Rofin-Baasel lasers weld Siemens VDO fuel injector nozzles

Siemens VDO, the specialist manufacturer of electronics and mechatronics, produces around 27million injector nozzles for the automotive industry each year. The product range includes both classic injector and intake-manifold fuel injection systems, together with highly innovative direct-injection valves for petrol engines.

When Siemens' San Piero facility, close to Pisa, was built in 1987, it was initially intended as a site for research, development and production planning. Before long, however, the facility had expanded and moved towards production of products for the European market. Today there are two locations, San Piero and Fauglia, with around 900 employees in total producing both high-pressure (direct-injection) and low-pressure (intake-manifold fuel injection) systems.

The Italians established a production record two years ago, manufacturing the 250 millionth injector nozzle. Riccardo Toncelli, who is responsible for the production in the low -pressure section, states: "Since starting production, we have been extending and strengthening our market position step by step. For current injectors, used for intake-manifold fuel injection, we targeted, for example, a market share of 40-45 per cent with a production output of 16million pieces. Today we are market leaders for this area."

Being a critical part for vehicles, fuel-injection systems are subject to special requirements. It is essential to achieve consistently high production quality, and Siemens VDO has been relying on laser technology for many years. Marco Fiaschi and Alessandro Baldini, the laser process engineers for the low-pressure section, say: "Here in Pisa we have about 50 solid-state lasers of all kinds. These are used for welding and marking applications on all of the production lines which run virtually around the clock. We use many types of lasers from lamp- and diode pumped rod lasers up to the new disc laser systems. Our injector valves are fine mechanical high-precision units for which you have to hold tight tolerances, and it is very important to control the welding process as precisely as possible. The solid-state technology used today offers us excellent monitoring of laser power and it is therefore the perfect tool for us."

Due to their excellent cost-value ratio, modern intake manifold valves still offer excellent potential. The Siemens DEKA family is now in its seventh generation, and during this time both the quality and efficiency of the production process has been improved. The number of individual components within the assembly has been reduced and the design has been enhanced to ensure that the injectors are less susceptible to seal deterioration.

18 laser welding stations

A total of 16 Rofin laser sources are integrated within 18 welding stations distributed throughout the production facility. As the assembly process progresses, the Rofin lasers are used to perform a variety of different welding tasks including a number of different weld seams, spot welds, fillet welds, lap welds and butt welds. The final operation is to mark each injector with a DataMatrix code prior to final testing and onward shipment to the various automotive engine plants across Europe.

To meet the ever increasing demand, one new injector is produced every 3.0 seconds. Running six days a week and three shifts per day means that every day 60,000 units satisfy the needs of 15,000 four-cylinder-engines. Riccardo Toncelli comments: "Over the years we have gained a lot of experience of the different laser applications, which in turn has helped us to minimise the production cycle times. Due to the high quality and process demands of the product, finding the right parameters, the correct protection gas and the optimum power setting was not that easy."

The laser sources are positioned in a separate room in the immediate vicinity of the production line, and a quiet constant hum is the only indication that the lasers are in use. From this calm and clean environment the laser light travels through fibre optics to the different application stations. Altogether 3km of fibre optic cables snake through the production area, bringing the laser light flexibly and safely to the required workstations. With multiple beam switches per laser, applications at different stations can take place at the same time. The high number of lasers on site requires dependable service and support from the supplier. "Due to the production rates of the valves, it is very important for us to receive quick and efficient response from laser manufacturer, together with readily available spare parts. Throughout our growth, Rofin have proven to be a reliable and responsive supplier and with the demand for the product still growing, we will continue to rely on Rofin in the future."

The excellent support and good business relationship developed between customer and supplier over the years was a prime factor in Siemens VDO once again choosing Rofin as the laser supplier for the new production plants used to manufacture the Piezo and XL-2 injectors. These direct-injection valves are able to produce more power for the same cubic capacity and at the same time it is also possible to reduce fuel consumption. These new production lines demand the highest precision, with extremely fine production tolerances. The new disc laser technology used on these lines provides Siemens VDO with excellent beam quality of 8mm*mrad. This is much better than that of rod lasers (24mm*mrad) and therefore enables even finer weld seams to be achieved.

Ing Baldini concludes: "On the one hand, our very first lasers are still welding effortlessly on our production lines, but on the other hand we need to continue developing new production methods and utilising the latest laser technology. And for sure this will not change in the near future."