Assembly of the individual components to produce
the finished CNC machining centre
Assembly is referred to in industrial manufacturing according to VDI 2860 as all the processes needed to assemble objects with a geometrically defined shape. But this description in no way does justice to all the heart, soul and experience that our fitters put into every single milling machine. Assembly at HG Grimme SysTech is performed by nine employees who have a wealth of expertise – and every single one of them works with a particular eye for detail and precise rigour. It is no accident that when finished a machine weighing 50 tonnes delivers a repeat accuracy of up to +/-0.025 mm.
“We have a large number of established measuring methods and equipment and some we have developed ourselves to allow us to align the CNC machining centres precisely to the point. But our most important asset are our experienced mechanical engineers who expertly assemble every CNC machine with a great deal of patience and skill.”
Assembly and alignment
of the CNC machines in our main factory
All CNC machining centres are assembled in our main factory. Our assembly workers ensure that every aspect of the assembled components fits perfectly. To ensure that the CNC machines ultimately work precisely in accordance with the customer’s requirements, the frame of the machine is levelled precisely using laser technology and other equipment. Other components are only added once this process has been completed successfully. The perfectly aligned frame is used with the gantry design, for example, as the basis for the subsequent measurement of the straightness of the guide rails during preassembly. They are measured and aligned with a laser. But all the other components of a CNC machine also require a perfectly measured and assembled frame as a reference point.
Drive types and pneumatics of the CNC machining centres
The wide range of different tasks include assembling the different drive types, which involve a ball screw drive, linear drive or gear rack drive depending on the CNC machining centre. To minimise the level of wear on the drives, they are aligned to 0.01 mm with the linear guide.
The pneumatics are also set up by our experienced fitters. The milling spindles are equipped with sealing air to ensure cone cleaning when there is a change of tool. The change of tool itself, so the “tool in – tool out”, is also performed pneumatically. But pneumatics are not just used in our different tool changer systems or external measurement systems – lots of other components of the CNC milling machine are also supplied with pneumatics. For example, each axis can also be provided with sealing air in order to prevent deposits such as dust and dirt from landing on the guides, drives or cable run during the milling process. The appropriate distribution of pneumatic units is ensured by our experienced mechanical engineers.
Geometry and measurement of the CNC machines
Once the specialist assemblers have assembled all the components, the geometry of the CNC machining centre is aligned – this is another important step for achieving a perfect milling result. One of the ways this is done is to measure any backlash and make adjustments if necessary.
The straightness of all axes and the spindle pitch is also measured by laser and each result is transmitted to the control system. Furthermore, all the angles of the linear axes are mechanically aligned and adjusted if necessary.
Another comprehensive measurement is the Renishaw ballbar test measurement. This is used to analyse the geometry of the linear axes and the performance of the CNC machine and make adjustments if necessary. All angles and linear axes are then mechanically aligned and adjusted via the control system.
The different versions of the tool changers used in our CNC machining centres are also aligned. Each tool slot is measured exactly by a specially developed measuring program in order to minimise the wear on the collet chucks, milling tools and the milling spindle.
Once they have been assembled, the machines are thoroughly inspected while milling over the tabletops or strips, and while producing sockets and threads as requested by the customer and following a series of other tests.
If adjustments need to be made at short notice during assembly, this can be done at any stage and without much delay in our assembly workshop or manufacturing facility. Once the individual components have finished being measured and aligned, they are joined together.
“I am the company’s longest-serving fitter and precision engineer and have been working at HG GRIMME SysTech for 32 years. Over such a long time, you do develop an affinity with certain CNC machining centres. The RT-F 1400, which is our smallest milling centre, has usually been assigned to me because I have now assembled more than 300 of them, in lots of different versions.”
Werner Kellner, fitter at HG GRIMME SysTech