Maximum precision in spite of high quantities: Extremes collide during the machining of crankshaft bearing bores. A German engine builder is successfully banking on line boring bars from LMT Kieninger - the process is faster, more precise and less expensive to use in production.
The machining of bearing bores has a special significance for every automobile manufacturer: Efficiency, smooth running and low-wear operation of the engine depend on the quality and dimensional accuracy of these central bores in the engine block. Its high-precision finishing is therefore done using line boring bars, whose design, holder systems and insert geometries have to be adapted and optimized for every engine type.
Using boring bars with wear compensation
The line boring bars with wear compensation from LMT Kieninger integrate a new generation of these tools.
The process can still be optimized, even for this high-precision fine machining. This is illustrated by a current example at a well recognized German automobile manufacturer. These specialists depend on line boring bars with indexable inserts from LMT Kieninger, which are used to machine the crankshaft bearing bores of three different engine types.
The new feature is that these tools for finish-machining of the bearing bores also have an automatic wear compensation system for the finishing cutting edges using an internal pull rod integrated into the line bar itself.
This new innovation eliminates the complicated and time-consuming manual readjustment of individual cutting edges during the process. To compensate for the wear that occurs on cutting edges, this new tool solution enables the simultaneous and fully automatic readjustment of all cutting edges for machining the surface in the bearing bore.
This machining process normally runs via a so-called measuring control loop, i.e. the bearing bore is measured after being machined and the actual value of the diameter is passed on to the control system and a comparison with the required tolerances is carried out via the measuring computer. The wear-related readjustment of the cutting edges is now done fully automatically via the system by readjusting all cutting edges to the new diameter.
The result is a significant increase in operating efficiency and a higher process quality.
Focused on the productivity of the overall process
All in all, users benefit from a whole series of advantages -The project specialists at LMT analyze the entire machining process.As a result, an additional chamfering feature of the bearing brackets with different widths was also integrated in the bearing bore pre-machining process.
This measure, in conjunction with the use of the new boring bar with wear compensation, has lead to an increase of approximately 50% in the tool life quantity in the customer's premachining process compared with the previous process that was used and over 100% improvement in the finishing process. Simultaneously, the production capacity utilization of the machines increased by over 10%.