1. 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 http://www.mas.bg.ac.rs/ http://cent.mas.bg.ac.rs/ MSc. Goran Mladenovic, PhD student gmladenovic@mas.bg.ac.rs Prof. dr Ljubodrag Tanovic, PhD thesis supervisor ltanovic@mas.bg.ac.rs

2. 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 http://www.sciencedirect.com/science/article/pii/S2212827112000169 http://www.sciencedirect.com/science/article/pii/S2212827112000169 – For example how to look forward paper http://www.sciencedirect.com/science/article/pii/S0010448514000086# (STL file --> Tool path generation --> Experiment --> Measurment --> Analisys)

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

4. 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

5. 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

6. Production and experimental setup Clamping the Workpiece to a dynamometer

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

8. 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 Y10.851 Z20 G00 X-10 Y10.851 Z-0.231 F2000 M0 G01 X-0.281 Y10.851 Z-0.231 F140 G01 X 1.686 Y10.915 Z-0.154 F140 G01 X 4.066 Y10.988 Z-0.333 F125 G01 X 6.363 Y11.066 Z-0.726 F123 G01 X 8.619 Y11.143 Z-1.257 F106 G01 X10.868 Y11.215 Z-1.875 F106 G01 X13.129 Y11.281 Z-2.539 F 91 G01 X15.411 Y11.338 Z-3.212 F 77 G01 X17.714 Y11.383 Z-3.861 F 77 G01 X20.037 Y11.415 Z-4.454 F 68 G01 X22.372 Y11.430 Z-4.959 F 68 G01 X24.712 Y11.425 Z-5.348 F 60 G01 X27.050 Y11.395 Z-5.594 F 60 G01 X29.382 Y11.339 Z-5.674 F 61 G01 X31.706 Y11.254 Z-5.567 F 63 G01 X34.030 Y11.139 Z-5.248 F 63 G01 X36.367 Y10.999 Z-4.692 F 78 G01 X38.736 Y10.839 Z-3.865 F 91 G01 X41.157 Y10.668 Z-2.725 F112 G01 X43.644 Y10.494 Z-1.219 F134 G01 X46.426 Y10.284 Z 0.884 F144 G01 X56 Y10.284 Z 0.884 F144 G54 G40 G49 G80 G90 G0 H0 Z-50. M5 M30

9. 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 http://www.kistler.com/us/en/product/force/9257BAhttp://www.kistler.com/us/en/product/force/9257BA Data acquisition system Example http://www.ni.com/data-acquisition/http://www.ni.com/data-acquisition/ http://www.hbm.com/en/menu/products/measurement- electronics-software/compact-universal-data-acquisition-system/http://www.hbm.com/en/menu/products/measurement- electronics-software/compact-universal-data-acquisition-system/

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

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

12. 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.

13. 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