Styli Technical / Quality Data
A.F.B.M.A. Grade Tolerances and Terminology
| A.F.B.M.A. Grade | Diameter Tolerance, per Ball Sphericity | Diameter Tolerance, per Unit Container | Basic Diameter Tolerance | Marking Increments |
| - | Inch | Inch | Inch | Inch |
| 3 | .000003 | .000005 | +/-.00003 | .000003 |
| 5 | .000005 | .00001 | +/-.00005 | .000005 |
| 10 | .000010 | .00002 | +/-.0001 | .000010 |
| 15 | .000015 | .00003 | +/-.0001 | .000015 |
| 25 | .000025 | .00005 | +/-.0001 | .000025 |
| 50 | .00005 | .0001 | +/-.0002 | .00005 |
| 100 | .0001 | .0002 | +/-.0005 | .0001 |
| 200 | .0002 | .0004 | +/-.0010 | .0002 |
| Grade: | The numerical value of the Diameter Tolerance per Ball expressed in millionths of an inch |
| Diameter Tolerance per Ball: | The permissible difference between the largest diameter and the smallest diameter measurable on one ball |
| Diameter Tolerance per Unit Container: | The permissible range of the average diameters of the individual balls within any one unit container. |
| Basic Diameter: | The size ordered which is the basis to which the basic diameter tolerances apply. The Basic Diameter is specified by a fraction plus a decimal or a decimal only to the sixth place, e.g. 1/4"+.0002" or .02502", 15-64"+.0003" or .234675". |
| Basic Diameter Tolerance: | The maximum allowable deviation of any ball diameter from the basic diameter, in any shipments to fill orders for that basic diameter. |
| Marking Increments | The standard unit steps in millionths of an inch used to express the Specific Diameter. |
Technical Data
| Item | Material | Form Deviation | Diameter Tolerance | Hardness (Vickers) | Density (g/cm3) | Surface Finish |
| Ruby Ball | Synthetic ruby AL2O3, monocrystalline | <0.25um | +/-.025um | 1800 | 3.9 | 0.015um |
| Hollow Ceramic Ball | AL2O3, polycrystalline | <0.6um | +/-0.6um | 1650 | 3.9 | 0.1um |
| Cylinder, Stainless Steel | Stainless Steel | <2um | +/-10um | 250 | 7.9 | 0.4um |
| Cylinder, Ruby | Synthetic ruby AL2O3 | <1um | +/-1um | 1800 | 3.9 | 0.05um |
| Cylinder, TC | Tungsten Carbide | <1um | +/-1um | 1550 | 15.0 | 0.2um |
| Ball Disc, Ceramic | Alumina AL2O3, ceramic polycrystalline | <0.6um | +/-0.6um | 1650 | 3.9 | 0.1um |
| Ball Disc, Steel | Stainless Steel | <3um | +/-10um | 250 | 7.9 | 0.4um |
| Disc Stylus, Steel | Hardened Steel | <2um | +/-10um | 720 | 7.9 | 0.2um |
| Shank and Extension, Stainless Steel | Stainless Steel | - | - | - | 7.9 | - |
| Shank and Extension, Ceramic | Alumina AL2O3, ceramic polycrystalline | - | - | - | 3.9 | - |
| Shank and Extension, Carbon Fiber | Carbon Fiber | - | - | - | 1.5 | - |
| Shank, Tungsten Carbide | Tungsten Carbide | - | - | - | 15.0 | - |
| Extension, Alu7075 | 7075 high strength aluminum | Hard coat anodized surface with PTFE inserts | 2.8 | - | ||
