High-precision double-column machining centres manufactured by Okuma (www.okuma.eu) in Japan are popular in the global automotive industry, as they are designed for manufacturing large parts.

With over 50 years’ experience and a production capacity of 40 units per month, Okuma is a world-leading CNC machine tool manufacturer — represented in the UK by NCMT Ltd (www.ncmt.co.uk).

Currently, there are over 8,000 Okuma double-column machines in use world-wide, of which around 3,500 are working in the automotive sector.

Machines like the MCR-BIII and the recently introduced MCR-S are used by nearly all automotive manufacturers world-wide, so most cars on the road include parts made by an Okuma machine.

In the automotive sector, Okuma’s double-column machining centres are mainly used for manufacturing the dies that produce car body shells — a process that poses various challenges, as the large workpieces require high dimensional accuracy.

Dies also need to have very smooth and clean surfaces, so achieving the required results is difficult and the manufacturing process can take several days.

The long machining time makes the workpiece vulnerable to deviations due to temperature changes and other external influences during the manufacturing process.

These problems are solved by multiple highly tailored applications and features: Okuma’s Thermo-Friendly Concept helps to both minimise the amount of heat generated and compensate for thermal deformations that cannot be avoided; the Premium Solution Hyper-Surface allows for excellent surface quality by correcting machining data automatically, which improves overall quality and eliminates the need for hand-finishing; the solid cast-iron double-column construction of the machines ensures great rigidity and close tolerances; and a touch probe enables on-machine gauging of complex shapes in mid-process.

Pablo Liechti, European product manager, said: “Manufacturers in the automotive sector appreciate our double-column machines’ high dimensional accuracy of less than 20µm — even for workpieces measuring up to 2,000 x 5,000mm in length.”

The machines are equipped with a multitude of applications, making them as productive as possible. The Intelligent Technology ServoNavi is a high-precision technology that improves cycle times and accuracy when machining heavy parts, and so optimises cutting and feed rates.

“This enables us to shorten production times by up to 25%.”

The Thermo-Friendly Concept also increases productivity by minimising warm-up times. Okuma’s double-column machining centres can be configured in many ways.

Customers can choose different spindles, a wide range of attachment heads and table sizes up to 4,500 x 12,000mm long. Many other features and set-ups are also available.