Basic Experimental and Simulation-Supported Analysis of Surface Structuring for Short- and Long-Stroke Honing

Honing is a finishing process which creates surfaces for components subjected to high tribological stresses. The surface topography of honed surfaces typically shows a cross-hatched pattern consisting of deep grooves and plateau-like areas. The cross-hatched surface structure is created by the honing kinematics whereby one infeed motion is an oscillation of the tool or the workpiece. Based on the range of this oscillation, long- and short-stroke honing are distinguished. Long-stroke honing is commonly used for the machining of boreholes. A typical application is the honing of cylinder liners in combustion engines. Short-stroke honing, also called microfinishing, is mainly used in external cylindrical machining. Here, the processing of crank- and camshaft bearings are application fields. Because of increasing requirements for surface integrity, the well-directed and defined production of surface topographies is a reasonable optimization approach. Also, the analysis of these processes is supported by simulation methods, which saves time and money, because the effort for practical trials can be reduced.

The project “Basic experimental and simulation-supported analysis of surface structuring for short- and long-stroke honing” is supported by the “Deutsche Forschungsgemeinschaft” (DFG). The aim of this project is to generate process knowledge and to improve the comprehension of honing processes by carrying out experiments and simulation-supported investigations. The influence of parameters like contact force, infeed velocity and machining time on the created workpiece surfaces will be analyzed. Up to now, the production of a defined surface structure requires extensive practical trials.

The experimental part of the project for long-stroke honing is accomplished by using a combination machining center with a stationary honing tool. The short-stroke honing is carried out with a microfinishing device, which is clamped on a conventional lathe. The test planning is optimized using “Design of experiments (DoE)”. Within DoE the measurement results are used to adjust a regression function, which covers the whole analyzed parameter range. Hence, the DoE improves the test output while the trial work is reduced.

For modeling the honing process, a kinematic-geometrical approach is used. Workpiece and tool surfaces are modeled as discrete 3D-surface models, which are gained by using optical measurement techniques. The process model represents the ideal process kinematics. The workpiece is mounted in a global coordinate system whereas the surface of the tool rotates on a stationary radius within the system. By moving the two surfaces relatively to each other and calculating their intersections, the new workpiece surface is created. The experimental results are used as input data for the modeling and for verifying the process simulation. By modeling and simulating the honing process, the necessary number of experiments is reduced and the determination of surface structures and properties becomes possible in advance.

The figure below shows a comparison between measured surfaces of real topographies and those from the simulation system. The presented results are in good agreement with respect to the surface structure and the roughness values.

Fig.: Comparison of a real surfaces and simulation results of honed workpieces