MTU Aero Engines manages challenging roughing applications for the military turboprop engine TP400-D6 with Haimer Safe-Lock. MTU is responsible for the TP400-D6's intermediate-pressure compressor, intermediate-pressure turbine and intermediate-pressure shaft and has a stake in the engine control unit. Furthermore, final assembly of all TP400-D6 production engines takes place at MTU Aero Engines in Munich.
Trochoidal milling makes the milling operation three times faster and deeper, even in hard materials like stainless steel or titanium. Ideal tools for machining are the HAIMER Power Mill end mills with Safe-Lock-chuck.
The HAIMER Safe-Lock pull out protection system is designed to provide safe cutting tool clamping. Special drive keys in the toolholder match the spiral shaped grooves on the cutting tool shank, thus creating frictional clamping forces and a positive locking form-fit. This prevents the cutting tool from pulling out of the toolholder. Furthermore, it increases the productivity through faster permissible speeds and increased tool life.
"By now Safe-Lock has become a de-facto standard in the area of toolholding for milling operations," said a company spokesperson. "Within the last 10 years, since the introduction of the Safe-Lock system, it has been confirmed that this method of clamping the tool is often superior to conventional toolholders. This is proven by a large number of license partners, some of which rank amongst the world's leading cutting tool and toolholder manufactures - for example Walter, Widia, Sandvik Coromant, Seco Tools, Sumitomo, Kennametal, Helical, Emuge Franken, Data Flute, Niagara, OSG and Mapal. In 2017, Iscar and Ingersoll also decided to offer tools with the Safe-Lock shank. Furthermore, the shrink, collet and hydraulic chuck Safe-Lock toolholder portfolio has become much larger within the last few years. In addition to the Safe-Lock hydraulic chucks from Kennametal, Mapal is already working to introduce its hydraulic chuck offering with Safe-Lock to the market."
Andreas Haimer, Managing Director of HAIMER GmbH, said, "We are proud that our Safe-Lock pull out protection system has established itself as the new standard in the heavy duty and rough milling industry and is also becoming more and more important in other areas such as trochoidal milling. We are also very happy about our new license partners, who help expand the Safe-Lock portfolio and also make it available for more end-users."
Aerospace Industry
Safe-Lock has emerged from the requirements of heavy-duty machining, which is a daily challenge in the aerospace and energy producing industries. Innovative materials such as various titanium alloys are not only light, but also very rigid, corrosion resistant and difficult to machine. This does not only affect the machine concepts and processes, but also the cutting tools and toolholders that are being used.
Many workpieces are made from a solid block - during this milling process up to 90% of the material is being removed. In order to optimize the process economically as well as qualitatively and in order to achieve a high metal removal rate, high torques and feedrates with low RPMs are chosen. But during this high performance cutting operation (HPC), high pulling forces occur. In combination with high cutting forces and aggressive feedrates, a flexing movement of the tool in the toolholder is created which in the end increases the risk of tool pull out. This especially affects all the toolholder designs which provide accurate clamping and a high run-out accuracy, like for example shrink, hydraulic or milling chucks.
"As a consequence Safe-Lock is now widespread within the aerospace industry," said the spokesperson. Alexander Steurer, Senior Manager NC - Programming Stator Components at MTU Aero Engines in Munich, explained the decision to use the HAIMER system: "Through the introduction of Safe-Lock and the shrinking technology from HAIMER, we can guarantee process reliability even with milling challenging high temperature materials. This is a prerequisite to guarantee smooth processing during manufacturing of frames and castings, given our high degree of automation." The combination of pull-out protection and highest concentricity of the Safe-Lock system leads to low vibration and as a result, a stable machining process. Due to the increased cutting depths and feeds, the metal removal rate can be increased. And due to the improved runout accuracy of HAIMER shrink fit chucks, tool life is improved by up to 50%.
The benefits of less than 3 µm runout, that the symmetrical Safe-Lock design provides, coupled with optimum balance and the possibility for easy length presetting were substantial reasons for MTU to switch to the HAIMER system instead of continuing to use Whistle Notch or Weldon tooling systems. "While these other systems do in fact prevent tool pull out, both are unsymmetrical by design, hence providing insufficient runout and balance accuracy," said the spokesperson.
Benefits of High Speed Cutting
Safe-Lock is also becoming popular in other industries and during HSC machining with high-helix end mills as well as in trochoidal milling. During trochoidal milling operations, where the cutting speed and axial depth of cut can be increased through software support, the productivity is improved. Thus, milling operations are carried out three times faster with deeper depths of cut, even when it comes to hard and difficult to machine materials.
However, this also increases the danger of tool pull out. Even though only a thin chip is usually removed during trochoidal milling operations, often the entire length of the cutting tool edge is used during the process. This results in higher axial forces which force the operator to pay attention to safe cutting tool clamping. A shrink fit chuck with Safe-Lock is a suitable solution since it offers more security than the Weldon system, is easier to install and can be clamped very precisely. The ideal balancing and runout characteristics of the shrinking technology in combination with the clamping safety of the Safe-Lock system permit the possibility of greater productivity achieved through faster permissible speeds and increased tool life all with complete tool security assurance.
For more information contact:
HAIMER USA
134 E. Hill Street
Villa Park, IL 60181
630-833-1500
haimer@haimer-usa.com
www.haimer-usa.com