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RENCOL® Tolerance Rings As A Slip Clutch
Both inline fixer and torque limiter, the RENCOL® Tolerance Ring is a robust, consistent and space-saving slip clutch offering mechanical protection.
The benefits of using a RENCOL® Tolerance Ring as a Slip Clutch
Simplified Solution - System torque limitation is provided through a singular RENCOL® Tolerance Ring. Mechanical protection is provided immediately, removing reliance on complicated electronics. After a torque slip event, the tolerance ring is immediately ready to provide protection from a future torque overload condition.
Space Saving - Both inline fixer and torque limiter, the RENCOL® Tolerance Ring is a robust, consistent and space-saving slip clutch. Providing slip clutch function within a radial space of around 1mm, reducing overall system weight and packaging size. Designed in diameters of 3mm to 300mm into your system, allows for smaller and lighter mating components.
Custom Design - The RENCOL® Slip Clutch is designed for your specific use case and engineered to your specific slip torque threshold (from 0.2Nm up to over 2000Nm). If the torque threshold is exceeded, the tolerance ring allows the components to slip, protecting the mechanical components from damage.
SIMPLIFIED SOLUTION - How Does a Slip Clutch work? 
As with any clutch, a slip clutch using RENCOL®, also known as an overload clutch or a torque limiter, is there to protect two mechanical components from each other. The slip clutch controls the torque by slipping between the two mating components. If the torque is exceeded or the output drive receives a shock load, the tolerance ring allows the components to slip.
After the slip, the RENCOL® Tolerance Ring automatically resets. The machine or robot can simply carry on with its operation, uninterrupted and with no delays.
Easy to install, the RENCOL® Tolerance Ring slides coaxially into the drive assembly – there’s no need for any major overhauls to retro fit the ring.
The RENCOL® Tolerance Ring is made from quality carbon steel, stainless steel or alloys, and uses both spring force and friction to operate. Its corrugated wave construction provides the necessary radial force. We use Spring Theory to calculate the force required to hold everything together, more details about Spring Theory can be found here.
SPACE SAVING - Why Use a Slip Clutch?
Instead of wasting space with separate inline fixing and a slip clutch unit, the RENCOL® Tolerance Ring does both jobs. You’ll save space, reduce weight and cut your costs.
The RENCOL® Tolerance Ring fixes two driven components together, transferring torque. If a threshold is exceeded, the tolerance ring offers overload protection by allowing the components to slip relative to each other, limiting the torque and protecting the system from damage.
Torque slip devices also known as torque limiters and overload clutches can be complicated systems with many components. A RENCOL® Tolerance Ring solution uses one component in-line with the mating components to reduce weight, space and overall cost.
The space saving for tolerance rings is enabled because tolerance rings work as an inline fixing between the driving and driven components. This means there is no need for an extra slip-clutch unit which takes up more space and weight.
This enables engineers to use lighter materials and to design less bulky systems; as the RENCOL® Tolerance Ring is highly efficient in protecting the components from overload.
CUSTOM DESIGN of RENCOL® as a Slip Clutch
One size doesn’t fit all. Each RENCOL® Tolerance Ring is designed in collaboration with our customers, engineer to engineer. A tolerance ring isn’t just a stand-alone component – it’s part of a larger system. RENCOL® Tolerance Rings are created by our engineers to suit your individual application; however, all our rings share the wave-based structure.
The tolerance ring is designed so the top of the waves embed slightly into the mating component, while the base of the waves acts as the slip surface. The wave compresses to provide a radial force, which acts as the spring force that provides the friction between the components to provide mechanical damage control and limit torque through slipping. Depending on the system, the RENCOL® Tolerance Ring can be designed to slip onto the shaft or bore. Coating the ring with a proprietary dry lubricant eliminates the need for manual greasing.
Each slip clutch is tested inhouse, using the correct mating components and under accurate conditions, to ensure that it’s 100% compatible with your system. You can have complete confidence in every component we create for you.
Torque Overload Protection For Individual Systems
The RENCOL® Tolerance Ring is custom designed to the optimal torque level, rather than having to choose a level.
Tolerance ring designs for 0.2 Nm to 2000 Nm torque range and beyond are possible (depending on the physical dimensions and strength of the individual system).
Figure 1: These are theoretical guidance values for typical tolerance ring configurations. It is possible to have applications outside these limits – please contact us to discuss.
Some applications require consistent torque over a large number of slip cycles. The RENCOL® Tolerance Ring can be designed to reduce torque-drop over multiple slip cycles, giving a consistent performance for the life of the system.
Figure 2: Typical torque performance of a 50mm diameter tolerance ring on a steel shaft over 5000 slip cycles.
Torque Slip Applications
A slip clutch protects equipment from a mechanical overload, this could be protecting a system from damage caused by input shocks, unexpected blocks or end user error. Slip clutches are commonly found in electric motors for robotics and automotive systems such as belt drives, powered tailgate hinges and braking-assist systems.
Torque slip devices come in many forms such as: magnetic clutch, friction slip devices, and ball detent devices. Compared to a RENCOL® Tolerance Ring, all of these devices require more space to reach similar levels of torque.
During daily operation, the RENCOL® Tolerance Ring helps to provide smooth operation, reducing vibration and noise.
RENCOL® Tolerance Ring as a Slip Clutch in a Servo Motor
The RENCOL® Tolerance Ring is introduced between the drive gear and the output shaft, so if, for example, the output drives against an obstruction, or receives a shock load, the Rencol ring will permit momentary slip between the gear and the shaft. The output shaft position is monitored by the servo angle sensor or potentiometer, so when slip occurs, the system ‘knows’ what happened and can deal with it whilst not losing positional registration.
The ring can be engineered so slip occurs at a torque level suited to the rating of the servo, or to that of the driven system, depending on what should be protected. The graphs in the 2 charts below show 0.4Nm torque slip, but an even higher torque setting of 2.5Nm for this particular servo would be possible with a RENCOL® Tolerance Ring design.
Torque slip results by no of cycles
Torque slip results by angle
RENCOL® Tolerance Rings as a Slip Clutch in a Spindle Drive
Within the automotive sector, the RENCOL® Tolerance Ring is used in exterior applications such as automated tailgates and side doors. In these applications the RENCOL® Tolerance Ring introduced between the worm gear hub and the spindle drive, either directly or via an adaptor hub in the worm gear, so if, for example, the output drives against an obstruction, or receives a shock load, the RENCOL® Tolerance Ring will permit momentary slip between the worm gear and the spindle drive, protecting the system from damage.
The main advantages of the RENCOL® Tolerance Ring in these applications is that of space saving and common architecture for the system - regardless of the torque level required.
The ring can be engineered so slip occurs at a torque level suited to the weight of the tailgate or side door, using the same mating components. Typical nominal torques required for these type of systems range from 1.0Nm to 6.0Nm.
How We Make a Big Difference
A Tolerance Ring isn’t just a stand-alone component; it is an integral part of a larger system that means a detailed, knowledge-based approach is needed for tolerance ring design. That is why a RENCOL® Tolerance Ring is designed in collaboration with our customers, engineer to engineer. This process is made more powerful by using our FEA capabilities along with in-house testing to analyze the system, with mating components included and under key conditions. This means that we and our customers can have confidence in the solutions we provide.
Benefits of using a Tolerance Ring as a Slip Clutch 
• Protects system from shock
• Reduces system inertia and increases responsiveness
• Reduces noise and vibration
• Two-in-one – acts as both inline fixing and torque protector
• Space saving – small installation envelope
• Provides consistent torque over multiple slip cycles, preventing drop
• Automatic resetting – no wasted time
• Design into system or retro fit
• Each ring individually custom-made
Speak to the team at Saint-Gobain
If you have an engineering challenge, talk to us at Saint-Gobain. You can contact us using the contact us form or email us at: makingabigdifference@saint-gobain.com.