The RENCOL® Thermoclad Tolerance Ring has been developed to solve the problem of thermal transfer, an issue which has become more prominent in electric motors. The challenge, presented to RENCOL®, was to increase the thermal transfer capability of tolerance rings so they could be used more effectively with stator mounting applications. This project resulted in the development of the Thermoclad bi-metallic material. The combined benefit of Thermoclad with our tolerance rings can help both with the thermal management and production of electric motors which are fast becoming a part of everyone’s future.
A tolerance ring is a custom-designed component that has waves, or similar features, that are used to join two cylindrical mating components. The waves of the tolerance ring act like springs; when compressed they create force which keeps the two components in position. The more the waves are compressed the greater the force created. By this tension, the two components are securely held together at an acceptable level of force to prevent damage to either the joining parts or surrounding mechanisms. How a tolerance ring works is fairly straight forward, however, the process to create them can be fairly complex, with each tolerance ring highly engineered to satisfy detailed specifications.
When designing a tolerance ring there are multiple factors to consider, some are listed below:
• mating component sizes and spacing
• minimum and maximum forces to be applied
• radial tolerances created by the force applied
• thermal expansion considerations
• the load that will be applied
• the load location and consistency
• component misalignment
• torque transfer
• slip torque
During the design phase Saint-Gobain engineers will be involved to capture and review the system requirements. Following this a design proposal outlining the design inputs and our recommendations is supplied for approval.
A tolerance ring has multiple uses and can be employed to satisfy a number of demands.
The trigger to use them is normally focused on one or two factors including: providing a certain radial load capacity, increasingly tight torque slip specifications, electrical conductivity and isolation characteristics, thermal expansion, heat transfer (solved by using our Thermoclad Tolerance Ring) and meeting a certain stiffness range.
Tolerance rings are used extensively in the automotive industry and with the shift to electric motors the demands being placed on component parts is changing. Cost and weight reduction have risen up the priority list and created a demand for lighter weight materials. The impact of this change and the use of alternative materials has resulted in new challenges:
• A difference in the thermal expansion coefficients of the materials, leading to retention problems.
• Costly assembly processes that are time inefficient and energy intensive.
Secure retention – Across thermal and tolerance ranges. The spring properties of the RENCOL® Tolerance Ring waves provide a more consistent range of forces over different temperatures, keeping your components together whatever the use case.
Reduce manufacturing costs – Maximise process efficiency by eliminating costly and time intensive heat shrinking or adhesive processes. A RENCOL® Tolerance Ring can help reduce the forces required to assemble parts, keeping the assembly requirements to a minimum.
Go Green – Reduce your carbon footprint by eliminating energy intensive processes. RENCOL® Tolerance Rings can be assembled at ambient temperatures and don’t need any further curing or cooling, saving you C02.
The wide range of applications and benefits that using a tolerance ring brings extend beyond the summary we have provided here. If you are interested in learning more about the different types and how they are designed, visit our The Ultimate Guide to Tolerance Rings pages
At Saint-Gobain we recognised that heat transfer was becoming an increasingly important factor, especially for electric motors. Standard tolerance rings are not optimised for the thermal transfer levels required to maintain a long and reliable eMotor life.
To overcome this, we have developed Thermoclad: a brand new, bimetallic technology combining a robust steel core with a softer, thermally conductive material.
Our tests have shown that our new Thermoclad technology increase the thermal transfer capability of tolerance rings by up to four times.
This means the gap between the best-performing thermal adhesive and a tolerance ring has closed – thanks to RENCOL® Thermoclad bimetallic material.
You get the advantages of using a tolerance ring: secure retention, low cost and greener production (no carbon-intensive heating and cooling stages), combined with the benefits of a high-performance thermal adhesive.
With RENCOL® Thermoclad engineers and designers working on electric motors now have more options. Across the four main eMotor applications, detailed below, Saint-Gobain have a RENCOL® Tolerance Ring to satisfy your use case. We have supplied over 100 million tolerance rings for electric motor applications; you are in safe hands.
The move to eMotors and the need for light weight components has caused a shift in the materials used in the manufacture of these parts. The aluminium housing used in electric motors will expand by temperature at a higher rate than the iron-based stator which can cause a drop off in retention force and, therefore, result in a dislodged stator. A RENCOL® Tolerance Ring can resolve this issue.
Roller bearings are an essential component in many rotating systems that require low friction. The choice of bearing mount method can have a significant effect on the roller bearing’s ability to perform. Press-fitting is a common method that introduces problems such as high assembly forces, loss of retention force of the mounted bearing at high temperatures and precision manufacturing costs. We’ve looked at the benefits that can be derived by using a tolerance ring as a bearing mount.
Also called a sensor mount or a simple fixing. Using a tolerance ring in this situation allows the sensor to be adjusted into position during fixing. Glue and adhesives do not provide the same flexibility during assembly. A tolerance ring can provide the secure, compact fixing needed whilst reducing assembly time and meeting the requirements for lightweight components.