There's a revolution going on in clutch/brake technology, thanks to advances in friction materials and the adaptation of electronics. Horton's Ron Losee talks about what all this means to customers today.
Design News: Development cycle times for just about all new products are shrinking, and clutch/brake technology is no exception. What have been some of the most significant developments in this area in recent years?
Losee: Two things: First, advances and developments in friction materials that allow greater controllability and more consistent performance under a wide variety of conditions, including heat, cold, high-speed, low-speed, high cycles rates and so on. The wider range of coefficients of friction now available allow the design engineer to tailor the performance of the clutch/brake system to meet very specific customer needs.
Second, the marrying of electronics with mechanical clutches and brakes to provide enhanced control of functions such as soft starts and stops, multiple operating torques, and so on, has had a tremendous impact on clutch/brake performance.
Q: What's behind the development of new materials and can you elaborate on what some of these materials are?
A: Historically, friction materials used to be the limiting part of the design. Any time you have a friction interface, you are going to be developing heat. It's a big challenge to dissipate that heat. Some of the new thermal spray coatings now available work really well. For example, you can spray these coatings onto an aluminum part and get some of the same properties as you get with steel.
Also on the materials front are new developments in plastics, composites, and lightweight metals to reduce weight and cost. By pushing the envelope with new materials like these, we're able to develop clutch/brake systems with significantly longer lives and that have consistent, repeatable performance.
Q: How else are engineers building reliability/longevity into their brakes and clutches?
A: We're increasing the heat sink capacity, optimizing matching materials to the application, and practicing good thermal management strategies. We're also using advanced tools such as solid modeling, FEA, FMEA, rapid prototyping, and accelerated life testing techniques to design the best product for the application.
One of the keys to building reliability into a product, however, is developing a good understanding of the application and the specific needs of the customer and target market.
Q: We keep hearing a lot about electronic control. In a survey Design News conducted of its readers, 10% reported using electronic control in 1995; by 1995 the percentage had jumped to 25%. What are some of the advantages of electronic controls when it comes to clutch/brake systems?
A: Ease of use, accuracy, flexibility (the ability to program different operations), and the ability to adapt to changing environments are some of the major advantages. Our customers also like the ease of setup, the precision and repeatability, and the responsiveness of electronic control.
One of the biggest benefits is the ability to network together the individual components of a system, enabling them to respond to multiple command signals and function as a fully integrated system. Servomotor brakes are a good example. The brake can be used for dynamic, static, and safety stops. In order to perform its function effectively, the brake must be able to interface with the servo control.
Q: Is there one breakthrough in clutch/brake technology that everyone is searching to overcome?
A: There is no single answer to that question. Each customer, depending on the specific application, is looking for a unique breakthrough. One customer might want higher torque in electromagnetic products, another needs better thermal management that can only be obtained through the use of new materials and processes.
Suppliers need to be constantly aware of the changing needs of their customers and provide equality of product design, performance, price, service support, and responsiveness. In a nutshell, the trend seems to be away from "one size fits all."†