Precision Flexible & Rigid Shaft Couplings


In This Issue:	Recent News from OEP:
Coupling Selection for Robotics Applications OEP's Classic Block Coupling Creatures of Habit OEP Couplings A Division of: Oren Elliott Products, Inc. 128 W. Vine Street Edgerton, OH 43517 USA Phone: 419-298-2306 sales@oepcouplings.com www.oepcouplings.com	Coupling Selection for Robotics Applications OEP Offers an Ideal Solution with Oldham/Universal Couplings In determining the best choice of coupling for your robotics applications, there are several key factors to consider. Backlash, often called lash or play, is the clearance between mating components and is sometimes described as the amount of lost motion. Backlash is not acceptable in robotics or other motion-control applications because as it interrupts the transfer of power, it dramatically decreases positioning accuracy. It also presents timing problems which cause unnecessary coupling movement and stresses which contribute to early failure. In selecting a coupling for robotics applications, it is imperative to choose one with zero-backlash. It is also very important to limit vibration in motion-control applications where it wastes energy and stresses system components. Damping would help minimize the transfer of shock and vibration across a coupling. The coupling selected should not contribute to vibration in robotics applications and ought to deliver the required damping. Robotics and other motion-control applications are typically designed with intermittent starts and stops. Inertia is the next key component in determining the correct coupling for your application. Couplings with a low moment of inertia do not have as much of an effect on the natural frequency of the system and thus allow engineers to fine-tune their systems for optimized performance. The next determining factor in coupling selection is shaft speed. Quick failure is in store when safe operating speed of the chosen coupling has not been taken into consideration. A coupling's stiffness and its ability to accommodate shaft misalignment are two sometimes overlooked factors to consider when determining the couplingâ€™s safe operating speed. In high-speed applications, coupling balance is key in the prevention of excess system vibration. Electrical and mechanical isolation are two more selection constraints to consider. Using nonmetallic or polymer inserts will maintain mechanical energy transfer while also preventing the flow of electrical current between functional components. Deciding whether to use a coupling that acts as a mechanical fuse (i.e. one that keeps energy from transferring between parts after failure), versus fail-safe coupling (i.e. one that continues to transmit rotation after failure), is dependent upon issues such as whether the interruption of material flow would cause safety concerns. Choosing the correct coupling for robotics and motion-control applications is simplified when you consider OEP Couplings' exclusive line of high performance Oldham/Universal couplings, which are precision machined from high strength materials. Each of OEP's Oldham/Universal variations (types UA, UI and UC) deliver the low rotational inertia and zero-backlash necessary in precision positioning applications. OEP's Oldham/Universal couplings can be customized on-site to meet your exact requirements. OEP's Classic Block Coupling Everything Old is New Again A classic block coupling works on the same principle as an Oldham coupling and can be considered a simple variation of the Oldham with the grooves in the hub, instead of in the mid. The block coupling does not have the mechanical fuse feature found in the Oldham (where under excessive torque, the inexpensive midsection will break leaving the hubs intact). When the block coupling is under excessive torque, the midsection won't break until the hubs fail. Thus, the block coupling is useful for applications requiring a fail-safe coupling. It can also include an internal grease reservoir which makes it very advantageous for harsh or dirty environments. Typical applications for the block coupling include submersible pumps, and agricultural and garden equipment. Everything old is new again at OEP Couplings. OEP offers type BC Block Coupling, a precision-CNC-machined unit. Because the couplings are machined from high strength alloys like 7075 aluminum and 17-4 stainless steel, OEP is able to manufacture units with higher torsional stiffness, longer service life and more consistent performance from one coupling to another. These advantages along with large radial and axial misalignment, low reactive forces, homokinetic transmission and zero backlash make the block coupling an attractive solution for the design engineer looking for a fail-safe alternative to the Oldham. Creatures of Habit Because we are all human, there is something we must do each and every day to ensure that our day runs smoothly. One person has to have a Diet Coke every morning at 9am; another might need to mow the lawn in a very particular alternating pattern each and every week of thesummer. Everyone has a habit that makes them unique and that helps to define their personality. People we look to for wisdom and guidance have confirmed that it is OK to settle for suboptimal solutions. For example, your dad may have related "if it ain't broke, don't fix it" a few times. Consequently, we often suffer from the Einstellung Effect. This is the human tendency to repeat a known solution, even if it no longer is optimal. We believe we know the best solution and therefore do not fully evaluate new or different ways to solve our everyday and work related challenges. We do look for satisfactory solutions and all too often everything does seem to work just fine...until something goes wrong further down the road. Being creatures of habit prevents us from reinventing the wheel for every project. However, after learning to solve a problem one way, we are often blind to more efficient methods. Design engineers are susceptible to the Einstellung Effect while in the process of choosing the correct coupling for their projects. Unfortunately, specifying out of familiarity often creates a divergence between e quipment needs and coupling capabilities. Being overly cautious with respect to cost of a coupling or choosing based on price to reduce machinery costs, typically works only on the upfront component costs. For example, the low-cost jaw coupling is often chosen as the default flexible coupling ignoring the fact that it is not that flexible. Considerable warranty claims can produce a huge negative effect on the product's profitability and reputation. Problems occur every time a coupling is chosen that is the wrong size for an application; the engineer must know and not guesstimate the forces and loads to which the coupling will be exposed. It is not the goal of the design engineer to develop a machine that is inefficient and costly. However, since it is the human tendency to repeat known solutions, all too often, incorrect couplings are chosen and improficient machines result. OEP Couplings offers expertise in the process of choosing the correct coupling. Each coupling is precision-CNC-machined with tight tolerances, optimal surface finishes and a geometry that maximizes peak torque. OEP's on-site engineers and machinists are highly skilled in the development and production of customized couplings.

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