ESR Pollmeier GmbH - Servo Drive Technology


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

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

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.

Packaging Machinery

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

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.

Coiling machines

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.

Other Applications

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”.