The Importance of Cutting Edge Preparation In Metal Cutting Technology Presented by

1. The Importance of Cutting Edge Preparation In Metal Cutting Technology Presented by Martin Moser OTEC Präzisionsfinish Germany The Importance of Cutting Edge Preparation

2. Topics: • Why is it so important to prepare cutting edges? • Influence of the tool’s surface to the performance • How much rounding is necessary? • What kind of edge rounding can we achieve? • Several methods of edge preparation • How to improve PVD coated surfaces. • Up to how many % can the tool life be increased? The Importance of Cutting Edge Preparation

3. General Observations The Importance of Cutting Edge Preparation

4. Edge Preparation Effects • Force • Torque • Wear • Tool life • Fringe, chipping • Chip formation • Chip removal • Surface roughness • Process precision • Micro outing • Coating thickness • Adhesiveness (of the coating) Edge preparation effects The Importance of Cutting Edge Preparation

5. Influence of Pressure to the Cutting Edge Bigger radius  less stress concentration  less chipping The Importance of Cutting Edge Preparation

6. Cutting Edge Tip of an end mill. Material: Tungsten Carbide Before processing After processing with a Drag Finishing Machine The Importance of Cutting Edge Preparation

7. Crack Formation Due to Stress Concentration Typical surface profile after the tool is manufactured Enlargement X Before coating F= Pressure R= Crack-formation due to notch effect (stress concentration) After coating Sharp and rough surface at the edges  chipping The Importance of Cutting Edge Preparation

8. How Stress Concentration can be minimized Typical surface profile treated with a Drag Finishing Machine from OTEC Enlargement X Before coating F= Pressure No crack-formation due to no notch effect (stress concentration) After coating Smooth and homogenous surface at the edges less chipping The Importance of Cutting Edge Preparation

9. Surface And Cutting Edge of a Tap Drill Before processing: Edge radius 7 μm • After 3 minutes of processing: • Edge radius 10 μm • Surface is much smoother The Importance of Cutting Edge Preparation

10. Influence of the tool’s surface to the performance • Radius at the cutting edge  less chipping • Smooth tool surface  less heat at the tool • A combination of both processes, rounding of the cutting edge AND smoothening of the surface after coating will improve your tool life up to 13 times longer. The Importance of Cutting Edge Preparation

11. Preparation Processes and the Radius size you can achieve Depending on the required edge radius, there are three main preparation processes in use. Blasting: 5 µm < r < 20 µm Brushing: r < 30 µm Drag Finishing: r < 150 µm The Importance of Cutting Edge Preparation

12. Blasting • How does it work? • Parameters which influence the result • Pressure • Distance • Energy • Size of the jet • Operator (manual work) Disadvantages: • the blasting method of edge preparation removes the binding agent cobalt from the surface. • Process is very depending on the operator The Importance of Cutting Edge Preparation

13. Brushing • How does it work? • Parameters which influence the result • Parameters which change during processing • Speed of rotation • Angle of penetration • Brushing time • Direction of the movement • Wire arrangement • Number of wires • Wire diameter • Wire shape • Length of the bristles • Free wire length • Depth of penetration • Pressure • Edge radius • Surface The Importance of Cutting Edge Preparation

14. DragFinishing • How does it work? The Importance of Cutting Edge Preparation

15. DragFinishing Parameters which influence the result • Speed of rotation • Process time • Direction of the movement • Abrasive media Rotor Driven holder The Importance of Cutting Edge Preparation

16. Advantages of processing cutting and forming tools in a Drag Finishing Machine machine prior to coating • Adapts the tool to the material which will be processed with it by achieving a predefined edge rounding. • Reduces the risk of edge chipping • Absolutely homogeneous cutting edge • Makes the tool run more smoothly when in use (chatter marks can be avoided)  smoother surface of the work piece. • Best possible surface finish • Increases cutting speed by up to 100% • Increases tool life by up to 1300% • Dimensional stability (e.g. in the case of stepped drills) The tool does not loose the diameter during performance. The Importance of Cutting Edge Preparation

17. Process Time to achieve different radiuses with a Drag Finishing Machine • The following recommended measurements have been derived from practical tests: • - Aluminium 1-3 µm (process time = 10-30 seconds) • - Steel 15-20 µm (process time = 3-5 minutes) • - Titanium alloys max. 30 µm (process time = 10-15 minutes) The Importance of Cutting Edge Preparation

18. Surfaces Before and After Edge Honing The Importance of Cutting Edge Preparation

19. Coated Surfaces Before and After Droplet Removal The Importance of Cutting Edge Preparation

20. Up to how many % can the tool life be increased? Some Feedback from our Customers: • Customer from Italy: “The life span of my tapping tools is 13 time longer after using Drag Finishing Machines” • Platit (Switzerland): “We can get an 8 times longer life span out of our tapping tools” Uncoated tool: 245 threads Coated tool: 423 threads Coated tool with edge honing using Drag Finishing Machines: 1980 threads • End mill manufacturer from Germany: “The life span of the end mills now up to 350% and I can cut between 20% and 100% faster” The Importance of Cutting Edge Preparation

21. Special Thanks Special Thanks to the University of Kassel / Germany The Importance of Cutting Edge Preparation