The machining service provider Feindreh in Arnsdorf is increasingly focusing on the production of small parts starting from 0.3 mm in diameter, which may have relatively deep holes and fine contours. The modernly equipped company achieves the best results on its long-turning machines since they have been equipped with KNOLL LubiCool high-pressure systems. This has made the machining faster, more precise, and more process-safe, and the tool life has significantly increased.
In 2023, F&G Normteile Dresden GmbH was renamed Feindreh GmbH, Arnsdorf - 'a renaming that reflects our new strategic orientation,' explains managing director Anja Peplinski, who took over the management of the company founded by the fathers in 2021 together with Michael Grünler. The two quickly realized that the previous main business - standard parts such as cylinder pins and bolts for the automotive industry - could not be operated economically in the long term in this country. Energy and labor costs are too high. Furthermore, there are fewer and fewer employees who can handle cam-controlled lathes.
New strategic orientation
'The future belongs to precision turned parts manufactured on modern CNC lathes,' says Anja Peplinski. 'The smaller, finer, and more demanding, the more we are happy to take on the orders, even if the requirements for technology and know-how in these areas are particularly high. We gladly face these challenges and have largely restructured our machine park along with peripheral devices and measuring technology.'
Of the 80 turning machines, half are already state-of-the-art CNC machines, short and long turning machines that are designated for the flexible production of precision turned parts. The rest are cam-controlled lathes that Feindreh needs for the production of standard parts. They remain an important part of the portfolio, as not everyone can manufacture such μm-precise cylinder pins for the automotive industry. On the one hand, certification of the quality management according to IATF 16949 is required, and on the other hand, the surface finishes of the parts often still need to be refined through grinding processes and galvanically.
For particularly demanding standard parts, Feindreh invested in 2022 in a centerless grinding machine Cube 350 from the Swiss premium manufacturer Tschudin, which can maintain diameter tolerances in the range of 2 μm and achieve surface qualities up to Rz=1.5 μm / Ra=0.05 μm. Through Tschudin, contact was also established with KNOLL Maschinenbau, Bad Saulgau, a company that is one of the world's leading suppliers of filtration systems and pumps for metalworking.
'For reliable and high-quality oil cleaning, company head Urs Tschudin recommended a KNOLL KSS system. Because it is suitable for getting the best out of his machine,' reports production manager Jan Weber. For this reason, the Feindreh management decided to acquire a two-stage KSS system with a KNOLL compact filter KF 600-E for pre-cleaning and a subsequent fine filter MicroPur.
High pressure - a productivity and quality factor
The experiences with this KNOLL system were consistently positive and laid the foundation for an intensive partnership, which primarily extends to the KSS high-pressure supply of new short and long turning machines. 'To qualitatively implement our strategic orientation towards small, complex precision turned parts, we need the right machines,' explains Anja Peplinski.
'That’s why we decided early on to gradually purchase new Star long-turning machines in different sizes and configurations.' Jan Weber adds: 'But that alone is not enough. For demanding machining, such as deep hole drilling or deep recesses, we additionally need a KSS high-pressure supply. Our previously existing HD systems seemed to us to be improvable, so we gladly accepted KNOLL's offer to test a retrofittable high-pressure device LubiCool-S.'
After the test phase, the Feindreh machining team was clear: The LubiCool-S high-pressure unit stays, and we will order more of these devices. Feindreh currently has six KNOLL LubiCool-S installed on Star Micronics SB-12 and SR-20JII long-turning machines. Two additional units are ordered. 'This shows how satisfied we are,' says Jan Weber. This is due to the fundamental advantages that the KSS high-pressure supply offers. 'Some components cannot be machined at all without high pressure, while others eliminate the need for subsequent deburring. In addition, tool life is significantly extended - the coolant lubricant hits the cutting edge precisely thanks to high pressure. This is supported by the AWL quick-change system developed specifically by ARNO.'
Compact design saves valuable production space
Jan Weber sees the individual strengths of the KNOLL LubiCool-S devices, among other things, in their design, which is so compact that they can be placed under the bar loader on short and long turning machines. He is also enthusiastic about the achievable 100 bar: 'This allows us to achieve short-breaking chips, which enables higher cutting speeds that are reflected in shortened processing times.' Matthias Wachter, the KNOLL sales representative responsible for the LubiCool high-pressure systems, explains:
'The pressure is generated by our proven KNOLL screw spindle pump KTS, of which we produce an average of 9,000 units per year. It is so wear-resistant that our customers can expect up to six times the service life compared to comparable pumps. A correspondingly high process reliability goes hand in hand with this.'
The LubiCool-S contains a replaceable filter element that ensures even the smallest chips, fine particles, and foreign substances are separated from the coolant with a filter fineness of up to 15 µm. Jan Weber explains: “When we need to replace the filter cartridge, it takes less than a minute. The contaminated one goes into our cleaning system, from which it is then available clean – almost like new. This is cost-effective and user-friendly.” The responsible KNOLL field service employee Markus Rölleke adds: “User-friendly is also the control concept SmartConnect developed by our engineers. It includes a small touch display through which the user can set the desired pressure level and other parameters. Additionally, various system operating data can be retrieved. An LED light strip positioned on the outside of the housing visualizes the most important states in eight colors.
High availability and minimal maintenance effort
Since the LubiCool-S systems were approaching their performance limits with larger orders involving copper materials, KNOLL recommended the next larger device, a LubiCool-M. “Getting approval for another test unit was a great help for us,” says Managing Director Anja Peplinski. “When we saw that the LubiCool-M was perfect for our purposes, we immediately ordered a second one.”
The two high-pressure systems are capable of providing up to 150 bar pressure and a flow rate of up to 30 l/min. Feindreh has therefore installed them on the more powerful long-turning machine SR-20JII from Star Micronics. This machine primarily processes parts with larger diameters made of non-ferrous metals, such as copper, aluminum, and lead-free brass. Jan Weber and his manufacturing team are enthusiastic about the KNOLL LubiCool-M systems: “They are largely maintenance-free. Because they work with a filter fleece that lasts forever, even when machining lightweight materials.”
Matthias Wachter also points out that the new LubiCool devices can be operated with an app: “This allows operators to view the most important operating data of the system at any time and easily check, for example, whether the service life of the LubiCool-S filter cartridge is still sufficient for the unmanned shift. Pressures and other settings can also be changed via the app.”
Anja Peplinski and Jan Weber appreciate this option: “We are in the process of increasingly automating and digitizing our production. It’s great that KNOLL also offers support in this direction.” They praise the partnership with KNOLL: “It’s the complete package that makes us so satisfied – the quality of the products, user-friendliness, low maintenance effort, and the exemplary service that works very quickly despite the long distance to Bad Saulgau.”
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