Precision Steel Balls
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
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. |
Hardness values are typical reference ranges. Final hardness, material grade, tolerance class, and documentation requirements should be confirmed on quote.
Bearing Balls
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 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. |
Values are nominal industry references. Confirm exact tolerance class, surface finish, dimensional variation, and inspection requirements during quote review.
Size Range and Availability
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.
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.
For the fastest response, include material grade, nominal diameter, ABMA or ISO grade, quantity, application, and any certificate or inspection requirements.
Applications by Industry
Steel ball selection depends on load, corrosion exposure, contact stress, required precision, documentation requirements, and the operating environment.
Typical grade: AISI 52100 chrome steel, Grade 10-25.
Used in ABS sensors, wheel bearings, suspension components, transmission bearings, and fuel-system check valves.
Typical grade: AISI 52100 or 440C stainless, Grade 5-25.
Used in ball bearings, thrust bearings, linear bearings, and precision instrument bearings.
Typical grade: AISI 304, 316, or 440C stainless, Grade 10-50.
Used in surgical instruments, drug delivery devices, dental tools, and medical pumps.
Typical grade: AISI 52100, 316, or 440C, Grade 25-100.
Used in ball valves, check valves, pressure relief valves, and hydraulic systems.
Typical grade: AISI 304 or 316 stainless, Grade 25-100.
Used in food-grade conveyors, sanitary valves, beverage equipment, and packaging machinery.
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
STR Industries supports steel ball orders with documentation for material, dimensional inspection, conformance, heat treatment, and automotive supply requirements when specified on the RFQ.
Include documentation requirements on the RFQ so they are quoted with the correct inspection and traceability scope.
How to Specify a Steel Ball
The more complete the specification, the faster STR Industries can confirm the material, tolerance, lead time, and pricing.
Specify carbon, chrome, or stainless steel based on load, corrosion exposure, temperature, hardness, and operating environment.
Confirm metric or inch dimensions and provide the nominal ball diameter.
Call out ABMA grade, ISO grade, sphericity, diameter variation, surface finish, or a drawing requirement.
Quantity affects pricing tier, inventory availability, production planning, and lead time.
List CoC, MTR, dimensional inspection, RoHS, REACH, PPAP, or customer-specific documentation needs.
Include bearing, valve, medical, automotive, food processing, grinding, or other use-case details so the quote matches the operating environment.
Not sure which grade you need? Send a drawing, datasheet, part number, or application details and STR Industries will review the requirement.
Request a Quote
Upload your drawing, datasheet, part number, or written specification. Include material grade, diameter, tolerance class, quantity, application, and documentation requirements.
FAQ
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.
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.
Yes. STR Industries can support steel ball specifications that reference ISO 3290 tolerance requirements. Include the ISO grade or drawing requirement on the RFQ.
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.
Minimum order quantity varies by diameter, material grade, tolerance class, inventory status, and production requirement. MOQ is confirmed on the quote.
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.
Yes. STR Industries can review intermediate or custom tolerance requirements. Specify sphericity, diameter variation, surface finish, or include a drawing with the RFQ.
Yes. Submit the competitor part number along with the drawing, specification, or application details. STR Industries can review material, tolerance, finish, and documentation equivalency.
