Rappold Winterthur - Diamond / CBN - Resin bonded - Marking of Vitrified CBN and daimond grinding wheels

It is general practice in the grinding wheel industry that vitrified CBN and diamond grinding wheels are marked with manufacturer specific designations, often quite unintelligible for the user. In order to make the marking and designations on grinding wheels more transparent and comprehensible for the user, two typical Winterthur specifications, one of CBN and one of diamond, are “decoded” and explained in detail:

CBN Grain

4B	126	R	100	BX506	BA	/K	50m/s
WST

WST	Coating	Grain size	Properties	Application
4B	Ni	46 - 252	mono-crystalline, blocky grain, free-cutting, friable	universal application for low to high loads
5B	Ni	46 - 252	mono-cristalline, medium to high grain stability and resistance to temerature	medium to high loads, creepfeed grinding and high material removal rates
9B	Ni	15 - 40	Blocky grain	lapping, high surface finishes on ferrous materials
8B	none	3 - 40	Blocky grain	lapping, high surface finishes on ferrous materials

Diamond

77D	126	R	100	B52	BA	/K	50m/s
WST

WST	Coating	Grain size	Properties	Application
77D	Ni	46 - 251	Micro-fracturing good bond anchoring	general grinding tasks
78D	Cu	46 - 251	excellent dry grinding properties, high mechanical stability	general dry grinding tasks
79D	Ni	46 - 181	high friable	grinding of composite tungsten carbides with 30% steel, large contact areas as in centerless grinding
80D	Ni	46 - 181	high friable	free-cutting grain for tungsten carbides and ceramic materials (on weak machine tools)
90D	Ni	46 - 181	extremly friable	free-cutting grain for tungsten carbides and ceramic materials (on weak machine tools)
81D	Ni	1 - 126	very tough, blocky grain	polishing and lapping of tungsten carbides and ceramic materials
82D	Ni	20 - 30	very tough, blocky grain with excellent bond anchoring properties	polishing and lapping of tungsten carbides and ceramic materials
84D	none	2 - 40	blocky, friable grain	polishing and lapping of tungsten carbides and ceramic materials
85D	Ni	20 - 30	blocky friable grain with excellent bond anchoring properties	polishing and lapping of tungsten carbides and ceramic materials

CBN grain size

4B	126	/2	R	100	BX506	BA	/K	50m/s
	Fepa grain

FEPA grain size in um		US grain in mesh
narrow	wide	narrow	wide
251	252	60/70	60/80
213		70/80
181		80/100
151		100/120
126		120/140
107		140/170
91		170/200
76		200/230
64		230/270
54		270/325
46		325/400
40		600
30		700
25		800
20		1100
15		1200
9		1800
7		3000
5		5000
3		8000
2		12000
1		14000

4B	126	/2	R	100	BX506	BA	/K	50m/s
		1 2 3 4 5 6

Designating number of grain combinations

In Europe, grain sizes of CBN and diamond are given as a statistical average in mm. For example, grain size B126 means that the average statistical grain diameter measures 0.126 mm (0.005 inch). The US system for sizing superabrasives is the same as for conventional abrasives such as aluminium oxide and silicon carbide and is given in mesh. Mesh sizes refer to the number of openings per linear inch on bronze sieves or silk screen cloth.

Surface finish in relation to grain size
The achievable surface finish is not only a function of grain size selection but also depends on the material to be machined, the dressing conditions, depth of cut and other machining parameters, and on the grinding fluid in use.

Hardness

4B	126	R	100	BX506	BA	/K	50m/s
		Hardness

Hardness	Application
R	universal, dry and wet grinding
N	dry grinding only

Concentration

4B	126	R	100	BX506	BA	/K	50m/s
			Designation

Designation	Carat/cm3	Volume%	Concentration
25 50	1.1 2.2	6.25 12.5	Low
75 100	3.3 4.4	18.8 25	Standard
125 150	5.5 6.6	31.25 37	High
175 200	7.7 8.8	43.8 50	Highest concentration

CBN Bond

4B	126	R	100	BX506	BA	/K	50m/s
				Bond

Bond	Hardness	Conc.	Usage	Application
B180	harder	50-125	S/O	narrow rim sections, creepfeed, saw sharpening
B190	standard	50-125	S/O	narrow rim sections, creepfeed, saw sharpening
B195	softer	50-125	S/O	narrow rim sections, creepfeed, saw sharpening
BX10		50-150	S/O	indexable inserts
BTX20		50-150	S/O	indexable inserts
B55C		50-150	S/O	saw tooth grinding into solid blanks
B57		50-100	S/O	OD cylindrical grinding, small contact areas
B55		50-100	S/O	OD cylindrical grinding, small contact areas
BX508		50-125	S/O/D	creepfeed grinding, excellent edge holding properties
BX507		50-125	S/O/D	creepfeed grinding, excellent edge holding properties
BX506		50-125	S/O/D	creepfeed grinding, excellent edge holding properties
BX50	standard	50-125	S/O/D	general applications
BX761		50-125	S/O/D	general applications for large contact areas
BX80		50-125	S/O/D	surface grinding
BX90		50-125	S/O/D	tool grinding, rim thickness > 3 mm
BX90S		50-125	S/O/D	tool grinding, rim thickness > 3 mm
BX97		50-100	S/O/D	surface and cylindrical frinding (fine finishing)
B250	standard	50-100	S/O/D	surface and cylindrical frinding (fine finishing)

S = soluble oil, O = neat oil, D = dry

Diamond Bond

77B	126	R	100	B52	BA	/K	50m/s
				Bond

Bond	Hardness	Conc.	Usage	Application
B180	harder	50-125	S/O	narrow rim sections, creepfeed, saw sharpening
B190	standard	50-125	S/O	narrow rim sections, creepfeed, saw sharpening
B195	softer	50-125	S/O	narrow rim sections, creepfeed, saw sharpening
BX10		50-150	S/O	tungsten carbide indexable inserts
BTX20		50-150	S/O	tungsten indexable inserts
B841		50-150	S/O	tool grinding, creepfeed, excellent edge retention properties
B84		50-150	S/O	tool grinding, creepfeed
B82		50-100	S/O	saw sharpening, general cutting tool grinding, fluteand plunge grinding
B64		50-100	S/O	production grinding with coarse grit sizes and high concentrations, suitable for steel - carbide compound materials
B53		50-125	S/O/D	high volume production tool grinding
B523		50-125	S/O/D	general grinding and sharpening tasks (slightly harder than B53)
B522		50-125	S/O/D	general grinding applications, free-cutting with good profile holding properties
B52	standard	50-125	S/O/D	general all purpose application
B52N		50-125	S/O/D	general grinding tasks, acts softer than B52
B521		50-125	S/O/D	general grinding tasks for large contact areas, acts soft and free cutting
B56		50-125	S/O/D	standard bond for micro grit specifications, for large contact areas and rim section > 3mm
B95		50-125	S/O/D	soft acting bond for micro grit specifications
B250	standard	50-100	S/O/D	fine finishing and polishing

S = soluble oil, O = neat oil, D = dry

Suffix

4B	126	R	100	BX506	BA /K	50m/s
					Suffix

Suffix	Material	Properties
/A	aluminium	high strength and rigidity
/BA	pressed compound made of powdered resin, copper and aluminium	medium strength, some vibration dampening, body partially self-wearing during grinding
/BC	pressed compound made of powdered resin, copper and aluminium	medium strength, some vibration dampening, body partially self-wearing during grinding, excellent heat removal capcity
/B	resin	low strength (brittle), excellent vibration dampening and self-wearing of body; risk of cracking at high temeperatures
/BS	graphite	medium strength, good to excellent vibration dampening, superior self-wearing of body
/E	steel	high strength, used for small and narrow rim sections for cutting-off and creepfeed operations
/K		dampening element made of plastic
/KP		polypropylene dampening element in main wheel body
/H	tungsten carbide
/De	heavy metal

Wheel peripheral (surface) speed

4B	126	R	100	BX506	BA / K	50m/s
						Vc (m/s)

Vc (m/s)	Approval	Colour mode
40	Not required	Not applicable
50 63	Clarify whether machine is considered open or fully enclosed	blue / yellow /
80 100 125	Only for fully enclosed machines	red / green / green/blue //