SFERE DI PRECISIONE

NOMINAL DIAMETER		NUMBER OF BALLS PER KG.	MINIMUM CRUSHING LOAD IN N
inch	mm
	1.50	72200
1/16	1.5875	68840
	2.00	30500
3/32	2.3812	18055
	2.50	15600
7/64	2.7781	11730
	3.00	9030
1/8	3.175	7628	5390
	3.50	5690	6370
5/32	3.9688	3902	8430
	4.00	3810	8530
	4.50	2680	10600
3/16	4.7625	2249	12100
	5.00	1950	13000
7/32	5.5562	1422	16300
	6.00	1130	18800
1/4	6.350	952	21300
9/32	7.1438	668	27000
5/16	7.9375	487	32900
11/32	8.7312	336	39700
3/8	9.5250	282	47100
	10.00	244	52100
13/32	10.3188	223	55000
7/16	11.1125	178	63800
15/32	11.9062	144	73500
	12.00	141	76200
1/2	12.70	119	83400
17/32	13.4937	99	94100
9/16	14.2875	83.55	105000
	15.00	72.20	116000
19/32	15.0812	71	117000
5/8	15.8750	60.84	129000
	16.00	59.5	131000
21/32	16.6687	52.68	142000
11/16	17.4625	45.85	155000
3/4	19.050	35.27	183000
25/32	19.8438	31.30	199000
	20.00	30.50	200000
13/16	20.6375	27.77	215000
15/15	23.8125	18.05	281000
	25.00	15.60	306000
1	25.400	14.88	319000

I.S.O. 3290 standard G.B. 308 form and surface roughness tollerance

GRADE	BALL DIAMETER VARIATION	DEVIATION FROM SPHERICAL FORM MAX VALUES IN MICROMETRES	SURFACE ROUGHNESS
3	0,08	0,08	0,012
5	0,13	0,13	0,02
10	0,25	0,25	0,025
16	0,4	0,4	0,032
20	0,5	0,5	0,04
28	0,7	0,7	0,05
40	1	1	0,08
100	2,5	2,5	0,125
200	5	5	0,2

Sorting tolerances and gauges

Grade	Lot diameter variation	Gauge	Preferred gauges	Subgauge interval values in micrometer	subgauges
3	0,13	0,5	-5 ~ -0,5 ~ 0 ~ +0,5 ~ +5	0,1	-0,2 ~ -0,1 ~ 0 ~ +0,1 ~ +0,2
5	0,25	1	5 ~ -1 ~ 0 ~ +1 ~ +5	0,2	-0,4 ~ 0,2 ~ 0 ~ +0,2 ~ +0,4
10	0,5	1	-9 ~ -0,5 ~ 0 ~ +0,5 ~ +9	0,2	-0,2 ~ -0,1 ~ 0 ~ +0,1 ~ +0,2
16	0,8	2	-10 ~ -2 ~ 0 ~ +2 ~ +10	0,4	-0,8 ~ -0,4 ~ 0 ~ +0,4 ~ +0,8
20	1	2	-10 ~ - 2 ~ 0 ~ +2 ~ +10	0,4	-0,8 ~ -0,4 ~ 0 ~ +0,4 ~ +0,8
28	1,4	2	-12 ~ - 2 ~ 0 ~ +2 ~ +12	0,4	-0,8 ~ -0,4 ~ 0 ~ +0,4 ~ +0,8
40	2	4	-16 ~ - 4 ~ 0 ~ +4 ~ +16	0,8	-1,6 ~ -0,8 ~ 0 ~ +0,8 ~ +1,6
100	5	10	-40 ~ - 10 ~ 0 ~ +10 ~ +40	2	-4 ~ -2 ~ 0 ~ +2 ~ +4
200	10	15	-60 ~ - 15 ~ 0 ~ +15 ~ +60	3	-6 ~ -3 ~ 0 ~ +3 ~ +6

ANSI / AFBMA - (USA)

Grade	Ball dia. variation μ	Deviation from spherical form μ	Surface roughness μ	Lot dia variation μ	Basic dia. tolerance μ
3	0,08	0,08	0,012	0,13	±0,75
5	0,13	0,13	0,02	0,25	±1,25
10	0,25	0,25	0,025	0,5	±2,5
16	0,4	0,4	0,025	0,8	±2,5
24	0,6	0,6	0,05	1,2	±2,5
48	1,2	1,2	0,08	2,4	±5
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	-	50	±125

DIN 5401 - (Germany)

Class	Nominal dia. mm.	Tolerences μ	Tolerences per group μ	Mean interval of each group μ	Spherical deviation μ
I	10 max	±10,25	0,5	-10 ~ -1,5 -1 -0,5 0 +0,5 +1 +1,5 ~ +10	0,25
II	25 max	±10,50	1	-10 ~ -3 -2 -1 0 +1 +2 +3 ~ +10	0,5
	25 max	±11	2	-10 -8 -6 -4 -2 0 +2 +4 +6 +8 +10	1
	25-50	±13,5	3	12 -9 -6 -3 0 +3 +6 +9 +12	1,5
	50-75	±14	4	-12 -8 -4 0 +4 +8 +12	2
III	75-100	±17,5	5	-15 -10 -5 0 +5 +10 +15	2,5
	100-125	±21	6	-18 -12 -6 0 +6 +12 +18	3
	125-150	±24,5	7	-21 -14 -7 0 +7 +14 +21	3,5
IV	10 max	±14	4	-12 -8 -4 0 +4 +8 +12	2
	25 max	±75	50	-50 0 +150	25
	25-50	±113	75	-75 0 +75	38
	50-75	±150	100	-100 0 +100	50
V	75-100	±188	125	-125 0 +125	63
	100-125	±225	150	-150 0 +150	75
	125-150	±263	175	-175 0 +175	88
VI		±200	±400
A	B	C*	D*	E*	F*

For Class III: Multiply Values Given in Columns C, D, E, F, AS follows:
By 5 for annealed chrome steel balls Aisi 52100
By 5 for unhardened or annealed stainless steel balls
By 2 for hardened stainless steel balls
By 10 for bronze or copper balls

DEFINITIONS. The following definitions will apply to terms used in these standards.

Nominal Ball Diameter. The diameter value that is used for the purpose of general identification of a ball size; e.g., 1/4”, 6mm, etc.

Single Diameter of a Ball. The distance between two parallel planes tangent to the surface of the ball.

Mean Diameter of a Ball. The arithmetic mean of the largest and the smallest actual single diameters of the ball.

Ball Diameter Variation. The difference between the largest and the smallest actual single diameters of one ball.

Deviation from Spherical Form. The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.

Lot. A definite quantity of balls manufactured under conditions which are presumed uniform and which is considered and identified as an entity.

Lot Mean Diameter. The arithmetic mean of the mean diameter of the largest ball and that of the smallest ball in the lot.

Lot Diameter Variation. The difference between the mean diameter of the largest ball and thet of the smallest ball in the lot.

Nominal Ball Diameter Tolerance. The maximum allowable deviation of any ball lot mean diameter from the Nominal Ball Diameter.

Specific Diameter. The amount by which the lot mean diameter differs from the nominal diameter, accurate to the marking increment for that grade.

Ball Grade. A specific combination of dimensional form and surface roughness tolerances. A ball grade is designated by a grade number.

Ball Gage. The prescribed small amount by which the lot mean diameter should differ from nominal diameter, this amount being one of an established series of amounts.

Ball Gage Deviation. The difference between the lot mean diameter and the sum of the nominal diameter and the ball gage.

Surface Roughness. Surface roughness consists of all those irregularities which form surface relief and which are conventionally defined within the area where deviations of form
and waviness are eliminated.

Waviness. The more widely spaced circumferential component of surface texture.

Hardness. The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specific indenting shape as determined by specified methods.

Case Depth. The distance measured radially from the surface of the ball to a point where the hardness becomes the equivalent to Rc 50. This term is applicable to case hardened balls only.

Passivation. A chemical treatment to remove corrodible surface impurities and to provide a protective film. This term is applicable to corrosion resisting balls only.