Cages made of phenolic laminated fabric are used in high-precision bearings with high speeds. These fabric-reinforced plastic cages prove their worth especially in challenging applications. This material is characterized by good dimensional stability and elasticity. The fabric structure absorbs small amounts of oil, thereby improving the sliding and emergency running properties of the material. The low weight combined with damping effects offers advantages. Corrosion resistance as well as neutrality toward most commercially available greases, oils, and solvents and cleaning agents should not be overlooked. The main function of the cage is to hold the balls or rolling elements at the optimal distance while preventing them from contacting each other.
Material:
Krütex 102 materials were specifically developed for use in sensitive areas. By using a finer cotton fabric with a minimum thread count of 30 threads/cm in both warp and weft, the layer bonding and strength of the material have been significantly improved. The Krütex®102 material thus far exceeds the minimum requirements as specified in EN 61212 with PF CC 21 or in DIN 7735 with Hgw 2086.
The manufacturing process:
Fine cotton fabrics are impregnated with modified phenolic resin on impregnation machines. From these fabrics, called prepregs, we produce corresponding tubular rods on winding machines. Following a precisely defined procedure, the windings remain on steel mandrels for several hours in curing ovens. During this process, the natural fibers and phenolic resin form a chemical and mechanical bond. The thermosetting material reaches its final state.
In the subsequent machining process, the ball cage is turned and drilled from the tube in a single operation using CNC lathes from Gildemeister. Afterwards, the surface of the parts is deburred, smoothed, and polished.
Technical Values:
Compressive strength perpendicular: 290 N/mm²
Bending strength: 120 N/mm²
Tensile strength: 60 N/mm²
Elastic modulus: 6000 N/mm²
Coefficient of friction vs. steel: 0.25
Density approx.: 1.25 g/cm³
Water absorption: 1 – 1.5%
Temperature resistance: 120°C
Ball indentation hardness:
perpendicular: 130 N/mm²
parallel: 120 N/mm²
Sizes
Bearings can be manufactured from approx. 10 mm inner diameter with any wall thickness and ring widths up to approx. 50 mm.
The maximum size for turned rings only is approx. 400 mm; for drilled or milled rings, the largest diameter is approx. 200 mm!