Guest Blog Post from Rob Mastromattei, Sierramotion
There are many options to connect two rotating shafts together. The most obvious path is to use a rotary coupling. Unfortunately, while there are many couplings that can be purchased or made, choosing the right one takes some practice and a little bit of luck.
Rotating shafts all have some type of bearing system. The manufacturing tolerances on the shaft and the bearing system, (including bearings and bearing journals), play a role in what happens when two of them are connected together. When doing this, it is important to understand the total indicated runout (TIR) of each shaft and its bearing system.
If the two shafts are rigidly connected, then you have one long shaft with too many bearings on it, a recipe for disaster. This problem is easily solved with a flexible coupling that allows misalignment between the two shafts and flexes. The problem with flexible couplings is that many of them allow misalignment, but also have very low stiffness. A good example is a traditional power transmission coupling that has a rubber insert. These are great for running a pump at a continuous speed, but they lack the torsional stiffness needed for a precision servo system. Two shafts connected by a spring make for a complicated dynamic situation if you are starting and stopping precisely under servo control.
Flexible Shaft Coupling for Power Transmission Applications
The best solution when connecting shafts for a motion control application is to use a bellows coupling. These couplings are stiff torsionally and flexible in X and Y planes. Coupling torsional stiffness is directly related to servo tuning bandwidth. For high response, you need high stiffness.
Bellows Coupling for Servo and Precision Motion Applications
Motus Labs is planning to provide several options for connecting to its ML1000 precision gearing solutions. They range from using a bellows coupling and motor adaptor to more custom applications that integrate a frameless motor kit to the gearbox and eliminating couplings altogether.
Rob Mastromattei, Owner & Sales Engineer at Sierramotion
Bio: Robert has over 30 years’ experience in motors and motion control. Formal education in Physics and an MS in Mechanical Engineering provide a strong background in magnetics and motion systems engineering. He has worked for Sigma Instruments, Pacific Scientific, Kollmorgen, Semipower Systems, Applimotion, and Celera Motion. Robert was also a founder of Applimotion in 2000 and a founder of Sierramotion in 2019. With many years in design, application engineering, marketing, and technical sales, Robert has technical and industry knowledge in Motion Control.
Sierramotion engineers help customers design solutions to complex motion problems. The company then builds, tests, and supplies these unique products or provides a path to volume production. Whether it is a simple coil, or a precision motion assembly working in a vacuum, Sierramotion has the experience to create a solution that works the first time. If your production volume warrants a globally competitive contract manufacturing source, Sierramotion can help you find and transition to that source. If you need prototypes to validate the design or process, Sierramotion can make them in-house, test, and deliver. The team as Sierramotion has accumulated decades of experience and know-how designing and applying products in electro-mechanical systems with moving magnets or moving coils for rotary, linear, and arc-shaped applications.