Views: 0 Author: Site Editor Publish Time: 2026-10-11 Origin: Site
A 1/4-inch low carbon steel ball is listed at 1,520 kgf in the reference table below. That figure needs some explanation. It is a crushing load—not the weight the ball can safely carry in a drawer slide or caster.
For a buyer, the next question is how that value was established. A load figure without a test method is difficult to compare with another supplier's result, even when the ball diameter is identical.
The catalogue used for this table adopts two-thirds of the crushing load values for chrome steel balls. That is the basis of these figures; it should not be treated as a conversion rule for every low carbon steel ball.
The figures below are catalogue reference values, not RISHENG batch test results or confirmed supply guarantees. Any minimum load used for an order needs an agreed test method and acceptance criteria.
| Ball Size（inch） | Diameter（mm） | Reference Crushing Load（kgf） | Reference Crushing Load（kN） |
| 1/8 | 3.175 | 444 | 4.4 |
| 5/32 | 3.969 | 660 | 6.5 |
| 3/16 | 4.763 | 913 | 9.0 |
| 7/32 | 5.556 | 1,200 | 11.8 |
| 1/4 | 6.350 | 1,520 | 14.9 |
| 9/32 | 7.144 | 1,873 | 18.4 |
| 5/16 | 7.938 | 2,253 | 22.1 |
| 11/32 | 8.731 | 2,667 | 26.2 |
| 3/8 | 9.525 | 3,113 | 30.5 |
| 13/32 | 10.319 | 3,587 | 35.2 |
| 7/16 | 11.113 | 4,093 | 40.1 |
| 15/32 | 11.906 | 4,627 | 45.4 |
| 1/2 | 12.700 | 5,187 | 50.9 |
| 9/16 | 14.288 | 6,393 | 62.7 |
| 5/8 | 15.875 | 7,733 | 75.8 |
| 11/16 | 17.463 | 9,133 | 89.6 |
| 3/4 | 19.050 | 10,667 | 104.6 |
| 7/8 | 22.225 | 14,000 | 137.3 |
| 1 | 25.400 | 17,733 | 173.9 |
Two low carbon balls of the same size can break at very different loads. Most of the spread comes from heat treatment and from the test itself, not from the nominal material.
A thin case or a soft core lets the ball flatten and the case crack early. Both are set during carburizing; see our guide to case-hardened carbon steel balls.
Check hardness with the corrected Rockwell value. On small balls the raw reading is several HRC low, so a sound batch can look under-hardened.
Surface decarburization, quench cracks, overheating or folds from cold heading all lower the breaking load. Each stage where they arise is described in how steel balls are made.
Results change with the fixture (ball-on-ball or between flat anvils), anvil hardness, loading rate and the failure definition (first crack or full fracture). Compare two results only when these match.
Can You Use Crushing Load to Select a Caster or Slide?
Not on its own. A ball may develop unacceptable permanent deformation or wear in service well before it fractures.
The load rating of a caster, drawer slide or bearing belongs to the complete assembly. Ball count, load distribution, raceway shape, mating materials and operating conditions all play a part. A crushing-load table does not account for those details.
The 1,520 kgf figure for a 1/4-inch ball therefore does not mean a caster using that ball can carry 1,520 kg. Nor should a working load be obtained by dividing the crushing value by an arbitrary safety factor. Use the assembly’s rated capacity and validate it for the application.
| Detail | What to Specify |
| Material and condition | Required steel grade and case-hardened supply condition |
| Ball size and precision | Nominal diameter, dimensional requirements and ball grade |
| Minimum crushing load | Agreed threshold for each size, preferably in kN |
| Test procedure | Applicable standard and edition, or an agreed written procedure |
| Fixture and loading | Ball arrangement, contact geometry, loading rate and alignment requirements |
| Failure endpoint | The event used to record failure under that procedure |
| Sampling and acceptance | Lot definition, sample quantity, permitted failures and retest rules |
| Inspection report | Whether individual results, test conditions and lot identification are required |
Not necessarily. Case depth has to be considered with the hardness profile and core condition. Specifying a deeper case by itself does not establish a higher crushing-load rating.
The grade number does not tell you that. Ball grades describe geometrical and surface-quality requirements, not crushing-load ratings. If load testing is required, specify it separately.
Soft balls can be compression-tested, but breaking them may not be the useful endpoint. For pressing or forming work, the requirement may concern deformation at a stated load, or the load needed to reach a stated deformation.
Use a test suited to the intended process. The case-hardened reference values above should not be carried over to soft annealed steel balls.
