1. A Guide to Selecting Ceramic Grades
Dale R. Hill
Applications Engineer
GREENLEAF CORPORATION
Saegertown, PA

2. Selecting Ceramic Grades
Work Materials
Nickel-Based Alloys
• Inconel
• Waspaloy
• Hastelloy
Cobalt-Based Alloys
• Stellite
• Haynes Alloys
Weld Overlays
400 and PH Series Stainless Steels (post heat treat)
Hardened Steels (45 – 65 R/c)
Nodular and Chrome Irons
Powdered Metals

3. Selecting Ceramic Grades
Ceramic Tool Materials
Alumina Oxide (White Ceramic)
Alumina Oxide + TiC (Black Ceramic)
Alumina Oxide + SiC (Whiskered)
Silicon Nitride - Sialon

4. Selecting Ceramic Grades
Tool Application
Alumina Oxide + SiC (Whiskered) – All Materials
Alumina Oxide (White Ceramic) – Gray Cast Iron
Alumina Oxide + TiC (Black Ceramic) – Hardened Steels and Irons

5. Selecting Ceramic Grades
Focus Materials
Nickel-Based Alloys
• Inconel
• Waspaloy
• Hastelloy
Cobalt-Based Alloys
• Stellite
• Haynes Alloys
400 and PH Series Stainless Steels (post heat treat)

6. Selecting Ceramic Grades
First Choice…
Alumina Oxide + SiC Whiskers
Greenleaf ® Grades WG WG WG-700
High Cutting Speed
Resists Catastrophic Failure
Predictable Performance
WG-300 whiskered aluminum oxide ceramic is the strongest grade of ceramic offered by Greenleaf. It is the first choice for the machining of heat resist aerospace alloys.

7. Selecting Ceramic Grades
The fracture toughness of
WG ceramics is enhanced by the phenomenon of whisker
“pull-out”. A close examination of the fracture surface at 3000x will reveal not only a clear indication of the whiskers randomly dispersed throughout the matrix, but also the obvious hexagonal holes where whiskers have actually been pulled out in the fracture process. A large amount on energy is required to pull the whiskers out. This greatly enhances the fracture toughness and thereby the high predictability of the inserts.

8. Selecting Ceramic Grades Hardened Steels and Irons (45 – 65 R/c)
Focus Materials
Hardened Steels and Irons (45 – 65 R/c)
Weld Overlays

9. Selecting Ceramic Grades
Machining Hardened Materials with Greenleaf ® Ceramic Inserts
WG Ceramics can be successfully applied to the machining of materials other than nickel alloys. Some application areas include hardened alloy steels, hard irons, die and mold steels, and hard weld overlays.
Common materials include : 4150, 52100, D2, A2, H13 Steels
Chilled Cast Iron, White Iron, Ni-hard, 400 Series Stainless, Weld Overlay

10. Selecting Ceramic Grades
In addition to WG-300, WG-600 & WG-700, Greenleaf’s GEM-7 composite ceramic has an important place in the machining of hard materials. WG Ceramics & GEM-7 can be cost effective alternatives to CBN in the heavy roll turning, and die & mold industries.
Use ceramic grade GEM-7 for turning under favorable conditions and WG-300 where additional strength is required such as interrupted turning and milling.
GEM-7:
Hot pressed Al2O3 + TiC, is used primarily for turning steels and irons above 32 Rc. It offers high wear resistance and moderate strength. GEM-7 can also be used on heat-resist alloys for light finishing work.
GEM-19:
Cold pressed and sintered Al203 offers high abrasion wear resistance. It is best applied in grooving operations on gray cast irons.

11. Selecting Ceramic Grades
C-CDH42 T4B GEM-7 – 400 SFPM, ” DOC
(120 m/min, 0,3 3,8 mm DOC)
Forged 55 Hr/c
WG-300 whiskered aluminum oxide ceramic is the strongest grade of ceramic offered by Greenleaf. It is the first choice for the machining of heat resist aerospace alloys.

12. Selecting Ceramic Grades Edge Prep for Heavy Machining
DESIGNATION
APPLICATION AREA A
For light finishing and grooving, also added to some negative lands B
Used in addition to heavy machining chamfers and lands
T2A
For scale cuts, light interruptions, weld overlays, turning and milling of hardened materials
T4B
Heavy machining inserts under ¾” IC (19mm), Roll turning,4V, CDH22, CDH33
T5B
Heavy machining inserts over ¾” IC (19mm), Roll turning, LNMN’s, SNGN 866’s
T7A
Similar application to T2A, use in heavier feed areas
T10B
Heavy machining inserts over ¾” IC (19mm), Roll turning in Severe Conditons, CDH43, CDH53
A chamfer and a hone is recommended when machining hardened materials. For heavy turning operations like roll manufacturing or roll reconditioning, a double chamfer (‘K’ land) is applied to the cutting edge. The Greenleaf T4B, T6B and T10B are examples of a double chamfer.

13. As with heat resist alloys, cutting speed and feed for turning hardened materials is based on the work material hardness.

14. Use these charts for Greenleaf ceramic grades GEM-7 and GEM-19.
GEM-19 is best used on work material less than 35 Rc, while GEM-7 works best on work materials above 35 Rc.

15. Selecting Ceramic Grades
C-CDH515 T4B GEM-7 – 300 SFPM, ” DOC
(91 m/min, 0,15 3,2 mm DOC)
Forged 62 Hr/c
WG-300 whiskered aluminum oxide ceramic is the strongest grade of ceramic offered by Greenleaf. It is the first choice for the machining of heat resist aerospace alloys.

16. Selecting Ceramic Grades
C-CDH515 T4B GEM-7 – 300 SFPM, ” DOC
(91 m/min, 0,15 3,2 mm DOC)
Forged 62 Hr/c
WG-300 whiskered aluminum oxide ceramic is the strongest grade of ceramic offered by Greenleaf. It is the first choice for the machining of heat resist aerospace alloys.

17. Selecting Ceramic Grades
Milling with Ceramic Tools
Focus – Hardened Materials

18. Selecting Ceramic Grades Milling Hardened Materials
Recommended Grade Choice…
Alumina Oxide + Sic (Whiskers)
Greenleaf Grade WG-300 & WG-600
WG-300 whiskered aluminum oxide ceramic is the strongest grade of ceramic offered by Greenleaf. It is the first choice for the machining of heat resist aerospace alloys.

19. Selecting Ceramic Grades
C-4 Series Ceramic Milling Cutters
Greenleaf C4, CP4 and Excelerator milling cutters are designed for high RPM applications.
Excelerator®
Milling System
Greenleaf Excelerator milling cutters designed for ceramic inserts are tested to perform at high RPM. Maximum RPM data is published in the Greenleaf 2006 catalog or available upon request from Greenleaf Corporation.
Available in Inch or Metric diameters from 3/8 inch (10mm) to 12” (305mm).

20. Selecting Ceramic Grades
Greenleaf ‘s Excelerator Ball End Mill offers the ability to use ceramic or carbide inserts in the same cutter body.
Available in Inch or Metric Diameters…
.375” ” ” ” & 1.0”
10mm - 12mm - 16mm - 20mm & 25mm
Greenleaf Excelerator milling cutters designed for ceramic inserts are tested to perform at high RPM. Maximum RPM data is published in the Greenleaf 2006 catalog or available upon request from Greenleaf Corporation.

21. Selecting Ceramic Grades
"Edge Prep"
Greenleaf ® Standard Edge Preps
T1A ” (0,05mm x 0,1mm) wide Negative Land
plus a ” (0,01mm – 0,02mm) Hone
T2A ” (0,15mm x 0,2mm) wide Negative Land
plus a ” (0,01mm – 0,02mm) Hone
NOTE – Ceramic Ball End Mill Inserts are ‘A’ Hone only!

22. Selecting Ceramic Grades
C404 Cutter w / RNGN45 T2A WG SFPM, ” DOC
(260 m/min, 0,1 1,78 mm DOC)
P20 Tool 55 Hr/c
WG-300 whiskered aluminum oxide ceramic is the strongest grade of ceramic offered by Greenleaf. It is the first choice for the machining of heat resist aerospace alloys.

23. Selecting Ceramic Grades
Chip Thinning
Programmed feed per tooth is affected by chip thinning in two directions.
Radial Chip Thinning - Width of Cut (WOC)
Axial Chip Thinning - Depth of Cut (DOC)
When milling hardened materials, it is important to maintain an acceptable chip thickness. Radial engagement affects average chip thickness. Axial engagement (depth-of-cut) affects average chip thickness when round inserts are employed.
WOC
DOC

24. Selecting Ceramic Grades
Axial Chip Thinning
The lead angle of a round insert is variable based on the depth of cut.
As the depth of cut is reduced the lead angle is increased on a round insert.
This will create a thinner chip, which should be compensated for by increasing the feed rate.

25. Selecting Ceramic Grades
90o Lead
Lead angle
Chip Thinning
Chip thickness is factored by the width & depth of cut, and further reduced by the lead angle.
100 % Chip Load
45o Lead
The lead angle affects a square insert by spreading the chip out over a longer surface.
70 % Chip Load

26. Selecting Ceramic Grades
Width of Cut
Maximum insert life can be achieved with a step-over width of 40 – 60%.
As the width of cut decreases, you should increase feed to maintain acceptable average chip thickness.
Width and depth of cut combined with feed rate control chip thickness.
Chip thinning occurs when radial engagement (width of cut) is less than 50% of the cutter diameter.
WOC

27. Selecting Ceramic Grades Internal and External Circular Interpolation
Average chip thickness at the cutting edge is affected during circular interpolation. Feed velocity is higher at the cutting edge when machining an internal radius, lower when machining an external radius.
Increase Feed
Decrease Feed

28. Selecting Ceramic Grades
The Excelerator Milling flyer has application data & tips for Hard Milling .
Starting Speed, Feed and Depth of Cut are based on material hardness and insert size.

29. Selecting Ceramic Grades Classification of Greenleaf ® Ceramics
Oxide Ceramic
(White) Al2O3
Black
Ceramics
Al2O3 + TiC
Whisker
Reinforced
Ceramic
Sialon
Ceramics
Silicon Nitride
GEM-19
GEM-7
WG-300
WG-600
WG-700
SIALOX
GSN100
Super Alloys
Hardened Steel Machining
Cast Iron Machining

30. Guidelines to Remember
Greenleaf ® ceramic inserts can be used in a variety of high productivity machining in a wide range of materials. The key to success is the proper application of the principles discussed in the WG-300 Application Guide.
1. Use a toolholder system designed for ceramic inserts.
2. Use the strongest insert shape possible.
3. Use the largest corner radius possible.
4. Use the correct edge preparation for the application.
5. Use the thickest inserts available for roughing.
6. Use toolholders and bars with the largest cross section.
7. Consider heavy metal or carbide bars whenever possible.
8. Keep toolholder overhang to a minimum.
10. Rethink the process