ECOROLL AG Werkzeugtechnik is the leading supplier of tools and machines for the mechanical surface finishing of metallic workpieces. Through close cooperation with their customers, demand-oriented tools and machines for roller burnishing and deep rolling as well as for cylinder tube machining are designed, produced and sold worldwide. In this interview we are talking to Markus Diedrich-Philippi, Head of Sales at ECOROLL about his experience in different branches.
(?) MFN: Hello Mr Diedrich-Philippi, thank you for taking the time for this interview. To start with, can you tell us a little bit about yourself and your job at ECOROLL AG?
(!) M. D. P.: I have been with the company since 1998 and initially worked in technical sales. My main task was to deal with customer enquiries and to find and offer an optimal technical solution. On the one hand, there were many applications that could be covered by our standard tool program, but there were also frequent special cases that were developed jointly, in close coordination with our customers, at our development department and design department.
Since 2014, I have taken over the sales management. My task is to support and manage the entire sales team, consisting of office staff, order processing and our own field staff. In addition, I am responsible for the cooperation with our other sales partners in Germany and abroad.
(?) MFN: Today we want to talk about different applications of deep rolling. Shot peening has some advantages, especially the accessibility and flexibility of the process, how would you compare roller burnishing and deep rolling?
(!) M. D. P.: Shot peening is particularly advantageous for irregular component contours, as geometrically inaccessible bodies can also be reached with the process. Roller burnishing and deep rolling is mainly used for machining rotationally symmetrical components, but free-form surfaces can also be machined very well with our hydrostatic tool system HG and the newly developed Hammer Peening tool type ECOpeen. Applications for this can be found in die and mould making. In contrast to shot peening, ECOROLL tools are used on standard machine tools and the rolling process is carried out directly after machining, in the same set-up. In this process, the corresponding tool, consisting of one or more rollers or balls, is rolled over the surface of the component. The required machining parameters are maintained by the CNC control of the machine tool. A very important parameter in this process is the rolling force, which in combination with circumferential speed and feed rate is responsible for the correct process sequence. It can be said that any machined component can also be finished by burnishing or deep rolling, so burnishing and deep rolling are widely used in all common industries.
(?) MFN: What are the typical industries in which rolling is used?
(!) M. D. P.: Ultimately, in all industries in which metal components are mechanically processed and which are subject to high dynamic loads. This includes the entire range of the automotive industry, from passenger cars to heavy-duty trucks. We find further applications in general mechanical engineering, in energy technology, shipbuilding, medical technology and, last but not least, in aviation.
(?) MFN: You just brought up the keyword energy technology. With the current energy crisis, we are interested in your solution in the field of energy technology. What solutions can you name from this field?
(!) M. D. P.: We have many years of experience with applications for the oil and gas industry. Drill pipes and directional drilling systems are subject to high mechanical loads during oil and gas exploration and must be designed to be fatigue-resistant. With the help of our technology, critical areas where there is a high notch effect are strengthened. In particular, transition radii, threads and thread undercuts should be mentioned here. Through deep rolling, compressive residual stresses are introduced in a targeted manner, strain hardening and hardness increase of the relevant edge zone is achieved, and thus a significant increase in service life as well as process reliability of the components is achieved.
Another example is the deep rolling of rotor shafts on steam turbines in the nuclear sector. Here, multi-stage radial grooves, which hold the turbine blades during operation, are deep-rolled. Incidentally, this is an area that is not accessible at all by shot peening. The advantage for our customer is the significant increase in strength in the area of the radial grooves, which leads to a guaranteed, revision-free extension of the service life of a turbine, optimised in this way, by 10 years.
Currently, the focus is on the expansion of renewable energies with the aim of reducing CO2 emissions. We have been successfully machining components of wind turbines by roller burnishing and deep rolling for quite some time. On very massive rotor shafts, transition radii are strengthened by deep rolling, thereby increasing the fatigue strength of these parts. In addition, bearing seats are roller-burnished in the same set-up so that additional machining by grinding can be omitted. A new application is the treatment of slewing rings for wind turbines, which are produced on vertical lathes and where the bearing raceway is roller-burnished.
(?) MFN: What were the special results in the application for wind turbines?
(!) M. D. P.: The great advantage and customer benefit is the process-reliable machining and the reliably reproducible results of the surface machining. Important to mention here is the surface material load-bearing component, which is particularly important for bearing seats. Due to the higher material content, bearing seats machined in this way have a significantly larger contact zone with the bearing and thus prevent wear of this zone.
Large components in particular can be machined safely and with reasonable effort using deep rolling. The complete machining, in one clamping, directly after the machining, ensures a high economic efficiency, because other cost-intensive processes such as heat treatment and grinding can be substituted. Other costs, such as retooling to other machines, or transport and handling costs for external machining, are also eliminated.
(?) MFN: Wind energy components are generally huge. In contrast, it's probably filigree in medical technology, isn't it? What have you been able to implement in this area?
(!) M. D. P.: A typical example are the components for hip endoprostheses. These components are made of either titanium or cobalt-chromium alloys. The demands on the surface quality are very high; on the one hand, a high degree of purity and biocompatibility must be achieved, and geometric and mechanical requirements must be met on the other. With our hydrostatic tooling system, both are possible, and it has ensured smooth operation for many years.
However, the strengthening of titanium wires for use in certain medical instruments is particularly delicate and challenging. These wires have a diameter of only 0.8 mm, but are over 100 mm long! A hydrostatic tool is also used to solve this task.
(?) MFN: A wire with diameter of 0.8 mm is very small. Here, the rolling forces must have been a big challenge?
(!) M. D. P.: Yes, with the diameter-length ratio mentioned, bending or breakage can occur quickly. But our creative design team has developed a force-neutral 3-point tooling system with which the machining of these small components can be done without bending, without any problems. The machining is carried out on a small precision lathe, in pulling operation. The required deep rolling force was determined through some trial machining and then included in the machining specifications for this process and firmly prescribed. Incidentally, correct machining results in an expansion of the wires in length where this change in length is measured after the process and used as proof of successful machining.
(?) MFN: Energy and medical technology are often special areas with lower quantities. What do the applications in the automotive sector look like? Here, cycle times and productivity are often very important.
(!) M. D. P.: That's right, short cycle times are an absolute must here. Typical here are the very large quantities, production in 24/7 operation and the high-cost pressure. At the same time, a high level of process reliability must be achieved. The use of our tools on standard machine tools is also identical here, so that roller burnishing and deep rolling can be integrated very well into the usual machining process and make the use of special machines or systems unnecessary.
Typical applications in the automotive sector are axle components for passenger cars and in particular, front axle stubs and stub axles for trucks, cylinder liners, connecting rods, bevel gears as well as steering components like ball studs, etc.
(?) MFN: Very good, now we have looked into the past a bit. As a sales manager, you have a lot of contact with customers. What are the current trends? What is currently in greater demand?
(!) M. D. P.: At the moment, the automotive industry is facing the big challenge of decarbonising its powertrains and every manufacturer is trying to develop its own solution. The main trend here is the further development of e-mobility, which has now found its way into all manufacturers. The future disappearance of the combustion engine will also have an impact on production sites and lead to a decline in the number of components currently still being manufactured there. Of course, this will not leave us unscathed, but we also see positive effects and trends that go hand in hand with the transformation to e-mobility. The topic of lightweight construction is gaining in importance, as the heavy batteries required for e-cars account for a considerable share, so weight savings must be achieved elsewhere. And this is precisely where strengthening through deep rolling comes into play, which leads to certain components being slimmer and lighter.
Another aspect is the higher torques generated by the electric drives and acting on the drive train. Here, too, deep rolling contributes to an increase in service life and has a positive influence on drive shafts, wheel flanges and transmission components.
The production processes themselves are increasingly unmanned and already have a high degree of automation, which will continue to grow in the future, here is the keyword "Industry 4.0".
(?) MFN: What solutions does ECOROLL offer in these areas?
(!) M. D. P.: For some time now, we have been offering process monitoring for our hydrostatic tooling system, where decisive process parameters such as pressure and flow rate are determined, compared to a tolerance band, and identified as a faulty process in the event of deviation. A new solution is the electronic rolling force monitoring system ECOsense for our single-roller tools of type EG and EF. This system sends the process rolling force via Bluetooth to a receiver that can process these signals in a variety of ways. It is also possible to identify faulty processes in order to create comprehensive process documentation.
(?) MFN: Additionally, on the topic of digitalization, what does ECOROLL do regarding the other important issue “Sustainability”? Are there any activities or customer demands?
(!) M. D. P.: Yes, that is a great question. We do talk to our customers about lightweight design and the possibilities coming with deep rolling. However, the focus for us has not been to reduce the CO2-emissions. That has been the internal motivation of the customer, but we believe that in the future, everybody has to show an amount of CO2 emission in every produced part. Therefore, we started a project to evaluate a method to define the amount of CO2 reduction due to deep rolling. For example, for a roller bearing we have already shown that is possible to reduce 30% CO2 when you use a smaller bearing that is deep-rolled.
(?) MFN: That is an impressive number of fields of application and possibilities for the future. Thank you very much for your time and good luck for the future.
(!) M. D. P.: Thank you as well, and thank you also for the opportunity to introduce a bit of our technology and solutions. The special advantage here is simply the versatility of the possible applications and the economic advantage of implementing an application on any machine tool with the smallest effort. With our standard tool programme, we are able to handle a multitude of different roller burnishing and deep rolling tasks. For all special cases, we fall back on our experienced development team, which has already developed countless customised solutions.
MFN would like to thank Markus Diedrich-Philippi for this
ECOROLL AG Werkzeugtechnik
Hans-Heinrich-Warnke Str. 8, 29227 Celle, Germany