7028 ACDGB/P4A Super-precision Angular Contact Ball Bearings, 25° Contact Angle, High-capacity Design
The 7028 ACDGB/P4A Ultra-precision angular contact ball bearings are widely used in conventional high-speed precision machining applications, such as machining center spindles, milling machine spindles, grinding machine spindles, lathe spindles, woodworking machinery, and ball screw support mechanisms.
The 7028 ACDGB/P4A bearing is a super-precision angular contact ball bearings with an inner diameter of 140 mm , an outer diameter of 210 mm, a width of 33 mm. It typically uses P4A grade precision tolerances and Carbon chromium steel rings, GCr15SiMn rolling mlement. Its dynamic radial rated load is approximately 145904 N, its static radial rated load is approximately 155846 N. open type, together determine its load-bearing capacity, rotational accuracy, and applicable working conditions.
7028 ACDGB/P4A bearings ( 140 mm x 210 mm x 33 mm) have the advantages of High speed, ultra-precision, high rigidity, low operating friction, and long service life, and are therefore widely used in the Machine tool spindles, high-speed motors, ball screws, industrial robots and precision rotating equipment.
| Part Number | 7028 ACDGB/P4A |
| Bearing Type | super-precision angular contact ball bearings |
| Internal design | ACD = 25° contact angle, high-capacity design |
| Series | 70..-ACDGB/P4A |
| Weight [kg] | 3.4 |
| Units | Metric |
| Contact type | 2-point contact |
| Accuracy class | P4A |
| Rows NO. | 1 |
| Cage | Cotton fabric reinforced phenolic resin or carbon fibre reinforced PEEK, outer ring centred |
| Dimension series | ISO dimension series 10 |
| Contact angle - α | 25 ° |
| Manufacturer Part Code | 7028ACDGB/P4A |
| Bore Type | Z = Cylindrical Bore |
| Ring material | Carbon chromium steel |
| Ball material | GCr15SiMn |
| Balls qty（single row） | 22 |
| Temperature - T(min) [°C] | -30 |
| Temperature - T(max) [°C] | +110 |
| Single bearing - execution and preload | GB = Single, universally matchable, light preload |
| Ring type | inner rings(1 piece), outer rings(1 piece) |
| Load Direction | Angular Contact |
| Seal type | open |
| Grease quantity - Gref [cm3] | 45 |
| Dimension | |
| d φ Inside [inch] | 5.512 |
| D Φ Outside [inch] | 8.268 |
| B Width [inch] | 1.299 |
| r1,r2(min.) Chamfer [inch] | 0.079 |
| r3,r4(min.) Chamfer [inch] | 0.039 |
| ra(max.) Fillet [inch] | 0.079 |
| rb(max.) Fillet [inch] | 0.039 |
| d1 [inch] | 6.362 |
| d2 [inch] | 6.362 |
| D1 [inch] | 7.417 |
| D2 [inch] | 7.602 |
| Balls diameter [inch] | 0.875 |
| Performance (Load Capacity and speeds) | |
| Cr Dynamic Radial [lbf] | 32799 |
| C0r Static Radial [lbf] | 35034 |
| Pu Fatigue Radial [lbf] | 1132 |
| Attainable speeds (Grease) [r/min] | 5560 |
| Attainable speeds (Oil-air) [r/min] | 8417 |
| Abutment dimensions | |
| da(min.) [inch] | 5.866 |
| db(min.) [inch] | 5.866 |
| Da(max.) [inch] | 7.913 |
| Db(max.) [inch] | 8.071 |
| dn [inch] | 6.547 |
The 7028 ACDGB/P4A Ultra-precision angular contact ball bearings are primarily composed of high-precision bearing steel inner and outer rings, steel balls, and a cage. The cage is available in ball-guided polyamide cages (silent series) or brass cages. Contact angles are available in various specifications, including 15°, 25°, and 40°, with precision grades reaching P4 and above.
Ultra-precision angular contact ball bearings offer a cost advantage while maintaining high rigidity and high speed. The silent series uses ball-guided polyamide cages, significantly reducing rotational noise and vibration. Optimized tolerance ranges result in more uniform load distribution in bearing groups, superior radial stiffness, and smooth and reliable operation.
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