Precision Steel Balls
Precision Steel Balls for Bearings, Valves, and Industrial Assemblies
STR Industries supplies carbon steel, chrome steel, and stainless steel balls in standard and custom specifications for OEM, engineering, procurement, and industrial supply requirements.
Steel Grade Selector
Compare Carbon, Chrome, and Stainless Steel Ball Grades
Select a steel ball material based on hardness, corrosion exposure, magnetic properties, wear requirements, and the operating environment.
| Material Grade | Type | Typical Hardness | Best For |
|---|---|---|---|
| AISI 1008 / 1010 / 1015 | Low-carbon steel | 60-65 HRC, case-hardened | Cost-sensitive bearing, slider, and general industrial applications. |
| AISI 1045 / 1050 | Medium-carbon steel | 60-65 HRC | General industrial ball components requiring moderate wear resistance. |
| AISI 1065 / 1085 | High-carbon steel | 60-66 HRC | High-wear bearing applications, rolling contact, and hardened industrial uses. |
| AISI 52100 | Chrome alloy steel | 60-67 HRC | Precision bearings, ball valves, dental instruments, medical instruments, and motion components. |
| AISI 302 Stainless | Austenitic stainless | 25-35 HRC | Corrosion-resistant and generally non-magnetic applications. |
| AISI 304 Stainless | Austenitic stainless | 25-35 HRC | Food-grade, pharmaceutical, sanitary, and corrosion-resistant applications. |
| AISI 316 Stainless | Austenitic stainless | 25-35 HRC | Marine, chemical, high-corrosion, and washdown environments. |
| AISI 420 Stainless | Martensitic stainless | 50-58 HRC | Hardened corrosion-resistant applications requiring stronger wear performance. |
| AISI 440C Stainless | Martensitic stainless | 58-62 HRC | High-load bearings and corrosion-resistant rolling applications. |
Bearing Balls
Steel Bearing Balls for Rolling, Linear, and Precision Motion
Bearing balls require repeatable diameter control, surface finish, sphericity, hardness, and traceability. STR Industries supplies bearing balls for radial bearings, thrust bearings, linear bearings, precision instruments, wheel assemblies, and motion-control applications.
Common bearing ball materials include AISI 52100 chrome steel for high-hardness bearing performance and AISI 440C stainless steel where corrosion resistance is required.
Tolerance Grades and Standards
Steel Ball Tolerances for Precision and Industrial Applications
Steel balls may be specified by ABMA, ANSI/ABMA, ISO 3290, DIN 5401, or ASTM F2215 references depending on the application, material, and tolerance requirement.
| Grade | Sphericity | Diameter Variation | Surface Roughness Ra | Typical Application |
|---|---|---|---|---|
| Grade 3 | 0.08 µm | 0.13 µm | 0.012 µm | Aerospace and precision instrument bearings. |
| Grade 5 | 0.13 µm | 0.25 µm | 0.020 µm | Critical precision bearings. |
| Grade 10 | 0.25 µm | 0.50 µm | 0.025 µm | Precision automotive bearings. |
| Grade 25 | 0.6 µm | 1.3 µm | 0.05 µm | Industrial bearings and ball valves. |
| Grade 50 | 1.3 µm | 2.5 µm | 0.08 µm | Standard industrial applications. |
| Grade 100 | 2.5 µm | 5.0 µm | 0.10 µm | General-purpose applications. |
| Grade 200 | 5.0 µm | 10.0 µm | 0.15 µm | Slider, conveyor, and transfer applications. |
| Grade 1000 | 25 µm | 50 µm | 1.6 µm | Grinding media, blast cleaning, and decorative uses. |
Size Range and Availability
Standard and Custom Steel Ball Diameters
STR Industries supplies steel balls from 0.5 mm through 100 mm diameter in standard inventory grades. Larger diameters and non-standard specifications may be available on custom order.
Quote review confirms whether the requested material, diameter, tolerance grade, and quantity are available from inventory or require a production run.
Common Fractional Diameters
Common Metric Diameters
Stock vs. Custom Run
In-stock steel ball orders may ship faster depending on grade, size, tolerance, and quantity. Custom production runs are quoted with lead time, material grade, tolerance class, documentation, and pricing.
Applications by Industry
Steel Balls Specified Across Bearings, Valves, Automotive Systems, and Medical Devices
Steel ball selection depends on load, corrosion exposure, contact stress, required precision, documentation requirements, and the operating environment.
Automotive
Typical grade: AISI 52100 chrome steel, Grade 10-25.
Used in ABS sensors, wheel bearings, suspension components, transmission bearings, and fuel-system check valves.
Bearings
Typical grade: AISI 52100 or 440C stainless, Grade 5-25.
Used in ball bearings, thrust bearings, linear bearings, and precision instrument bearings.
Medical & Pharmaceutical
Typical grade: AISI 304, 316, or 440C stainless, Grade 10-50.
Used in surgical instruments, drug delivery devices, dental tools, and medical pumps.
Industrial Valves
Typical grade: AISI 52100, 316, or 440C, Grade 25-100.
Used in ball valves, check valves, pressure relief valves, and hydraulic systems.
Food Processing
Typical grade: AISI 304 or 316 stainless, Grade 25-100.
Used in food-grade conveyors, sanitary valves, beverage equipment, and packaging machinery.
Grinding and Finishing
Typical grade: Carbon steel, chrome steel, or stainless steel by application.
Used in grinding media, burnishing media, polishing, deburring, paint, pigment, and chemical processing applications.
Certifications and Documentation
Quality Documentation for Engineering and Procurement Requirements
STR Industries supports steel ball orders with documentation for material, dimensional inspection, conformance, heat treatment, and automotive supply requirements when specified on the RFQ.
Documentation Available on Request
- Certificate of Conformance
- Material Test Report / Mill Certificate
- Dimensional Inspection Report
- Heat Treatment Certificate, where applicable
- PPAP Level 1-5 documentation for automotive customers
- Lot traceability documentation
How to Specify a Steel Ball
Send the Right Details for a Faster Steel Ball Quote
The more complete the specification, the faster STR Industries can confirm the material, tolerance, lead time, and pricing.
1. Material Grade
Specify carbon, chrome, or stainless steel based on load, corrosion exposure, temperature, hardness, and operating environment.
2. Diameter
Confirm metric or inch dimensions and provide the nominal ball diameter.
3. Tolerance Class
Call out ABMA grade, ISO grade, sphericity, diameter variation, surface finish, or a drawing requirement.
4. Quantity
Quantity affects pricing tier, inventory availability, production planning, and lead time.
5. Certification Requirements
List CoC, MTR, dimensional inspection, RoHS, REACH, PPAP, or customer-specific documentation needs.
6. Application Details
Include bearing, valve, medical, automotive, food processing, grinding, or other use-case details so the quote matches the operating environment.
Request a Quote
Request a Steel Ball Quote
Upload your drawing, datasheet, part number, or written specification. Include material grade, diameter, tolerance class, quantity, application, and documentation requirements.
Request for Quote
FAQ
Precision Steel Ball Questions
What is the difference between AISI 52100 chrome steel and AISI 440C stainless?
AISI 52100 is a chrome alloy bearing steel with excellent hardness and wear life, but it does not provide the same corrosion resistance as stainless steel. AISI 440C is a martensitic stainless steel with high hardness and better corrosion resistance, making it a common choice for bearings exposed to moisture or chemicals.
What does ABMA Grade 10 mean?
ABMA Grade 10 refers to a precision steel ball tolerance class with tight control over sphericity, diameter variation, and surface finish. It is commonly used for precision automotive and bearing applications.
Can STR Industries supply balls to ISO 3290 specification?
Yes. STR Industries can support steel ball specifications that reference ISO 3290 tolerance requirements. Include the ISO grade or drawing requirement on the RFQ.
Are PPAP submissions available for automotive customers?
Yes. PPAP documentation may be available for automotive steel ball orders when specified during quote review. Include PPAP level and customer-specific requirements on the RFQ.
What is the minimum order quantity for steel balls?
Minimum order quantity varies by diameter, material grade, tolerance class, inventory status, and production requirement. MOQ is confirmed on the quote.
What is the standard lead time for a steel ball order?
Lead time depends on whether the requested grade and size are in inventory or require a production run. Lead time is confirmed with the quote based on material, quantity, tolerance, and documentation requirements.
Does STR Industries supply balls in non-standard intermediate tolerance grades?
Yes. STR Industries can review intermediate or custom tolerance requirements. Specify sphericity, diameter variation, surface finish, or include a drawing with the RFQ.
Can STR Industries match a competitor part number?
Yes. Submit the competitor part number along with the drawing, specification, or application details. STR Industries can review material, tolerance, finish, and documentation equivalency.
Get a Steel Ball Quote With Material, Tolerance, and Lead Time Confirmed
Upload your drawing or send your specification. STR Industries will review the grade, diameter, tolerance class, documentation needs, quantity, and application.
Request a Steel Ball Quote