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The SNL Bearing Housing From SKF(Pic)
SKF followed the company's tradition of carefully considering customer requirements when designing new products, and conducted a global customer survey to identify the features of a bearing housing to best satisfy diverse customer demands. These valuable findings from a broad customer base were combined with extensive R&D and SKF expertise in application engineering, bearings, seals, lubrication and condition monitoring, to design and manufacture the unique, modular, versatile SNL bearing housing ideal for self-aligning bearings.
"Bearings are frequently blamed for various problems such as noise, vibration, over-heating and premature bearing failure, but", says Warren Walker, SKF Engineering Manager, "in many cases it is the housing that is the root cause of the problem. The role of the housing is often down-played yet it has numerous quintessential functions. The housing is responsible for transmitting the load from the shaft via the stationery bearing outer ring to the support foundation. An important secondary function is to protect the bearing against contamination and water ingress", explains Walker.
"After tightening of the housing base bolts during mounting, the bore diameter of inferior design housings can distort significantly thereby deforming the bearing outer ring. This often leads to uneven load distribution within the bearings, increased stress and internal friction and, in severe cases, complete lubricant breakdown. The worst case scenario would be premature bearing seizure and extensive damage to associated components", warns Walker. "The use of superior quality housings with the increased stiffness offered by the addition of support in critical areas, will lead to significantly improved bearing performance and the highest possible service life."
SKF's SNL housings are manufactured to world-class quality standards at the company's own foundry and machine shop, in Katrineholm, Sweden.
The extensive global customer survey done prior to the start of the re-design project for SNL housings, made it clear that the most important end user needs were longer service life, ease of mounting, reduced maintenance requirements and longer relubrication intervals. SKF's SNL housings meet these customer requirements to even the smallest detail. Features and benefits of the SNL housing include:
A wide range of sizes and accessories are available
Standard SNL housings are available to suit shaft diameters from 20 mm to 530 mm. Larger sizes can be considered upon request.
A wide range of readily available standard seals are offered to suit virtually any application conditions. Depending on the type and amount of contamination in the operating environment, SNL housings can be equipped with the most cost effective and appropriate seal configuration. Easy to use seal selection guidelines are available in SKF SNL housing product literature.
Optimised housing bore tolerance and improved bore roundness
The bearing seating diameter is machined to an ISO G7 dimensional tolerance with an equivalent IT7/2 geometric form tolerance to ensure roundness and cylindricity after machining.
Comprehensive finite element modeling formed part of the design process to ensure that optimum strength and stiffness were attained.
Unique extra ribbing in the housing base prevents distortion and ensures a stiffer design for reduced sensitivity to bad mounting surfaces.
Transverse webs prevent deformation of the housing bore when the housing base bolts are tightened.
Due to the design features outlined above, the bearing seating retains its roundness, not only on delivery, but also after bearing has been mounted.
Improved heat transfer for longer lubricant life
Increased contact surfaces on the base abutment surface (a cross web and transverse webs) improve heat transfer and significantly reduce bearing operating temperatures. The lower temperatures lead to increased grease/oil life, longer relubrication intervals and reduced maintenance requirements.
Unique markings and features for simpler handling and faster mounting / dismounting
Alignment notches are included in the castings. The shaft centre line as well as the centre line perpendicular to the shaft are clearly marked.
The housing cap bolts are loosened after manufacturing for fast, easy separation of the cap and base during installation.
The cap and base of each housing are marked with the same unique designation to avoid incorrect matching when mounting more than one housing.
Unique numbering ensures full traceability.
Notches in cap and base are provided to allow for easy separation using a screwdriver.
Grease level indication marks are included in base castings.
Larger eye-bolts are provided for ease of handling.
New generation SNL are supplied pre-prepared for grease lubrication. They are supplied as standard with 2 threaded holes for grease nipples, one in the centre of the housing cap and the other to one side of the housing cap. A grease nipple and adapters are provided inside the housing.
The design also incorporates flat surfaces for attachment of magnetic or fixed condition monitoring sensors. These surfaces are positioned to offer the most effective monitoring of the bearings.
According to Walker, SKF's local Project Engineering team is well versed with local conditions and can offer custom designed assemblies incorporating the versatile SNL housings to suit specific application requirements. In addition to the SNL housing's numerous features to ensure fast mounting and dismounting, step-by-step installation instructions are included in the applicable product catalogues that are available on request from SKF. Product selection advice is available from the SKF Application Engineering Department and an on-site installation service is available from the SKF Mechanical Field Service department.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| SD8×15×3 bearing | 8 | 3 | |
| SD8×12×3 bearing | 8 | 3 |