bearings:
Ball Bearings
Tolerance rings can normally handle a ½ degree draft angle per side in a bearing housing. For this reason, they can often be used with zinc die-cast housings as well as glass-filled plastic housings, with no secondary machining operation. The rings also work well in aluminum housings in terms of handling thermal growth, but some machining is often recommended to clean up the draft.
The graph above illustrates ring performance in retaining a 2.00” OD bearing in an aluminum housing. With .0012” traditional interference fit, an installation force of 500 pounds is required. Due to thermal growth between the steel bearing and aluminum housing, the bearing becomes loose at a temperature of 170 °F. With the Tolerance Ring, an initial installation force of only 320 pounds is required, and retention remains high at 230 pounds at 270 °F.
Zinc-Diecast Bearing Brackets:
Since draft angle on these brackets is minimal, they normally require no secondary machining operation. Oftentimes ANL or light duty AN-style rings are used to keep assembly forces low to avoid brinelling the bearing during assembly. Whereas glue and rubber boots trap heat, airflow around the rings may allow the bearing to run cooler. Elastomer boots can vary in their durometer readings (stiffness) and allow unwanted side movement of the bearing, while tolerance rings have a predictable spring rate to better center the bearing.
Glass-Filled Molded Plastic Housings:
The ring’s waves expand and contract to accommodate thermal expansion of the housing. Glass is needed as a hardener to prevent the ring from wallowing its way (creeping) into the housing. Typically, there is no need for an insert ring or any secondary machining operations.
Stampings:
Tolerance Rings allow mounting precision bearings in stamped housings. As the tooling wears and the housing bore decreases with later production runs, the waves deflect without taking up all the internal clearance of the bearing. Tolerance rings compensate for tool wear with stampings.
Molded Bearings:
Power tools, which operate near energized wiring, often use molded bearings (outer race insulated with plastic) for electric shock prevention. Tolerance rings are ideal for dealing with both mechanical and thermal tolerance stack-up occurring with these molded bearings.
Mounting Bearings Inside Tubes:
Straight tubular sections, with a centered hole already bored, are natural housings for ball bearings. The tubes can be cut to the desired length and then welded to one another, forming a structural framework.
Problems arise, however, due to tube bore tolerances not being acceptable for a bearing press fit. Other dimensional distortions occur from the heat produced during welding operations and the application of paint layers. What was previously a circular tube ID may now be out of round due to manufacturing processes.
Tolerance rings can compensate for these incurred dimensional variations. An example is use of USA Tolerance Ring part number AN35X11S with a 6202 bearing inside a tube. Despite a 0.007” tolerance stack up in the final tube bore ID, the tolerance ring keeps the bearing fully functional.
Improves Ball Bearing Alignment:
When bearings are pressed onto a shaft, low axial force tolerance rings can allow for easy alignment of the bearing ODs, minimizing the risks of cocking the bearings during assembly. The tolerance ring will also compensate for minor misalignments of bore /shaft centers.
Eliminating Fretting & Corrosion:
Fretting and corrosion constitute a detrimental wear process occurring at the contact area between materials under load and subject to minute relative motion by vibration or other forces. Tolerance Rings may reduce or eliminate this damaging wear process by shifting the vibrational frequency of the bearing away from the natural frequency of the system or by preventing rotation of the bearing outer race while allowing it to float axially. In one such application, 100mm OD preloaded bearings in the generators of electronically controlled wind turbines were encountering strong vibration. The bearings were prematurely failing due to fretting & corrosion. Upon mounting the bearings in the housing with Tolerance Rings, they no longer encountered fretting & corrosion and endured for their full design life-cycle.
Repair Worn or Oversized Housing Bores:
Tolerance rings can be used to reclaim worn housing bores or bores which have been accidentally machined oversized. By adjusting the inside diameter with additional machining to accommodate the Tolerance Ring, the original intended (or alternate) ball bearing size can be installed. AN-style rings for popular ball bearing sizes are packaged individually and sold as TR packs in the aftermarket.
Bearing Series
| Bearing Number | d Nominal | BRG O.D. d (in) | BRG W W (in) | Part Number | Radial Capacity | Typical Bore for Bearing Mount | |
|---|---|---|---|---|---|---|---|
| D min (in) | D max (in) | ||||||
|
R3 R4 34 35 38/608 R6 6000 6001 R8 6200 6201 6202/6300 6301 6203 6302 6204/6303 6205/6304 6206/6305 6305W 6207 6306 6208 6307 6209 6210 6308 6211 6309 6212 6310 6213 6311 6214 6215 6312 6216 6313 6217 6314 6218 6315 6316 6317 6318 |
1/2 5/8 16 mm 19 mm 22 mm 7/8 6 mm 28 mm 1-1/8 30 mm 32 mm 35 mm 37 mm 40 mm 42 mm 47 mm 52 mm 62 mm 62 mm 72 mm 72 mm 80 mm 80 mm 85 mm 90 mm 90 mm 100 mm 100 mm 110 mm 110 mm 120 mm 120 mm 125 mm 130 mm 130 mm 140 mm 140 mm 150 mm 150 mm 160 mm 160 mm 170 mm 180 mm 190 mm |
0.5000 0.6250 0.6299 0.7480 0.8661 0.8750 1.0236 1.1024 1.1250 1.1811 1.2598 1.3780 1.4567 1.5748 1.6535 1.8504 2.0472 2.4409 2.4409 2.8346 2.8346 3.1496 3.1496 3.3465 3.5433 3.5433 3.9370 3.9370 4.3307 4.3307 4.7244 4.7244 4.9213 5.1181 5.1181 5.5118 5.5118 5.9055 5.9055 6.2992 6.2992 6.6929 7.0866 7.4803 |
0.1960 0.1960 0.1969 0.2362 0.2756 0.2500 0.3150 0.3150 0.2500 0.3543 0.3937 0.4331 0.4724 0.4724 0.5118 0.5512 0.5906 0.6299 0.9055 0.6693 0.7480 0.7087 0.8268 0.7480 0.7874 0.9055 0.8268 0.9843 0.8661 1.0630 0.9055 1.1417 0.9449 0.9843 1.2205 1.0236 1.2992 1.1024 1.3780 1.1811 1.4567 1.5354 1.6142 1.6929 |
AN12.7X5S AN16X5S AN16X5S AN19X6S AN22X7S AN087025S AN26X8S AN28X8S AN112025S AN30X9S AN32X10S AN35X11S AN37X12S AN40X12S AN42X13S AN47X14S AN52X15S AN62X16S AN62X23S9 AN72X17S9 AN72X19S9 AN80X17S9 AN80X20S9 AN85X19S9 AN90X20S9 AN90X22S9 AN100X21S9 AN100X25S9 AN110X22S9 AN110X25S9 AN120X22S9 AN120X25S9 AN125X22S9 AN130X25S9 AN130X31S9 AN140X25S9 AN140X33S9 AN150X25S9 AN150X33S9 AN160X25S9 AN160X33S9 AN170X39S9 AN180X39S9 AN190X39S9 |
180 250 250 420 550 580 770 840 720 980 670 820 900 1000 1200 1400 1600 2000 3600 2900 3600 3250 4000 4300 4550 5350 5100 6550 6525 7190 7190 7950 7480 8550 10500 9200 12200 9950 13000 10550 13950 17250 19000 20500 |
0.555 0.680 0.685 0.823 0.941 0.950 1.098 1.177 1.199 1.256 1.334 1.452 1.531 1.649 1.727 1.924 2.140 2.533 2.533 2.910 2.910 3.224 3.224 3.422 3.618 3.618 4.051 4.012 4.406 4.406 4.799 4.799 4.996 5.193 5.193 5.587 5.587 5.980 5.980 6.374 6.374 6.767 5.161 7.555 |
0.558 0.683 0.688 0.826 0.944 0.953 1.101 1.181 1.203 1.259 1.338 1.456 1.535 1.653 1.731 1.928 2.145 2.538 2.538 2.913 2.913 3.227 3.227 3.425 3.621 3.621 4.054 4.015 4.409 4.409 4.802 4.802 4.999 5.196 5.196 5.590 5.590 5.983 5.983 6.377 6.377 6.770 7.164 7.558 |
