Goratu: the longest grinder in Spain with Fagor CNC

Goratu, machine-tool manufacturer located in Elgoibar (Basque Country, Spain) in its process of providing machines more and more customized has just completed the retrofit of the longest surface grinder in Spain.

Retrofitting consists in restoring a machine that has become obsolete or damaged over time in order to get as much productivity as possible out of it. Making retrofitting feasible requires re-using most of the parts of the machine.

The machine, (Heckert SZ25188) manufactured in the old East Germany got here in pretty bad shape (worn out) and after refurbishing it for a year its start-up has finally been successful. For this particular project, Goratu has chosen Fagor’s new digital systems; linear and angular encoders, drives, motors and the CNC 8070.

This surface grinder characterizes not only by its size, but for having two heads, universal and tangential. With these heads, it is possible to grind different planes of the machine quickly and accurately without having to move the part.

Preparing large and accurate beds becomes very complicated. Since there are no large grinders that can handle the whole bed, using masters that to adjust the different sections. This operation is manual and visual and, consequently, any error can cause a considerable waste of time and money. Usually sections of the bed are ground and then assembled later on. Having the bed made up of several sections makes it hard to achieve great accuracy.

Heckert SZ25188

  • Capacity: 2950mm x 20000mm
  • Table dimensions: 2500 x 20000
  • Maximum part height. 2500mm
  • Distance between columns. 3000mm
  • Maximum weight of the part: 100tn
  • Accessories:
*Universal head
*Tangential head
*Cross leveling device

For the Goratu machine, the original size of the table was 6 m x 2.5 m, but in order to make more accurate parts, they have lengthen the longitudinal axis travel up to 20 m. This makes it possible to grind entire beds or in fewer sections, thus obtaining great accuracy.

This grinder has been especially designed for the machine-tool sector providing a solution to other sectors such as naval, wind energy, etc. they are now grinding a 17m-long part that will be mounted on a horizontal lathe, Goratu model GHT 11 for turning heavy parts.

In order to validate the machining process, Goratu is going to start using the machine to grind its own beds but without ruling out grinding parts for other companies in the near future.

CNC 8070 and personalized cycles

To make the operator’s job easier, Fagor Automation and Goratu, have developed a number of screens and cycles adapted to the operation of the machine. In cooperation with Fagor Automation engineers, typical grinding cycles have been added to the CNC 8070-OL. The added cycles are: Plunge, Intermittent cross grinding, Continuous cross grinding, part and diamond zero offsets, cutting conditions, etc. where the cycle only has to enter the machining or measuring characteristics and the CNC will perform the necessary operations.

To make data entry easy, the cycles come with help texts and graphics to guide the operator. With these cycles, the user can machine parts without having to know ISO language programming simply combining automatic and semi-automatic cycles.

“Power OM” project

The machine is part of the European project Power-OM “Power consumption driven Reliability, Operation and Maintenance optimization” that deals with the machine lifespan from the CbM (Condition Based Maintenance) technique point of view and it is based on the consumption changes originated on a machine when its elements wear out or deteriorate in time.