O-rings require a perfectly plane fit to reliably fulfil their sealing function. In order to produce the highest quality fit, the INDEX Group has been using the HAIMER Duo-Lock™ system, a modular interface for carbide cutting tool heads and extensions, for two years in all German production plants. With specially ground Duo-Lock™ milling heads, the lathes manufacturer obtains 60% higher productivity compared to their previous manufacturing solution.

The INDEX Group, with its brands INDEX and TRAUB, is one of the world's leading manufacturers of CNC lathes, automatic lathes, multi-spindle machines and turn-mill centers. In order to control the quality of their machines at all times, the company relies on their German sites (Esslingen, Deizisau and Reichenbach) and produces the important core components for its machine tools at those plants. Also, if possible, they produce parts on their own lathes and turn-mill centers.
Experienced and well-educated employees pay attention to the highest quality down to the last detail. One of them is Klaus Andres, who is responsible for the production of parts, programming and tool purchasing as a Team Leader in Production Planning. His considered opinion: "It's often the small features that make a big difference in quality." 
As an example, he mentions the o-ring fit, which can be found on numerous machine components. Everywhere a medium flows through the component, the connections must be sealed with an o-ring. For the sealing surface, evenness is required. "It cannot be machined by a circulating milling strategy," explains Andres, who previously worked as a foremen focused on turning for 16 years. "That would create a minimal screw geometry, in which the medium finds a way out. Instead, we need to countersink the o-ring fit with a special end mill characterized by its facial cutting edges being parallel to the surface, not having the usual eight-degree angle."

The alternative: a modular milling head with a special geometry

Since it was not possible to buy milling cutters with this special geometry and the desired diameters, the production managers at INDEX initially decided to grind the tools themselves and later outsource the tool grinding for these cutters. However, two years ago, Andres found a better solution. He got the inspiration from Christian Bauer, Key Account Application Engineer at HAIMER GmbH, Igenhausen. He had introduced him to the new HAIMER Duo-Lock™ system, a modular tooling system with interchangeable solid carbide milling heads and extensions in various geometries and lengths. 

Specialists in tool and tool clamping Technology 

The HAIMER Group is a family-owned company. In 42 years, it has developed into the world market leader in tool clamping technology and has become a system provider around the machine tool. At INDEX, HAIMER has been well-known for many years - both as a customer using INDEX turning machines for the production of its quality products and as a supplier of tool holders, shrinking and balancing technology.
Klaus Andres came up with the idea of having the Duo-Lock™ special cutters designed for his o-ring countersinking needs. "We are pursuing the strategy of using the same tools in our three German production plants, where possible", he described. In the case of o-ring end mills - in terms of geometry - that is generally possible.  However, in the large-scale production in Deizisau, since the tools have to be with much more overhang, these have been procured individually so far. "With the Haimer Duo-Lock™ system and their extensions program, I saw an opportunity to standardize the milling heads," says the Team Leader of Production Planning, Klaus Andres.

Quality criteria: a robust, high-precision interface

Why choose the HAIMER system when other manufacturers have been offering similar exchangeable end mills for a long time already? "Haimer's Duo-Lock™ interface is extremely rigid and precise. Therefore we can use these modular cutters like a solid carbide tool", states Klaus Andres. Christian Bauer adds: "The difference is the thread of our screw-in end mills. A double cone with an additional third support area in the back part of the interface ensures maximum stability and rigidity."  The Duo-Lock™ tools offer a total system runout of less than 5 μm and can be exchanged with a repeat accuracy of 0.01 mm in Z in the machine tool. Time-consuming presetting or set-up processes can thus largely be eliminated. This is a true reflection of HAIMER's high quality and precision. 

60 percent more efficient

In close cooperation with Klaus Andres, HAIMER developed a special geometry and transferred it to the Duo-Lock™ modular end mills. For the first tests, the Team Leader of Production Planning used them on an INDEX R300 turn-mill center, machining among other things, complete base bodies of tool turrets. This challenging workpiece is particularly suitable for the trial because, depending on its design, it has at least twelve o-ring fits which the milling result can be assessed.
Klaus Andres and his colleagues of the manufacturing department were happy with the test results. "Haimer did a very good job at grinding the tools. Despite the difficult geometry, the cutters are designed to be extremely aggressive. We get a perfectly plane surface meeting the high demands in quality and precision of the turret", Klaus Andres explained.
Compared to the previous solutions, the Duo-Lock™ tools reduce the o-ring countersinking machining time, improve the surface finish and extend the tool life. It passed the test. "We calculated that the overall profitability improved by about 60 percent," says Klaus Andres. Logically, the INDEX Group is now using the HAIMER Duo-Lock ™ system in 18 different diameters and with various extensions.

Fast installation without calibration

At the Esslingen plant, the Duo-Lock™ system is used on all machines making such o-ring countersinking operations. There are five stations available for the modular tool assembly, each being equipped with a two-hand torque wrench supplied by HAIMER along with the setting parameters depending on each diameter. "The two-hand torque wrench was particularly important to me," reveals Andres. "It gives better handling compared to a single-lever tool which tilts easily and may damage the solid carbide." It also makes it easier to set high torques. For example, 60 Nm for the 16 mm Duo-Lock™ tool head.
Also, at the Deizisau and Reichenbach sites, the interchangeable Duo-Lock™ heads have replaced the previously used customized cutters for o-ring countersinking. Thanks to the available standard extensions in sizes S, M and L, they can furthermore be used in the large parts production. Even for other applications, INDEX now uses the Duo-Lock™ system. For example, Klaus Andres requested customized 30-degree countersinks and with HAIMER's steadily growing range of standard geometries, Duo-Lock™ solid carbide cutting tool heads offer promising prospects for further machining applications.