Optimised lead times

Diesel engines for automobiles and lorries have to be ever more economical and emit less and less pollutants. The same applies to larger diesel engines such as those in ships, locomotives or power plants. The determining factor for increased efficiency here is the fuel injection system, where the fuel is injected into the combustion chamber under a pressure of 2200 bar and thereby forms a fine mist, which produces lower emissions during fuel combustion. One of the leading manufacturers of fuel injection systems for large diesel engines is the Togum subsidiary L’Orange. This company that was founded in 1933 in Stuttgart by Rudolf L’Orange was founded on the diesel pre-combustion chamber invented by his father Prosper L’Orange. The L’Orange fuel injection system can realise injection pressures of up to 2500 bar. This means tight tolerances and the most modern inspection technology to verify the finished results for the factory in Glatten in the Black Forest that is responsible for producing the fuel injection system. In the quality control, the tasks are becoming more demanding and more extensive. To optimise the lead times in the metrology Mr Holger Bisinger, Meister in the Quality Control / Metrology in the factory in Glatten, together with his team, have optimised the process for handling inspection tasks. Inspections during production, e.g. after setups or during shift changes, are now carried out at three inspection islands by the production workers themselves. The installation of a rational CNC metrology system together with an inspection program developed by the technicians from Quality Control, allow the machine operators to carry out inspection tasks completely autonomously. This was only made possible by the acquisition of a modular, reproducible workholding system. The specifications from the injection nozzle manufacturers for this system were quite clear. The employee must be able to operate the fixture quickly and easily, wrong positioning must be prevented from the outset. A uniform interface must guarantee the use of all clamping devices on all metrology machines.

L’Orange opted for a clamping system from dk Precision Technology and Machine Construction, Reutlingen. The modular systems Spannfix and Schienenfix provide the user with a flexible solution to easily and safely secure different parts for all inspection tasks. The first dk clamping devices were procured at the same time as the metrology machines were ordered. Mr Bisinger was satisfied with the decision: “The acceptance by the operators was immediate. For us, that was an essential prerequisite for extensively introducing the dk clamping devices over the entire factory.” Magnetic prisms were previously used for the many rotationally symmetrically workpieces. This has the advantage of simplicity, but has the annoying effect of magnetising the workpieces. Through this magnetism, bits of swarf remain stuck to the workpiece surface which leads to difficulties by subsequent processing of the component. The use of prisms with strap tensioners provided the sought after solution. With the use of strap tensioners even complex forms can be quickly and safely secured to a prism leaving optimal accessibility for measuring the workpiece. Magnets are no longer required. The often small production series lead to frequent setups of the metrology machine. The dovetail interface on the clamping element allows clamping devices to be exchanged within a short time. When guided by a clamping plan which is supplemented by photos, an employee should be able to carry out all the steps independently. Alternatively, one could use workholding pallets onto which the clamping element is mounted. “What is also important for us is the quick delivery times for the clamping system modules. In urgent cases we could have the required clamping element delivered within one day”, said Mr Bisinger.