Tooling solutions Precision machining: Innovative spindle ensures quality
In recent years MS Feinmechanik has not only seen a dramatic increase in the volume of machined parts but also increasingly stricter requirements placed on precision and final product quality. To keep on top of these growing requirements, the company has taken the strategy of continuous investment in industry-leading machinery and tooling solutions.
Founded in 2005 by Markus Schenk, MS Feinmechanik, based in the Bavarian town of Unterammergau, is a medium-sized high-tech company that prides itself on its high precision, flawless quality and flexibility. It employs eight skilled professionals. “Thanks to our modern, highly automated machinery, we can meet all our customers' requirements quickly and efficiently. Many would say that this should be standard, but we all know that's not the case,” explains Markus Schenk, Founder and Managing Director of MS Feinmechanik.
The company focuses its core technological expertise on milling. “It goes without saying that 5-axis CNC milling is centre stage and forms our core competency, but this is also supplemented by 3 and 4-axis capability. We precision mill materials such as high-temperature steel, brass, aluminium or plastic, and we also have an in-house CAD/CAM department. Our customers come mainly from the mechanical engineering, toolmaking and plant engineering sectors, medical technology and the aviation industry,” Schenk adds.
“To manufacture high-precision components, the entire system must function flawlessly, with no weak spots. In other words, the machine, the clamping system, the spindle, the tool holder, and the tool itself — all have to merge into a perfectly tuned holistic system that outputs the finest high-precision components possible,” Schenk delves deeper. To achieve this, MS Feinmechanik has implemented 5-axis Matsuura machining centres utilising Big-Plus spindles. “I was simply not satisfied with the industry standard machinery used for high-precision machining, so I went with Matsuura from the very beginning. Not only do these machines meet the highest quality standards, but they come with the BIG-PLUS spindle as standard, which, in my opinion, is a key prerequisite for machining high-precision components,” Schenk remarks.
Quintessential double contact spindle system
The Big-Plus spindle system is a defining invention of Big Kaiser. This spindle system is characterised by its stable contact interface between the machine spindle and the tool holder. This coupling strength is achieved through the simultaneous face and taper contact of the tool holder when inside the machine spindle. Conversely, on a conventional steep taper coupling interface, the tapered base forms the strongest possible connection point. Whilst, in contrast, the Big-Plus tool holder provides additional support and rests against the flange itself, which substantially increases the rigidity and stability of the connection.
“Big-Plus is far superior to the other spindle designs because it is the only one that offers simultaneous taper and flange contact between the machine spindle and toolholder. This rock-solid double-contact connection between the machine and the tool makes it particularly robust and reliable. Its proven vibration damping and rigidity noticeably improve machining accuracy and production repeatability. It facilitates heavy machining and high-speed machining while also increasing tool life,” says Alexander Hartl, application engineer at Big Kaiser and the first point of contact at MS Feinmechanik for expert advice on tool holders and machining tools.
“We use Big-Plus for high-performance machining and finish machining applications, where accuracy is the primary requirement. With our Big-Plus spindle, we are vastly more accurate and eliminate undesirable length fluctuations,” notes Markus Schenk, and Alexander Hartl adds: “When a standard industrial spindle is placed under a prolonged load, it tends to expand and the taper is drawn into the spindle. We once carried out just such a test at a customer's site, where the spindle ran continuously for six hours and ended up with a change in Z of 0.02 mm. That simply does not happen with a Big-Plus spindle; not to mention its higher concentricity, superior rigidity and vibration damping characteristics."
Convincing concentricity and quality
Depending on the Big-Plus holder application area, MS Feinmechanik utilises a wide variety of clamping technologies, such as various collet systems, power chucks, as well as hydraulic expansion chucks from Big Kaiser. “Choosing the right tool holder has a deciding impact on the final lifetime of the tool and the quality of the final product. For example, the hydraulic expansion chuck from Big Kaiser is used for a finishing cutter with a 16 mm diameter and 80 mm cutting edge length. We mill stainless steel parts with this chuck and you can see a visible difference both in terms of smooth operation and surface quality,” says Schenk.
“Mr. Schenk always keeps an open mind concerning new tools, tool holders and advanced technologies. We both have application engineering backgrounds and exchange ideas freely in an attempt to always identify the optimal solution for the respective application," says Hartl. Schenk adds: “Currently, we're using two spindle tools from Big Kaiser. To be honest, I was a little sceptical at first, but after the test run, I have to say that we achieved over double the tool life with a tight fit in stainless steel, a superior surface quality, and much faster operation.”
“When I initially stressed the fact that you can only achieve optimal precision with a complete, finely-tuned production package, then another product from Big Kaiser also comes to mind — the Torque Fit. This is a tool that facilitates the precise tightening of various collet holders and greatly simplifies our work,” remarks Schenk.
The Torque Fit that is available from ITC is a tool assembly station for collet holders with a built-in torque measuring device. To further enhance its ease of use, all torque values for Big Kaiser’s wide variety of collet holders are pre-set and an LED indicator on the Torque Fit warns of over-tightening.
“The Torque Fit makes a relatively modest but significant contribution to ensuring that the highest precision is achieved quickly, easily, and consistently, under real-world working conditions. The machine operator places the tool into the Torque Fit and immediately sees on the display the force with which he must tighten the clamping nut. This prevents errors and damage to the collet caused by overtightening, and the operator needs only a single device instead of several torque wrenches for the complete range of tool holders,” concludes Hartl.