71821 CDGC/HCP4 Super-precision Angular Contact Ball Bearings, 15° Contact Angle, High-capacity Design
The 71821 CDGC/HCP4 Ultra-precision angular contact ceramic ball bearings are widely used in high-speed, high-precision applications and situations where there is a risk of shaft current, such as: high-speed machining center spindles, high-speed electric spindles, grinding machine spindles, lathe spindles, ball screw support mechanisms, and medical equipment (high-speed dental drills).
The 71821 CDGC/HCP4 bearing is a super-precision angular contact ball bearings with an inner diameter of 105 mm , an outer diameter of 130 mm, a width of 13 mm. It typically uses P4 grade precision tolerances and Carbon chromium steel rings, HC = Balls made of bearing grade silicon nitride Si3N4 (hybrid bearing) rolling mlement. Its dynamic radial rated load is approximately 22793 N, its static radial rated load is approximately 29795 N. open type, together determine its load-bearing capacity, rotational accuracy, and applicable working conditions.
71821 CDGC/HCP4 bearings ( 105 mm x 130 mm x 13 mm) have the advantages of ceramic balls materials, high speed, ultra-high precision and high thermal stability, corrosion resistant, non-magnetic, and are therefore widely used in the Machine tool spindles, high-speed electric spindles, precision instruments, aerospace and semiconductor equipment.
| Part Number | 71821 CDGC/HCP4 |
| Bearing Type | super-precision angular contact ball bearings |
| Internal design | CD = 15° contact angle, high-capacity design |
| Series | 718..-CDGC/HCP4 |
| Weight [kg] | 0.29 |
| Units | Metric |
| Contact type | 2-point contact |
| Accuracy class | P4 |
| Rows NO. | 1 |
| Cage | Cotton fabric reinforced phenolic resin or carbon fibre reinforced PEEK, outer ring centred |
| Dimension series | ISO dimension series 18 |
| Contact angle - α | 15 ° |
| Manufacturer Part Code | 71821CDGC/HCP4 |
| Bore Type | Z = Cylindrical Bore |
| Ring material | Carbon chromium steel |
| Ball material | HC = Balls made of bearing grade silicon nitride Si3N4 (hybrid bearing) |
| Temperature - T(min) [°C] | -30 |
| Temperature - T(max) [°C] | +110 |
| Single bearing - execution and preload | GC = Single, universally matchable, heavy preload |
| Ring type | inner rings(1 piece), outer rings(1 piece) |
| Load Direction | Angular Contact |
| Seal type | open |
| Grease quantity - Gref [cm3] | 4 |
| f0 Calculation coefficient | 17.4 |
| Dimension | |
| d φ Inside [inch] | 4.134 |
| D Φ Outside [inch] | 5.118 |
| B Width [inch] | 0.512 |
| r1,r2(min.) Chamfer [inch] | 0.039 |
| r3,r4(min.) Chamfer [inch] | 0.012 |
| ra(max.) Fillet [inch] | 0.039 |
| rb(max.) Fillet [inch] | 0.012 |
| d1 [inch] | 4.457 |
| d2 [inch] | 4.457 |
| D1 [inch] | 4.803 |
| Performance (Load Capacity and speeds) | |
| Cr Dynamic Radial [lbf] | 5123 |
| C0r Static Radial [lbf] | 6697 |
| Pu Fatigue Radial [lbf] | 262 |
| Attainable speeds (Grease) [r/min] | 10976 |
| Attainable speeds (Oil-air) [r/min] | 15904 |
| Abutment dimensions | |
| da(min.) [inch] | 4.315 |
| db(min.) [inch] | 4.315 |
| Da(max.) [inch] | 4.937 |
| Db(max.) [inch] | 5.039 |
| dn [inch] | 4.512 |
The 71821 CDGC/HCP4 Ultra-precision angular contact ceramic ball bearings are primarily composed of high-precision bearing steel inner and outer rings, silicon nitride ceramic balls, and a cage. The cage is available in ball-guided polyamide (silent series) or brass. Contact angles are available in various specifications, including 15°, 25°, and 40°, with precision grades reaching P4 and above.
Ultra-precision angular contact ceramic ball bearings feature low-density ceramic balls, resulting in low centrifugal force, significantly improved limiting speed, and lower heat generation. The electrical insulation properties of the ceramic material effectively prevent electrolytic corrosion, extending bearing life. The silent series uses ball-guided polyamide cages to reduce vibration and noise, and optimized tolerances ensure more uniform load distribution and superior radial stiffness in bearing groups.
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