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Tel: 860-571-3602  |

FAQ – Precision Balls

Q: What gives chrome balls better performance properties than plain carbon steel?

A: Chrome balls contain greater percentages of key alloying metals, including chromium, silicon and manganese. Chromium contributes toughness, and helps resist wear, corrosion and discoloration; silicon and manganese both increase strength.

Q: Where are precision miniature balls used?

A: Precision miniature balls are those under 1/8 inch (3 mm) in diameter. Precision miniature balls are commonly used in medical, dental and optical instruments, miniature bearings, ball screws and pumps. Material options include chrome steel, stainless steel, tungsten carbide, plastic and glass.

Q: What are the best options for stainless steel bearing balls?
A: Our page on stainless steel bearing balls can help you decide.

Q: What are some good criteria for deciding whether a ball or roller is best for a given rolling motion application?
A: There are several factors to consider – here’s how balls and rollers compare on that basis:

Ball bearings are typically lower cost than an equivalent sized roller bearing.

Rollers support more load than balls. Rollers offer a theoretical line of contact, while balls provide a theoretical point of contact.

Type of load
Balls can provide both radial and axial load carrying capacity. Cylindrical rollers are designed for radial loads (although there are other types of rollers that can support both axial and radial loads).

Ball bearings are typically used for the highest speed applications.

In some applications where space is very limited, it may be easier to design with balls as the rolling element.

Q: What are the main differences between 300 and 400 series stainless steel balls?
A: 300 series “austenitic” stainless steel balls contain chromium and nickel and are non-magnetic. They have better corrosion resistance than 400 series, (in fact, the highest corrosion resistance of the stainless group). They are less brittle, and can be hardened by cold working. A 400 series stainless steel ball is “straight chromium.” It contains more carbon to make it magnetic, and offers less corrosion protection than 300 series. “Martensitic” can be readily heat treated to increase hardness, making it more brittle. Martensitic grades are specified for applications that demand strength, hardness and wear resistance.

Q: What standards does Hartford adhere to for ball manufacturing?
A: Hartford products conform to these major standard industrial specifications for precision balls:

  • ANSI / AFBMA Standard 10 Metal Balls
  • ISO 3290 Rolling Bearings – Balls – Dimensions and Tolerances
  • DIN 5401 Finished Steel Balls for Rolling Bearings
  • ASTM F 2215
  • ASTM F2215
  • ASTM F2215-08
  • ASTM F 2215-08
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