Walter Tools has released a new white paper on the advantages and benefits of dynamic milling. Higher process reliability, and shorter machining times at ever lower costs—many industries, especially suppliers, are in this dilemma. In addition, there are always new materials, driving the need for weight savings, corrosion resistance and resistance to very high temperatures. And then there are materials that are often difficult to machine.
For all of these, dynamic milling offers a solution that promises both higher productivity and higher process reliability under the right conditions. In a new whitepaper, Walter Tools discuss the advantages of dynamic milling compared to other milling processes. It also highlights all the facts that you need to know about the process, including prerequisites, technologies in comparison, and effects, among others.
Reducing CO2 greenhouse gas emissions has a considerable impact on the development of machining tools, as new fields of application are emerging, and existing ones need to be adapted. This is because alternative drives, new, lighter materials, and concepts that save energy and resources are now more in demand than ever before. Article by Walter AG.
The Walter Xtra·tec XT shoulder milling cutter and face milling cutter are suitable for virtually all requirements in shoulder and face milling, in all common material groups.
Reducing CO2 greenhouse gas emissions has become an objective throughout the world. In many places, there are now discussions about imposing taxes on CO2 emissions. The German government has set itself the objective of reducing carbon dioxide emissions in Germany by 55 percent by 2030.
This also has a considerable impact on the development of machining tools, as new fields of application are emerging, and existing ones need to be adapted. This is because alternative drives, new, lighter materials, and concepts that save energy and resources are now more in demand than ever before. Developers see great potential in design modifications to tools, new coatings, new machining strategies, and digital solutions, which respond to the existing framework conditions in real time.
Increase Tool Life
The current trend is for new, lightweight aluminium-lithium alloys. These materials quickly overwhelm conventional tools, resulting in an increasing demand for high performance tools specifically designed for this range of applications.
For instance, aircraft components made of aluminium alloys often have machining volumes of up to 90 percent. Depending on the required component geometry, numerous bevels and cavities need to be milled out of the metal, with the goal of ensuring stability and reducing weight. To manufacture the components economically and to a high quality, they need to be machined using high speed cutting (HSC) processes involving cutting speeds of up to 3,000m/min. Cutting values that are too low lead to build-up on the cutting edge, and therefore result in rapid wear and frequent tool changes. This results in high costs due to long machine running times. Machine operators specialising in aluminium therefore have good reason to demand above-average cutting data and tool life from their tools, as well as particularly high process reliability.
With the design of the M2131 ramping milling cutter, the tool developers at Walter AG have shown how such complex requirements can be dealt with. The 90 deg milling cutter is equipped with a new class of indexable inserts, with the grade designation WNN15. This refers to a new PVD coating, which is manufactured using the HIPIMS method. The term HIPIMS stands for “High Power Impulse Magnetron Sputtering”, a technology based on magnetron cathode sputtering. The special feature of the physical coating process is that it produces an extremely dense and smooth PVD coating, which greatly reduces friction and the tendency to cause built-up edges. At the same, this method increases cutting edge stability and resistance to flank face wear, enabling a maximum metal removal rate as a result. Field tests have confirmed the advantages of HIPIMS indexable inserts compared to standard types. Increases in tool life of up to 200 percent were achieved.
“We are seeing an increasing demand for high-performance tools for machining aluminium, particularly in the aerospace industry but also increasingly in the automotive industry,” explains Wolfgang Vötsch, Senior Product Manager for Milling at Walter AG.
Suitable workpieces, milling tools, machines and CAD/CAM systems are required for the dynamic milling strategy. Image: Walter AG
Milling Strategy with a Focus on Efficiency
Many sectors, particularly the supply industry, are under pressure to provide increased process reliability and faster machining—at ever lower costs and with consistent quality. The demands for surface quality and dimensional stability are often increasing at the same rate as requirements for process reliability and cost efficiency. Moreover, there is a growing need for lightweight or heat-resistant materials. However, these materials from the ISO M and ISO S material groups are often difficult to machine precisely because of these properties.
Dynamic milling provides a solution in this area, offering both productivity and process reliability. This is why a growing number of metalworking companies are relying on this method.
High Performance Cutting vs. High Dynamic Cutting
The main differences between conventional high performance cutting (HPC) and high dynamic cutting (HDC) are in the movement of the milling cutter and the forces generated. During HPC, the milling tool moves with relatively low depths of cut. During HDC, the CAD/CAM control system adapts the machining paths so that the tool moves according to the shape of the workpiece. This prevents non-cutting time, or at least reduces it. Moreover, the depth of cut is significantly greater during HDC than during conventional HPC, meaning that travel distances are also reduced because the complete tool length can be used.
The engagement angle is usually very large during HPC. The forces that occur in the process are accordingly high. This in turn quickly causes signs of wear to appear on the tool and the machine spindle. Dynamic milling, on the other hand, is characterised by a high level of process stability and a long tool life. The engagement angle chosen for HDC is normally small, meaning that the forces which impact the tool and machine are much lower than for HPC. Higher cutting parameters, less non-cutting time and increased process stability result in a much higher metal removal rate for HDC milling compared to HPC.
Cutting Data Optimisation Using Live Data
Automation, digitalisation and networked processes have been everyday aspects in many areas of metalworking for a long time. In particular, the hardware and software used to collect and analyse live data have produced huge leaps in performance.
The Comara iCut software tool demonstrates how this provides opportunities to optimise processes. The adaptive feed control analyses incoming machine data in real time and adjusts the machining accordingly. This answers one of many users’ key questions. Namely, how can you get the most out of a machine without making major changes to the process or carrying out complex reprogramming work?
The iCut software enables the machining time per workpiece to be significantly reduced. This software is integrated into the existing control programme and applies the data from this for the machining process. During the first cut, iCut “learns” the idling output of the spindle and the maximum cutting efficiency per cut. Subsequently, it measures the spindle output up to 500 times per second and automatically adjusts the feed in each case. This means that the machine always operates at the maximum possible feed for each tool. Should the cutting conditions change (depths of cut, machining allowances, wear, etc.), iCut adjusts the speed and output in real time. This not only has a positive effect on the machining time for the workpiece, the optimised milling characteristics also increase the process reliability. The forces acting on the spindle are more constant and this also results in a longer service life.
If the tool is in danger of breaking, iCut reduces the feed straight away or stops the action altogether.
Florian Böpple, Digital Solutions Manager at Walter, says, “We have already achieved astonishing increases in efficiency for customers using iCut. If the machining operation is compatible, a 10% reduction in machining time is always achievable. We have already managed to reduce machining times by double this amount. When the quantity is high, this frees up considerable machine capacity.”
In addition, this works irrespective of whether Walter tools are used; all that is necessary is for the machine’s system requirements to be met.
Milling with ‘Xtended Technology’
Walter recently showed the potential of the tools themselves with the entirely new generation of Xtra·tec XT milling cutters. They combine design improvements with high-performance cutting tool materials. This means that the focus is always on increased productivity and process reliability. The most striking design feature is the installation position of the indexable inserts, at a greater incline and with a larger contact surface. This reduces the surface pressure in the seat while increasing the stability. The larger screw hole cross-section stabilises the indexable insert and the longer screws hold it in place more securely. The cutter body has also been made stronger, now with much more material behind the insert seat.
Besides increased process reliability, the special installation position of the inserts also allows for the addition of an extra tooth, thereby increasing productivity. The precise 90 deg shape of the shoulder milling cutter helps to reduce what would otherwise be additional required finishing operations. Clamping screws which are easier to access optimise handling and help prevent assembly errors.
Another new feature, which applies to the face milling cutter M5009, is the smaller indexable inserts which can be fitted to the milling cutters. These continue the current trend towards reduced machining allowances. The M5009 milling cutters combine small depths of cut with the economic advantages of double-sided indexable inserts—with eight usable cutting edges rather than the usual four. Thanks to these cutting edges, as well as a reduced number of finishing operations, the milling cutter achieves increased efficiency.
Our innovation also extends to sustainability. As part of Walter Green, the production and supply chain of the Xtra·tec XT milling cutters is CO2-compensated.
The four examples illustrate where we are heading in the metalworking industry—with respect to tools, machining strategies and the field of digital innovation. At the same time, they highlight four approaches showing where the opportunities lie and how the trends and challenges of the future can be dealt with successfully.
Walter Enables Automatic Detection For correct pre-positioning of tools and blanks prior to machining, WALTER now offers a new TOOL VISION SYSTEM for all its tool grinding / eroding machines with robot loader. This Walter Automatic Detection system detects contact free, the orientation of the tool or blank, with e.g. brazed PCD plates on the front, sintered PCD veins or with cooling channels. The detecting is done automatically and during idle time. This means significant timesaving compared to the manual measurement method, eliminates human errors and avoids damage to the tool due to the non-contact method.
The WALTER TOOL VISION SYSTEM is permanently installed in the robot cell and available with two lenses. The one lens for tool diameter from 1.7 mm to 12 mm, the other lens for tool diameter from 6 mm to 32 mm.
For 17 years now, tool manufacturers have been successfully implementing Walter’s two-in-one concept in production. Here’s a look at what exactly is behind this concept. Article by Walter Maschinenbau GmbH.
Now more than ever, the ability to be flexible and agile in your production is a key competitive advantage in the metalworking industry. The more process steps you can eliminate, the leaner your become, with improved efficiency and less waste—in terms of the time it takes to switch to a new machine to do a second process, and the energy needed to run the machine; what more in a volume production operation.
From a production viewpoint, the two-in-one concept means that users can completely erode tools (PCD or polycrystalline diamond) and also completely grind tools (carbide) using one and the same machine. What is more—and this is one of the key advantages of a two-in-one concept—both processing methods can be used on one and the same tool without the time-consuming step of switching to a second machine. This is especially necessary and more efficient in the case of modern PCD tools where the carbide blank already has soldered PCD.
The ability to erode, grind, or even do both in one clamping operation gives the user an unparalleled level of flexibility in their production processes. Walter Maschinenbau GmbH’s two-in-one machines can be used to process any PCD tool in any field, whether it be the wood, automotive or aerospace sectors, or even special applications. As the use of complex and modern full-headed PCD tools is constantly increasing, so is the demand for combined processing, i.e. eroding and grinding using a single machine. This trend is already clearly evident when one considers the new kinds of PCD tools required, amongst other things, for carbon fibre reinforced polymer (CFRP) processing in the aerospace sector, for example. Combined processing is the only way to efficiently produce such PCD tools.
A further advantage can be derived from this in business terms: The fact that the user can perform both eroding and grinding or combinations of the two processing methods using one machine means that investing in such a two-in-one machine represents a risk-free introduction to the PCD field for companies that have not been able to or have not wanted to produce such tools until now. If it turns out that the PCD business does not develop as expected, the same machine can simply be used to completely grind the previous product range.
Enhancing the Two-in-One Concept
Ever since presenting it to the world at the EMO tradeshow in 2001, Walter has been continuously further developing this two-in-one concept, and today offers a total of three machines based on it. Even back then, the company knew that a powerful grinding spindle was essential for perfect production results and that many tools could be manufactured more efficiently with rotary eroding than with wire eroding.
In 2006, Walter introduced a software module that boosted the benefits of the two-in-one concept because it now also allowed electrode/grinding wheel changers to be automatically implemented. That same year also saw the introduction of ‘Fine Pulse Technology’ for all two-in-one machines, setting new standards in terms of the surface quality, cutting edge roughness, and process reliability of PCD tools.
In particular, the generator was recognised as a central element and therefore has been completely redesigned. Improvements in eroding software and a variety of other factors based on the machine design were also optimised as part of Fine Pulse Technology. The difference to the other tools on the market can even be seen with the naked eye on the most common PCD types with 10µm grain size. A tool produced with Walter’s technology on a two-in-one machine shines on its free surface, similar to a polished (ground) tool. Even coarse-grained PCD types, which previously could not be fine finished on the market, can be eroded with the new technology, and a perfect surface quality can be produced.
In some cases, even entire steps in the production chain can be omitted because the eroded tools no longer have to be re-sharpened or polished. Finally, the Helitronic Tool Studio software solution was enhanced with the software licence ‘Eroding’ in 2017, making the tool shaping process even easier and clearer, especially for PCD tools.
Producing threads in hardened steel is costly. This applies to blind hole machining in particular because reversing the tap during this process can cause torque peaks when the root of the chip is sheared off, resulting in fractures.
Walter is solving this problem with two new taps – offering its customers a full product range for producing threads in hardened steels with an additional thread milling cutter: The TC388 Supreme (50–58 HRC) or TC389 Supreme (55–65 HRC) and the TC685 Supreme (> 44 HRC). The TC388 and TC389 Supreme solid carbide taps boast special cutting geometries. These fully shear off the root of the chip when reversing; torque peaks are minimised. This prevents fractures, prolongs the tool life and increases process reliability. Lubrication with oil, which was often necessary until now, is no longer required. Instead, emulsion can be used, which optimises handling and saves additional machining time. Both taps are characterised by a short machining time.
The TC685 Supreme orbital drill thread milling cutter enables maximum process reliability and the highest possible tool life quantity. The core hole and thread (chamfer if required) are produced in a single operation, thereby saving tool spaces. The milling geometry on the face produces stabilising forces in the axial direction. This improves the stability when milling and reduces the deflection. Advantages for the user: Fewer radius corrections and reduced wear, with a high tool life quantity and minimal costs per thread. The 15° helix angle and internal coolant from M6 guarantee reliable chip evacuation. This allows even tougher steels and deep threads to be machined reliably. Common applications for all the tools mentioned include mould and die making, for example.
Walter has expanded its Perform product range with the launch of the new MC232 Perform solid carbide milling cutters. The MC232 milling cutter features a corner radius and reduced neck, allowing the user to better approach individual component geometries. It also improves the tool life of the milling cutter, as the edge stability is increased. The reduced neck in turn makes the milling cutter more flexible, as the user can use it with an even wider variety of cutting depths.
Other features of the Perform line have been adopted: the high level of cost efficiency for small and medium batch sizes, or Walter’s own WJ30ED grade, which provides a high level of wear resistance. ISO P materials are the primary application of the MC232 Perform, with ISO M and ISO K as secondary applications. The new milling cutters are likely to be of particular interest to job shops and manufacturers with frequently changing orders or quantities.
The Walter range in the MC232 Perform family now includes solid carbide cutters with or without a reduced neck and with or without a corner radius in a total of 126 dimensions, of 2–20mm in diameter. The milling cutters can be used for all typical milling applications (lateral milling, full slotting, pocket milling, helical plunging, ramping) and are suitable for a variety of materials and milling strategies.
Walter AG has launched new single-sided indexable inserts with HU5 geometry for ISO M and S materials, helping users produce more components using the same number of machines.
The HU5 has a larger contact surface to the tool holder, increasing the stability and allowing for greater cutting depths, feeds and a larger metal removal rate—specifically, in the practical test, this comes to 18.36l/h instead of 10.71l/h. In addition to the stable fit, the decisive factor behind this is the combination of the geometry and Walter Tiger·tec Silver cutting tool materials, which allows for increases in tool life of up to 75 per cent. The geometry itself has been specially developed for heavy roughing of stainless steels and high-temperature alloys. It is typically used for applications in the oil and gas industry, for instance, in large valves made from AISI 316 material, or in the aerospace industry with Inconel 718 or titanium materials.
The main cutting edge, which is protected by a negative chamfer, prevents fractures when machining hard edge zones and optimises the performance for hard scale, for example, of forged parts. Components with interrupted cuts and other demanding machining operations are equally feasible.
The curved cutting edge and a deep chip breaker groove produce low cutting forces with high feed rates, consequently reducing the machining temperature. The variable rake angle in the area of the corner radius allows for soft chip reforming and increases the tool life. Available in standard CNMM, DNMM and SNMM, Walter rounds off its vast product range in the areas ISO S and M with the HU5 geometry. Walter now offers a total of 12 geometries in six grades as well as tools with precision cooling and ceramic or CBN inserts.
Walter AG has expanded its range of threading tools with the release of the TC410 Advance HSS-E thread former with TiN coating and a new geometry, which can be used universally for blind and through-hole threads (metric, metric fine, UNC/UNF and G), all formable materials from the ISO material groups P, M and N as well as for ISO K and S as a secondary application.
The tool’s new geometry and special post-treatment help reduce the cutting time in the material—hence reducing friction and, consequently, the amount of heat generated, which in turn reduces wear and ultimately increases the edge life of the tool. Likewise, the post-treated, extremely smooth surface of the tool reduces the torque and increases the tool life as a result.
Walter’s TC410 Advance is available in two variants: without lubrication grooves or with lubrication grooves for deeper threads up to 3.5 × DN. The tool is suitable for users with medium to large batch sizes in particular, because it can produce more threads with the same tool.
Over 1,500 international visitors—including customers, experts and industry representatives—experienced new metalworking technologies and current trends in the manufacturing industry at the Grinding Symposium 2019, a three-day trade event held by the United Grinding Group in Thun, Switzerland.
Packed with technology presentations and lectures, the Grinding Symposium also featured FutureLAB—which highlighted the future technologies in the metalworking and manufacturing industries.
“Our aim in presenting these future technologies is to create a dialogue with our customers and to discover more about their individual expectations and requirements,” explained Christoph Plüss, chief technology officer at United Grinding Group.
Through the 16 lectures at the symposium, attendees were able to discuss opportunities and challenges in the cooperation of human and machine, the potential of artificial intelligence (AI) and machine learning in the manufacturing industry, and practical production topics.
The 13 technology presentations provided opportunities for attendees to experience the latest machines and solutions—from the Mägerle MFP 30, an innovation in machining aircraft engine blades, to the European premiere of the Studer S31 for machining very long workpieces; and from the extensive services offered by the United Grinding Group’s Customer Care department through to the production of ultra-hard tools using laser on an EWAG LASER LINE ULTRA.
The United Grinding Group is one of the world’s leading manufacturers of precision machines for grinding, eroding, laser cutting, measuring and combination machining. Its corporate brands include Mägerle, Blohm, Jung, Studer, Schaudt, Mikrosa, Walter and EWAG.
Walter AG, a provider of machining tools for milling, turning, drilling and threading applications, celebrated the centenary of its foundation on May 14, 2019.
Guests included international customers and partners, as well as Klaus Tappeser, Chief Commissioner of the district of Tübingen; Joachim Walter, District Chief Executive of Tübingen; and Boris Palmer, Lord Mayor of the city of Tübingen.
“For 100 years now, Walter AG has been a synonym for high-calibre engineering with a strong commitment to innovation. The company is an extraordinary exponent and shining example for manufacturing precision tools, where it holds a leading role in Germany,” said Dr Nicole Hoffmeister-Kraut, Baden-Württemberg’s State Minister for Economy, Labour and Housing, during the foundation day celebration.
The celebration focused on the innovation, creativity and future potential of Walter. Prof Dr Peter Post, Member of the German Council of Science and Humanities as well as Head of Applied Research at Festo AG, spoke about the meaning of digitalisation and innovation for the German industry.
The event featured the grand opening of the new company museum.
Richard Harris, president of Walter, said, “Walter employees have not only further developed the numerous inventions of company founder Richard Walter, but also created new tools, coatings and production methods. Our new company museum is a testimony to the Walter spirit of innovation, and it will be an inspiration to new generations of Walter engineers and technicians. Today, we celebrate their inventiveness and creativity.”