Precision Ball and Gauge

High quality, precison made balls and related products

Call us: +44 (0) 1903 231831

Precision Ball and Gauge Large Ball Bearing

A world leader in the manufacture of high precision and quality balls

and related products

Reputable

We take pride in our reputation for delivering high quality balls and ball products in a wide variety of materials and tolerance grades.

Precision

Our Quality Control department, using state of the art equipment, rigorously measure and check statistically for compliance with our customers' orders and relevant international standards ISO 3290, AFBMA Standard 10, and Din 5401. Certificates of Calibration or Conformance can be supplied, giving you the peace of mind in knowing these really are balls of the finest quality available today.

Availability

With massive stocks of quality balls from 0.4mm to 100.00mm diameters, we are certain to stock your exact requirements. From our highly organised delivery system to our three day turn around on most special production orders (subject to quantity ordered) .... we offer a service rarely matched by our competitors.

Adaptable

Our flexibility combined with extensive experience of ball finishing allows us to tailor our products and production capabilities to meet any requirement for precision balls. Whatever your precision ball needs, we have the ability and desire to deliver the right product, on time, everytime.

Call us on +44 (0) 1903 231831

or email sales@precisionball.co.uk

Ceramic

Alumina, Silicon Nitride, Zirconia

Precision Ball and Gauge - Blue Ball Bearing

Tungsten Carbide

Nickel Binder, Cobalt Binder

Steel

Carbon, Chrome, Stainless

Precision Ball and Gauge - Black Ball Bearing

Other Materials

Titanium, Aluminium, Plastic

...... and ball related products

Ball Ended Plug Gauges

Gauges are available double or single ended with wire-type handles.

Tooling Fixture and Checking Balls

Used to provide locations and position reference for both manufacturing tooling and for metrology.

Balls on Shafts, Stems, or Wires

For handling or identification purposes, having a ball attached to a stem or wire of some form can greatly simplify the use of the ball.

Modified Balls

Half or part balls, balls with through or blind holes, balls with internal threads, or flats. In many instances where a spherical or partially spherical surface is required.

Specialist and bespoke products are not a problem

.... call us with your requirements

Steel Balls are manufactured to a number of international standards produced to meet the needs of Bearing manufacturers. Of these standards, AFBMA 10, ISO 3970, and DIN 5401 are probably the most common. ISO and DIN are well known organisations, AFBMA, the "Anti Friction Bearing Manufacturers Association", is probably less well known, but in relation to ball specifications is probably the most important, and in general terms all major ball standards are based on AFBMA 10. DIN 5401 used to be the exception, but was brought into line with AFBMA 10 in 1993.

The specifications define balls in terms of a series of properties:-

Basic Diameter - The nominal diameter of the ball eg. 10mm
Ball Diameter Variation - The difference between the largest and smallest diameter measured for a single ball.
Ball mean diameter - The arithmetic mean of the maximum and minimum diameters measured for the ball.
Sphericity or Deviation from spherical form.
Lot - Normally a manufacturing batch manufactured under uniform conditions.
Lot Mean Diameter - the arithmetic mean of the smallest and the largest mean ball diameters within the lot.
Lot diameter variation - The difference between the smallest and the largest mean ball diameters within the lot.
Gauge - The deviation of the lot mean diameter from the nominal diameter.
Grade - A number by which the properties of the ball are specified.

Specifications

AFBMA Std 10 - Principle Tolerances

Grade	Basic Diameter Tolerance	Ball Diameter Variation	Deviation From Spherical Form	Surface Roughness R_a	Allowable Lot Diameter Variation
3	± 0.75µm	± 0.08µm	± 0.08µm	0.012µm	± 0.13µm
5	± 1.25µm	± 0.13µm	± 0.13µm	0.02µm	± 0.25µm
10	± 1.25µm	± 0.25µm	± 0.25µm	0.025µm	± 0.50µm
15	± 2.50µm	± 0.38µm	± 0.38µm	0.025µm	± 0.75µm
20	± 2.50µm	± 0.50µm	± 0.50µm	0.05µm	± 1.00µm
25	± 2.50µm	± 0.64µm	± 0.64µm	0.05µm	± 1.25µm
40	± 2.50µm	± 1.00µm	± 1.00µm	0.08µm	± 2.00µm
50	± 5.00µm	± 1.25µm	± 1.25µm	0.08µm	± 2.50µm
100	± 12.50µm	± 2.50µm	± 2.50µm	0.125µm	± 5.00µm
200	± 25.00µm	± 5.00µm	± 5.00µm	0.20µm	± 10.0µm
500	± 50.00µm	± 12.5µm	± 12.5µm	not specified	± 25.0µm
1000	± 125µm	± 25µm	± 25µm	not specified	± 50µm

ISO 3290 - Principle Tolerances

Grade	Basic Diameter Tolerance	Ball Diameter Variation max.	Deviation From Spherical Form max.	Surface Roughness R_a max.	Lot Diameter Variation max.
3	± 0.75µm	± 0.08µm	± 0.08µm	0.012µm	± 0.13µm
5	± 1.25µm	± 0.13µm	± 0.13µm	0.02µm	± 0.25µm
10	± 1.25µm	± 0.25µm	± 0.25µm	0.025µm	± 0.50µm
15	± 2.50µm	± 0.38µm	± 0.38µm	0.025µm	± 0.75µm
20	± 2.50µm	± 0.50µm	± 0.50µm	0.05µm	± 1.00µm
25	± 2.50µm	± 0.64µm	± 0.64µm	0.05µm	± 1.25µm
40	± 2.50µm	± 1.00µm	± 1.00µm	0.08µm	± 2.00µm
50	± 5.00µm	± 1.25µm	± 1.25µm	0.08µm	± 2.50µm
100	± 12.50µm	± 2.50µm	± 2.50µm	0.125µm	± 5.00µm
200	± 25.00µm	± 5.00µm	± 5.00µm	0.20µm	± 10.0µm
500	± 50.00µm	± 12.5µm	± 12.5µm	not specified	± 25.0µm
1000	± 125µm	± 25µm	± 25µm	not specified	± 50µm

DIN 5401 - Part 1 - Principle Tolerances

Grade	Nominal Size in mm		Basic Diameter Tolerance	Deviation from Spherical Form max.	Ball Diameter Variation max.	Surface Roughness R_a max.	Lot Diameter Variation max.
Grade	Over	Up to	Basic Diameter Tolerance	Deviation from Spherical Form max.	Ball Diameter Variation max.	Surface Roughness R_a max.	Lot Diameter Variation max.
G 3	-	12	± 5.32 μm	0.08 μm	0.08 μm	0.010 μm	0.13 μm
G 5	-	12	± 5.63 μm	0.13 μm	0.13 μm	0.014 μm	0.25 μm
G 10	-	25	± 9.75 μm	0.25 μm	0.25 μm	0.020 μm	0.5 μm
G 16	-	25	± 11.4 μm	0.4 μm	0.4 μm	0.025 μm	0.8 μm
G 20	-	30	± 11.5 μm	0.5μm	0.5 μm	0.032 μm	1 μm
G 28	-	50	± 13.7 μm	0.7μm	0.7 μm	0.050 μm	1.4 μm
G 40	-	100	± 19 μm	1 μm	1 μm	0.060 μm	2 μm
G 100	-	150	± 47.5 μm	2.5 μm	2.5 μm	0.125 μm	5 μm
G 200	-	150	± 72.5 μm	5 μm	5 μm	0.200 μm	10 μm
G500	-	25	± 75 μm	25 μm	25 μm	not specified	50 μm
	25	50	± 112.5 μm	25 μm	25 μm	not specified	75 μm
	50	75	± 150 μm	25 μm	25 μm	not specified	100 μm
	75	100	± 187.5 μm	32 μm	32 μm	not specified	125 μm
	100	125	± 225 μm	38 μm	38 μm	not specified	150 μm
	125	125	± 262.5 μm	44 μm	44 μm	not specified	175 μm
G 600	all sizes		± 200 μm	not specified	not specified	not specified	400 μm
G 700	all sizes		±1000 μm	not specified	not specified	not specified	2000 μm

Note:

Previous versions of DIN 5401 used class rather than grade.
In general terms these classes can be represented by current grades as follows:-

Class I - Grade 10
Class II - Grade 20
Class III - Grade 40
Class IV - Grade 100
Class V - Grade 500
Class VI - Grade 600
Class VII - Grade 700

However, in all cases it is important to confirm the suitability of the new specification for the specific application in which it is to be used

Relevance to non bearing applications

All of the Ball Specifications discussed have been developed to cover the requirements of the bearing industry. As a result some aspects of the specifications whilst important to the needs of bearing manufacture have little relevance to other applications.

For example:

A high precision angular contact bearing may contain 40 or more balls. If the bearing is to function correctly with minimum run-out, it is essential that variation in ball size is minimised. For this reason the maximum lot diameter variation is specified as twice the allowable spherical error 0.5µm for grade 10. When the same ball is used singly in a check valve this tight control of size within a lot is unnecessary.

For this reason it is helpful to the requirements of a specific application in terms of the properties required from the ball, and then look for the highest grade that will satisfy them.This approach can avoid the specification of an unnecessarily high grade of ball and by doing so considerably reduce cost.

Chrome Steel

Specifications:	AISI 52100, 100Cr6, 1.3505, SUJ2, EN31B
Material Composition	Carbon (C) 0.98 - 1.1% Chrome (Cr) 1.30 - 1.6% Silicon (Si)0.15 - 0.30% Manganese (Mn) 0.25 - 0.45%
Hardness	58 to 62 HRC
Density	7.82
Corrosion Resistance	No natural resistence to corrosion, prone to rusting in damp atmosphere. Care must be taken to avoid moisture in both use and storage.
Special Properties
Availability	Excellent, Available in a wide range of sizes from 0.5mm to 150mm, although availability is limited for sizes above 75mm.
Applications	Ball Bearings, Valves, Ball Screws
General Information	By far the most used ball material, Chrome steel balls provide the most cost effective solution for the vast majority of applications

Stainless Steel

Specification	AISI 440C
Material Composition	Carbon (C) 0.95 - 1.2% Chrome (Cr) 16.0 - 18.0% Silicon (Si) < 1.00% Manganese < 1.00% Molybdenum <1.00%
Hardness	56 to 60 HRC
Corrosion Resistance	No natural resistence to corrosion, prone to rusting in damp atmosphere. Care must be taken to avoid moisture in both use and storage.
Special Properties	Provides a good combination of corrosion resistance with hardness, at an affordable price
Availability	Good Available in a fair range of sizes from 0.5mm to 50mm, although availability is limited for sizes above 30mm.
Applications	Ball Bearings, Valves, Ball Screws where corrosion resistance is required.
General Information	440C provides very similar mechanical properties to Chrome Steel, combined with good corrosion resistasnce

Specification	AISI 420
Material Composition	Carbon (C) 0.15% min Chrome (Cr) 12.0 - 14.0% Silicon (Si) < 1.00% Manganese < 1.00%
Hardness	52 to 56 HRC
Corrosion Resistance	Provides a good combination of corrosion resistance with hardness. Although not quite as good as 440C it provides a good alternative in most situations.
Availability	Good, Available in a wide range of sizes from 0.5mm to 50mm+. Availability in larger sizes tends to be better than 440C.
Applications	Ball Bearings, Valves, Ball Screws
General Information	A hardenable stainless steel with similar properties to 440C, it provides a less expensive alternative to 440C.

Specification	AISI 316
Material Composition	Carbon (C) <0.08% Chrome (Cr) 16.0 - 18.0% Nickel (Ni) 10.0 - 14.0% Silicon (Si) < 1.00% Manganese < 2.00% Molybdenum 2.00 - 3.00%
Hardness	28 to38 HRC
Corrosion Resistance	Very high corrosion and chemical resistance. Can be supplied with approval for food processing and medical applications.
Availability	Good. Available in a fair range of sizes from 1.0mm to 25mm, but can be produced in almost any required size.
Applications	Ball Bearings, Valves, Ball Screws, Food Processing and Medical applications where the low hardness can be overcome. Body Jewelery.
General Information	An Austenitic stainless steel, 316 provides a high degree of corrosion and chemical resistance. However, its low hardness can provide problems if loadings are high.

Specification	AISI 304
Material Composition	Carbon (C) <0.08% Chrome (Cr) 16.0 - 20.0% Nickel (Ni) 8.0 - 10.50% Silicon (Si) < 1.00% Manganese < 2.00%
Hardness	28 to 38 HRC
Corrosion Resistance	Very high corrosion resistance, although not quite as good as 316. Chemical resistance is also reduced.
Availability	Good, Available in a fair range of sizes from up to approximatley 25mm. As with 316, can be produced in almost any required size.
Applications	Ball Bearings, Valves, Ball Screws where the low hardness is acceptable.
General Information	An Austenitic stainless steel, 304 provides a high degree of corrosion resistance. However, its low hardness can provide problems if loadings are high, and balls are easilydamaged.

Ceramic - Silicon Nitride

Of all the engineering ceramics so far developed, silicon nitride offers by far the best combination of properties for most applications.
Its hardness, combined with toughness allows use in many situations where conventional ball materials fail, or have unacceptably short life.
Its increasing use for high speed bearing applications and resulted in significant cost reduction such that it can now provide a cost effective solution for an ever increasing range of problems.

Types:	Various Types are produced, but for ball production material should be Hot Isostatically Pressed.
Material Composition	Silicon Nitride with either Yttria or Magnesia. Material producers include Toshiba, and Norton Abrasives.
Hardness	Typically 1500 to 1600 Hv5
Corrosion Resistance	Extremely Good Resistance to most chemical environments.
Density:	~3.2
Special Properties	Low mass can significantly reduce forces and inertia in high speed applications. Hardness is retained to above 1100 degrees Celsius. Low wear rates in rolling contact with steel. High toughness.
Availability	Improving, but tends to be available in a small range of sizes.
Applications	Ball Bearings, Valves, Ball Screws, Pumps, Measuring Application, Fuel injection Systems.
General Information	Widely regarded as the most significant of the engineering ceramics, Silicon Nitride is being used in an ever increasing number of applications where it unique combination of hardness, low mass provide significant performance advantages. Cost has decreased significantly over the last 5 years, to the extent that Silicon Nitride is becoming a cost effective option for many applications.

Ceramic - Alumina

Type:	Fused Ceramic
Material Composition	Balls are produced in a number of diferent materials with purities ranging from 98.5% to 99.999%
Hardness	~2400 Hv
Corrosion Resistance	Excellent
Special Properties	Cream or Off White colour
Availability	Limited range of sizes are produced as standard.
Applications	Valves, Pumps, Medical Applications (hip replacement), Measurement and calibration standards
General Information

Type:	Single Crystal
Material Composition	Balls are produced from synthetic Ruby and Saphire.
Hardness	~2400 Hv
Corrosion Resistance	Excellent
Special Properties	Balls are translucent red/pink (ruby) or clear (saphire). Colour of ruby balls can vary from pale pink to dark red. Note: Single Crystal Alumina is bi-refringent.
Availability	Reasonable availability in sizes from 0.35mm up to about 15mm.
Applications	Principle use as contact piont in measuring equiment, transducers, touch probes.
General Information	Single Crystal Alumina are used in significant quantities for stylus applications. For this reason balls are often supplied pre-drilled with blind hole for mounting purposes. It should be noted that when measuring aluminium, alumina is transfered from the component surface to the styli and can reduce the accuracy of measurement.

Ceramic - Zirconia

Specifications:	Various Dependent upon Manufacturer
Hardness	Typically 1200 to 1300 HV
Corrosion Resistance	Generally Inert, although may be effected by some extreme chemical environments.
Special Properties	Balls retain hardness and structural integrity to very high temperatures - ~ 1900#C. Toughness is high although the material has a tendency to porosity, which may degrade performance in high load applications. Modulus of thermal expansion is similar to that of steel allowing design clearances to be maintained after material substitution. Good low temperature performance
Availability	Good - balls are produced in a range of sizes, and can be made to almost any size required.
Applications	Low load Bearings particularly for X-ray applications. Valves, Pumps, Ball Screws
General Information	Zirconia balls are used across a wide range of chemical process aplications, and are extensively used in oil well pumps. They offer long life in arduous environments.

Tungsten Carbide - Cobalt binder

Specifications:	ISO K10 and K20 are most common
Material Composition	Typical Material composition is 6% Cobalt 94% Tungsten Carbide But other compositions are available with Cobalt content up to 25%. Hardness reduces and toughness increases with increasing cobalt content.
Hardness	1500 to 1600 HV
Corrosion Resistance	Cobalt binder material is reasonably resistant to corrosion. The Cobalt binder will corrode in contact with water, but the effect is largely cosmetic in that the balls loose their polished appearance, with little effect on performance. De-ionised water does pose a more severe problem, as it can tend to promote 'leeching' of Cobalt from the binder. Erosion of the binder can be a problem when in contact with abrasive particles as may occur in some valve and pump applications.
Special Properties	Hardness if retained to approx. 800 degrees Celsius. Balls can be brazes to steel stems to allow mounting, or hole may be produced by spark erosion.
Availability	Balls are made in a wide range of sizes from 0.5mm to 50mm and can be made in larger sizes.
Applications	Valves, Pumps, Ball Screws, Measurement Standards, Gauging, Wear Parts.
General Information	Cobalt Binder Tungsten Carbide is in many ways an ideal material for ball production. Its hardness and stiffness allows the production of extremely accurate balls, with very fine control of final size. The material is extremely stable and these properties make Tungsten Carbide Balls and ideal choice for reference standards in metrology. Equally, the same properties make the balls and ideal choice for all applications where wear rates need to be low.

Tungsten Carbide - Nickel binder

Specifications:	Various, dependent upon manufacturer
Material Composition	Typical Marerial composition 8 to 10% Nickel (Ni) 90 to 92% Tungsten Carbide (WC) Some types have Chromium Cardide content to improve corrosion resistence.
Hardness	Typically 1250 to 1350 HV
Corrosion Resistance	Generally good, and considerably improved over Cobalt binder material. Nickel Binder Tungsten Carbide can often be used in a range of chemically agressive environments, where they offer a significant cost/performace advantage.
Special Properties	Corrosion Resistant, Effectively Non magnetic, athough some varieties do exhibit minimal magetic effects. Hardness is retained to approx. 800 degrees Celsius. Balls can be brazed, although special fillers and fluxes may be required.
Availability	Good, Balls are made in a range of standard sizes, but can be made in any size from 0.5mm to 50mm if required.
Applications	Bearings, Valves, Pumps, Spray Guns, Liquid and Paste dispensing equipment.
General Information	Nickel Binder Tungsten Carbide offers an attractive package of properties for a range of common industrial applications. It can be succesfully use in many aggressive environments where it offers performance simmilar to that of ceramics without some of the attendant difficulties, often at a significant cost advantage.

Calibrated Master Ball Sets These high quality ball sets are used extensively in: Standard Laboratories, Inspection Depadments, Tool Rooms and for measuring internal grooves, tapers and setting comparators.
Each individual set can be supplied with or without its own wooden display case and certificate of calibration. These are the ultimate ball sets for total accuracy. l All Ball Sets available in Grade 10 or 25.
l Manufactured in Tungsten Carbide of hardened Stainless Steel. l Supplied in an attractive solid ash case. l Available in Standard sets of 1mm to 25mm in 1mm increments. 1/32 inch to 1 inch To Customer specification l All sets can be supplied with a certificate of Calibration which lists the actual diameter for each balls. l In house (ISO 9002) Certificates supplied with each set. l Certificates traceable to NIST or NAMAS available on request.

Ball Ended Plug Gauges
Gauges are available double or single ended with Wire type handles. Applications:
General Bore Gauging, Checking Radii, Thread and Gear Measurement. Advantages: Gauging is carried using a single ball diameter, and is correct irrespective of gauge alignment allowing rapid in-process checking without the risk of jammed or broken gauges.

Fixture and Checking Balls

Tungsten Carbide and hardened Stainless Steel Balls are widely used to provide locations and position reference for both manufacturing tooling and for metrology. Tungsten carbide has the advantage of high hardness 1500 - 1600 Hv, and a low coeficient of expansion.

Stainless Steel offers the same dimensional accuracy, and has a coefficient of expansion which matches most steels. It does require greater care in handling, but is prefered in some metrology and fixturing applications.

Examples shown are of our standard types, which are available in a range of sizes and configurations.

Additionally, we frequently manufacture to customers drawings and specifications.

Precision Ball and Gauge - composition 1

Custom Made Products Balls on Shafts, Stems, or Wires. For handling or identification purposes, having a ball attached to a stem or wire of some form can greatly simplify the use of the ball. In measurement applications, particularly if a range of similar size balls are used the ability to identify size visible can be of great advantage
Modified Balls Half or part balls, Balls with through or blind holes. Balls with internal threads, or flats. In many instances where a spherical or partially spherical surface is required, manufacture from all ball offers significant advantages in terms of accuracy or cost.
Ballizing Balls Ballizing provides a simple method of producing tightly controlled hole tolerances at very low cost. In practice ball of the appropriate size is pressed through a pre-machined bore causing plastic deformation to occur in the bore wall. Elastic recovery then takes place, and produces the final the final hole size.

The Daily Grind - Perpetual Motion??

Ceramic Balls

Modern Engineering Ceramics are being used in increasing volumes throughout manufacturing industry. They offer a range of interesting and often valuable properties are difficult or indeed impossible to achieve with other materials. The nature of these materials, particularly the combination of hardness and stiffness makes them ideally suited to the production of high precision balls.
Three materials have attracted particular attention for ball manufacture:-

Silicon Nitride
Combining hardness and toughness with low mass, Silicon Nitride offers significant advantages in high speed bearing applications, and for these reasons it is finding increaing application in arduous bearing applications such as machine tool spindles and vacuum pumps. Increasing use and production volumes have dramatically considerably reduced the once astromomic cost of the material so that silicon nitride balls can offer extremely cost effective solutions to common industrial problems.
Alumina (Aluminium Oxide)
Alumina is used in 2 forms for ball production.
- Fused Ceramic
  Alumina balls range in colour from almost white to a creamy yellow colour. The material is very harder, but less tough than either silicon nitride or alumina. Structurally the balls perform well, but are prone to localised surface damage, which ultimtly promotes failure. Alumina balls are wideley used medical applications particularly for replacement hip joints, and in valves and pumps for agressive chemical environments.
- Single Crystal - Synthetic Ruby and Saphire
  Single Crystal alumina is widely use for contact point for measuring equipment, and in this application provides good wear resistance at an effective price. Saphire balls are clear, perhaps with a blue tint, and are far less common than ruby which range in colour from almost clear to dark red, Balls are often supplied with drilled holes for mounting purposes.
Zirconia (Zirconium Oxide)
Zirconia in its partially stabilised form offers a number of useful properties. It can withstand very high temperatures without deterioration, it has a similar rate of thermal expansion to steel, it has a high toughness, and it is relatively inexpensisive. It does have a tendency to porosity, and which can prompt failure in some circumstances, and tends to make it unsuitable for high stress applications, but it is widely used in pumps and valves for agressive environments, and for measurement satndards.

Balls shapes are made in other ceramic materials, usually for very specific applications. Cubic Zirconia balls are used as lenses in some very specialised fibre optic systems, but they are not generally available. Silicon Carbide is interesting for some applications, particularly its "conductive" forms, but its inherently low toughness makes ball production difficult and consequently expensive.

Steel Balls

Off all of the precision balls produced, probably more than 90% are steel, and the bulk of these are chrome steel. The scale of production is such that steel balls provide the most cost effective solution for all applications where their properties are appropriate.

Steel
- Chrome Steel
  (AISI 52100, 100cr6 SUJ2, EN31B, 1.3505)
- Stainless Steel
  - 440C
  - 420
  - 316
  - 304
- Other Steels
  - High Speed Steel
  - Carbon Steel
  - Mild Steel

Tungsten Carbide Balls

Tungsten Carbide or more correctly Cemented Tungsten Carbide is strictly a "cermet" - ceramic metal combination, where particles of ceramic, tungsten carbide, are bonded together in a metal matrix. Originally produced as a cutting tool material - a market which it now dominates, Tungsten Carbide is widely used where hardness and high wear resistance is required. Variation in the binder percentage, and the size of the carbide particles allows fine control over the properties of the material, hardness reducing and toughness increasing with increaing binder content. The binder material also contributes to the overall properties of the material.
The two most common types are:-

Cobalt Binder Tungsten Carbide
By far the most common form of Tungsten Carbide, Cobalt binder material is made in a range of compositions with up to 25% binder. Balls are generally made of material with a 6% binder content. It is suceptible to corrosion of the cobalt binder, particularly in contact with water, and although this rarely results in structural falure it can cause severe degradation of the ball surface.
Nickel Binder Tungsten Carbide
Nickel binder Tungsten Carbide is far less common than cobalt binder material, is not made in same range of composition, and tends to be slightly softer. However. it offers significantly better resitance to corrosion. It is particularly usefull in valve and pump applications, and it performs well in more agressive chemical environments.

Other Materials

Apart from the materials discussed separately, balls are made as standard in a variety of other materials. Some of the more common materials are listed here:-

Stellite (Cobalt Chrome)
Stellite balls are made in a small range of sizes, and are used in a number of specific applications. The material provides a useful combination of properties in that it is metalic, conductive, non magnetic, has good hot hardness and shock resistence and corrosion resistence. Where precision balls are required with combinations of these properties, Stellite often offers the most effective solution.
Titanium
Used for a number of medical applications, body jewelry, and some industrial applications, titanium balls are available in a small range of sizes. The low hardness ~40 HRC, limits the precision to which balls can be made, but where other properties of titanium are necessary they can often be used effectively. Titanium balls can be supplied in medically approved grades, and for decorative applications can be supplied eith coloured surface.
Brass & Bronze
Brass and Bronze balls are made in a good range of sizes, and are often used in gas applications where non sparking materials are specified. They are also used in decorative applications.
Copper
Aluminium
Glass
Plastics
- Nylon
- Delrin
- PTFE (Teflon)
- Phenolic
- BUNA
- Polypropylene
- Rubber

Hardness Conversion Chart

Tensile Strength (N/mm2)	Hardness Vickers	Hardness Brinell*	HRB	HRF	HRC	HRA
770	240	228	98.1	114.3	20.3	60.7
785	245	233			21.3	61.2
800	250	238	99.5	115.1	22.2	61.6
820	255	242			23.1	62.0
835	260	247	(101)		24.0	62.4
850	265	252			25.8	62.7
865	270	257	(102)		25.8	63.1
880	275	261			26.4	63.5
900	208	266	(104)		27.1	63.8
915	285	271			27.8	64.2
930	290	276	(105)		28.5	64.5
950	295	280			29.2	64.8
965	300	285			29.8	65.2
995	310	295			31.0	65.8
1030	320	304			32.2	66.4
1060	330	314			33.3	67.0
1095	340	323			34.4	67.6
1125	350	333			35.5	68.1
1155	360	342			36.6	68.7
1190	370	352			37.7	69.2
1220	380	361			38.8	69.8
1255	390	371			39.8	70.3
1290	400	380			40.8	70.8
1320	410	390			41.8	71.4
1350	420	399			42.7	71.8
1385	430	409			43.6	72.3
1420	440	418			44.5	72.8
1455	450	428			45.3	73.3
1485	460	437			46.1	73.6
1520	470	447			46.9	74.1
1555	480	(456)			47.7	74.5
1595	490	(466)			48.4	74.8
1630	500	(475)			49.1	75.3
1665	510	(485)			49.8	75.7
1700	520	(494)			50.5	76.1
1740	530	(504)			51.1	76.4
1775	540	(513)			51.7	76.7
1810	550	(523)			52.3	77.0
1845	560	(532)			53.0	77.4
1880	570	(542)			53.6	77.8
1920	580	(551)			54.1	78.0
1955	590	(561)			54.7	78.4
1995	600	(570)			55.2	78.6
2030	610	(580)			55.7	78.9
2070	620	(589)			56.3	79.2
2105	630	(599)			56.5	79.5
2145	640	(608)			57.3	79.8
2180	650	(618)			58.7	80.0
	660				58.3	80.3
	670				58.8	80.6
	680				59.2	80.8
	690				59.7	81.1
	700				60.1	81.3
	720				61.0	81.8
	740				61.8	82.2
	760				62.5	82.6
	780				63.3	83.0
	800				64.0	83.4
	820				64.7	83.8
	840				65.3	84.1
	860				65.9	84.4
	880				66.4	84.7
	900				67.0	85.0
	920				67.5	85.3
	940				68.8	85.6

* calculate from HB = 0.95 x HV

Ball Hardness Corrections for Curvatures

Ball Dia	Rockwell 'C' Readings
(mm)	55	56	57	58	59	60	61	62	63	64	65
3.175	6.1	5.7	5.4	5.1	4.8	4.5	4.2	4.0	3.8	3.6	3.4
3.968	5.6	5.3	5.0	4.7	4.4	4.1	3.8	3.6	3.4	3.2	3.0
4.762	5.1	4.7	4.3	4.0	3.8	3.6	3.4	3.2	3.0	2.8	2.5
5.562	4.6	4.3	4.0	3.7	3.5	3.3	3.1	2.9	2.7	2.5	2.3
6.350	4.1	3.8	3.6	3.3	3.1	2.9	2.7	2.5	2.3	2.1	1.8
7.000	3.7	3.4	3.2	3.0	2.8	2.6	2.4	2.2	2.0	1.8	1.6
7.938	3.1	2.9	2.7	2.6	2.4	2.2	2.0	1.9	1.7	1.5	1.3
8.000	3.1	2.9	2.7	2.6	2.4	2.2	2.0	1.9	1.7	1.5	1.3
9.000	2.7	2.5	2.4	2.2	2.0	1.9	1.7	1.5	1.4	1.2	1.1
9.525	2.5	2.3	2.2	2.0	1.9	1.8	1.6	1.4	1.2	1.1	1.0
10.000	2.4	2.2	2.0	1.9	1.8	1.7	1.5	1.3	1.1	1.0	0.9
11.000	2.1	2.0	1.8	1.7	1.6	1.5	1.3	1.1	0.9	0.8	0.7
12.000	1.9	1.7	1.6	1.5	1.4	1.3	1.1	1.0	0.8	0.7	0.6
12.700	1.8	1.7	1.6	1.5	1.4	1.2	1.0	0.9	0.7	0.6	0.5
13.000	1.8	1.7	1.6	1.5	1.4	1.2	1.0	0.9	0.7	0.6	0.5
14.000	1.6	1.5	1.4	1.3	1.2	1.0	0.9	0.8	0.6	0.5	0.4
15.000	1.5	1.4	1.3	1.2	1.1	0.9	0.8	0.7	0.5	0.4	0.3
15.875	1.4	1.3	1.2	1.1	1.0	0.9	0.8	0.7	0.5	0.4	0.3

This table is useful for converting Rockwell 'C' readings taken on ball surfaces to equivalent value applicable to flat surfaces. Hardness readings of balls are affected by the curvature and hardness level of the ball. Because of these factors, corrections are necessarily added to the as-read hardness. For ball sizes and hardness values other than shown, values shall be interpolated.

Material Comparison Chart

Material AISI No.	Equivalents	Hardness HRc	Corrosion Resistance
			Air		Water			Food			Liquor		Dilute Acids				Acids			Alkali
			Industrial Atmosphere	Salt Air	Wet Steam	Domestic Water	Sea Water	Food Products	Fruit and Veg Juices	Dairy Products	Hot Sulphite	Dye	HCL	H2SO4	HNO3	Phosphoric	H2SO4	HNO3	Phosphoric	Ammonia	Alkaline Salts
Low Carbon AISI 1010-16	Wks 1.0010 ASTM A29 EN32	60 min	3	T	4	4	T	T	T	T	T	T	T	T	T	T	S	T	TS	2	3
High Carbon AISI 1065-85	Wks 1.0616 C85 EN8-9	60 min	3	T	4	4	T	T	T	T	T	T	T	T	T	T	S	T	T	2	3
High Carbon Chrome Alloy AISI 52100	Wks 1.3505 100 CR6 EN31	60/67	3	T	4	4	T	T	T	T	T	T	T	T	T	T	T	1	T	3	2
Stainless Steel AISI 440C	Wks 1.4125 X105 CR M017	57/60	2	3	2	2	T	2	2	3	T	4	T	T	T	T	T	T	T	2	3
Stainless Steel AISI 420	Wks 1.3541 X45 CR13 EN56D	52/55	2	4	1	1	T	3	3	2	T	3	T	T	T	T	T	T	T	2	3
Stainless Steel AISI 302/304	Wks 1.4301 X5 CR NI 1810 EN58E	25/39	2	1	1	1	1	1	2	2	1	4	2	2	2	2	2	2	2	1	1
Stainless Steel AISI 316	Wks 1.4401 Z2 CND17.12 EN518J	25/39	2	1	1	1	1	1	1	1	2	4	T	2	1	2	1	1	1	1	2

Numbers indicate order of preference
1 = Excellent
2= Good	T = Will not withstand conditions
3 = Fair	S = Satisfactory only over 75% concentration
4 = Poor

Measurement Conversion

Inch Fractions	Inch Decimals	Metric (mm)	Weight 1000 balls (kg)	Approximate Qty per Litre	Inch Fractions	Inch Decimals	Metric (mm)	Weight 1000 balls (kg)
1/64	.0156	0.397	.00026	-	-	.7480	19.000	27.98
-	.0197	0.500	.00051	-	3/4	.7500	19.050	28.20
1/32	.0312	0.794	.00210	2,100,000	25/32	.7812	19.844	31.87
-	.0394	1.000	.00407	1,210,000	-	.7874	20.000	32.63
3/64	.0469	1.190	.00688	695,000	13/16	.8125	20.637	35.85
-	.0472	1.200	.00704	676,700	-	.8268	21.000	37.77
-	.0590	1.500	.01377	347,000	27/32	.8437	21.431	40.15
1/16	.0625	1.588	.01632	289,000	-	.8661	22.000	43.43
5/64	.0781	1.984	.03187	151,000	7/8	.8750	22.225	44.78
-	.0787	2.000	.0326	146,000	-	.9055	23.000	49.63
3/32	.0937	2.381	.0550	87,000	29/32	.9062	23.019	49.75
-	.0984	2.500	.0638	75,500	15/16	.9375	23.812	55.07
7/64	.1094	2.778	.0875	55,000	-	.9449	24.000	56.39
-	.1181	3.000	.1101	43,000	31/32	.9687	24.606	60.77
1/8	.1250	3.175	.1305	37,000	-	.9842	25.000	63.73
-	.1378	3.500	.1749	27,200	1	1.0000	25.400	66.84
9/64	.1406	3.572	.1859	25,700	-	1.0236	26.000	71.69
5/32	.1562	3.969	.2550	18,700	1.1/16	1.0625	26.987	80.17
-	.1575	4.000	.2610	18,500	-	1.1024	28.000	89.54
11/64	.1719	4.366	.3394	14,300	1.1/8	1.1250	28.575	95.17
-	.1772	4.500	.3716	13,000	-	1.1811	30.000	110.10
3/16	.1875	4.762	.4406	10,700	1.3/16	1.1875	30.162	111.90
-	.1968	5.000	.5099	9,500	1.1/4	1.2500	31.750	130.50
-	.2165	5.500	.6786	7,150	-	1.2598	32.000	133.70
7/32	.2187	5.556	.6996	6,800	1.5/16	1.3125	33.337	151.10
15/64	.2344	5.953	.8605	5,450	-	1.3386	34.000	160.30
-	.2362	6.000	.8810	5,400	1.3/8	1.3750	34.925	173.80
1/4	.2500	6.350	1.044	4,550	-	1.3780	35.000	174.90
-	.2559	6.500	1.120	4,300	-	1.4173	36.000	190.30
17/64	.2656	6.747	1.253	3,800	1.7/16	1.4375	36.512	198.50
-	.2756	7.000	1.399	3,400	-	1.4960	38.000	223.80
9/32	.2812	7.144	1.487	3,250	1.1/2	1.5000	38.100	225.60
-	.2953	7.500	1.721	2,800	1.9/16	1.5625	39.687	255.00
19/64	.2969	7.541	1.749	2,750	-	1.5748	40.000	261.00
5/16	.3125	7.938	2.040	2,350	1.5/8	1.6250	41.275	286.80
-	.3150	8.000	2.088	2,150	1.11/16	1.6875	42.862	321.20
-	.3346	8.500	2.505	1,900	1.3/4	1.7500	44.450	358.20
11/32	.3437	8.731	2.715	1,750	-	1.7716	45.000	371.70
-	.3543	9.000	2.973	1,600	1.13/16	1.8125	46.037	398.00
23/64	.3594	9.128	3.102	1,480	1.7/8	1.8750	47.625	440.60
-	.3740	9.500	3.497	1,350	1.15/16	1.9375	49.212	486.10
3/8	.3750	9.525	3.525	1,300	-	1.9685	50.000	509.90
25/64	.3906	9.922	3.983	1,150	2	2.000	50.800	534.70
-	.3937	10.000	4.079	1,125	2.1/8	2.1250	53.975	641.40
13/32	.4062	10.319	4.481	1,050	-	2.1653	55.000	678.60
-	.4331	11.000	5.429	820	2.1/4	2.2500	57.150	761.30
7/16	.4375	11.112	5.597	810	-	2.3622	60.000	881.00
-	.4528	11.500	6.203	720	2.3/8	2.3750	60.325	895.40
29/64	.4531	11.590	6.219	720	2.1/2	2.5000	63.500	1044.40
15/32	.4687	11.906	6.884	620	-	2.5590	65.000	1120.10
-	.4724	12.000	7.048	615	2.5/8	2.6250	66.675	1209.00
31/64	.4844	12.303	7.596	610	2.3/4	2.7500	69.850	1390.10
1/2	.5000	12.700	8.355	550	-	2.7559	70.000	1484.70
-	.5118	13.000	8.961	490	2.7/8	2.8750	73.025	1588.40
17/32	.5312	13.494	10.02	450	-	2.9528	75.000	1720.70
-	.5512	14.000	11.19	410	3	3.000	76.200	1804.70
9/16	.5625	14.288	11.90	380	3.1/8	3.1250	79.375	2039.80
-	.5905	15.000	13.77	325	-	3.1500	80.000	2088.30
19/32	.5937	15.081	13.99	320	3.1/4	3.2500	82.550	2294.40
5/8	.6250	15.875	16.32	300	-	3.3464	85.000	2530.90
-	.6299	16.000	16.70	275	3.1/2	3.5000	88.900	2865.70
21/32	.6562	16.669	18.89	240	-	3.5433	90.000	2993.40
-	.6693	17.000	20.04	230	-	3.7401	95.000	3521.10
11/16	.6785	17.462	21.72	205	3.3/4	3.7500	95.250	3524.70
-	.7087	18.000	23.79	190	-	3.9370	100.000	4078.80
23/32	27187	18.256	24.82	180	4	4.000	101.600	4277.70

The weights shown are based on Chrome Alloy Steel balls.
Approximate weights for other materials can be obtained by multiplying the weight per 1000 balls by the following figures:-

Carbon Steel	1.004
Stainless Steel AISI 420/440	0.979
Stainless Steel AISI 302/304	1.011
Stainless Steel AISI 316	1.025
Brass	1.074
Tungsten Carbide	1.907

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