1. Edge Rounding and Polishing of Tools
Process and application
Straubenhardt, 2 June 2008
Dipl.-Ing. (FH) Martin Bott
OTEC Präzisionsfinish GmbH
Dieselstrasse 8-12
75334 Straubenhardt

2. Contents 1.) TOOL CUTTING EDGE system
2.) Process for rounding the cutting edge
3.) Drag finishing 3.1) Process description
3.2) Processing goals
3.2.1) Edge rounding
3.2.2) Polishing
3.2.3) Removal of droplets
3.3) Key factors
3.3.1) Machine
3.3.2) Media
3.3.3) Workpiece
3.4) Machine specifications
4.) Outlook

3. 1.) TOOL CUTTING EDGE system
Nowadays tool experts are concerning themselves with the TOOL CUTTING EDGE system consisting of: tool material tool cutting edge geometry preparation of the cutting edge coating of the cutting edge

4. 1.) TOOL CUTTING EDGE system
OTEC offers you a process for preparing the cutting edge of the tool consisting of rounding of the cutting edges and polishing of the cutting surfaces VIBRATORY DRAG FINISHING

5. 2.) Processes for rounding the cutting edges
- Sandblasting
- Brushing
- VIBRATORY DRAG FINISHING

6. 3.) Drag finishing

7. 3.) Drag finishing 3.1) Process description
Since the workpieces can not come into contact with each other, the result is a finishing process which is gentle on the workpiece surfaces. In this process, it is impossible for the workpieces to collide.
The drag finishing process enables multistage processes such as fine grinding and polishing to be carried out.

8. 3.2) Drag finishing - processing goals
3.2.1) Edge rounding
achieves the following:
Removes grinding burs
Stabilizes the cutting edge
Gives uniform surface structure at the cutting edge
Extends tool life
Gives better bonding for coatings
Reduces jaggedness at the cutting edge
Reduces chipping at the cutting edge
Reduces build-up edges

9. 3.2.1) Edge rounding Example of a punching die

10. 3.2.1) Edge rounding Example of a die

11. 3.2.1) Edge rounding Example of an end milling cutter
Workpieces:
Chip removing tools of all kinds requiring edge rounding.
Material:
All materials used, but mainly carbides
Processing goal:
Rounding of the primary and secondary cutting edges for immediate use or prior to coating
Media:
HSC granulates in the case of required edge rounding of up to 10 µm
SIX granulates in the case of required edge rounding of up to 30 µm
QZ 1-3 in the case of required edge rounding of more than 30 µm
Direction of rotation:
100% clockwise
Processing time:
1 – 20 minutes depending on degree of edge rounding required

12. 3.2.1) Edge rounding Example of an end-milling cutter

13. 3.2.1) Edge rounding unprocessed cutting edge

14. 3.2.1) Edge rounding processed cutting edge

15. 3.2) Drag finishing - processing goals
3.2.2) Polishing
achieves the following:
Improves the surface quality
Reduces roughness
Improves chip flow
Improves flow characteristics when drawing
Extends tool life
Gives better bonding for coatings
Reduces cutting forces needed
Reduces tendency to cold welding

16. 3.2.2) Polishing Example of forming dies
Unbearbeitet
3.2.2) Polishing Example of forming dies
Before processing
After initial grinding
After polishing

17. 3.2.2) Polishing Example of a forming tool
unprocessed processed

18. 3.2.2) Polishing Example of a forming die

19. 3.2.2) Polishing Example of a thread-cutting tap

20. 3.2.2) Polishing Example of a tool holder

21. 3.2) Drag finishing - processing goals
3.2.3) Droplet removal
achieves the following:
Improves surface quality
Reduces roughness
Improves chip flow
Improves flow characteristics when drawing
Extends tool life
Reduces cutting forces required
Creates microscopic lubricant pockets

22. 3.2.3) Smoothing of a coated surface

23. 3.2.3) Droplet removal Example of an end milling cutter

24. 3.2.3) Example: smoothing of a coated surface
As a result of the PVD coating process, droplets (tiny balls of material embedded into the surface) often become lodged in the protective coating.
This in turn causes friction.
The drag finishing process removes these droplets.
The miniature “pockets” that remain improve the wetting properties of the surface.
These “pockets” serve to store lubricant.

25. 3.3) Key factors 3.3.1) Machine parameters 3.3.2) Media
3.3.3) Workpieces

26. 3.3) Key factors
3.3.1) Machine parameters ) Speed ) Processing time ) Direction ) Immersion depth ) Angle of holder ) Control functions

27. 3.3.1) Machine parameters
Overview
Parameter input

28. ) Speed
Higher speeds give greater rounding values N.B. The rounding at corners increases more quickly

29. ) Effect of speed

30. 3.3.1.2 + 3.3.1.3) Processing time and direction
The processing time and the direction of rotation can be controlled during the process.

31. 3.3.1.2) Effect of processing time
Longer processing times give higher degrees of rounding. The increase in rounding values is not linear to the processing time. N.B. The rounding at the corners increases faster than at the edges. Depending on the media, the maximum value can vary.

32. 3.3.1.2) Effect of processing time

33. ) Effect of direction
The choice of direction of rotation affects the flow of media against the workpiece.
A change of speed is absolutely essential for homogeneous media flow and uniform processing.
Uneven finishing, which is more pronounced on one side than the other, is often undesirable.
Differences between the workpiece and the speed or direction of the rotor affect have an effect on edge rounding.
(Low workpiece rotations give a uniform finish)
(High workpiece rotations give a more pronounced rounding of the corners)

34. ) Immersion depth
Different immersion depths can be achieved by preselecting the operating modes.

35. 3.3.1.4) Effect of immersion depth
Because of the static pressure, the contact pressure of the media increases with the immersion depth. In general we can say that a difference of 100 mm in the vertical results in a difference of about 25% in the amount of material removed.
In the case of lightweight media with a low bulk density, this effect is less pronounced.

36. 3.3.1.5) Effect of the angle of the holder and/or workpieces
An angled position for the holders and/or the workpieces offers advantages for the processing of the workpiece face and of large flat areas.

37. Goal: reliable processes
) Control functions
In addition to the adjustable machine parameters, the following additional parameters are monitored:
Media life for 5 different,
freely selectable, media types
Workpiece length
(Sensor for avoiding collisions)
Media level
(Sensor for measuring the
level)
Goal: reliable processes

38. 3.3) Key factors
3.3.2) Media H granulates polishing HSC granulates gentle edge rounding µm K granulates gentle edge rounding < 15 µm SIX granulates more pronounced edge rounding up to 30 µm QZ granulates more pronounced edge rounding over 30 µm

39. 3.3.2) Media H granulates - Finishing of HSS tools
Polishing, gentle deburring
Gentle edge rounding
Low rate of chip removal, depending on grinding or polishing additive

40. 3.3.2) Media HSC granulates Finishing of HSS and carbide tools
Polishing of coated tools and removal of droplets
Smoothing and polishing of carbide tools
Edge rounding of carbide materials up to max. 15 – 20 µm
Removal of solder residues
Rate of chip removal medium to high depending on grain size
Creates very high surface qualities (Rz 0.5 for an initial value of Rz 2.5)

41. 3.3.2) Media K granulates Finishing of HSS and carbide tools
Polishing of coated tools and removal of droplets
Smoothing and polishing of carbide tools
Edge rounding of carbide materials up to max. 10 – 15 µm
Natural granulate bonded with PP1 polishing powder

42. 3.3.2) Media SIX granulates Finishing of carbide tools
Deburring and edge rounding of HSS tools
Smoothing and edge rounding of chip removing tools in carbide up to max. 30 µm
Finishing of inserts
High rate of chip removal
Creates high quality surfaces

43. 3.3.2) Media QZ granulates Finishing of carbide tools
Gives especially high degree of edge rounding over 30 µm
Rate of chip removal approx. twice as high as with SIX granulates
Carborundum with grain size of 1-3 mm
Very high rate of material removal
In the case of small edge radii under 30 µm; gives rougher surfaces than SIX or HSC granulates.

44. 3.3.2) Media - Changing the media
It is a quick matter to change the media by simply changing the process container. This makes it possible to carry out multi-stage processing very efficiently.
The drag grinding or drag finishing process is the only type of vibratory grinding that enables targeted surface finishing such as deburring, grinding, polishing and targeted edge rounding – all from the same machine.

45. 3.3.2) Media - Changing the media

46. 3.3) Key factors
3.3.3) Workpiece ) Workpiece size ) Workpiece geometry ) Workpiece materials

47. 3.3.3.1) Effect of workpiece size
In the case of single-drive DF machines, the transmission ratio between rotor and workpiece can not be adjusted. Here the diameter accounts for only about 10% of the effect.
In the case of dual drive versions with two motors, the satellite speed can be set independently of the rotary speed.
Areas of application:
Thread-cutting taps  high satellite speed, low rotor speed
Carbide drills  low satellite speed, high rotor speed
In the case of high satellite speeds, the diameter of the workpiece has a much greater effect than it does with low satellite speeds.

48. 3.3.3.2) Effect of workpiece geometry
Larger workpieces displace more media, which ‘glides’ over the edges and removes more material.
The processing has little effect on the central areas of large, flat workpieces.
“Scooping” workpieces push the media away from themselves.
This reduces the effect of processing.
Inner surfaces can be processed to a limited extend. With small bore holes, the media grain size should not be too large.

49. 3.3.3.3) Effect of workpiece materials
Workpieces made from hard materials can be rounded more accurately than soft ones.

50. 3.4) Machine specifications
DF-3
DF-4
DF-5
DF-6
DF-10
Maximum immersion depth
250 mm
Holder connections 3 4 5 6 10
Maximum workpiece diameter
210 mm
200 mm
Maximum holder weight
15 kg
Adapter interfaces for 4-way / 6-way holders
12 / 18
16 / 24
20 / 30
24 / 36
40 / 60
Maximum workpiece diameter with 4-way / 6-way adapter
85 mm
55 mm
82 mm
65 mm
Maximum workpiece weight with adapter
0.5 / 2 kg
Extra drive
optional
Connection voltage
400 V
Power requirement depending on configuration
2-3 kW
2 -3 kW
3 – 5 kW
3.5 – 7 kW

51. 3.4) Machine specifications
Independently rotating holder systems Holder type 4-way 2B up to 500 g Holder type 6-way 2B up to 500 g Holder type 4-way 2B up to 2 kg Holder type 6-way 2B up to 2 kg Holder type 4-way 2B SL Holder type 6-way 2B SL Special types on request

52. 4.) Outlook
DF-3/4 and DF-5/6 available with additional drive unit

53. 4.) Outlook
DF-3/4 and DF-5/6 with angled holders

54. 4.) Outlook
DF-6 Automation

55. 4.) Outlook
DF-6 Automation

56. 4.) Outlook
DF-6 Automation

57. Thank you
for your attention !