HORN Mastering Processes: Hard Machining

 

Mastering Processes: Hard Machining

Shorter machining times, high surface quality and the saving of grinding operations. These are just three of the advantages that hard machining with a geometrically defined cutting edge can bring to the user. With a high level of know-how in tool technology, Paul Horn GmbH offers numerous tool solutions to economically machine steels harder than 56 HRC. The cutting material CBN has proven itself suitable for grooving operations.

CBN (cubic boron nitride) is the second hardest known material on earth after diamond. Tools made of CBN wear much more slowly than other cutting materials when used appropriately. On  one hand, this makes it possible to achieve higher shape and dimensional accuracy, and on the other hand, hard materials (steel up to 70 HRC) can be machined reliably. There are no different grades of CBN. Differentiation is made by the CBN volume fraction, the fillers, the grain size and the ceramic/metallic binder phase (cobalt/nickel). This results in different CBN substrates. Numerous tool systems from Horn can be equipped with the cutting material CBN. In most cases, these are tools specially adapted to the respective application. However, Horn also offers standard tools equipped with this  very hard cutting material.

Hard machining with CBN cutting materials is usually done dry. This is possible because the cutting material has  high heat resistance and the high temperature within the chip formation zone has a positive effect. An insufficient supply of coolant or interruptions in cutting lead to high, thermally induced stresses in the structure of the insert. This can lead to cracks in the structure and thus possibly destroy the insert. During hard machining, the steel in the shear zone undergoes intense heating and is thus softened. Most of the heat generated in the shear zone is dissipated via the chip and not  transmitted into the workpiece. This means that there is no thermal influence on the insert edge  in the process. While carbide  suffers a massive loss of hardness at around 800 degrees Celsius, the hardness of CBN remains almost unchanged even at up to 1,200 degrees Celsius. Another important aspect is the chemical resistance, especially at the prevailing temperatures.

Numerous Advantages

Hard machining with a geometrically defined cutting edge in combination with CBN  has numerous advantages over grinding . High metal removal rates are possible with this process, which results in shorter machining times. Conventional machines  may be used. This offers the possibility of complete machining of the component. Even complex contours can be easily produced on a lathe. With grinding, on the other hand, the  wheels have to be elaborately profiled. The high surface quality that can be achieved with hard turning also saves on further grinding operations.

Lothar Horn (09.12.1956 – 05.02.2023)

Horn Group mourns the death of company director Lothar Horn

The entrepreneur Lothar Horn passed away on 5th February 2023 at the age of 66 after a long, serious illness. Lothar Horn was the managing director of Paul Horn GmbH in Tübingen. He shaped the Horn Group into an internationally successful manufacturer of precision tools with production sites in England, Italy, the Czech Republic and the USA. In addition, there are subsidiaries in France, Hungary, China, Mexico, Turkey and Thailand. At the same time, Lothar Horn made his company the largest commercial employer in Tübingen. In 1991, the IT-experienced and technologically-enthusiastic son of company founder Paul Horn joined his parents’ company. He became Managing Director on 1st January 1995. From 2009 to 2019, he was Chairman of the Precision Tools Association of the VDMA. In 2021, he received the Tool and Mould Making Medal of Honour, which recognises pioneers, visionaries and exemplary personalities in the industry. In 1999, Lothar Horn created new production and administration facilities as well as a demonstration, research and development centre at the main plant in Tübingen. Over the years, various expansions followed. Currently, the largest building in industrial use in Tübingen belongs to Paul Horn GmbH. With Lothar Horn’s son Markus, Managing Director of Paul Horn GmbH since 2018, the third generation is now leading the family business into the future, together with Matthias Rommel, also Managing Director.

Lothar Horn coined phrases such as “Technology determines costs” and “No car drives, no plane flies and no artificial joint can be inserted by doctors without using precision tools”. Loyalty to Tübingen was a major concern for him. Not only were investments in the company at this location important to him, but also social commitment. In addition to visible signs such as the Paul Horn Arena in Tübingen and the Paul Horn Hall at the Stuttgart Trade Fair Centre (Hall 10), he supported above all social institutions as well as the youth and junior staff of sports clubs, for example.

With Lothar Horn, the Horn Group loses an outstanding entrepreneur and a wonderful person.

The entire Horn Group mourns with the family.

KNOLL Case Study: High Pressure for a Reliable Process

Compact high-pressure units from KNOLL can be retrofitted easily and in a space-saving manner

  • Small but powerful: The KNOLL LubiCool®-S high pressure unit, fits under standard bar feeders, generates a high pressure of up to 100 bar, causing small chips to form and enabling higher cutting speeds

For the difficult lathe machining of VA materials, tools with an internal coolant supply and a high-pressure cooling lubricant system have a decisive advantage. For this reason, sensor housing production at ifm in Tettnang has retrofitted its fixed and sliding headstock automatic lathes with high-pressure units from KNOLL. The results: Higher process reliability, less machine downtime, improved chip control, shorter machining times and longer tool service life.

Advances in production are essentially determined by automation and digitalization technology. One of the most important suppliers in this respect is the ifm group of companies – a global leader in the development and manufacture of sensors, controllers and systems. Among others, development and manufacturing are located at the Tettnang site. “These important departments work very closely together, which has a beneficial effect on product improvements, new product launches and economic efficiency,” explains ifm technical officer Frank Watzlawik.

In particular, production is constantly optimized. This applies to assembly, which is already largely automated, but also to machining – for example, in so-called sleeve production. “Up until 20 years ago, we had the housings for inductive sensors manufactured externally,” Matthias Finsterle recalls. “At that time, they were made from solid material. Then those responsible decided to bring this prefabrication work in-house. A new development made it possible to manufacture the housings from calibrated VA tubes. That means that the inner diameter requires no further machining, only threads had to be added on the outside.”

Six million sensor housings a year

What started back then with an initial sliding headstock lathe is now an independent part of the central prefabrication department belonging to ifm electronic gmbh. Around 25,000 sensor housings are produced daily on twelve fixed and sliding headstock lathes, all made of 1.4404 stainless steel (colloquially “V4A”) in 220 variants. Matthias Finsterle, who has been responsible for this machining from the beginning, explains that ifm uses it for all the sensor series from M8 to M30, i.e., capacitive and inductive sensors, as well as for pressure, flow and heat sensor products. The sleeves are supplied to all ifm production plants worldwide.

In 2021 Matthias Finsterle handed over the group management to his colleague Jakob Sauter, who since then has mainly been responsible for the capacity planning and organization of a total of 15 employees in production and quality inspection. As the person responsible for technology, Finsterle can thus concentrate fully on optimizing the machines in terms of productivity and quality. His first goal is to improve process reliability and to reduce machine downtime.

An end to chip buildup, tool breakage and machine downtime

“Since we only machine long-chipping stainless steel, there was an increasing amount of chip buildup in the past, especially on our MAIER sliding headstock lathes as well as on the Sprint 20 from DMG MORI used as a fixed headstock lathe, and as a result, tool breakage and machine downtime,” explains Matthias Finsterle. “This is due to the fact that their linear tool carriers offer only limited space between the tools and the cooling lubricant supply does not remove the chips via standard volume pumps.”

The solution: Finsterle was certain that the problem should be solved for tools with an internal coolant supply and a corresponding high-pressure pump. After all, experience with high-pressure supplies for other machines was already available. This technical manager therefore started looking for a retrofittable high-pressure system that was suitable for sliding and fixed headstock lathes.

Mobile high-pressure station for uncomplicated retrofitting

Ralf Spöcker, Area Sales Manager at KNOLL Maschinenbau, was able to offer him an interesting solution. He was actually in-house because of a chip conveyor in the toolmaking section. However, since the sleeve production department had been equipping sliding head lathes with coolant pumps and hinged belt conveyors from KNOLL right from the start, a visit to Matthias Finsterle was a must. When the conversation turned to the required high-pressure supply, Spöcker had a possible solution ready: the mobile KNOLL LubiCool®-M high-pressure station. It is capable of generating a coolant pressure of up to 150 bar and a flow rate of up to 27 l/min.

This was exactly what Matthias Finsterle was looking for. Especially since the LubiCool®-M is equipped with the KNOLL compact filter KF with filter fleece, which ensures an automated filtering process with a filter fineness down to 20 μm. “On other machines, we have installed high-pressure units with cartridge filters,” Finsterle mentions. “We have to clean these almost daily, which involves enormous effort and corresponding machine downtimes. In addition, their filter fineness is not sufficient for the fine channels of the internally cooled tools.”

So the decision was made quickly. KNOLL was able to deliver the LubiCool®-M just as quickly. With its successful use, Matthias Finsterle and the sleeve production team desired to equip other machines with such a high-pressure unit. During his next visit on site, Ralf Spöcker was able to present another, newly developed KNOLL LubiCool®unit, in size S. With a height of only 663 mm, a depth of 635 mm and a length of 985 mm, it is so compact that it fits under standard bar feeders – ideal for sleeve production that has to cope with limited space.

LubiCool®-S fits under standard bar feeders

In terms of its internal values – high pressure up to 100 bar and a flow rate of up to 23 l/min – the LubiCool®-S is not significantly inferior to its bigger brother, as Matthias Finsterle assures us. He had reservations, however, because it uses a replaceable and cleanable filter element rather than a belt filter. To convince him that the maintenance intervals remain within tolerable limits, KNOLL provided a test unit. It was installed on a fixed headstock lathe, which – like all other machines in sleeve production – runs in three-shift operation. “The performance of the KNOLL LubiCool®-S ensures reliable machining of our stainless steel products. The filter technology also impressed us,” reports group leader Jakob Sauter. “We only have to replace the filter element every six weeks, which takes no longer than five minutes when a second one is used. Afterwards, we can clean the dirty filter and prepare it for the next use.”

Jakob Sauter and Matthias Finsterle are absolutely delighted with both KNOLL LubiCool®units: “It starts with the competent product advice, which was specifically targeted for our use case and focused on the most economical solution.”

As additional pluses, they emphasize the quick delivery and the simple installation: “KNOLL actually delivered a plug-and-play solution with all the accessories – such as hose packages and connections – matched to the particular machine. We also received professional instruction during the start-up phase. Then, if a technical problem did arise, the hotline with the specialist department was always able to help us.”

Excellent cost-benefit ratio

Most important, however, is the good cost-benefit factor of KNOLL’s LubiCool® high-pressure systems, which relates to both acquisition as well as operating costs. “Thanks to the high pressure, we achieve greatly improved chip control, so that machine downtimes have dropped to a minimum,” says a pleased Finsterle, who is responsible for technology. “In addition, we have been able to reduce production times per unit. This is because the targeted high-pressure lubricant feed to the tool cutting edge enables higher feed and cutting speeds without sacrificing tool service life.”

As an additional positive effect, Group Manager Sauter mentions that the internal coolant channels of the tools eliminate the need for the time-consuming adjustment or readjustment of the flexible coolant nozzles after tool changes. In addition, he emphasizes the energy efficiency and low noise generation due to frequency-controlled pumps. Both managers come to the same conclusion: “Based on these positive experiences, we will successively equip other lathes with a KNOLL LubiCool®-S or -M high-pressure system, depending on requirements and space availability.”
The strengths of the LubiCool®-S high-pressure system

  • Compact design – perfect for limited spatial conditions
  • Attractive price and short delivery time
  • Wear-resistant high-pressure pump for long service life and high process reliability
  • Effective filtration thanks to affordable filter element
  • SmartConnect control unit for simple, intuitive operation
  • Coloured LED status display
  • Numerous additional options
  • Fast plug-and-play installation and retrofit

HORN Mastering Processes: Swiss Turning and Micromachining

 

Mastering Processes: Solutions for Micromachining and Swiss-type Turning

Outer diameters of 0.1 mm (0.004″), recesses of 0.5 mm (0.020″) and feed rates of 5 µm (0.0002″) – welcome to the world of micromachining! Screws for hearing aids, balance weights for automatic wristwatches or micro-turned parts for medical assemblies: Manufacturing such parts requires know-how, precise machines and special tools. With cutting depths of down to 0.01 mm (0.0004″), users place very high demands on the tools used. They include shiny surfaces and high dimensional accuracy of the components through the use of low cutting force. HORN has developed suitable solutions with the μ-Finish system for micromachining as well as with other tool systems and manufacturing processes for Swiss-type lathes.

The demands on the tools for micromachining with Swiss-type lathes are high. Due to the sometimes very small cutting depths, the tool edges must be very sharp in order to keep the cutting force as low as possible. However, the ground cutting edges are susceptible to microchipping. Even limited chipping in the range of a few µm at the cutting edge has a negative effect on the surface of the machined workpiece. Furthermore, the surface quality of the rake face plays an important role. To counteract built-up edges, the rake face must have good sliding properties. For this reason, it is finely ground or polished.

Changeover Accuracy of 2.5 µm

Clamping of the inserts is another important point in tool design. When machining turned parts of small diameter, the centre height of the tool must be precisely measured. Even slight deviations in centre height have a negative effect on the quality of the workpiece when machining the smallest diameters. In the best case, the machine operator should be able to turn the insert without having to readjust the centre height. With the μ-Finish system, HORN offers a changeover accuracy of +/- 0.0025 mm (0.0001″) when indexing a double-edged insert. This is made possible by the precise peripheral grinding of the insert in conjunction with the stable insert seat. In addition, the contact surfaces of the square shank toolholder are also ground, which has an effect on the holistic precision of the HORN system.

The grinding of a sharp, flawless tool cutting edge requires a lot of know-how. Grinding wheels with the finest grits, special new grinding techniques and a microscope with 400x magnification are necessary to ensure that the tool performs as required. In the process, every batch of the μ-Finish system produced is subject to 100 per cent inspection. Important quality assurance criteria are the tightly toleranced high surface quality of the rake and flank surfaces, the centre height and, in particular, the sharpness of the cutting edge. There must be no visually recognisable irregularities on the cutting edge with the µ-Finish system.

HORN presents itself as a holistic supplier of tools for all Swiss-type machining operations. The extensive insert portfolio can be easily adapted to the requirements of different processes in sliding-headstock turning. Close partnerships have been established with the companies Graf Werkzeugsysteme, Boehlerit and W&F Werkzeugtechnik to provide solutions for the interfaces between the cutting insert and the machine, including for ISO tools.

Broad Knowledge

Horn’s know-how does not only apply to cutting tools. The tool manufacturer also supports its customers and partners with knowledge of the correct application data and the development of new tool systems and manufacturing processes for sliding-headstock operations. This includes, for example, competence in driven tools, tool holders for backworking and entire tool solutions.

WANGEN: Hygenic Progressive Cavity Pump

 

Hygienic conveying and dosing applications in the Food & Beverage, Pharmaceutical and Cosmetics industry

The WANGEN MX progressing cavity pump precisely fulfills the demanding requirements of the food, pharma and cosmetics industries. State-of-the-art design features allow excellent ease of cleaning and maintenance. The pump is available with all common certifications.  And thanks to its great pressure stability, the MX can also be used in many ways in the chemical, paint and paper industries, among others.

Design Features:

  • Modular design
  • Quick to disassemble, e.g. due to clamp locks
  • Robust cardan joint with hygienic joint liner
  • EvenWall® stators with even elastomer wall thickness
  • Solid bearing housing with generous sealing space

Benefits:

  • 10 bar per pressure stage thanks to EvenWall® technology
  • Compact dimensions with high pressures
  • Gentle product delivery
  • Quick and easy cleaning, CIP and SIP capable
  • Low dead space, hygienic design
  • Easy to service

Please contact us for more information on WANGEN Pumps for any of  your requirements in the Food & Beverage, Pharmaceutical and Cosmetics Industries.