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Products (Machinery - Machine Tool)

Okuma Corporation: Double-Column Turning Center VTR-160A, 350A


Okuma Corporation is one of the world’s leading manufacturers of machine tools. It is primarily involved in the production and sales of NC lathes, machining centers, multitasking centers, and NC grinders. It is particularly noted for the production of machine tools for industries and processing where high quality is demanded.

Okuma Corporation was established in 1898, and at first conducted the manufacture and sales of noodle-making machines. In 1904, however, it began to shift its focus toward the manufacture and sales of machine tools, and by 1918 had launched an OS lathe on the Japanese market. This OS lathe was a major success, and Okuma Corporation followed it up with business expansion. By 1937, the machine tool production value represented by Okuma was the highest in Japan. In 1963, Okuma’s in-house team developed an NC device with an absolute position feedback encoder, known as the Okuma Control. This pioneering achievement allowed Okuma to become one of the most successful manufacturers of both machine and electrical tools in both Japan and the rest of the world.

Since then, Okuma Corporation has used its all-round abilities to provide solutions to market demands for high precision processing. In 2005, Okuma Corporation merged with three other companies, with Okuma Corporation at the head of the merger, to create a merged organization with formidable reputation and capability. In 2008, the Global CS Center was established along with the Logistics Center, representing a significant step forward for the corporation’s international business strategy. Today, the brand enjoys a strong reputation overseas as a leading Japanese machine tool manufacturer competing at the highest international level.

The turning centers introduced here are an example of an NC-type device, capable of multiple processing work including grinding, that uses numerical control. Tools can be automatically changed, enabling multiple processes to be carried out with ease and without any cumbersome tool changing procedures.

In recent years, and in all parts of the world (particularly industrialized countries), the demand for larger parts for railroad cars, airplanes, construction machinery, and power generation facilities has increased. Such parts often need to be subject to heavy duty cutting, including difficult-to-machine materials, and lightweight or cylindrical materials. Machine tool operators are vocal in their demand for machinery that can perform with high precision and high definition and can also be adapted as required by the characteristics of each workpiece. The VTR-A Series has been designed specifically to meet this type of industry need. It was developed as a double-column turning machine capable of working with lightweight through to long & cylindrical workpieces, conducting diverse grinding and processing work of varying size, from boring to hole processing, as well as milling.

In 1968, Okuma Corporation began to manufacture MDB double-column machining centers, and since then the company has launched more than 7,000 machining centers onto the domestic and international markets. Okuma’s machining centers are distinguished by their high rigidity and the precision of which they are capable. The VTR-A Series is the latest lauded Okuma range, and includes the following three innovations, based on and developed through the experiences of the corporation since its establishment. 

1) Adoption of large-diameter cylindrical roll bearing and thrust bearing in the table (spindle) to keep heavy workpieces stable
2) Adoption of built-in motor drive for milling tool spindle in a highly rigid ram structure
3) Inclusion of Okuma’s own Thermo-Friendly Concept function

Features 1) and 2) have enabled greater accuracy in turning while reducing vibration. Feature 3) allows the machine to control thermal deformation over time, keeping it to less than 20 μm even with room temperature changes of up to 8°C. This also minimizes changes to processing dimensions over time. 

Moreover, one of the main problems in grinding and cutting working is the chip discharge and disposals. The VTR-A solves this issue with the inclusion of wide chip drops either side of the table. Furthermore, coolant is injected directly from an eyeball nozzle built into the ram, protecting the injection from being affected by the chips. Other options are available, such as rotating scrapers around the table which rake out the chips, and a holder that breaks up chips using high pressure coolant. 

The VTR-160A and VTR-350A are the two most recent models in the VTR-A series. As global demand for large double-column machining centers rises, these two products have been redesigned and upgraded to provide the international market with the best possible version of the VTR-A model possible today. 

Looking at China, India and various countries in the Middle East, it seems likely that demand for machine tools able to process large parts and components will continue to rise in the near future. This will doubtless encourage top-level machine tool manufacturers, such as Okuma Corporation, to continue to innovate in order to remain at the top of the machine tool market.

Apr 7, 2011

About the author
Eriko Kinashi is a reporter for Japanest NIPPON
(Okuma Corporation)
Model : VTR-160A
Swing (mm) φ1,600
Max. machining height (mm) 1,250 [1,600]
Max workpiece load (kg) 10,000
Floor to table surface (standard table)(mm) 900
Table diameter (mm) φ1,250
Ram size (mm×mm) 250×250
X axis (mm) 1,130 (machining)+600 (ATC)