Fatigue Strength:
C-Flex tests at 10e7 cycles using, a conservative value of 75,000 psi flexure bending stress for modelling and indefinite life.
See Material Properties.

Material Properties:
What are the standard material specifications?
See Material Properties.

Maximum Rotation:
See Life Projection Curves.

What is the operating temperature of the bearing?
Between -100 deg. F to 375 deg. F. The bearing can be held up to 450 deg. however for no more than 8 hours otherwise damage may occur.

Life expectancy question:
Q: If rotated 25 deg. but only in one direction from zero deflection, and the radial and axial loads are low, what would be the cycle life?
A: Since the bending stress is non-reversing (0-25 deg.), cycles should be 500,000 to 1 million cycles.

Corrosion Question:
Q: If the bearings are made of stainless steel, why do you use dessicant in packaging?
A: The high strength stainless steel is 400 series stainless and will corrode under certain conditions. We try to protect against this in storage and shipping to provide the best overall quality part that will ultimately arrive at our customers facility.

Loading the bearing with a moment load:
The C-Flex specifications are for loads applied at the OD of the bearing, directly through the centerline of the bearing. When a load is applied in an offset manner, it creates a moment load or rotational force through the bearing center as determined by the force and length of lever arm (distance from the center of the bearing). This moment load creates a condition of placing one of the outer flexures in tension and one in compression. In evaluating bearings which have failed due to this type of loading, it is an obvious cause of failure. Compression overloading is a common misuse of the bearing and will cause it to fail.
Please call C-Flex if a diagram is preferred for reference.
To correct for this situation, the customer has 3 options:
1. Choose a larger bearing with heavier load capacity.
2. Reduce the load.
3. Reduce the moment load through better alignment or reduced offset from center. Moment loads, especially in dynamic situations are relatively complex issues, which may take several attempts to achieve success. Customers should take care to determine the actual combined load at the bearing OD which includes static as well as acceleration related dynamic loads.

Q: How do I install/mount the bearing?
A: See C-Flex Typical Locator Flat Dimensions. *C-Flex will put locator flats on the bearings at a small additional charge for sizes B and larger.
A: See site page Loading Diagrams. Suggested Methods for Installing C-Flex Bearings. These are available by downloading the C-Flex brochure, a .pdf file.
The preferred method is by set screw making sure the load is centered between two springs and NOT bearing down through one spring.
Q: What is the Recommended Tightening Torque?
Q: What size set screw should I use?
A: See page: Set-Screw Size & Tightening Torques.

Q: Can I use adhesive/epoxy?
A: If using EPOXY, apply through a perpendicular hole, taking care not to allow the adhesive to migrate into the bearing structure where it will impede performance.

Q: Can I press fit the bearing?
A: Press fitting is NOT recommended (ESPECIALLY FOR THE -10 series BEARING) although feasible as long as the maximum axial load rating is not exceeded during the pressing process (see chart for bearing properties, Lc and Lt). Consider SHRINK FIT as an alternative: cool the bearing to -100 deg. F (liquid nitrogen) and heat the mating part to allow the shrink fit upon temperature normalization.

Q: How do I determine moment loading?
A: Moment loading and expected bearing deflection can be calculated using the Radial and Axial Stiffness Chart (found in our .pdf downloadable brochure) once the mass c.g. is determined using vector diagramming or FEA analysis. This is up to the customer to determine.

Q: Centershift Questions.
A: The centershift is basically an exponential relationship which is largely unmeasureable at small angles and diameters, yet progresses to relatively large proportions at large angles of deflection of large bearings.
A: When the C-Flex bearings are rotated, they exhibit geometric centershift. It is a radial movement of the bearing segments relative to each other as they rotate. Assuming one end is restrained and the other is rotated, the axis of the rotated member moves radially although remains parallel to the original axis. This is predictable and is dependent upon the diameter of the bearing and amount of rotation. See chart on performance characteristics.

Calculating centershift using the downloadable chart from our .pdf Technical Brochure.
Example: Diameter and Angle of Rotation. 1.0" diameter rotated 5 degrees. From the chart on the x-axis a 5 degree deflection results in a geometric centershift of 0.08 (as a % of bearing diameter). Therefore, centershift would be 0.08/100 x 1.0" = 0.0008
Example2: For a 3/8 diameter (part no. F20) bearing, rotated +3degrees, using the chart at 3 degrees the geometric movement of center is 0.035% of bearing diameter . .375 x .00035 = 0.00013".

Q: What is the weight of ______?
A: See C-Flex Bearing Weight Chart (Grams).

Q: What is the difference between the double and single end bearings?
A: Mounting / Installation preference.
A: The double end bearings are slightly stiffer, radially, than the cantilever, by approx. 15% when mounted at both ends so the center is free to move. Axial stiffness is the same.
A: Under Radial and Axial Stiffness Properties, the data applies to standard cantilever bearings located at mid point of unsupported 1/2, at zero degrees rotation.
A: Total stiffness of a pair of tandem mounted cantilevered bearings connected very stiffly in a mechanical system is determined by dividing the values of downloadable .pdf file Radial and Axial Stiffness Properties from our Technical Brochure by 3. For double end bearings, divide by 2.

Q: Do you have a price list?
A: Please call for pricing.

Q: How accurate can you specify torsional spring rates?
A: Due to manufacturing and material variables, our flexure bearings are produced wth an advertised TSR range of +/- 10%. We can however measure the exact TSR (within +/-1%) of each bearing. There is a slight cost added for this service. Minimum life expectancy is 30 million cycles when the load and angle combine at a constant stress of 60000 psi.

Q: How is it driven?
A: The bearing is driven mechanically, electrically, via air.... whatever the application requires.

Q: Is the force required to cause rotation linear?
A: The bearing is linear on an x- y chart where y = force and x = angle of deflection. Constant linear torsional spring rate in either direction over range of travel. The cylindrical envelope which encases the crossed springs results in an axially and radially stiff structure. No grounding is need for electrical applications.

Q: Spring rate when zero load is applied - is this represented by torsional spring rate (lb-in/degree)?
A: The catalog values of TSR is determined at zero load.

Q: Is there a graph showing spring return rate, natural frequency, or delay in accceleration/deceleration?
A: TSR is how the bearing acts with zero load. As mass increases, so does the moment of inertia and relative energy needed to accelerate it. This effect would have to be determined by calculation FEA analysis or experimentation.

Q: Pivot Life Data and Comparison between Single and Double End bearing:
Q: Is there any life test data to determine the statistical distribution of the infinite fatigue line?
A: After life testing many single and double end bearings, we have never had a failure at the bearings rated angle (e.g 20 series = +/- 7.5 deg) of rotation when tested to ten million +/- oscillations. Also, we have never had a failure below 220,000 cycles when testing to 150% of the rated angle, nor below 35,000 cycles when tested to 200% of the rated angle. This is a result of a 25% de-rating from their actual max. to provide an adequate margin of safety. We can provide a quotation for life cycle testing to specific rotation angles if necessary. (Standard bearings).

Q: Understanding Radial and Axial Stiffness Note in brocure... the note indicates that the radial stiffness no.s (Lc, Lt) in in/lb for single pivots are to be divided by 2 (this doubles the stiffness) for the double end bearings. Is this true? Assuming that the axial stiffness is the same for both single and double end?
A: The double end pivots have a greater radial stiffness due to their typical mounting where each end is rigidly fixed, thereby avoiding the catilevered load and moment load affects seen by the single end bearing. The axial stiffness for both single and double is the same.

Q: Is load capacity the same for single and double end?
A: Yes.

Q: Is radial runnout half for double end compared to single end?
A: Radial centershift is the same for both single and double end.

Q: Is TSR the same for both single and double end?
A: Yes.

Q: When using a double end bearing, should the mid section be supported?
Q: How do I install / mount/ use the double end bearing?
Q: How does the double end bearing work?
A: The normal method for utilizing the double end bearing is either to mount the two ends rigidly, and allow the center section to rotate, or vice versA: The two ends are ridigly connected to each other, and rotate independently of the center section. The bearing cannot rotate if any portion of the center section is rigidly clampled ALONG WITH the outer section.

Q: Best method for retaining the bearing?
A: Set screws are the recommended method. Some customers utilize low viscosity adhesives which can wick into the bearing/linkage interface before setting. It is not absolutely necessary to utilize bearings with flats, as the set screw can impinge directly on the OD, as long as it is in the heavy or solid section of the outer sleeve.

Q: Geometric Centershift or Hysteresis?
A: In many cases the effect of centershift / hysteresis is balanced out between multiple bearings however at a rotation of 2.5 degrees, the de-centering movement of a single set of bearings will be less than 1 micron. * Call C-Flex for your specific application.

Q: Any thermal restrictions on the bearing?
A: The temp. range we provide, -100 F to +375 F is a conservative value for continuous operation. They can be cooled and heated to ranges well in excess of these temperatures PERIODICALLY without damage.

Q: Not sure how to assess my application against the TSR for the bearing?
A: The TSR is merely a function of how much force it will take to cause the bearing to rotate. This is required for customers who have only limited amount of energy to expend and need to know the total energy requirements of their system.

Q: Vibration
A: The bearing does NOT stop vibration transfer.

Q: Frictionless
A: There is no energy loss due to friction.
A: There is an extremely predictable rotation movement in response to the external force.
A: Accurately produce specific amounts of rotation in response to an energy input. Other bearings simply facilitate the motion.
A: They do require continuous energy to rotate to a certain position and hold it because of their natural self centering ability.

Q: Temperature changes.
A: Uniform expansion and contraction will occur without a change in rotational axis or position.

Q: What is the load rating:
A: The load rating is the maximum load Lc or Lt which is recommended for extended cycle life. Lc is the direction of radial load which places the flexures in compression and Lt places them in tension.

Q: Why are Lc and Lt different?
A: Thinner flexures (10 and 20 series) can experience buckling under large compressive loads, however do not experience this problem in tension.

Q: Why is determining Load important?
Loads on the bearing create stress in the flexures, which along with the bending stress created during rotation, must be considered in determining the life expectancy of the bearing. As the load increases, the angle of rotation must be decreased to maintain indefinite cycle life. Please consult the life cycle curves for each series bearing (10, 20, 30) to determine allowed angle of rotation with expected load values.

Q: Why are there three series bearings (10,20,30)?
A: The 10 series bearings have the thinnest flexures, which allow the greatest angle of rotation (+/-15 degrees), however are restricted to relatively light loads. The 20 series has heavier flexures and can support heavier loads, however at smaller angles of rotation (+/- 7.5 degrees). The 30 series has the heaviest standard flexures and can support the largest loads, however at the smallest rotation angles (+/-3.7 degrees).

Q: What is the shock load capacity?
A: The load ratings published for the bearing operation are operating loads needed to determine life expectancy. Shock loads of 1.5 times the published load ratings can be experienced by the bearings without damage, as long as the bearing is in the undeflected (null) position.

Q: How does the TSR value work?
A: For example, a force moment of 0.9486 lb-in applied to one end of a J-20 bearing will cause it to rotate 1 degree about its axis of rotation.

Q: Can I get a bearing which has greater radial or torsional stiffness than the standard parts listed?
A: C-Flex can usually satisfy customer requirements by utilizing heavier flexures, heavier core structure, or even paired flexures for larger sizes.

Q: Can I get a bearing which has a greater angular rotation (>15 degrees)?
A: Large loads and high angles of rotation are mutually exclusive properties, however in some cases C-Flex can provide bearings which will operate at greater than +/- 15 degrees for applications with very light loads.

Q: What other types of customizing can C-Flex provide?
A: In addition to greater stiffness or higher angles of rotation, C-Flex can provide extended length or shorter bearings, special diameters, custom TSR, and very large capacity (5000 lbs plus).

Q: What can cause a bearing to fail?
A: Excessive loading can cause flexures to buckle when placed in compression, or braze joints to fail if in tension. Flexures can fracture if placed under excessive loads during constant rotation. Flexures can also fracture if operated at angles higher than recommended for extended periods.