With the new GGTronic, Italian OEM GIANA decided to position itself on the higher level of machine-tools technology. It is the only way to survive explains Giulio Maria Giana, the company manager and technical director. As this milling & turning equipment in one set solution for big mechanical parts, very high rigidity becomes obviously a crucial design feature. Positioning has also to be very precise, reaching values as low as ±0.01mm, with a repeated accuracy of ±0.005 mm. To achieve these performances, GIUSEPPE GIANA went one step ahead by implemented REDEX-ANDANTEX´s TwinDRIVE on the machine, the original rack and pinion drive solution.

The GGTronic outstanding performances enable us to face the pressure of the costs and the evolving needs of our customers. Formerly, our customers were looking first for power and second for high speeds. Nowadays, materials are tougher and tougher and precision requirements are becoming higher and higher», explains Giulio Maria Giana.

The new line of GGTronic turning and milling centers can machine cylinders and complex components up to 4,000 mm in diameter and 25,000 mm in length. They are also designed to be used in a complete unmanned environment. These high powered machines are particularly suited to heavy-duty machining in the precision mechanics sector, to the machining of ship masts, wind turbine masts, turbine shafts, oil pipeline valves, crankshafts and rolls, to the machining of large winch drums, etc.

Machining process for this kind of part can last for hours and may need several types of machining before to be achieved. They have very tight tolerances despite huge weight and dimension.

On the other hand, and to make the machining process as fast as possible, traverse speeds of 20,000 mm/min can be reached, as well as accelerations up to 4 m.s-2.

The machine structure, built entirely of cast iron, is even strong enough to hold anti-vibration boring bars suitable for internal boring to a depth of over 5,000 mm.

Among all the design key points taken in account at the beginning of the project, and including for instance machine's ergonomic features (ease of clamping, tools visibility throughout the various stages of machining, access to different measurements once the part has been finished), both machining precision and machine frame´s rigidity were of course absolutely crucial.

As GIUSEPPE GIANA company´s idea with the GGTronic was that to keep its position one step ahead to the competition, the global machine´s productivity needed to be dramatically increased by eliminating most of the usual needs for regrinding the parts after machining.

That target easily explains the very high level of requests for final precision of the machine, and then the very high level of global stiffness which is mandatory to reach this level of precision under dynamic conditions.

Rigidity and precision are achieved through a unique technological concept

The main technical issue in terms of rigidity was the Z axis which features the longest strokes (up to 25.000 mm). To ensure getting the best performances from the chosen linear drive technology, GIUSEPPE GIANA decided to implement a TwinDRIVE Rack & Pinions system produced by REDEX ANDANTEX. This turnkey system offers unique innovations which enables outstanding performances.

And the final results were clearly reaching the designer´s expectations with positioning precision and repeatability as low as ± 0.01 and ± 0.005 mm, together with an exceptional global stiffness.

TwinDRIVE Rack & Pinion drive systems are made up of 2 parallel mounted planetary servo reducers that are coupled electrically. This preload system eliminates the backlash and contributes to offer high precision.

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