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Case Study

The machining of long and several tons of heavy parts is particularly demanding when at the same time high precision and tightest tolerances are required. It is not only the technical competence of the machine operator that is important, the turning center must also be able to comply with the high demands of the machining process for large, accurate and heavy workpieces. In order to be able to produce even small and smallest batch sizes economically and precisely, Hyss Metallberarbeitung in Lennestadt, Germany, for many years has been counting on large turning centers from Hwacheon, a South Korean machine tool manufacturer.

Gerhard Hyss (right) and his son Steffen (left) invested in the extremely robust and precise turn-mill center Hi-TECH 850L YMC
Hyss Metallverarbeitung produces large and heavy turned parts in small batch sizes on its XL lathes

The contract manufacturer specializes in turning of large and heavy parts, up to 8 tons, 1,100 mm in diameter and 3,500 mm in length. These are often one-off productions or small series in small quantities.

While in 1982 Gerhard Hyss started his business with two partners and the production of small turned parts, they envisaged manufacturing larger parts and decided to invest in machines for processing maximum diameters of 550 mm and peak weights of 1.5 tons. “This allowed us to expand our range of services and gain new market segments,” explains Hyss.

“The concept worked, and more and more orders for large precision turned parts were received. Eventually, the previously available production area reached its capacity limits and subsequently a new production facility was built in 1999 at the current location. The new halls offered space for even larger machines and thus also for machining larger and heavier work-pieces.


With the rigid Hi-TECH 700 from Hwacheon, workpieces up to a diameter of 700 mm and a turning length of 2,000 mm can be processed.

At the Metav exhibition in Düsseldorf, Gerhard Hyss spotted the Hwacheon Hi-TECH 700, a horizontal turning center for heavy-duty machining, which offers an extremely rigid spindle design. The high-precision cylindrical roller bearings and the particularly impact-resistant angular roller bearings of the headstock are specially designed for tough and hard turning operations. Torques of up to 3,071 Nm at 115 rpm can be achieved via the integrated gearbox. Hyss was fascinated with this extremely stable and qualitatively well-processed lathe in XL format and decided to buy his first Korean machine: “With the Hi-TECH 700, new doors opened for us. Now we were able to machine parts up to a diameter of 700 mm and a turning length of 2,000 mm and achieve more flexibility and speed in production,“ he says.

With the new machine, more new orders came for even larger workpieces. The company had found its niche market and at the same time acquired a reputation as a specialist in the manufacture of large parts for the engineering industry. In the period that followed, the order backlog continued to grow, so another Hi-TECH 700 was purchased to adjust the production capacity.


While space available for storing raw material was no longer sufficient, an additional hall was added. At the same time, the contract manufacturer received more and more inquiries for larger size turned parts with integrated milling work. Therefore, the procurement of a turning-milling center was planned

Steffen Hyss, son of the company founder and co-managing director, saw the Hi-TECH 850L YMC turning and milling center at the opening of the new Hwacheon European headquarters in Bochum. With this XXL machine, workpieces up to eight tons and diameters of up to 920 mm can be precisely machined up to a turning length of 3,500 mm. In addition to classic turning tasks, milling work can also be carried out in one setup in combination with an additional Y axis. This increases precision of machined parts, because clamping errors that can occur when changing from the turning to the milling machine are excluded. Hyss was so impressed with the Hi-TECH 850L YMC that the company decided to buy the machine.


The spindle, tailstock and extremely rigid machine bed of the Hwacheon Hi-TECH 850L YMC are designed for large, heavy workpieces. The machine bed is bevelled by 45 degrees for optimal heat management. This prevents excessive heating of the workpiece and machine, while ensuring high precision.

The stable and robust machine has a particularly rigid monolithic machine bed with a weight of 23.5 tons, which is manufactured in Hwacheon’s own foundry. For optimal heat management, it is bevelled by 45 degrees so that hot chips can be reliably removed. This means that the machine and workpiece are not excessively heated, even during roughing operations with a large amount of chips. All flat guides of the machine are hand scraped and polished. Especially with this time-consuming work process, the manufacturer’s more than 75 years of mechanical engineering experience become clear. The flat guides have significantly lower vibrations even for heavy-duty machining tasks and thus ensure greater stability for greater precision and longer tool life.

Thanks to the massive design of the extra wide turret with a width of 250 mm, even large boring bars up to a diameter of 100 mm and a turning length of 1,000 mm can be clamped. The four-stage main spindle gear offers exceptionally high torque, especially in the lower speed range. The bearings are lubricated and cooled using the oil cooling system specially developed by Hwacheon. The temperature of the four-stage gear is continuously regulated in order to minimize thermal expansion, while ensuring accuracy during long operating times and heavy machining. With a drive power of 45 kW, the machine achieves a maximum torque of 6,873 Nm.

On the Hi-TECH 850, the company is able to machine all materials from structural steels, tempered steels, quenched and tempered steels, stainless steels, brass to plastics and super duplex steels.

For more information, contact Lead Machine Tools – Tel: 021 534-5351

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