Servo Drives in Practice
Machine parts usually have to be accelerated and decelerated quickly in order to arrive at a certain position precisely in short time. At the same time the path of movement or the speed may be predetermined by the application. A servo drive system is capable to carry out these tasks (see also FAQ).
Important characteristics of ESR servo drive systems are
- high dynamics
- high accuracy
- wide speed range
- good control behavior
Fields of Application
Both machinery manufacturer and end users who build their own machines use servo drive systems by ESR. Usually they are small and medium-sized businesses e. g. from the following fields
- Handling and assembly systems
- Electronics production machinery
- Semiconductor production machinery
- Measuring and testing machinery, test stands
- Machine tools and metal working machinery
- Packaging machinery
- Textile machinery
- Plastics processing machines
- Coiling machines
- and many more
Handling and Assembly Systems
For processing in automated industrial production, handling systems are used for feeding and removing material, workpieces, or components. Assembly systems carry out the assembly process automatically or support the activities of the operator of the machinery (e. g. screwing, welding, gluing, clipping, soldering, deburring, controlling). Often, these are simple, repeating point-to-point positioning tasks of one or several axes, but the production process may also require a certain motion profile or the coupling of several axes.
The permanent change between phases of fast movements and stopping at a defined position or synchronous running makes the servo drive perfect for such tasks. With their high dynamics and peak torques exceeding the rated torque considerably, ESR servo motors are perfectly suitable for handling and assembly systems. Depending on the application, the repeat accuracy that can be achieved is another determining factor for the selection of the right drive.
In fully automated production, the networking of drives and controller is essential. Therefore, the digital servo drives by ESR are equipped with the common communication interfaces. For semi-automated processes, solutions with operating terminals are suitable for making the settings required in workflow quickly and to call up all functions easily.
Examples in Practice
Many products in everyday life are manufactured by machines in which ESR servo make things move, for example radiator valves, coffee capsules, window handles, CDs and DVDs, furniture fittings and hinges, beverage cans, brushes for vacuum cleaners, and many more. For linear and rotary movements in the feeding equipment and the individual production steps, we offer servo drives providing for a high throughput due to their dynamics and avoiding expensive standstill times thanks to a reliable operating principle. With our professional configuration, we determine the optimal drive with positive effects on purchasing and operating costs.
The conversion of the manual production to automated production of glass spirals for laboratory and industrial use pays off: The reject rate drops from 90 per cent to 0. We deliver the servo drives for this 3-axis system which are run synchronously in real-time by a controller.
During the assembly of zippers in a sheltered workshop, the material is cut to length and processed in the desired numbers according to the order. We deliver servo drives and operating terminals together with a programming which includes the calculation of remaining lengths making a higher-level controller redundant.
In co-operation with several engineering offices specialized in retrofitting, ESR servo drives are used in machines producing faster and more reliably due to the modernization. Frequently, hydraulics and pneumatics are replaced by electrical actuators for an economic and clean operation.
Electronics Production Machinery
Examples in Practice
In the production of discrete components, rotary tables are used to turn the carrier repeatedly and quickly by a defined angle in a timed movement. During standstill times, the product is picked up at a station, tested at the next station and, depending on the test result, handed over to the further processing or sorted out. It is essential to carry out the movement as fast as possible and to hold the exact target position. We do not only provide for the optimal drive configuration of the torque motors but also give hints for the mechanical improvement of the facility so that the throughput per rotary table is increased and the customer is even able to save one drive axis.
For the fully-automated assembly of circuit boards, SMD components are fed to the pick-and-place system on tapes. For the filling of the tapes, a high repeat accuracy and complying with the specified positioning times are essential. We deliver the complete drive system and support the customer in optimizing the motion sequences using high-speed cameras.
After circuit boards consisting of several parts have been equipped with SMD components by a pick-and-place machine, they are cut into the individual panels. We deliver a 3-axis system with two toothed-belt axes for fast XY movements and a spindle axis for the feed movement of the cutter in Z direction.
For the production of yaw rate sensors for the automotive industry, several contacts are installed at the circumference of the sensor. We deliver high-dynamic servo drives rotating the components quickly and precisely. With their reliability, they support the machine in achieving the required quantities.
Drilling circuit boards, equipping boards with components, testing resistors, diodes, capacitors, etc. – in electronics production, it is always essential to reach positions quickly with high accuracy. Every millisecond that can be saved when moving from one target position to the next is valuable because in many thousands of point-to-point positionings which are carried out during the day, even minor times sum up to become a measurable advantage providing for more throughput in the machine.
For drilling and equipping circuit boards, usually multi-axis systems consisting of three linear drives are used. With the ESR linear motors, high accelerations can be achieved providing for short positioning times. By using high-precision linear measuring systems, accuracies meeting highest demands can be achieved. For processes without delay, fast, real-time communication interfaces such as EtherCAT connect the digital servo drives by ESR closely with the controller.
In mass production of electronic components, ESR torque motors are used which are able to accelerate and decelerate quickly with high torques. Being direct drive systems, they are backlash-free and low-wear. For the often uniform movements repeating many thousands of times per day, the digital servo drives by ESR offer special motion profiles (for example for minimum jerk) as well as customized solutions for quick and simple control.
Semiconductor Production Machinery
In the production of semiconductors, a wide range of procedures is applied, from etching and cleaning processes to various coating processes and crystallizing processes. Therefore, different drive concepts are required in automated production with different requirements to performance, dynamics, or accuracy.
Especially this industry often uses special types of ESR servo motors matching the requirements of the customer. These include motors for high speeds, motors with particularly long shafts or hollow shafts, motors in high-grade steel design, and many more.
Examples in Practice
In coating modules of single-wafer processing systems, varnish is applied to the wafers and spun. We deliver special servo motors reaching the required high speed of up to 15,000 r.p.m. which provide for an even layer of varnish due to the high speed constancy.
In systems for the surface treatment of power semiconductors, the process chamber is set into rotation in order to spread the chemicals used (e. g. acids, bases, or solvents) evenly over the up to 50 wafers. We deliver servo motors with hollow shafts which can be integrated into the facility concept of the manufacturer in a space-saving way.
Measuring and Testing Machinery, Test Stands
Examples in Practice
For balancing shafts, wheels, and other solids of revolution, the servo drive sets the workpiece into a rotary motion, and precise measuring systems determine the imbalance. For that, the assignment of the measuring result to the angle of rotation is very important. We deliver customized drive systems including digital servo drives with a fast measuring function which provides for best results.
In the continuous quality control of a supplier in the automotive industry, turbochargers are subject to an endurance test in order to check the stated service life. During that, a lever is operated repeatedly until material fatigue leads to a loss of function of the component. We deliver drives carrying out the test reliably with defined force.
In prototype manufacturing of a shoe production, walking is simulated in individual test specimens in order to determine wear and tear. The repeated movement corresponds to a distance of many thousands of kilometers in which the shoe is exposed to various loads. We deliver servo drives with high service life which permits such long-time tests under consistent conditions.
In the production of lamps for vehicles, the exact observance of the areas in which the light is bundled is essential. In the automated serial testing of the manufacturer, a test stand with high-precision goniometer is used. We deliver drive systems achieving a repeat accuracy of less than 1 µm using an additional, external position sensor.
Measuring devices and coordinate measuring systems are used for the semi or fully automated measurement of the surfaces of components in order to test their quality. To do so, the measuring head is moved to various points on the test specimen in order to collect their spatial coordinates. The measuring systems are usually CNC-controlled multi-axis applications; or, in simple cases, individual axes are sufficient moving the sensor back and forth in the running production process. The ESR servo motors and linear drive systems provide for the high precision essential for precise measuring applications. Industrial Ethernet or field bus interfaces are used for the control of the digital servo drives by ESR.
In the interaction of testing machinery and test stands, the test specimen is often stressed, for example in order to determine the wear of a prototype or to simulate the material fatigue for individual parts of a series in ongoing quality control. These are usually simple, repeating movements with the essential task to load the test specimen with a defined tension or pressure or to strain it with a specified, permanently changing acceleration. Direct drive systems including the ESR torque motors and linear motors carry out these tasks powerfully and with a high service life. The motion or the application of force on the test specimen can frequently be realized with the positioning control integrated in the servo drive so that a higher-level controller is not required.
Machine Tools and Metal Working Machinery
In machine tools and metal working machinery, a wide range of methods of forming, cutting, and joining are applied, for example bending, pressing, straightening, folding, milling, drilling, turning, eroding, cutting, punching, welding, or forging. These are frequently CNC-controlled milling machines or automatic lathes in manufacturing centers, but they also include eroding machines or mechanical presses. In addition to the serial production of such machinery, special mechanical engineering companies and manufacturers building machinery for their own production exist, as well.
Thanks to high dynamics and high accuracy, the ESR servo motors and linear motors are perfectly suitable for these fields of application. Depending on the degree of automation, the networking of the drives with the controller becomes more important. The digital servo drives by ESR are available with the common communication interfaces, function blocks facilitate the integration into the program sequence. For simple applications or local machinery concepts, the positioning control integrated in the servo drive can be used as an alternative, as well.
Examples in Practice
In automatic lathes and milling machines, tool change and loading/removal of the workpiece are carried out using drives supplying and removing the parts. We deliver servo motors providing for a quick change and servo drives which can be integrated into the automation system of the machine operator without problems via their communication interface.
For the production of knotted wheel brushes, the wire bundles are inserted into the plate and twisted to become a knot. We deliver the complete drive system technology for this application, consisting of a linear axis for loading and two rotary axes for plate movement and knot twisting.
For a plasma cutting machine, we deliver the servo drives for the X-Y axis. In many years of serial production, the machine construction is permanently being revised and improved. During that, servo motors and drives are replaced with newer types, as well. We support the customer in doing that and provide for the fact that the new components can be integrated into the existing concept without problems.
Examples in Practice
A newly developed packaging machine for catalogs and brochures packs these stack-wise in cardboard boxes. We deliver two linear motor actuators and one torque motor for the central tasks of this machine together with servo drives with CANopen interface.
For the modernization of a facility with machinery for the production of tooth paste tubes, the existing drives are replaced with high-dynamics AC servo motors. We deliver servo drive systems for pre-screwing and tightening of the tube covers with a precisely specified torque and support the gradual commissioning on site during running production.
Before lipsticks are equipped with a transparent cover and inserted in the transparent packaging in an optically appealing way, they have to be extended to a defined length. We deliver a servo drive for this step in the packaging process which, thanks to its fast measuring function, meets the requirements regarding accuracy and throughput.
In packaging machinery, products are packed in cardboard, wrapped with foil and/or strapped with strapping, labeled, and, if applicable, sealed. For transportation, the goods are stacked or grouped on pallets. The packaging itself is usually supplied in its initial form and prepared for use within the machine.
Many axes are involved in these processes which have to be controlled centrally and run in a co-ordinated way. For that, the digital servo drives by ESR with their Industrial Ethernet or field bus interfaces are used. All drive types are available for different movements: conventional servo motors with gearboxes, if required, or torque motors for rotary movements as well as toothed-belt axes, linear motors, or linear motor actuators for linear movements. The latter ones are also suitable for modernizing existing machines in which pneumatic cylinders are to be replaced with more economical electric drives. For applications in the food or pharmaceutical industry, high-grade steel designs are used.
Textile machinery includes many different types of machines serving for the industrial manufacturing of textiles such as weaving machines, knitting machines, cutting machines, and sewing machines. There are textile machines designed for one process (e. g. buttonhole machines) and others producing a wide range of items which requires frequent retooling.
The high degree of automation in modern textile machinery is realized with reliably working drives with a high service life. For these applications, ESR servo motors make use of their ability to deliver the required working speeds even under high loads in continuous operation. For the networking of the drive systems with the controller, the digital servo drives by ESR are equipped with the common communication interfaces.
Examples in Practice
In a sewing machine for technical textiles used in automotive industry, six drives are required in four axes: Three axes move sewing head and sewing table, one axis carries out the actual sewing process. We deliver the servo drives and adjust the functionality of the servo drives to the controller specified by the customer.
CNC-controlled 3- and 4-axis systems are used for the multi-layer cutting of textiles. We deliver the complete drive system technology for that.
In a newly developed circular knitting machine, cotton fibers are processed without having been spun to become yarn before. We deliver the drive system technology for supplying the drafting system and support the customer during commissioning and optimization on site.
Plastics Processing Machines
Examples in Practice
In the production of sausage casings using extrusion machines, the drives are located in a screw conveyor in an area with high environmental temperatures. We deliver water-cooled servo motors made of high-grade steel equipped with additional temperature sensors in the bearing plate for temperature monitoring.
To make injection molding machines work more silently, more energy-efficiently, and more cleanly, electrical drives are used instead of the common hydraulics. This permits faster movements, even parallel in time. We supply the machinery manufacturer with powerful servo motors together with servo drives for screw, clamping unit, and ejector.
By extrusion, injection molding, thermoforming, or blow molding, products made of plastics are produced in plastics processing machinery. During that, the focus is always on producing with high productivity, however, energy- and resource-efficiently.
In extrusion machines, ESR torque motors are used which, being direct drive systems without gearboxes, have more compact designs and work reliably with low noise. Pumps driven by ESR servo motors are able to reduce the energy requirements of injection molding machines. For use at high environmental temperatures, special motors with water cooling are available. Using the digital servo drives by ESR, the drives can be integrated into the automation system of the machine without problems.
Foils, paper, yarn, wire, and many other products are coiled in coiling machines in order to be able to transport them safely in a space-saving way. For the electrical industry, enameled copper wire is wound on bobbins in order to produce coils, electromagnets, transformers, and similar things.
For these applications, the good smooth running features of ESR servo motors are often very important. For yarns, wires, and similar things, the synchronization of the axis of rotation and traversing axis is essential, the digital servo drives by ESR with the functions of axis coupling are used here.
Examples in Practice
In coiling machines for mono- and multi-layer films, motors with high torque and high moment of inertia are used. We deliver torque motors and servo motors optimized for a particularly smooth running.
For a manufacturer of transformers building machinery of his own, we deliver the servo drives and a controller including programming so that after selection of the wire thickness and bobbin used, the specified number of windings is carried out automatically.
Examples in Practice
For an antenna following the orbit of a satellite with a repeat accuracy of ±1 arc second, we deliver torque motor and servo drive with special firmware for a travel speed of 0.25 degrees per minute.
For applications in university research, we deliver a multi-axis system with three linear motors as gait simulator for medical technology, and linear motors for traction-free bending tests, a linear motor axis moving with 18 mm per hour for testing shape-memory alloys, as well as a 2-axis system consisting of torque and linear motor for the production of a thin chip of 50 µm thickness.
We deliver radiation-resistant DC servo motors for manipulators applied in the dismantling of nuclear power plants.
For an application with vibrating conveyors, we deliver linear motors and servo drives with special motion profile for transportation and separation of bulk material.
For a large research project, we deliver special linear motors integrated in a particle accelerator and servo drives with special design permitting access to inner control loops.
For testing sealing rings, we deliver a drive system package achieving speeds of up to 30,000 r.p.m. using a contact-free magnetic gear.
ESR servo drive systems can be used flexibly – correspondingly, the fields of applications in which they are able to prove their advantages are versatile. In some cases, fast positioning is required, other applications are movements so slow that they cannot be detected by the eye. In one application, the repeat accuracy when approaching a target position is important, in the other application, the smooth running of the motion es essential, or a high force that can be regulated, even in standstill. The compact design of the motor and the resulting high power density can also be criteria for a decision.
In projects of university research, the focus is usually on unique experimental set-ups, often with sophisticated requirements. This is frequently connected with increased consulting activities – especially for projects outside the fields of mechanical or electrical engineering.
Being a specialist for servo drive systems, we can rely on many decades of experience in configuring the right servo drive system for an application. No matter how “exotic” the application is, whether it is a multi-axis serial application, a single-axis individual design or a prototype and whether the task can be realized with standard components or only with special designs. For further information, see page “Made-to-Measure Solutions”.