GE Additive reports that it has collaborated with the automotive parts team at Bosch in Bamberg, Germany, to redesign and additively manufacture a metal oil header for use in a common rail injector (CRI) on a diesel engine. The result was a consolidation of the header from two parts to one and the elimination of lubrication blind spots.
With conventional diesel injection systems, fuel pressure has to be generated individually for each injection. Conversely, in CRIs, pressure generation and injection are separate, meaning that diesel fuel is constantly available at the required pressure for injection.
According to Bosch, it has become increasingly important that newer generations of CRI, which have different surface properties, are lubricated on the outside diameter of the thread to prevent friction. In a recent examination of the oil process during CRI assembly at Bosch’s Bamberg plant, the part was found to have ‘lubrication blind spots’.
Dr Anna Ebert, who is responsible for CRI assembly at the plant, discovered that the component was wet with oil only on the upper thread geometry and not on the bottom side. Initially, the team attempted to rectify this with a redesign of an oil header in three or four parts using conventional machining, but reportedly found this approach too complex and cost-prohibitive.
On deciding to explore metal AM for the redesign, the team partnered with Concept Laser, a GE Additive company. The conventional design was assessed by Concept Laser and a new design created incorporating a new geometry for the oil channels, for production in CoCr. Though a Concept Laser M2 cusing system was already installed at Bosch’s Nuremberg facility, a smaller Mlab cusing system was selected as the more suitable choice to produce the oil header due to the part’s size and complexity.
Having tested the redesigned component, Dr Ebert stated, “The process fluctuations were visibly smoothed out. The 3D printed oil header was much better at delivering the right amount of oil to the right place.” She reported that wetting now takes place not just at the top of the thread, but also at the bottom, meaning that the lubrication blind spots identified in the previous design have been eliminated in the new header.
“The new oil header looked different – smaller and more compact,” added Wolfgang Schliebitz, Production Planner at Bosch in Bamberg. “But what was really surprising was the effect on our process during trials.” GE Additive reported that the redesigned component has now been introduced to four other Bosch plants in Korea, Turkey, Germany and France.