been integrated in the coating equipment. It generates a wide, collimated plasma beam for treating large substrates. It is used to pre-clean surfaces by removing the surface oxides and hydrocarbons in order to improve the adhesion of the deposited thin films. At the same time, the process is tailored to ensure that the original features such as roughness, etc. are retained.

This study presents some of the developments which achieve the industrial demands, both through optimised coating design, and through equipment developments that enable the combination of different treatment and deposition technologies to improve the coating performance.

To obtain more environmentally friendly and cost efficient production processes, lubricants in milling applications are either removed completely or reduced to a minimum. Thereby, protective coatings for tools gain even more importance. Dry machining of hardened steels presents significant challenges due to elevated temperatures and the simultaneous occurrence of abrasive and adhesive wear. AlTiSiN based coating systems have been the state of the art for milling applications under these demanding conditions. In this study, milling tests were conducted to evaluate the performance of milling tools with different coatings. The coated tools exhibited varying degrees of wear and service life. Hence, understanding the underlying wear mechanisms is decisive for the development and selection of next-generation coatings, as wear is closely linked to tool longevity. Two types of coating systems were investigated: one AlTiSiN coating and one AlTiXN-TiSiZN coating. Wear was analyzed using confocal microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy. Distinct wear patterns and mechanisms were identified for each of the coatings. The results demonstrate that the AlTiXN-TiSiZN coating exhibits superior wear resistance, which makes it particularly suitable for milling of hardened steels with a hardness higher than 55 HRC.

The combination of laser surface texturing and diamond-like carbon (DLC) coatings represents a promising strategy to achieve superior tribological performance in demanding mechanical applications. In this work, the influence of controlled micro- and nano-scale surface patterns generated by laser texturing on the adhesion, morphology, and stress distribution of optimized DLC films was systematically investigated. Different laser parameters were tuned to tailor dimple density, depth, and distribution, enabling improved lubricant retention and reduced real contact area. Parallel optimization of the DLC deposition process (Dialong VS Dropless Argor Aljba Technologies) focused on intrinsic film properties such as macroparticles distribution, hardness, elastic modulus, residual stress, and sp²/sp³ bonding ratio. Tribological tests under dry and lubricated conditions demonstrated that the synergistic effect of surface texturing and DLC optimization leads to a substantial reduction in friction coefficient, enhanced wear resistance, and increased load-bearing capacity compared to conventional coatings. These results highlight the potential of integrating laser surface engineering with advanced carbon coatings as a robust pathway for the design of high-performance components in automotive, aerospace, and precision mechanics industries.

Over the past six decades, the requirements for hard coatings in protective applications have increased significantly. The progression from simple TiC monolayer coatings deposited via Chemical Vapor Deposition (CVD) in the 1960s to today’s sophisticated multilayer systems has been driven by several key factors: enhanced reliability of industrial coating equipment, continuous optimization of substrate materials and new pre- and post-treatment processes.

Among the most notable advancements are aluminium oxide (Al₂O₃) coatings, which have become a benchmark in modern cutting applications. Their unique phase structures offer performance benefits that are difficult to replicate with other coating systems. Alumina’s high hardness, electrical insulation, chemical inertness, and thermal stability make it exceptionally well-suited for demanding environments.

Beyond cutting tools, aluminium oxide is widely used across various industrial sectors. Its mechanical strength and thermal resilience support its role in protective coatings, while its excellent insulating properties are essential for sensor technologies. Additionally, its optical transparency and chemical resistance make it ideal for advanced protective layers.

In cutting tool applications, CVD remains the established method for depositing aluminium oxide. However, over the past 30 years, Physical Vapor Deposition (PVD) has gained increasing relevance, because of the lower deposition temperatures compared to CVD —initially driven by high-temperature cutting applications and more recently expanding into low-temperature applications such as insulating coatings for sensors.

Despite its versatility, scaling the PVD deposition of alumina thin films for industrial use presents several challenges. RF sputtering from compound targets can produce stoichiometric, high-quality coatings, but its low deposition rate limits its practicality for mass production. PVD techniques—particularly dual magnetron sputtering (DMS) from metallic targets—offer significantly higher deposition rates and effectively address issues such as the disappearing anode.

In this presentation, we will highlight ongoing developments in PVD oxide coatings—including innovations in coating equipment and advanced deposition technologies—that are opening new possibilities for enhanced cutting performance and broader industrial applications. We will compare various regulation strategies, examine the properties of alumina films deposited at different temperatures, and discuss future technological improvements that could further optimize deposition processes.

Carbon fiber reinforced plastic (CFRP) is a composite material consisting of a polymer matrix and carbon fibers, which requires excellent mold release, low friction, and high wear resistance during cutting. To meet these demands, cutting tools are often coated with high-hardness carbon-based films. Among these, tetrahedral amorphous carbon (ta-C) coatings exhibit outstanding hardness and low friction while minimizing chipping and substrate damage due to their nanolayer structure. However, the high intrinsic stress of ta-C limits its achievable thickness, hindering its application as a thick, durable coating.

In this study, a filtered cathodic vacuum arc (FCVA) system was employed to deposit thick ta-C coatings (>2.5 μm) on cutting tools. The effects of substrate bias voltage and process temperature on internal stress were investigated through multilayer film design. The deposition system consisted of an anode-layer ion source, a magnetron sputtering source, and a 90°-bent magnetic FCVA source. Stainless steel strips (100 μm) were used for stress analysis, and WC–Co inserts (15 × 15 mm) were used as substrates.

Prior to deposition, the substrate surface was cleaned using Ar ion etching at 2.5 kV and 400 mA, followed by deposition of a 500 nm Ti buffer layer via magnetron sputtering (6 A). The ta-C films were deposited using the FCVA source with alternating high-hardness (–70 V) and low-hardness (–200 to –500 V) layers, each 250 nm thick, yielding a total thickness of 2.5 μm. Additionally, the low-hardness layer (–500 V) was fixed at 100 nm, while the ratio between high- and low-hardness layers (1:2, 1:3, 1:4) was varied to optimize stress control.

The optimized multilayer structure (–500 V/–70 V, 1:3 ratio) produced a 63 GPa hardness and 4.5 GPa residual stress, enabling stable and uniform deposition even on the cutting edge of the inserts. These results demonstrate that proper stress control through multilayer engineering allows the formation of thick, high-hardness ta-C coatings suitable for CFRP machining applications, offering a promising route to improve tool performance and durability.

Keywords:

ta-C (tetrahedral amorphous carbon); Filtered Cathodic Vacuum Arc (FCVA); Cutting Tool; Hardness; DLC (Diamond-Like Carbon); Wear Resistance

The substitution of tungsten carbide (WC) and cobalt (Co) in hardmetals has gained increased attention in recent years due to the reclassification of Co as a carcinogenic substance and the designation of both Co and W as critical raw materials by the European Union and under the U.S. National Toxicology Program. Thus, this study investigates the development and performance of advanced NbC-based hardmetals utilizing nickel (Ni) and iron (Fe)-based binders as sustainable alternatives for metal machining applications within the electric vehicle (EV) manufacturing sector.

The materials were developed using a Machining Property Led Tailored Design (MPLTD) approach, a reverse engineering strategy that leverages machining performance data to guide the optimization of microstructural, mechanical, and tribological properties. Four novel NbC-based hardmetals were synthesized, two with Ni-based binders and two with Fe-based binders. These were benchmarked against two reference materials: a standard WC-Co composition and a conventional NbC-12Ni grade. Comprehensive material characterization was conducted using field emission scanning electron microscopy (FE-SEM), annular dark-field scanning transmission electron microscopy (ADF-STEM), Vickers hardness testing, fracture toughness measurements, and elastic modulus evaluations.

Cutting tool inserts were manufactured from these hardmetals were further enhanced via femto-second laser surface engineering (Fs-LSE), which was employed to form laser induced chip breakers and modify cutting edge morphology. The microstructural effects of Fs-LSE were examined through ADF-STEM and selected area electron diffraction (SAED) analyses. The performance of both untreated (blank) and Fs-LSE-modified inserts was evaluated through interrupted face milling tests on AZ31 automotive grade magnesium alloy. As AZ31 is considerably lighter than both steel and aluminum, its use in EV components significantly improves power-to-weight ratios and operational efficiency. The laser enhanced Fe- and Ni-bonded NbC inserts demonstrated machining performance comparable to industrial WC-Co benchmark grades. Furthermore, the Fs-LSE process resulted in over 100% reductions in flank wear and up to 80% decreases in resultant cutting forces. The inserts’ performance in this study provided valuable insights into the suitability of alternatives to WC and Fs-LSM for automotive industrial applications