For precise equipment, ensuring an optimum coupling is vital for performance and reliability. For over 50 years Huco has offered a wide range of standard couplings designed to meet the needs of the precision automation, motion transfer, medical and laboratory sectors. However, as application demands for couplings in these industries can vary widely, Huco offers machine builders a dynamic customization service based on this proven range.
The Huco catalog is made up of a series of different coupling styles, each one designed to accommodate varying degrees of misalignment and perform to different levels of precision. While all offer zero-backlash characteristics to ensure positional accuracy, different couplings use different mechanisms to suit specific misalignment scenarios. Ensuring misalignment is properly accommodated means that mechanical stresses and loads are not unduly transmitted to associated equipment such as bearings and drives. Huco’s Bellows, Beam and Oldham couplings each take a different approach.
Bellows couplings owe their name to the flexible steel membrane mounted between metal hubs that connect to the users’ shafts. The bellows can bend to accommodate misalignment, a capability that can be enhanced by increasing its length. Adding to this benefit, Bellows couplings are torsionally stiff, providing high accuracy which allows for excellent positional feedback. This makes them ideal for closed-loop servo systems, as, while the bellows can accommodate misalignment, their intrinsic stiffness raises the resonant frequency of the system, thus maintaining system stability while ensuring positional integrity.
Typically machined from a single piece, Beam couplings are single components, which eliminates the possibility of components separating.
Beam couplings have slightly lower stiffness due to their spring-like construction. Typically machined from a single piece, Beam couplings are single components, which eliminates the possibility of components separating. Additionally, Beam couplings can be manufactured in a wide variety of diameters and lengths, which provides versatility. Beam couplings can be directly machined onto shafts as complete assemblies. Their relatively simple construction also ensures a lower cost than many alternatives.
The simplicity of Beam couplings ensures they combine high accuracy and low inertia, which is ideal for driving encoders, helping to deliver accurate positioning.
A flagship coupling in the Huco range, the Oldham solves the problem of side forces due to misalignment. Misalignment couplings that bend or flex do cause some side loading on bearings and shafts as the coupling tries to ‘spring back’. Of course, over prolonged use can result in rapid deterioration of bearings, extra load on the motor, and eventual coupling fatigue.
The Oldham coupling design accommodates misalignment by allowing sliding between metal hubs and a plastic disc, and so does not create any lateral forces.
The Oldham coupling design accommodates misalignment by allowing sliding between metal hubs and a plastic disc, and so does not create any lateral forces. This effectively protects equipment from the side loads, improving reliability. Discs are made from engineering plastics and are replaceable and interchangeable for different properties. Standard discs are Acetal, for strength, but Nylon discs can also be chosen for resilience or damping properties.
PEEK discs are sometimes chosen to insulate against electric current leakage or heat transfer. Furthermore, the disc can provide overload protection, as it will break under extreme load to protect associated equipment. The Oldham’s three-piece construction allows easy assembly and installation too.
While a general-purpose coupling, the Oldham is particularly suited for use in stepper-driven positioning, as it handles high torques while still delivering high accuracy.
The need for customization
The precision applications that Huco’s couplings are designed to fit demand a high level of specialization. The design of a motion system in, for example, medical devices or food production lines varies greatly, so a ‘one size fits all’ approach isn’t optimal for precision couplings. The coupling may have to fit a predetermined shaft size or operate within the constraints of existing device packaging. To meet this need, Huco can extensively customize couplings to meet unique requirements.
Huco can design and deliver custom Beam, Bellows, and Oldham couplings to fit shafts from <1 up to 50 millimeters diameter. Designed to provide couplings in low volumes to support prototyping, testing, or small production runs, customers can expect the design process to be complete in a few days and orders produced and delivered within 10 working days – well ahead of average UK delivery times.
The service is enabled thanks to a high-tech lean manufacturing facility that allows custom designs to be realized quickly. This also means that Oldham and Beam couplings can be machined onto custom shafts as a complete assembly. Injection molding and 3D printing are also available to produce unique components.
Anything but standard
Different coupling designs accommodate misalignment in different ways. Huco’s standard range of couplings offers design engineers a wide range of solutions to accommodate it, along with consistent zero-backlash capabilities, to safeguard the reliability of associated equipment.
However, when it comes to specifying couplings for precise machinery, a standard coupling will not always provide the specialization that is often required. For engineers requiring a single coupling, machine builders building and testing a new prototype, or device makers starting a production run – an off-the-shelf item may not provide an optimal solution to secure reliability and performance.
To serve these specialized devices and machines, Huco, a leading brand of Altra Industrial Motion Corp., has built a global customization service based on a proven range of standard couplings. An extensive in-house capability means that custom solutions can be delivered efficiently, exactly to specification. Ultimately, providing couplings for precision applications is anything but standard.