Proposal for collaboration Subject: Free form machining – tool path optimization University of Belgrade, Serbia Faculty of Mechanical Engineering Department of Production Engineering Centre for New Technologies MSc. Goran Mladenovic, PhD student Prof. dr Ljubodrag Tanovic, PhD thesis supervisor

INTRODUCTION Free form surfaces are used in many areas of mechanical engineering. Machining of free form surfaces can be done using 3 and 5 axis machines. Commercial CAM software unfortunately cannot simulate tool damage or overloading of axis servomotors. The area of my research/thesis involves optimization of rough machining with several criteria, one of them being feedrate scheduling. This presentation gives a description of my recent research and proposal for an experiment which results I intend to publish in collaboration with the University of Liverpool –Department of Physics colleagues, and of course use it as a massive/key contribution for my thesis. References – For feedrate scheduling – For example how to look forward paper (STL file --> Tool path generation --> Experiment --> Measurment --> Analisys)

Tool path generation using commercial CAM software Free form CAD model created by Solid Works Pro/ENGINEER SolidCAM

Work description The machine part designed in a commercial software is exported to STL (STereoLitography) file format. This file is loaded into matlab and a tool path with feedrate scheduling is generated. The condition for tool path generation is maintaining the cutting force at a user defined level. Developed a matlab code for cutting force prediction, which gives the results shown Comparison of cutting forces (Fx and Fy) determined based on simulation and experiment Discretization of the ball-end mill cutting edge (a), scheme of cutting forces (b) Side step and forward step in free form machining

Work flowchart Free form surface (STL file format) generated in a commercial CAD software MATLAB software Generated tool path Real machining NC code Depiction of a machined part Measurement

Production and experimental setup Clamping the Workpiece to a dynamometer

Experimental setup The dependence of force in relation to movement The dependence of force in relation to time Detail G

The experiment and the results :0407 G54 G40 G49 G80 G90 G0 H0 Z-50. M5 G58 X0. Y0. B0. S1060 M03 G00 X-10 Y Z20 G00 X-10 Y Z F2000 M0 G01 X Y Z F140 G01 X Y Z F140 G01 X Y Z F125 G01 X Y Z F123 G01 X Y Z F106 G01 X Y Z F106 G01 X Y Z F 91 G01 X Y Z F 77 G01 X Y Z F 77 G01 X Y Z F 68 G01 X Y Z F 68 G01 X Y Z F 60 G01 X Y Z F 60 G01 X Y Z F 61 G01 X Y Z F 63 G01 X Y Z F 63 G01 X Y Z F 78 G01 X Y Z F 91 G01 X Y Z F112 G01 X Y Z F134 G01 X Y Z F144 G01 X56 Y Z F144 G54 G40 G49 G80 G90 G0 H0 Z-50. M5 M30

The needs for the proposed experiment 3 axis milling machine Machine Vise Ball-end cutter with a diameter of 12mm Workpiece 50x50x50 mm or similar – Material: AlMg4.5Mn If available: Multicomponent Force Plate Piezo-Dynamometer for cutting force measurements Example Data acquisition system Example electronics-software/compact-universal-data-acquisition-system/ electronics-software/compact-universal-data-acquisition-system/

Suggested steps 1. Machine the workpiece according to the NC code which I would send you already prepared.

Suggested steps 2. Measure the machined part with a coordinate measurment machine or an optical scanner (for the estimation of errors)

Suggested steps 3.If there is a software included with the measurement machine, it would be easiest to calculate the error distribution for machined part there directly, compared to a CAD model which I would send to you. If however this would not be possible, you could just send me the point cloud and I will calculate the error distribution in matlab or some other CAD software.

This would really mean a lot to me, and hopefully would be beneficial for both parties… Thank you for your time!! Sincerely yours Goran Mladenovic