70 Series — Medium Angular Contact Ball Bearings
Maximum Versatility with Enhanced Load Capacity for Universal Machine Tool Applications
The 70 series provides the ideal balance between load capacity and speed, with a medium cross-section suitable for the broadest range of machine tool applications. From high-speed milling spindles to heavy turning centers, the 70 series delivers consistent precision and reliability across all operating conditions.
70 Series — Medium Angular Contact Ball Bearings
The 70 Series — Medium 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 B70XX medium series offers the most balanced combination of load capacity, speed capability, and rigidity in our angular contact bearing range. With a wider cross-section than 718 and 719 series, the 70 series accommodates larger-diameter balls for substantially higher dynamic and static load ratings — typically 1.5–2× that of equivalent-bore 719 bearings. This makes the 70 series uniquely suited for applications where a single bearing must handle both heavy roughing cuts and high-speed finishing passes without compromise.
The 70 series provides enough ring cross-section stiffness to compensate for typical housing and shaft deformations while maintaining competitive speed limits. This inherent robustness, combined with universal face-grinding for interchangeable DB/DF/DT matching, makes the 70 series the preferred choice for general machine tool builders who need one bearing series to cover their entire spindle product range. Available in P5 through P2 grades, with steel or Si₃N₄ ceramic hybrid variants. The medium cross-section also permits direct lubrication via outer ring grooves and radial oil holes for oil-air and oil-jet systems.
70 Series — Medium 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 | ||||
| 7007 | 35 | 62 | 14 | 19.3 | 17.5 | 20000/34000 | 18.3 | 16.6 | 19000/32000 |
| 7008 | 40 | 68 | 15 | 19.9 | 19.1 | 19000/32000 | 18.9 | 18.2 | 17000/28000 |
| 7009 | 45 | 75 | 16 | 26.7 | 25.3 | 17000/28000 | 25.4 | 24.1 | 16000/26000 |
| 7010 | 50 | 80 | 16 | 27.6 | 27.5 | 16000/26000 | 26.2 | 26.2 | 15000/24000 |
| 7011 | 55 | 90 | 18 | 36.7 | 37.1 | 14000/22000 | 34.8 | 35.3 | 13000/20000 |
| 7012 | 60 | 95 | 18 | 37.8 | 40.0 | 14000/22000 | 35.8 | 38.0 | 12000/19000 |
| 7013 | 65 | 100 | 18 | 38.9 | 42.9 | 13000/20000 | 36.8 | 40.7 | 11000/18000 |
| 7014 | 70 | 110 | 20 | 49.9 | 55.5 | 12000/19000 | 47.2 | 52.7 | 10000/17000 |
| 7015 | 75 | 115 | 20 | 51.3 | 59.2 | 11000/18000 | 48.5 | 56.2 | 9500/16000 |
| 7016 | 80 | 125 | 22 | 61.6 | 70.4 | 10000/17000 | 58.3 | 66.9 | 9000/15000 |
| 7017 | 85 | 130 | 22 | 63.3 | 75.0 | 9500/16000 | 59.9 | 71.3 | 8500/14000 |
| 7018 | 90 | 140 | 24 | 66.9 | 84.0 | 9000/15000 | 63.2 | 79.7 | 8000/13000 |
| 7019 | 95 | 145 | 24 | 79.1 | 97.6 | 8500/14000 | 74.8 | 92.7 | 7500/12000 |
| 7020 | 100 | 150 | 24 | 81.2 | 103.3 | 8000/13000 | 76.7 | 98.0 | 7000/11000 |
| 7021 | 105 | 160 | 26 | 93.9 | 118.2 | 7500/12000 | 88.8 | 112.2 | 7000/11000 |
| 7022 | 110 | 170 | 28 | 110.4 | 139.8 | 7000/11000 | 104.4 | 132.8 | 6700/10000 |
| 7024 | 120 | 180 | 28 | 112.7 | 148.7 | 7000/11000 | 106.5 | 141.1 | 6700/10000 |
| 7026 | 130 | 200 | 33 | 144.8 | 190.8 | 6700/10000 | 136.8 | 181.0 | 6000/9000 |
| 7028 | 140 | 210 | 33 | 148.7 | 202.6 | 6000/9000 | 140.4 | 192.2 | 5600/8500 |
| 7030 | 150 | 225 | 35 | 168.4 | 232.5 | 5600/8500 | 159.1 | 220.6 | 5000/7500 |
| 7032 | 160 | 240 | 38 | 189.1 | 264.5 | 5000/7500 | 178.6 | 251.0 | 4800/7000 |
| 7034 | 170 | 260 | 42 | 205.6 | 299.3 | 4800/7000 | 194.2 | 284.0 | 4300/6300 |
| 7036 | 180 | 280 | 46 | 229.5 | 352.1 | 4500/6700 | 216.8 | 334.1 | 4000/6000 |
| 7038 | 190 | 290 | 46 | 235.1 | 370.8 | 4300/6300 | 222.1 | 351.8 | 3800/5600 |
| 7040 | 200 | 310 | 51 | 289.1 | 471.4 | 3800/5600 | 273.1 | 447.3 | 3600/5300 |
| 7044 | 220 | 340 | 56 | 325.3 | 559.4 | 3600/5300 | 307.3 | 530.8 | 3200/4800 |
| 7048 | 240 | 360 | 56 | 344.2 | 623.6 | 3200/4800 | 325.1 | 591.7 | 3000/4500 |
| 7052 | 260 | 400 | 65 | 491.1 | 700.0 | 2800/4300 | 462.8 | 664.3 | 2500/3900 |
| 7056 | 280 | 420 | 65 | 499.0 | 739.6 | 2500/3800 | 469.9 | 701.4 | 2100/3500 |
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 70 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 70 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.
70 Series Recommended Configuration
For optimal performance in universal machine tool spindles, we recommend: Medium (M) preload + 15° (C) contact angle + Phenolic cage. For heavy turning applications, substitute 25° (AC) contact angle + Heavy (H) preload + machined brass cage. The medium cross-section works well with direct oil-air lubrication for sustained high-speed operation.
How to Select 70 Series — Medium 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 70 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) — Suitable for high-speed motorized spindles where the 70 series medium cross-section already provides substantial inherent rigidity.
Medium preload (M) — Recommended for 70 Series. The standard choice for universal turning and milling spindles. Delivers the best all-around combination of stiffness, speed, and service life.
Heavy preload (H) — Recommended for heavy turning centers, vertical lathes, and applications with interrupted cuts where maximum spindle stiffness is the primary design criterion.
70 Series Lubrication Recommendation: The medium cross-section generates more heat than lighter series at equivalent speeds — oil-air or oil-jet lubrication is recommended for continuous operation above 10,000 r/min. Direct lubrication via outer ring groove and radial oil holes is available and recommended for oil-jet systems.
Cage Materials, Lubrication & Precision Tolerances
Detailed technical specifications to support proper bearing selection and application engineering for 70 Series — Medium 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 70 Series — Medium Angular Contact Ball Bearings
70 Series — Medium Angular Contact Ball Bearings are trusted across a wide range of precision industries worldwide. Below are the primary application areas where the 70 series delivers measurable performance advantages.
Heavy-Duty Machine Tool Spindles
Turning centers, vertical lathes, and heavy milling spindles where substantial metal removal rates demand high load capacity without sacrificing precision.
Electric Spindle Support Bearings
Widely used as front and rear support bearings for high-speed motorized spindles in internal and external grinding machines — low vibration and minimal temperature rise are essential.
Industrial Pumps & Compressors
High-pressure pump shafts and compressor rotors where combined radial-thrust loads require robust bearing arrangements with long service intervals.
Turbo Reducers & Gearboxes
Precision gearbox input and output shafts in industrial power transmission — the 70 series handles both radial gear mesh forces and axial thrust loads.
Centrifuges & Separators
High-speed centrifuge spindles in chemical, pharmaceutical, and food processing — demanding corrosion-resistant materials and reliable long-term operation.
Food Processing Equipment
Hygienic-design spindle bearings for mixers, homogenizers, and filling machines where washdown compatibility and consistent performance are required.
Railway Traction Motors
Traction motor support bearings requiring high reliability, electrical resistance, and extended service life under variable load conditions.
Wind Turbine Generators
Generator-end bearings in small-to-medium wind turbines — the 70 series medium cross-section handles variable radial loads from rotor imbalance and gust response.
Why Choose Luoyang Songju 70 Series — Medium Angular Contact Ball Bearings
The 70 series provides the ideal balance between load capacity and speed, with a medium cross-section suitable for the broadest range of machine tool applications. From high-speed milling spindles to heavy turning centers, the 70 series delivers consistent precision and reliability across all operating conditions.
Balanced Performance
Medium cross-section delivers the best all-around combination of load capacity, speed, and rigidity for universal CNC spindle applications.
Superior Load Capacity
Significantly higher dynamic and static load ratings than 718/719 series. Ideal for applications with substantial cutting forces.
High Precision Standards
Available in P4S and P2 grades with dmN values of 1.3–1.8 × 10⁶ /min. Average service life exceeds 1,500 hours.
Flexible Configuration
Available as individual bearings, matched pairs, or multi-bearing sets. Single row, double row, back-to-back, face-to-face, or tandem arrangements.
Optimized for Electric Spindles
Widely used as support bearings for high-speed electric spindles in internal grinding machines — a key application requiring low vibration and minimal temperature rise.
Wide Application Range
From machine tool spindles to pumps, turbo reducers, centrifuges, and food processing equipment — the 70 series serves diverse precision industries.
Need 70 Series — Medium 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.