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Most Important Electrical Considerations for Mechanical Engineers

• Create a clean mechanical design to ensure that whatever motion the machine undergoes, its long- term stability is engineered-in.

• Couple the motor directly to the load to greatly reduce windup and backlash, improving machine commissioning time.

• Utilize electronic gearing and Using direct drive, direct motors and linear motors vs. mechanical couplings allows camming to dramatically improve machine designers to run higher gains and improve machine performance. axes synchronization and accuracy.

By Dan Throne, Sales and Marketing Manager, Bosch Rexroth • Incorporate energy-efficient technology to cut down on Mechanical and electrical engineers often overlook operation costs and reduce wasted important issues when specifying their respective parts energy. of an electromechanical system. Consider these five targeted pieces of advice for mechanical engineers • Use HMIs for troubleshooting to responsible for electromechanical systems, as provided show where a problem is and steps by an electrical engineer. to take to put the machine in safe mode for maintenance. Mechatronic systems are the designing electromechanical state-of-the-art technology in systems, mechanical engineers These five considerations simplify automation systems, intelligently and electrical engineers may tend mechanical design challenges integrating mechanical and to emphasize the technologies, and provide resources for driving electrical elements to perform components and design innovation and creativity in increasingly complex and principles from their single area machine design. demanding functions. When of expertise—which can lead to systems with higher operating costs, mounted out of alignment with a increased maintenance demands pillow block bearing or gearbox and less than optimal performance. input planetary gear. Place motors As an electrical engineer involved in on the machine in the best location helping OEMs and manufacturers so that operators aren’t accidentally design and build mechatronic stepping on cables and connectors systems, I’ve seen how inefficiencies causing damage, and design and unnecessary complexity machine guarding with easy access can be unintentionally designed points to get to motors mounted into machines. under the wing base of the machine while still protecting them against With Rexroth’s IndraDrive Mi integrated Consideration #1: Create a harsh environments. motor/drive system, multiple drives are clean design daisy-chained together and share power Good mechatronic design starts Most importantly, a clean design from the same bus, significantly reducing energy consumption. with good mechanical design—the balances mass and motion: sturdy, best electronics and electrical durable framing that withstands systems can’t compensate for poor years of vibration and shock, a surprising number of machine mechanical design. The most combined with lighter-weight designs do not utilize). First, successful designs are “clean”: components for the moving parts consider cost: every time you they feature a strong, rigid frame, of the machine. This helps reduce add a gearbox, you add multiple utilizing materials and structural mass, provides more energy- costs: it’s an additional point of principles to ensure that, whatever efficient motion, and makes it easier failure, it has to be lubricated, and motion the machine undergoes, its to size-up smaller motor/drive it needs spare parts. Plus, you add long-term stability is engineered-in. components for the machine. mechanical backlash that needs to Make sure that rigid bearings and be compensated for during machine support are utilized where motors Consideration #2: Directly commissioning and every time are mounted on machines; this couple the motor to the load you have a product changeover— helps prevent shafts being sheared Effective mechatronics starts with motion and axes synchronization off, due to microfractures that a clean slate design. In the past, complexity that today’s intelligent occur because the motor shaft is machines were often built around drives and servomotors eliminate. a single AC motor powering a machine line shaft, to which When you strategically locate were attached gearboxes, pulleys, servomotors as close as possible to sprockets, chain drives and other the area of motion they are serving, mechanical devices for moving the incremental cost of electric drive individual areas of the machine components is almost completely in synchronization—an approach offset by eliminating the cost of to powering manufacturing that mechanical components and labor literally can be traced back to the that must be purchased, machined, dawn of the Industrial Revolution. assembled and configured. In particular, not having to stock Consider replacing this architecture multiple sets of sprockets, gears and with individual servomotors cams, as well as the time involved coupled directly to the load you are in changeovers with mechanical A clean design makes the largest moving. There are multiple design, drives, can really drive down contribution to a machine’s longevity, robustness and lowest overall cost machine cost and operational the total cost of ownership for of ownership. advantages to this solution (which the machine. Consideration #3: Utilize synchronization and camming, electronic gearing and camming the proper sizing of the servo Today’s electronic drives and system can create a highly energy- motion control platforms give the efficient machine. mechanical engineer a powerful, flexible tool to improve the accuracy Proper sizing requires an accurate and performance of the machines assessment of several motion factors you design. This technology lets (motor by motor): How fast the you create a virtual “electronic axis needs to accelerate, the size line shaft” that can electronically of the mass you’re trying to move, synchronize all the drives and and how precise the acceleration motors on the machine, eliminating and deceleration needs to be. the mechanical line shaft. In the Undersizing will lead to strains on process, you can dramatically the drives and motors; oversizing improve axes synchronization and will draw too much power to do too accuracy—from 1/16th or 1/32nd little work. Regenerative power supplies feed power of an inch typical with mechanical back through a shared bus to re-use line shafts, down to motion on the machine rather than dissipating Some of today’s most cutting precision closer to hundredths or excess power as heat. edge systems, such as the Rexroth even thousandths of an inch with IndraDrive Mi integrated drive/ electronic line shafting. electronic cam through a recipe motor systems, include a highly change through the HMI, the energy-efficient feature: bus And this synchronization can be control platform will automatically sharing. Multiple drives are accomplished with zero mechanical optimize the rest of the cam profile daisy-chained together and share backlash—and fewer product across all of the machine’s motion power from the same bus; in jams. It also eliminates a host of elements. This enables the machine many multi-axis machines, as mechanical adjustments to bring to run a shorter cycle time, or some motors are accelerating up the machine online, as well as the provide smoother dynamics for the to speed (drawing power) , others operator adjustments each time the machine, even though a change has are decelerating (regeneration machine is stopped and restarted. occurred such as a different bag seal power). With bus sharing, rather time or flap tucking cam position than having to deliver maximum Electronic gearing and camming on a cartoning machine. power to the accelerating motors makes machine changeover and bleed off the decelerating completely programmable: Using Consideration #4: Incorporate motors into heat across a bleeder FlexProfile technology, with the energy-efficient technology resister, power is shared, so the touch of a button on the HMI One of the fastest growing costs machine’s power consumption is screen, you can load a machine for any manufacturing operation significantly reduced. recipe, and the changes are made in is energy—and good mechatronic the control and servo system to run design can help control these costs, A further energy-efficient the next product. through the application of electric technology is called regenerative drive and motor systems designed power supplies. In many machines, This new FlexProfile camming to save energy. multiple servomotors will decelerate technology makes it possible at the same time, boosting the to build multi-segmented cam In machines that utilize voltage to excess levels on the power profiles based on position, velocity servomotors directly coupled to bus. Older generation electrical or time-based motion profiles. critical axes of motion on the drives would bleed that excess When you change a section of the machine, and also utilize electronic electrical energy as heat—wasting the power, and adding to the factory also show how to open enclosures floor’s heat production, requiring and what steps an operator can additional cabinet cooling. With take to put the machine in safe regenerative power supplies coupled mode for initial maintenance, to a shared bus system, what was and other support resources to once wasted power can now be fed resolve a problem and step the back through the shared bus and operator back through the tasks to sold back to the electric company. restart production.

Consideration #5: Use HMI’s Advanced graphics like this can for better troubleshooting be combined with the distributed The computer revolution has spread intelligence inherent in servomotor- to today’s machine control panel, driven machines, to prevent replacing knobs and pushbuttons machine failures or faults before Intelligent predictive maintenance alerts with sophisticated PC-based and they happen. Called predictive can be displayed via the HMI to the Embedded HMIs with advanced maintenance, this capability operator, along with next steps necessary programming and Windows-based lets machine designers set fault to correct the issue. operating systems. tolerance bands in drives and then monitor drive performance. issue before it becomes a serious Consider your typical office Electric drives and motors such production problem or something copier: when there’s a paper jam, as Rexroth IndraDrive systems that can damage the machine. a touchscreen control indicates allow a broad range of conditions where the jam is, what door to to be monitored—conditions Blending technologies open, how to correct the problem, that are directly associated for optimal value and prompts you what to do next with mechanical performance: Every electromechanical system once you’ve cleared the jam. The variations in load, temperature, should perform its designed same user-friendly intelligence is vibration, torque, belt tightness, function with the minimal use of now available to machine designers gear meshing are all mechanical energy, motion and components through today’s touchscreen HMIs events that generate changes in the required to get the job done— featuring the latest graphical user torque profile of an electric drive that’s the fundamental goal of interfaces. Machine layout drawings and motor moving those machine any manufacturing engineer. and schematics can be incorporated elements. Mechanical engineers Electrical drive and servomotor into control menus and diagnostic can set tolerance bands for these systems now offer a wealth of tools, to better manage the components, and if they exceed reliable, energy-efficient, digitally machine’s day-to-day operation them, then predictive maintenance intelligent platforms to power the and troubleshooting ease. Drawings alerts can be clearly and intelligently integrated vision of mechatronics and interactive instructional tools displayed via the HMI to operators, to greater value and more can not only show the precise point along with specific advice about innovative manufacturing and where a problem is—they can next steps to take to correct the automation solutions.

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