Industry 4.0, Big Data, Internet of Things (IoT), digitalisation, networked production – these topics seem to be everywhere. So much so that the mere mention of the buzzword “Industry 4.0” causes uncertainty among many technicians in medium-sized companies. This is because they are unsure what “Industry 4.0” will actually mean for their own day-to-day work and their future-proof production strategy and production planning. By Florian Böpple, Digital Manufacturing Manager at Walter.
WPV10 and WPV20 are the latest insert grades that Walter USA has introduced to its Perform line of turning tools. Designed for versatility and cost-effectiveness, they cater to users whose machines are limited in cutting parameters. These resourceful inserts can handle different materials, as well as machines that come in small or medium sizes.
Both grades have chemical vapour deposition coating and gold colour for easy wear detection. In field testing, the inserts demonstrated superior process reliability and good chip control with tool life increases of up to 100 percent when compared to their counterparts.
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Dirk Masur, aerospace component manager and specialist in titanium machining, Walter AG, tells APMEN how Walter is improving methods in which this difficult element is fabricated with the aid of special tools.
Tübingen-based specialist Walter’s Xpress range is made to measure for the exacting requirements of the aerospace industry. In particular, their solid carbide tools with customer-specific dimensions are available for delivery within two to a maximum of three weeks. An innovative and new tool coating and tool technology ensure that tool life is more than doubled in some cases.
In the aerospace industry, things are done a little differently in comparison to other sectors. Weight plays a pivotal role, and every gram less counts. It is ultimately a product’s weight that determines its profitability, rather than part and component prices. It’s no wonder then that titanium is enjoying considerable growth and popularity in this sector. This is the case especially for structural components for which high strength also matters. Typical examples are doors and door frame surroundings, landing gear supports, undercarriage struts or landing flap tracks. Titanium is also corrosion- and temperature-resistant.
However, manufacturers of aircraft for civil aviation in particular are finding themselves increasingly subject to the pressures of a series manufacturer, as is familiar for example from the automotive industry. Up until now, Boeing, Airbus, and to a lesser extent Bombardier, have mainly shared the market between themselves. Meanwhile, new competitors from China and Russia are preparing to enter the market. The pressure for manufacturing to become as cost-effective as possible is therefore increasing.
Further Development Of The Tooling Systems
The challenge lies in titanium being more difficult to machine than aluminium, which has largely been used until now. Its high chemical reactivity leads to chips becoming fused at the cutting edge during machining. The poor thermal conductivity of the material allows temperatures at the cutting edge to rise significantly. The resulting chips are often extremely tough and abrasive. The minimal modulus of elasticity leads easily to the workpiece bending. Together with material solidification in the edge zone, this reduces the tool edge life even at low cutting speeds.
The tool costs also significantly depend on the demands placed on the component and the material, as well as on the process. Decreasing the wall thickness can cause the parts to become extremely unstable, thus an important focus is the stability of the machine and the clamping. Using the right coolant strategy also has a significant influence on tool life. Walter is continually developing its tooling systems with the aim of reducing machining times. Carbide substrates, new coating technologies and macro- and micro-geometries of the cutting tools play an important role here. The machining strategy can, however, also be further optimised in collaboration with CAD/CAM specialists.
This all makes high-performance cutting (HPC) and high-dynamic cutting (HDC) for finishing and roughing titanium possible today. Dynamic milling with the Walter Prototyp Ti38 Z6-10 and innovative new coating enables cutting speeds of up to 140 m/min to be achieved. Multi-tooth solutions with up to ten teeth allow the feed to be increased by up to 50 percent at low contact widths. These solid carbide tool solutions can ultimately achieve an increase in metal removal rate of up to 50 percent in comparison to conventional solutions.
Coating Determines Tool Life
An example of the newly developed substrate and coating technologies is the PVD-based coating (physical vapour deposition) for solid carbide tools in the Walter Prototyp Ti range. This coating substantially increases tool life in comparison to the conventional aluminium chromium nitride coating— by up to 100 percent and more.
This means that the tool life of a window frame made of 3.7164 titanium with a tensile strength of 1250 N/mm² when semi-finishing and finishing using a Prototyp HPC Ti40 has been able to be raised by 154 percent from 175 minutes to 444 minutes. Using a Prototyp HDC Ti38 L for finishing the outer contour has extended tool life by 116 percent. The speed has been increased by 25 percent and the machining volume by 23 percent.
A further innovation is CVD coating technology for the indexable insert cutting tool material WSM45X, which is used for example for the Walter BLAXX M3255 porcupine milling cutter. The coating functions as a heat protection shield, facilitating high cutting speeds of up to 65 m/min and extending tool edge life to up to 130 minutes. This makes it possible to double the tool life of titanium structural components, which are typically made using a mixture of full slotting and climb milling at a cutting speed of 45 m/min and a feed of 0.12 mm. A further option is to increase the cutting speed to 65 m/min with a constant tool life of around 60 minutes. Finish-milling can also be carried out with PCD (polycrystalline diamond) cutting edges, which are amongst the hardest materials known.
An appropriate coolant strategy must be implemented in this case, however, in order to keep the machining temperature at the cutting edge under 600 deg C. In general, the cutting fluid and the concentration of the cooling medium have a significant influence, especially on tool life. It is most important to introduce the cooling medium as directly as possible into the working zone. This is facilitated by special coolant-throughs in the tools. High-pressure cooling at up to 70 bar is very advanced for new machine tools. Special tool solutions for cryogenic machining go even further, working with liquid carbon dioxide or nitrogen, which is even colder.
From Tool Supplier To Technology Partner
Walter considers itself to be a digital process partner and is therefore developing tools which are ever more closely related to applications in the sense of “component solutions”. This requires an entire team of specialists. Appropriate CAD/CAM skills are a key prerequisite for complete evaluation of the processes. Walter caters to its customers’ needs and offers tools, solutions and services throughout the entire process.
With regard to this development, Walter developed the “Component Solutions” project in collaboration with the Advanced Manufacturing Research Centre at the University of Sheffield some time ago. In the course of the project, special machining strategies were developed for all pocket shapes occurring for structural components, using the CAM programs commonly used in the aviation and aerospace industries. This “toolbox” enables a suitable machining process to be quickly and efficiently derived from a 3D model of a customer component.
Highest Quality In The Shortest Time
“Good things come to those who wait” no longer rings true today. Even high-performance tools with special, customer-specific dimensions are subject to immense time pressure. Since the beginning of the year, Walter has therefore been offering the Walter Xpress service especially for the aerospace sector too. Xpress tool solutions are available for delivery within two to a maximum of three weeks. The speed starts from the ordering process itself. The my.Walter software solution enables the customer to design the tool online themselves or together with a trained field service employee.
With “Walter Online Xpress”, the customer receives a binding quotation including a 2D drawing and 3D model by e-mail within a maximum of one hour. The order itself, which is frequently a bottleneck within the company, is also significantly accelerated using Walter tool management.
Walter’s Tool Life app is for visualising and analysing tool data. The browser-based user interface can be called up universally via the intranet network of the relevant customer. The user interface has improved menu navigation handling, while a newly structured database in the background enhances performance. The app does not need a code to identify the tools for the system. This means that users benefit from multi-device functionality and flexible working.
Users will need the company’s appCom package—comprising an industrial PC and standard software developed—to make full use of the app.
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Lightweight yet high-performance drive systems are the order of the day for the rapidly changing automotive industry, but some of the new materials used to achieve this are challenging to machine. By Lim Gan Shu, Southeast Asia marketing manager, Walter
Roughing and finishing turbine housings is particularly challenging in the case of passenger cars with spark-ignition engines. By Lim Gan Shu, marketing manager, Walter AG Singapore.
Downsizing makes engines more economical. In order to ensure that their performance is not compromised, turbochargers are increasingly being used to compensate in smaller vehicles. The market is growing – but so is the pressure on prices.
Vehicle fuel consumption needs to be reduced – not just in the lab. Legal provisions from all over the world are driving the automotive industry to implement measures in almost every vehicle class. This has given rise to huge challenges for the automotive industry. An important factor: Turbochargers that squeeze high performance out of small yet efficient engines. However, the turbochargers themselves are also under pressure to be smaller, more efficient and, importantly, more cost-efficient.
Reducing Machining Costs
“We expect—and studies by leading turbocharger manufacturers agree—that the number of turbochargers used for petrol engines will experience a 2.5-fold increase over the next five years,” says Rolf Buob, component manager for turbine housings at Walter AG in Tübingen.
Currently, turbochargers for petrol engines place particularly high demands on machining when compared with diesel engines. The exhaust gases in the turbine housing reach temperatures of between 1,000 and 1,050 °C; in diesel engines, however, they reach relatively low temperatures of between 800 and 850 °C.
“Temperatures of 1,000 °C or higher require high temperature-resistant steels, typically chrome-nickel alloy steels that have a material identification number beginning with 1.48 and ending in 49, 48, 37 or 26 – with a tendency towards the material identification number 1.4826. These 1.48 steels are constantly being developed further and it is becoming more and more difficult to machine them,” explained Mr Buob.
They also make the turbine housing the most expensive component in terms of machining. Mr Buob explained further: “We anticipate different machining costs for each component, depending on the presence of an exhaust manifold.” Above all else, a high chrome content reduces service life. “There are applications where tools only last long enough for twenty to thirty components.” For comparison: The materials used for diesel engine turbine housings extend the service life by up to five or ten times, while also being 50 percent faster to machine.
Walter machining experts have therefore developed a new milling cutter concept especially for roughing, semi-finishing and finishing turbocharger housings. It reduces the all-important cost per finished part, while also significantly improving surface quality. Over the course of the development process, the cartridge system used for finishing, which had previously been the norm, was replaced with an intentionally simple tool design with a fixed insert seat.
This “plug-and-play” solution eliminates the need to carry out presetting operations, which required accuracy to between 3 and 5 µm.
Further saving measures: The use of identical indexable inserts with 16 cutting edges as semi-finishing and finishing inserts. Previously, the market standard was to use 12 for semi-finishing and four for finishing. This also simplifies inventories and eliminates errors when changing the indexable inserts. The indexable inserts are coated with PVD or CVD and are available in various geometries.
Indexable inserts belonging to the Walter WSP45S or WSM45X grades are typically used. Short cutting edges reduce the pressure on the unstable components. This results in reduced vibration, which improves surface quality, increasing it from the usual Rz 7-8 to approximately Rz 5. “Overall, these measures lead to improvements in handling and process reliability,” said Mr Buob.
As a rule, every third to fifth insert is positioned differently on the finishing tool. The position of the semi-finishing inserts can be adjusted by approximately 5° in the same way as when carrying out rough machining; the finishing inserts are inserted so as to cut in a flat plane.
Mr Buob explained: “This is why we distinguish between semi-finishing and finishing inserts on the same tool, even when the inserts are identical. Only the insert seats are rotated differently when inserted.”
The cutting speed when finishing is approximately 140 m per min at a feed rate per revolution of up to 4 mm. This milling cutter is also available for machining allowances of up to 3 mm for roughing in particular. Here, the indexable inserts are aligned uniformly both axially and radially, in contrast to the finishing face mill. They all have the same function for machining operations.
However, the new milling cutter concept does not mean that development has finished. Walter is expected to make further advances involving new PVD coatings that are currently still in development.
Walter has developed the DC170 and is offering the first two models in dimensions 16xDc and 20xDc. The drill offers more process reliability, stability, running smoothness and efficiency than carbide drills with traditional geometries.
The drills are internally cooled. As a result, the coolant flows unimpeded, while hazardous chip jams are at the same time avoided. The manufacturer also says that the solid carbide mass directly behind the cutting edge makes the drill sturdy.
Finally, drills straight from the factory are supplied with eight visible channels that can be used as a scale for regrinding. The drills can be reconditioned up to three times, until only two cooling channels are left remaining.
Aluminium is one of the most important materials in the aerospace industry. Furthermore, typical components are extremely machining-intensive and therefore require long production times. Tools designed to precisely suit these requirements, such as the M2131 ramping cutter from Walter AG, help to reduce machining times and costs. Lim Ganshu, Walter marketing, explains
Producing components for modern gas turbines is a challenge that machining experts are familiar with; they are often faced with the task of machining difficult-to-cut materials such as titanium alloys and superalloys and creating shapes such as onion-shaped profiles and flutes. This difficulty is compounded by the fact that the turnaround time for machining the components must be as short as possible, while the process must be incredibly precise. Lim Gan Shu, marketing manager, Walter AG shows how precision tools, developed machining concepts and optimised tools set new standards in the field.
The new M4256, M4257 and M4258 porcupine milling cutters are versatile in terms of both the range of applications and the materials for which they can be used, which include steel, cast iron, stainless steels, and difficult-to-cut materials.
They are available with Weldon shank, modular ScrewFit interface and bore adaption. Their compact length and half-effective design with low cutting pressure allow for a smooth operation, reducing the tendency to oscillate and vibrate to make them suitable even in unstable conditions.
The features of these milling cutters become more prominent when paired with the D51 geometry insert. The chip clearance integral in these porcupine milling cutters make for an effective chip evacuation, especially in flute design where chips cannot fly to the side.
The milling cutters can also be used for ramping, pocket milling, shoulder milling and circular interpolation. They are most likely to be of interest to users operating in the general mechanical engineering sector.