718 Series — Ultra-Light Angular Contact Ball Bearings
Ultra-Thin Cross-Section for Space-Constrained Spindle Designs
The 718 series is the ultra-light cross-section angular contact ball bearing series, designed for spindle applications where radial space is critically constrained but precision cannot be compromised. With the thinnest cross-section in our angular contact range, 718 bearings enable larger shaft diameters within a given housing envelope — directly increasing spindle rigidity.
718 Series — Ultra-Light Angular Contact Ball Bearings
The 718 Series — Ultra-Light Angular Contact Ball Bearings delivers industry-leading precision and reliability for demanding machine tool spindle applications. Manufactured in our ISO 9001:2015 certified facility in Luoyang, China — the historic heart of bearing manufacturing — each bearing undergoes rigorous dimensional, running accuracy, and vibration testing before shipment.
The SONGJU B718XX ultra-light series is engineered with the maximum number of small-diameter balls for any given bore size — more balls than any other angular contact series. Smaller, lighter balls reduce centrifugal loads on the outer ring raceway, lowering rolling contact stress and enabling higher rotational speeds. For a given housing envelope, the ultra-thin cross-section accommodates the largest possible shaft diameter, directly increasing spindle system rigidity — a critical advantage where radial space is at a premium.
The ultra-thin cross-section means thicker bearing rings relative to ball diameter, making 718 series bearings inherently less sensitive to deformation caused by irregularities in the bearing mounting surface, housing bore, or shaft journal. This forgiving mounting characteristic, combined with universal face-grinding for interchangeable DB/DF/DT matching, significantly reduces assembly time and eliminates the need for selective fitting. Available in P5 through P2 precision grades with steel or Si₃N₄ ceramic hybrid variants for ultra-high-speed applications.
718 Series — Ultra-Light Angular Contact Ball Bearings — Complete Model Parameters
Full model list with α=15° (C) for high-speed and α=25° (AC) for high-rigidity applications. Custom sizes available upon request.
| Model | d | D | B | α=15° (C) — High Speed | α=25° (AC) — High Rigidity | ||||
|---|---|---|---|---|---|---|---|---|---|
| Cr | C0r | Speed | Cr | C0r | Speed | ||||
| 71807 | 35 | 47 | 7 | 4.6 | 5.5 | 26000/40000 | 4.3 | 5.2 | 24000/38000 |
| 71808 | 40 | 52 | 7 | 4.8 | 6.2 | 24000/38000 | 4.5 | 5.8 | 20000/34000 |
| 71809 | 45 | 58 | 7 | 4.9 | 6.7 | 20000/34000 | 4.6 | 6.3 | 18000/30000 |
| 71810 | 50 | 65 | 7 | 7.4 | 10.0 | 18000/30000 | 6.9 | 9.5 | 16000/26000 |
| 71811 | 55 | 72 | 9 | 10.2 | 13.8 | 16000/26000 | 9.6 | 13.1 | 15000/24000 |
| 71812 | 60 | 78 | 10 | 13.4 | 18.0 | 15000/24000 | 12.6 | 17.0 | 14000/22000 |
| 71813 | 65 | 85 | 10 | 13.4 | 18.8 | 14000/22000 | 12.6 | 17.8 | 13000/20000 |
| 71814 | 70 | 90 | 10 | 13.8 | 20.3 | 13000/20000 | 13.0 | 19.1 | 12000/19000 |
| 71815 | 75 | 95 | 10 | 14.2 | 21.7 | 12000/19000 | 13.3 | 20.5 | 11000/18000 |
| 71816 | 80 | 100 | 10 | 14.5 | 23.1 | 11000/18000 | 13.6 | 21.8 | 9500/16000 |
| 71817 | 85 | 110 | 13 | 21.5 | 32.2 | 10000/17000 | 20.2 | 30.5 | 9000/15000 |
| 71818 | 90 | 115 | 13 | 21.7 | 33.5 | 9500/16000 | 20.4 | 31.6 | 8500/14000 |
| 71819 | 95 | 120 | 13 | 21.9 | 34.7 | 9000/15000 | 20.6 | 32.8 | 8500/14000 |
| 71820 | 100 | 125 | 13 | 22.5 | 37.0 | 8500/14000 | 21.2 | 34.9 | 8000/13000 |
| 71821 | 105 | 130 | 13 | 22.7 | 38.3 | 8500/14000 | 21.3 | 36.1 | 8000/13000 |
| 71822 | 110 | 140 | 16 | 31.8 | 51.6 | 8000/13000 | 29.9 | 48.7 | 7500/12000 |
| 71824 | 120 | 150 | 16 | 33.1 | 56.9 | 7000/11000 | 31.1 | 53.7 | 6700/10000 |
| 71826 | 130 | 165 | 18 | 38.7 | 67.6 | 6700/10000 | 36.3 | 63.8 | 6000/9000 |
| 71828 | 140 | 175 | 18 | 44.8 | 79.2 | 6000/9000 | 42.0 | 74.7 | 5600/8500 |
| 71830 | 150 | 190 | 20 | 51.2 | 92.0 | 5600/8500 | 48.0 | 86.8 | 5000/7500 |
| 71832 | 160 | 200 | 20 | 52.4 | 97.7 | 5000/7500 | 49.2 | 92.2 | 4800/7000 |
| 71834 | 170 | 215 | 22 | 66.5 | 123.4 | 4800/7000 | 62.4 | 116.5 | 4300/6300 |
| 71836 | 180 | 225 | 22 | 83.8 | 151.6 | 4800/7000 | 78.6 | 143.0 | 4300/6300 |
| 71838 | 190 | 240 | 24 | 100.0 | 179.0 | 4500/6700 | 94.4 | 169.2 | 4000/6000 |
| 71840 | 200 | 250 | 24 | 102.5 | 189.3 | 4300/6300 | 96.2 | 178.6 | 3800/5600 |
| 71844 | 220 | 270 | 24 | 106.4 | 209.3 | 3800/5600 | 99.8 | 197.4 | 3400/5000 |
| 71848 | 240 | 300 | 28 | 145.0 | 277.0 | 3400/5000 | 136.0 | 261.0 | 3000/4500 |
| 71852 | 260 | 320 | 28 | 148.8 | 299.3 | 3100/4600 | 139.6 | 282.3 | 2700/4100 |
| 71856 | 280 | 350 | 33 | 182.0 | 363.8 | 2800/4100 | 170.8 | 343.3 | 2400/3700 |
All models available in P5, P4, and P2 precision grades. H-prefix = high-speed variant, HQ1 suffix = ceramic hybrid (Si₃N₄ balls). Phenolic, PEEK, or machined brass cages. Contact our engineering team for specific preload and arrangement recommendations.
Configuration Options for 718 Series Angular Contact Ball Bearings
Luoyang Songju offers multiple design variants to meet the full spectrum of spindle design requirements. Below are the standard configuration options available across the 718 series.
Mounting Configuration
Single universally ground bearing (U) for individual mounting, or matched sets: Duplex / D (two bearings), Triplex / T (three bearings), Quadruplex / Q (four bearings) in DB, DF, or DT arrangements.
Universal Matching
Precision face-ground for universal pairing. Interchangeably mount any two bearings of the same size in DB (back-to-back), DF (face-to-face), or DT (tandem) without shims or selective fitting.
Ball Material
Standard: premium GCr15 (100Cr6 / 52100) hardened steel balls. Hybrid option: Si₃N₄ silicon nitride ceramic balls — 40% lighter, lower thermal expansion, superior high-speed performance.
Sealing Options
Open bearings for oil-mist or oil-air lubrication systems. 2RS sealed variant with non-contact rubber seals on both sides for grease-lubricated, contamination-protected applications.
Direct Lubrication
Optional circumferential lubrication groove and radial oil holes in the outer ring for direct oil injection — ensures reliable lubricant delivery at ultra-high speeds.
Preload Classes
Three standard preload levels: Light (L) for maximum speed and minimal heat; Medium (M) for balanced rigidity and speed; Heavy (H) for maximum stiffness in rigid spindle systems.
718 Series Recommended Configuration
For optimal performance in high-speed spindle applications, we recommend: Light (L) preload + 15° (C) contact angle + Phenolic or PEEK cage + Si₃N₄ ceramic hybrid balls (HQ1). This configuration maximizes speed capability while the ultra-thin cross-section and high ball count provide sufficient inherent rigidity for light-to-moderate cutting loads.
How to Select 718 Series — Ultra-Light Angular Contact Ball Bearings
Understanding your application requirements is the first step to specifying the correct bearing configuration. Below are the key selection parameters and recommendations for the 718 series.
1 Determine Contact Angle
Choose for high-speed applications where radial stiffness is the priority. Lower axial stiffness but permits significantly higher rotational speeds. Ideal for grinding spindles and high-speed machining.
Choose when maximum axial rigidity and combined load capacity are required. Higher axial load capacity suits turning centers, milling spindles, and applications with substantial thrust forces.
2 Select Precision Grade
| Grade | ABEC | Radial Runout (max) | Bore Tolerance | Typical Application |
|---|---|---|---|---|
| P5 | ABEC-5 | ≤ 0.004mm | +0 / -0.008mm | General machine tool spindles, pumps |
| P4 | ABEC-7 | ≤ 0.002mm | +0 / -0.005mm | CNC machining centers, precision grinding |
| P2 | ABEC-9 | ≤ 0.001mm | +0 / -0.003mm | Ultra-precision spindles, CMM, optical grinding |
3 Choose Bearing Arrangement
4 Specify Preload and Lubrication
Light preload (L) — Recommended for 718 Series. The ultra-light cross-section and small-ball design achieve maximum speed with Light preload. Ideal for high-speed grinding, engraving, and micro-machining spindles where minimal heat generation is critical.
Medium preload (M) — Use when additional radial stiffness is required at moderate speeds. Suitable for woodworking spindles and light milling applications.
Heavy preload (H) — Generally not recommended for 718 series; the ultra-thin ring cross-section limits the benefit of heavy preload. Consider stepping up to 719 series if heavy preload is required.
718 Series Lubrication Recommendation: Grease lubrication is standard for most 718 applications given the inherently low heat generation. For speeds above 20,000 r/min, oil-air or oil-mist lubrication is recommended. Ceramic hybrid (HQ1) variants reduce operating temperature by 15–25°C at equivalent speeds.
Cage Materials, Lubrication & Precision Tolerances
Detailed technical specifications to support proper bearing selection and application engineering for 718 Series — Ultra-Light Angular Contact Ball Bearings.
Cage Material Selection
| Material | Max Operating Temp | Speed Suitability | Best For | Available Series |
|---|---|---|---|---|
| Phenolic Resin | 120°C | High speed | Standard spindle applications; lightweight, low friction | 718 / 719 / 70 / 72 |
| PEEK | 250°C | Very high speed | High-temperature spindles; superior chemical resistance | 718 / 719 / 70 / 72 |
| Machined Brass | 300°C | Moderate speed | Heavy-duty / shock loads; maximum strength & durability | 70 / 72 (recommended) |
| Polyamide (PA66) | 100°C | Moderate speed | Cost-effective; general industrial, non-spindle use | 70 / 72 |
Lubrication Method Comparison
| Method | Speed Factor (dmN) | Cooling | Complexity | Best Application |
|---|---|---|---|---|
| Grease | Up to 1.0 × 10⁶ | None | Low | Standard spindles, periodic maintenance OK |
| Oil-Mist | Up to 1.5 × 10⁶ | Minimal | Medium | High-speed grinding, continuous operation |
| Oil-Air | Up to 2.0 × 10⁶ | Good | Medium-High | Ultra-high-speed spindles, ceramic hybrids |
| Oil-Jet | Up to 2.5+ × 10⁶ | Excellent | High | Maximum speed; requires oil recovery system |
| Direct Lubrication | +15–20% vs standard | Application-dependent | Medium | Optimizes delivery via outer ring groove & radial holes |
Speed factor (dmN) = pitch diameter [mm] × rotational speed [r/min]. Values are indicative — actual limits depend on bearing size, preload, and cage material.
Precision Grade Tolerance Table (ISO 492)
| Parameter | Symbol | P5 (ABEC-5) | P4 (ABEC-7) | P2 (ABEC-9) |
|---|---|---|---|---|
| Bore deviation (nominal d ≤ 80mm) | Δdmp | 0 / -8 μm | 0 / -5 μm | 0 / -3 μm |
| Bore deviation (80 < d ≤ 180mm) | Δdmp | 0 / -10 μm | 0 / -7 μm | 0 / -4 μm |
| Bore deviation (180 < d ≤ 250mm) | Δdmp | 0 / -15 μm | 0 / -10 μm | 0 / -5 μm |
| OD deviation (nominal D ≤ 150mm) | ΔDmp | 0 / -9 μm | 0 / -6 μm | 0 / -4 μm |
| OD deviation (150 < D ≤ 250mm) | ΔDmp | 0 / -13 μm | 0 / -8 μm | 0 / -5 μm |
| Inner ring radial runout | Kia | ≤ 4 μm | ≤ 2 μm | ≤ 1 μm |
| Outer ring radial runout | Kea | ≤ 5 μm | ≤ 3 μm | ≤ 1.5 μm |
| Axial runout (inner ring face) | Sia | ≤ 5 μm | ≤ 3 μm | ≤ 1.5 μm |
| Width tolerance (all sizes) | ΔBs | 0 / -40 μm | 0 / -25 μm | 0 / -15 μm |
Industries & Applications for 718 Series — Ultra-Light Angular Contact Ball Bearings
718 Series — Ultra-Light Angular Contact Ball Bearings are trusted across a wide range of precision industries worldwide. Below are the primary application areas where the 718 series delivers measurable performance advantages.
High-Speed Machining Centers
Primary spindle bearings where speed capability up to 26,000 r/min (grease) is critical for small-diameter tooling and high-RPM finishing operations.
Internal Grinding Spindles
Ultra-light cross-section enables maximum wheel spindle diameter within compact grinder housing — critical for achieving required surface finish quality.
Woodworking Machinery
High-speed router and moulder spindles benefit from the low centrifugal load and reduced heat generation of the 718's small-ball design.
Engraving & Engraving Spindles
Precision engraving and micro-machining spindles requiring minimal vibration and high accuracy at elevated rotational speeds.
Robotics & Automation
Compact rotary joints and precision positioning axes where space is at a premium but bearing precision directly impacts end-effector accuracy.
Printing Machinery
High-speed printing cylinder support bearings demanding ultra-smooth rotation and minimal runout for consistent print quality.
Measuring Devices & Metrology
Precision rotary tables and measurement spindles where minimal friction torque and exceptional rotational accuracy are non-negotiable.
Tool Holder Spindles
Compact tool-holder turret bearings where thin cross-section allows larger tool capacity within the same housing envelope.
Why Choose Luoyang Songju 718 Series — Ultra-Light Angular Contact Ball Bearings
The 718 series is the ultra-light cross-section angular contact ball bearing series, designed for spindle applications where radial space is critically constrained but precision cannot be compromised. With the thinnest cross-section in our angular contact range, 718 bearings enable larger shaft diameters within a given housing envelope — directly increasing spindle rigidity.
Ultra-Thin Cross-Section
Minimum radial envelope for space-critical spindle designs. Enables larger shaft diameters for enhanced spindle rigidity.
High Speed Capability
Smaller ball diameter and optimized internal geometry minimize centrifugal force. Grease speed limits up to 26,000 r/min for smaller sizes.
Low Friction Design
Optimized ball-to-raceway contact geometry and precision surface finish (Ra 0.025–0.05μm) minimize friction and heat generation.
Universal Matching
Universally face-ground for interchangeable DB, DF, and DT arrangements. Available in Light (L), Medium (M), and Heavy (H) preload classes.
Ceramic Hybrid Option
Si₃N₄ ceramic ball variants (H prefix + HQ1 suffix) for ultra-high-speed applications where thermal stability and reduced mass are critical.
P4/P2 Precision
ISO P4 (ABEC-7) and P2 (ABEC-9) grades available. Radial runout held to ≤0.001mm for P2 grade bearings.
Need 718 Series — Ultra-Light Angular Contact Ball Bearings?
Tell us your bore size, contact angle, precision grade, preload class, and quantity — our application engineers will respond within 24 hours with a competitive quotation and detailed technical documentation.