Precision grades

ISO 3290

Grade	Ball Dia. Variation (µm)	Deviation from Spherical Form (µm)	Surface Roughness (µm)	Lot Dia. Variation (µm)	Gauge Interval (µm)	Preferred Gauge (µm)	Subgauge Interval (µm)	Subgauge (µm)
G3	0.08	0.08	0.010	0.13	0.5	-5…-0.5 0 +0.5…+5	0.1	-0.2,-0.1, 0, +0.1,+0.2
G5	0.13	0.13	0.014	0.25	1	-5…-1 0 +1…+5	0.2	-0.4,-0.2, 0, +0.2,+0.4
G10	0.25	0.25	0.020	0.5	1	-9…-1 0 +1…+9	0.2	-0.4,-0.2, 0, +0.2,+0.4
G16	0.4	0.4	0.025	0.8	2	-10…-2 0 +2…+10	0.4	-0.8,-0.4 0, +0.4,+0.8
G20	0.5	0.5	0.032	1	2	-10…-2 0 +2…+10	0.4	-0.8,-0.4 0, +0.4,+0.8
G24	0.6	0.6	0.040	1.2	2	-12…-2 0 +2…+12	0.4	-0.8,-0.4 0, +0.4,+0.8
G28	0.7	0.7	0.050	1.4	2	-12…-2 0 +2…+12	0.4	-0.8,-0.4 0, +0.4,+0.8
G40	1	1	0.060	2	4	-16…-4 0 +4…+16	0.8	-1.6,-0.8, 0, +0.8,+1.6
G60	1.5	1.5	0.080	3	6	-18…-6 0 +6…+18	1.2	-2.4,-1.2, 0. +1.2,+2.4
G100	2.5	2.5	0.100	5	10	-40…-10 0 +10…+40	2	-4,-2, 0, +2,+4
G200	5	5	0.150	10	15	-60…-15 0 +15…+60	3	-6,-3, 0, +3,+6

	Dw			VDws	tDw	Ra5)	VDwL	VDwA	IG;ST
Grade	Nominal Ball Diameter		Gauge Allowance	µm Max.	µm Max.	µm Max.	µm Max.	µm Max.	µm Max.	Mean Allowances in Each Grade (µm)
G3	–	12,7	± 5,32	0,08	0,08	0,010	0,13	–	0,5	-5 .. .-0.5	0	+0.5 … +5
G5	–	12,7	± 5,63	0,13	0,13	0,014	0,25	–	1	-5 … -1	0	+1 … +5
G10	–	25,4	± 9,75	0,25	0,25	0,020	0,5	–	1	-9 … -1	0	+1 … +9
G16	–	25,4	± 11,4	0,4	0,4	0,025	0,8	–	2	-10 … -2	0	+2 … +10
G20	–	38,1	± 11,5	0,5	0,5	0,032	1	–	2	-10 … -2	0	+2 … +10
G28	–	50,8	± 13,7	0,7	0,7	0,050	1,4	–	2	-12 … -2	0	+2 … +12
G40	–	100	± 19	1	1	0,060	2	–	4	-16 … -4	0	+4 … +16
G80	–	100	± 14	2	2	0,1	–	4,0	4	-12 … -4	0	+4 … +12
G100	–	150	± 47,5	2,5	2,5	0,1	5	–	10	-40 … -10	0	+10 … +40
G200	–	150	± 72,5	5	5	0,15	10	–	10	-60 … -10	0	+10 … +60
G300	–	25,4	± 70	10	10	0,2	–	20	20	-60 … -20	0	+20 … +60
G300	25,4	50,8	± 105	15	15	0,2	–	30	30	-90 … -30	0	+ 30 … +90
G300	50,8	75	± 140	20	20	0,2	–	40	40	-120 … -40	0	+40 … +120
G500	–	25,4	± 75	25	25	–	–	50	50	-50	0	+50
G500	25,4	50,8	± 112,5	25	25	–	–	75	75	-75	0	+75
G500	50,8	75	± 150	25	25	–	–	100	100	-100	0	+100
G500	75	100	± 187,5	32	32	–	–	125	125	-125	0	+125
G500	100	125	± 225	38	38	–	–	150	150	-150	0	+150
G500	125	150	± 262,5	44	44	–	–	175	175	-175	0	+175
G600	all		± 200	–	–	–	–	400	–	–	0	–
G700	all		± 1000	–	–	–	–	2000	–	–	0	–

Dw	Nominal ball diameter
Dws	Single diameter of a ball
Dwm	Mean diameter of a ball
VDws	Ball diameter variation
VDwl	Lot diameter variation
Ra	Surface roughness
∆S	Deviation from ball gauge
tDw	Deviation from spherical form (roundness)
IG	Sorting gauges

Tolerances by Grade for Individual Balls				Tolerances by Grade for Lots of Balls
	VDws	∆Rw	Ra	VDwt		∆S
Ball Grade	Allowable Ball Dia. Variation	Allowable Deviation from Spherical Form	Maximum Surface Roughness Arithmetic Average	Allowable Lot Dia. Variation	Nominal Ball Diameter Tolerance	Allowable Ball Gauge Deviation High Low	Container Marking Increment
INCH
3	.000003	.000003	0.5	.000005	*	+.000030 -.000030	.000010
5	.000005	.000005	0.8	.000010	*	+.000050 -.000030	.000010
10	.000010	.000010	1	.000020	*	+.000050 -.000040	.000010
16	.000016	.000016	1	.000032	*	+.000050 -.000040	.000010
24	.000024	.000024	2	.000048	*	+.0001 -.0001	.000010
48	.000048	.000048	3	.000096	*	*	.00005
100	.0001	.0001	5	.0002	±.0005	*	*
200	.0002	.0002	8	.0004	±.001	*	*
500	.0005	.0005	*	.001	±.002	*	*
1000	.001	.001	*	.002	±.005	*	*
METRIC µm
3	0.08	0.08	0.012	0.13	*	+0.75 -0.75	0.25
5	0.13	0.13	0.02	0.25	*	+1.25 -1	0.25
10	0.25	0.25	0.025	0.5	*	+1.25 -1	0.25
16	0.4	0.4	0.025	0.8	*	+1.25 – 1	0.25
24	0.6	0.6	0.05	1.2	*	+2.5 -2.5	0.25
48	1.2	1.2	0.08	2.4	*	*	1.25
100	2.5	2.5	0.125	5	±12.5	*	*
200	5	5	0.2	10	±25	*	*
500	13	13	*	25	±50	*	*
1000	25	25	*