Retaining Rings Make Shaft-SenseApril 05, 2017
What Makes Retaining Rings the Right Solution?
In today’s mechanical motion systems, the vast majority of power transmission is rotational, and, as a result, shafts are omnipresent in everything from motors in UAV drones to 3-D printers. When shafts are assembled into final products, fasteners are placed at the ends or at fixed linear distances along the shaft where components need to be located. Traditional fasteners like screws, nuts, bolts, cotter pins, and washers require threading, tapping, drilling, and other machining operations. Retaining rings are metal fasteners installed into a groove on a shaft or in bore creating a shoulder that resists thrust loading and keeps the assembly together.
There are three main types of retaining rings: Constant section retaining rings feature a uniform, constant section that provides three point contact with the groove. Tapered section rings grip the entire periphery of the groove along the ring’s edge. Spiral rings are wound from a single section of flat wire and provide 360 degree axial contact.
Retaining rings provide several advantages over traditional fasteners. They almost always provide a smaller finished design footprint with reduced weight. A single retaining ring can replace multiple pieces of hardware in an assembly. There is no need for complicated shaft or housing preparation such as threading, tapping, and drilling leading to lower fabrication time and costs. Lower cost hardware and reduced labor costs mean an economical fastening solution for the manufacturer.
Retaining rings are used industry wide and can be found throughout cars, trucks, and other rolling vehicles. Aerospace products are full of retaining rings from high bypass turbofan engines to fly-by-wire control surfaces. Other industries that rely heavily on retaining rings include wind power, power generation, oil and gas, power tools, motion systems, and HVAC to name just a few. Retaining rings’ light weight, simple, and fast assembly properties make them ideal candidates for product assembly simplification and cost reduction.
Spiral Retaining Ring’s Unique Assembly Proposition
Spiral retaining rings are a simple, elegant solution for retaining ring applications that require 360 degree contact with the groove and shoulder of the part being assembled. They are designed not unlike a torsion spring and allow expansion (unwind) to slip over shafts and contraction (wind) to squeeze into bores. Spiral retaining rings require additional force to operate over taper and constant section rings, and, in return, offer a stronger fixing strength for the assembly. These rings are manufactured by coiling a single flat wire and can be single or multi-turn; depending on the application requirements giving spiral retaining rings a broad range of standard and custom sizes up to 25 inches in diameter. Key advantages of this manufacturing technique are that there is no stamping waste or edge burrs and no concern about orientation of metal grain. Rolled flat wires have a natural radiused edge making them easier to slide into or onto position. Dedicated tooling is not necessary, making spiral retaining rings attractive for low-quantity custom applications. This manufacturing method avails itself to popular materials such as carbon and stainless steel as well as alloys such as Inconel, Hastelloy, and beryllium copper.
A good example of this unique solution provided by spiral rings occurred recently when a customer came to Rotor Clip, a leading source of retaining rings, with a need to modify the dimensions of a tapered section retaining ring. The client wanted to increase the thickness of the ring to counter higher than expected axial (thrust) loading in the assembly. Simply manufacturing a thinker ring per the customer request would involve the expense of new tooling to stamp the part or changing the manufacturing process to a custom laser cutting, which would also be more expensive than desired. On top of these additional costs, dimensional changes would have to be made to maintain proper aspect ratios for assembly and spring force retention properties as well as tightness of fit would be affected by the change. Doubling up of two standard rings was explored, but the increased chance of assembly error created unacceptable quality issues. Looking at the core requirements of this application, Rotor Clip engineers were able to use the flexibility of the spiral retaining ring by doubling the number of turns to four. This solution required no special tooling with its affiliated costs and potential project delays offering the customer everything they were looking for: a simple, quality part that meets application demands without the extra costs affiliated with a custom design.
Rotor Clip Company—A Mechanical Assembly Resource
Rotor Clip manufactures a full line of tapered retaining rings, constant section rings, spiral retaining rings, and wave springs to world standards and supports its market with a full line of installation tools, including applicators, pliers, dispensers, and automated assembly equipment. They also offer self-compensating hose clamps featuring the latest innovations in engineering, R&D, and testing. Rotor Clip manufactures in the USA at a 238,000 square foot facility in Somerset, New Jersey, and also has operations in Sheffield, England, Idstein, Germany, The Czech Republic, and Shanghai, China—providing worldwide service to its customers. The company is certified to ISO 9001, ISO/TS 16949, AS 9100, and ISO 14001 and has received numerous quality awards from major OEMs, automotive manufacturers, and distributors worldwide. To encourage designers and engineers to realize the benefits of using retaining rings in their designs, Rotor Clip offers a very responsive sample request service and provides support for the marketplace before and after the sale by providing technical assistance, product training, and cost-reduction programs, along with competitive pricing and JIT delivery.
The automotive industry offers an impressive though certainly not complete illustration of the many components and assemblies in a car that can be improved through the use of retaining rings.
Retaining rings can be a solution for the cost and weight reduction goals you would like to achieve in your designs. Simplification of component machining and assembly as well as part count reduction could provide your business with additional labor and inventory cost savings. Rethinking assembly to incorporate retaining rings is a worthwhile investment for all engineering teams that produces results.
Rotor Clip Company, Inc.
187 Davidson Avenue
Somerset, NJ 08873 USA