Successful alternative for the highest precision

Highly accurate HAIMER BT40 shrink fit chucks with face contact ensure high quality and economic efficiency for precision machining

Precision toolmaker Alhorn recently started to use shrink fit technology and BT40 tool holders with face contact by HAIMER on Japanese high-end machining centers. The high-precision tool holders are available in a wide variety of options – versions with extra-slim design included. According to Alhorn, they are perfect for multi-sided machining of small, intricate components. Together with the precision machines and tools, they ensure top results when it comes to accuracy, surface quality and economic efficiency.

Alhorn has been developing and manufacturing injection mold tools and items for diverse applications and industries in Lübbecke, North Rhine-Westphalia, Germany for over 40 years. Plant manager Timo Schwiering explains: "Above all, people turn to us when they need injection molds made with pin inserts or punch contacts. Upon request, we offer these customers complete solutions – from the development and design of the injection mold tool to the perfect turnkey solution for series production."

According to Schwiering, their core business is complicated plug connector tools, which can be delivered to almost any larger plug supplier: "We have the know-how to build high-performance injection mold tools with up to 128 cavities, which are unparalleled in their quality, precision and economic efficiency." Around 30 percent of Alhorn tools are supplied for internal manufacturing, the remaining 70 percent go to customers all around the world. 

"Our aim is to be the best-in-class," says the plant manager, "and to remain so for the long term." This means that the highest requirements on geometries, tolerances and process reliability are a part of the daily business for Alhorn toolmaking. The foundation for "best-in-class" is a team of highly qualified employees, which also includes Sascha Soldato. The technician is a member of the toolmaking Continual Improvement Process (CIP) team, which takes care of the optimal production equipment along with other responsibilities. He is convinced: "The only way to reach our goals is to work with the best suppliers. This applies to the entire production process – to the machines with the highest possible degree of automation, to the tools, as well as the tool holders."

The finest mechanical engineering

Schwiering and Soldato feel well-positioned with their machining centers. The two Yasda machines, one of which was purchased two years ago and the other three, play an important role here. The Alhorn toolmaking team use the YMB Vi40 exclusively for milling copper electrodes, which are needed for narrow, deep cavities with sharp edges and corners. "Although Yasda offers this 5-axis vertical jig machining center specifically for hard milling and coordinate drilling," Sascha Soldato acknowledges, "its precision – the positioning accuracy of the linear axes is under 3 µm, and the repeat accuracy is 1.2 µm – makes it ideal for our electrode machining." To ensure they were able to get maximum economic efficiency from the YMB Vi40, Alhorn equipped it with an Erowa Robot Compact system, which provides 147 magazine positions for ITS-50 electrode holders.

The second Yasda machining center, type PX30, has been factory designed for automated operation and unmanned shifts because it contains 33 workpiece pallets for component sizes of up to 200 x 200 mm, automation software and a tool magazine with 300 positions. Alhorn puts the machines to work machining the mold inserts out of soft and hardened steel. The requirements placed on precision and shape-position tolerances are similar to those of electrodes. Plant manager Schwiering is extremely impressed by these machines: “They achieve the highest performance both for roughing and finishing. Very high surface qualities can be attained during finishing, which often means further processing steps such as flat grinding are no longer necessary.”

The tool holder, a core element in the process chain

Sascha Soldato also pays attention to first-class tools and tool holders to achieve the desired precision and surface quality: "We only use BT40 tool holders with face contact for our Yasda machining centers because the decisive benefit of face contact like this is that it reliably prevents axial displacement, even in a high speed range. This is essential to ensure accuracy in the µm range."

Up until recently, Alhorn had been purchasing the BT40 holders exclusively through a supplier certified by Yasda. However, multi-sided machining of intricate components has increased over the last few years, making it necessary to use tools with the slimmest-possible interfering contour. "This is the reason that shrink technology was brought to our attention," reports Soldato. "Particularly at the tips, shrink fit chucks are slimmer than our previous collet chucks and have considerably fewer interfering contours."

As the previous supplier did not offer a particularly wide range of shrink fit chucks, Sascha Soldato and the CIP team began to look around for alternatives. They first sought the opinion of a sister company from the OKE Group, which is also involved in precision machining. It was here that they first heard about Haimer GmbH from Igenhausen near Augsburg, Germany. HAIMER also came out on top in benchmarking for shrink fit technology, which included both tool holders and shrink fit machines. 

Complete package from a single source

"The benchmark and the positive feedback from our sister company was what prompted us to get in contact with HAIMER," reports Soldato. Their first contact was Thorsten Böker, who is the technical sales representative at HAIMER for Alhorn. He supplied basic information regarding the quality of HAIMER products and the different versions: "The BT30 and BT40 interfaces versions with face contact have also been a part of HAIMER’s standard product range for some time. All other steep taper holders can be supplied as semi-standard as well as with face contact. HAIMER is well known for the high accuracy of the interface, as we grind all functionally relevant surfaces ultra-precisely in production and subject the holders to a double 100% quality inspection process. Generally, our shrink fit chucks are made of heat-resistant steel, hardened to 54-2 HRC. They are suitable for HSS and solid carbide tools with shaft tolerance h6 and guarantee runout accuracy less than 0.003 mm at 3 x D with extremely high clamping force. They are available in various versions including the extra-slim Power Mini Shrink Chuck with 1.5-mm wall thickness and 3° slope in the tip area."

The comprehensive range also features various different interfaces, an important point for Alhorn, as Sascha Soldato stresses: "We not only required the slim contours of the shrink fit chuck but also tool holders with a BT40 interface and face contact as well as HSK-A63. The interfering contours of these tool holders in various spindle interfaces need to be precisely symmetrical, which is the case for HAIMER." The reason for this wish is the benefits for programming and system maintenance  because Alhorn has digitalized and saved all tool holders and machinist vices, etc. in their CAD / CAM system. Using the same holder contour, production planning can easily switch tools from the Yasda to a machine tool from another manufacturer with the same spindle interface.

The HAIMER BT40 shrink-fit chucks with face contact, which are new to the program, have been used on the Yasda machines for several months. Alhorn uses the corresponding holders with the HSK-A63 interface on other machining centers. Plant manager Timo Schwiering concludes: "The shrink fit chucks completely fulfil our requirements on interfering contours, true runout accuracy, diversity and manufacturing quality. We are also very satisfied with the HAIMER Power Clamp Comfort NG shrink machine. As we consider ourselves to be a growing and innovative company, we plan to continue to expand our collaboration with HAIMER in the future."