Servo press is an important asset to the manufacturing industry and you may be wondering why. In this article, we capture everything to you stand to benefit from a servo press in your production processes.
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Servo press is the kind of press machine that uses servo motor as its main motor for driving the ram or slide. Unlike classical mechanical presses using a flywheel and clutch mechanism as well as hydraulic presses that depend on fluid power, servo presses feature an electric motor with enhanced control of the power output.
Servo presses offer several advantages over traditional mechanical or hydraulic presses. Let&#;s explore
With servo motor control mechanism, you are guaranteed of precise motion and force control. This parameter of high precision is very important for applications which are demanding accuracy and applications where the part size matters.
Servo presses can be continuously reprogrammed to accomplish a wide variety of tasks. Therefore, they are able to easily shift processes and make necessary changes. Such high adaptability of servo presses serves as an efficient tool for practically all manufacturing industries and products.
Unlike hydraulic presses that always operate on power to make out the pressure, servo presses take energy only when pressing happens. Such performance is attainable not only in terms of monetary savings at the end of operational cycle runs. Servo presses also help in terms of applications that involve frequent turn-on and off cycles.
The sound level of servo presses is much lower than that of a hydraulic press. Therefore, the staff members are less likely to suffer as much inconvenience from the undertone levels.
The servo presses have lower mechanical parts compared to the hydraulic presses. Therefore, working principle expenses for repairs are lower and the amount of downtimes is smaller.
The majority of the times, they get installed with state-of-the-art safety measures. For instance, light shields and interlocks that would precisely guard operators against accidents and injuries.
They are equipped with features that allow you to adjust the driving profile to meet the purpose of the particular application. Whatever way this customization is done, the machine can have very good and well-adjusted results in the forming process. This will result in a better production efficiency and part quality.
For instance, TNSIFA offers a range of profiles including dual cylinder hydraulic press, C-frame hydraulic press, and heated platen hydraulic press, among others.
Most servo presses come notionally equipped with a monitoring and feedback system. These systems can help operators to know the performance of the device now. Due to this capability, problematic issues are identified in the early stage, and potential production errors are prevented hence save the price.
Less energy consumption and no use of hydraulic fluids make them less environmentally harmful. Servo presses have proven to be eco-friendlier as compared to conventional presses.
Servo motors can manage with high velocities and dynamics. It is the key factor that facilitates fast and repetitive loop in manufacturing and helps to improve the productivity of producers.
The servo type presses are designed in such way that adjusting the stroke length is possible according to the needs. The integration of this capability translates to a streamlined manufacturing process. Here, various part sizes and complex geometries are produced without any manual manipulation and tool changes.
With complete management provided by servo presses, breakdown of die and tooling wear will be reduced hence, increasing the lifespan. Through this, the total cost of ownership on maintenance and tool replacement will reduce as the company gets older.
With servo press, you parts will make parts with consistent and accurate dimensions. This is because of their control over the forming process that is set precisely. It also ensures that there is very little variation in the quality of parts. This will, therefore, reduce wastage of the rejected items, leading to better reliability of products.
The integration of servo presses is clean with Industry 4.0 innovations. Such include; robotics, automation, and data analytics, which combine their workforce with the Internet of Things and Machine Learning. This integration provides for the rapid diagnostics and prognosis of the equipment and condition-based predictive maintenance. These features ensure the high efficiency and productivity.
On the contrary, servo presses usually represent a situation where the floor area is less occupied relative to that of the hydraulic presses. This is the possibility of reduced floor area consumption and engagement installation without changes or adjustments of the production lines.
Servo drives can adjust their speed and position quickly through their programmable control systems while tooling changes takes very little time. This results in no time wasted in between the production runs and a maximum equipment usage ratio.
Servo presses, in general, have a combination of precision, flexibility, energy efficiency, and safety. These features make them an appealing choice for modern manufacturing processes.
All these features put together help servo presses to be an extremely adaptable and efficient tool for modern production processes. They assist companies to cope with a rapidly changing market while being focused on high standards of quality and productivity.
More resources:
Hydraulic Press Machine &#; Source: TSINFA
Hydraulic Press vs. Pneumatic Press &#; Source: TSINFA
How Hydraulic Press Work &#; Source: TSINFA
Hydraulic Press &#; Source: IQS Directory
by Matthew Gulleen, Applications Engineering Manager
Tolomatic, Inc.
Conventional hydraulic presses have been the workhorse of manufacturing for decades in industrial applications such as metal forming and bending, bearing pressing, and assembly. These remain the choice for many extremely high-force pressing applications. However, the advent of servo-electric press technologies offer significant advantages in precision, programmability, energy efficiency, reliability, and flexibility compared to hydraulic machines, in a wide range of applications. This white paper examines the benefits and design considerations of servo-electric presses and explains the differences between servo-mechanical and advanced Linear Servo Press technologies for engineers developing new press equipment, retrofitting hydraulic systems, or specifying press technologies to modernize existing production lines.
On a traditional hydraulic press, hydraulic pumps generate pressure to extend the cylinders and produce force via fluid compression. Servo-electric presses, however, use brushless AC servo
motors (often with gearboxes) coupled to linear actuators to drive the press fixture. The electric actuator assembly (motor, gearbox, and linear actuator) provides the pressing force, while the control system coordinates the operation through precision programmed motion profiles. Unlike conventional hydraulic systems, a major advantage of servo-electric presses is that ram force, speed and position is continuously monitored and adjusted in real-time throughout each process cycle.
A primary reason engineers select a linear electric actuator over a hydraulic cylinder (or other press systems) is the ability to apply complex, real-time motion control. Electric actuators, when coupled to a servo motor and motion control system, have the ability to provide infinite control over position while monitoring accuracy and repeatability levels with fewer components, less maintenance, and higher levels of consistency than a traditional hydraulic system.
Modern servo motor technology enables very high continuous force capacity in a compact package, with single actuator options up to 50 tons of force. Beyond the 50 Ton range, engineers will often look at a dual electric actuator design (doubling the force capability) or a custom actuator solution. This allows linear servo-electric presses to match the force capacity and tonnage of similarly sized hydraulic machines, but also provide numerous advantages over conventional hydraulics including:
Today, there are two technologies that define servo-electric presses. The main difference between the two technologies is how the servo motor force is transferred to generate the pressing motion.
In a Servo-mechanical electric press, the servo motor drives a mechanical system such as a crankshaft, flywheel, and connecting rods to convert the rotary motion into linear motion. The press tooling is driven from the crankshaft&#;s reciprocating movement.
In contrast, a Linear Servo Press utilizes a direct-drive linear actuator. The servo motor directly drives a roller screw or ball screw mechanism which converts the torque into a linear thrust force. The press fixture is typically coupled directly to the thrust rod end of the screw assembly.
This white paper will focus on the benefits and design considerations for the Linear Servo Presses.
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The Linear Servo design eliminates the rotary-to-linear mechanical transmission used in servo-mechanical presses, focusing the full servo motor power into direct linear thrust. This more efficient design provides significant performance benefits compared to rotary servo press mechanisms:
In summary, Linear Servo Press technology combines the best of both worlds &#; the high forces of similarly-sized hydraulics with the precision, speed, and flexibility of servo control. These advantages, versus traditional servo presses using mechanical force transmission, make Linear Servo technology the better choice for high-precision press applications.
Linear Servo Presses are applied in industries where high degrees of precision and controlled force application is required. Some common machine applications for Linear Servo Presses include:
These are just a few examples of the machine applications for Linear Servo Presses. Versatility and precision make this technology a vital solution for a wide range of industries and manufacturing processes where precise force control and accurate motion control are essential.
Manufacturers of Linear Servo Presses often work with a linear actuator specialist such as Tolomatic, to select or design high-force electric actuators as the cornerstone of their products. With the wide variety of servo motors, controls and standard components, a growing number of engineers are also choosing to configure electric linear actuators for their presses as purpose-built to their unique application requirements.
Evolving from conventional hydraulic presses to higher-efficiency Linear Servo Presses is helping manufacturers achieve more sophisticated production capabilities and greater productivity in a host of applications and products. This results in powerful gains in versatility, quality and throughput compared to more conventional press methods.
Whether seeking a pre-configured integrated Linear Servo Press solution, designing one to meet your specific application challenge, replacing obsolete equipment, or seeking one of the industry&#;s most capable linear motion control partners for their new product developments, design engineers should seek a provider offering a wide selection of linear actuator solutions designed to meet the high accuracy, forces and motion control to perform with desired levels of precision. For example, here are solutions offered by Tolomatic:
Extreme High-Force Electric Linear Actuators
Select from one of the industry&#;s widest ranges of high-force linear actuators, including the RSX Series featuring the RSX096P, a press-specific electric linear actuator enhanced with a proprietary precision-ground planetary roller screw, oversized tie rods, high-strength steel front flange, and a bearing system optimized for high force press moves.
Hydraulic Replacement
RSX, RSA, IMA, RSH and IMA-S actuators are modular components that are also an ideal solution to retrofit and replace hydraulic cylinders or mechanical flywheel systems in existing press machinery. Whether for a technology upgrade that alleviates the high maintenance challenges of hydraulics, or to create a solution that integrates with contemporary factory automation and safety solutions, download this Guide to Hydraulic Replacement to learn more. In addition to typical industrial applications, Tolomatic also offers stainless steel IP69K hygienic actuators that can be leveraged for a host of demanding washdown press applications.
Actuator Modifications
If your requirements fall outside of standard product configurations, a capable linear motion control partner can often to modify a solution to meet your needs, including stroke, speed, force or other requirements. Starting with a proven product platform lets you evolve the actuator solution to your unique requirements. Design and model a linear actuator into your press application using sizing and selection software. You, or a machine builder, can then complete the design and specify the press fixture, load cell and safety devices to your requirements. You may then specify your motor of choice with Tolomatic&#;s Your Motor Here program, which provides proper mounting hardware, or the option to ship your motor for factory installation.
Pre-Engineered Solutions: E-Press
Because of its broad application in Linear Servo Press applications, Tolomatic has partnered with SOLVE Industrial Design NYC to offer E-Press &#; proven, pre-engineered C-frame press designs. This design-time-saving option introduces base models available in a range of rod style electric options with force ranges up to 267 kN (60,000 lbf). Each model is stroke configurable and complete, including electric motor, actuator and fixture, and can be equipped with your choice of safety features including light curtains, two-hand control and/or guarding configurations depending on your requirements. The Your Motor Here program can also be leveraged to use any preferred motors with these pre-engineered selections.
Custom Solutions
Some manufacturing challenges simply can&#;t be solved by existing standard linear actuators. That&#;s when you should consider a custom designed system. A capable linear motion systems expert can offer decades of experience and innovative products to help get you to a press solution quickly. However, not all providers care enough to collaborate on your challenges or are willing to make modifications to their products. In this case you should seek a partner that offers more than catalog solutions, embraces technical challenges, and partners with local distributors and integrators, such as SOLVE, who can effectively bring your press solution to life from concept to reality. A strong partner will also be represented by experienced distributors, who collectively can bring a wealth of design knowledge, engineering creativity and technical assistance to your manufacturing challenge.
Because the foundation of a Linear Servo Press are linear actuators, there are numerous options to choose from. However, just as not every actuator can perform to your requirements, not every provider is equipped, or willing, to provide the answers and assistance you need. A good partner offers many ways to explore and achieve your goals, including:
When specifying electric actuators for a Linear Servo Press application, several engineering design considerations come into play. Here are some key factors to consider:
Ball screws and planetary roller screws are both types of mechanical components used in rod-style electric actuators to convert rotary motion into linear motion. While they serve the same general purpose, there are differences in their design and performance characteristics which result in varying benefits in high-force applications. Here are the key differences and benefits of ball screws and planetary roller screws:
In summary, ball screws are advantageous for applications that require precision, moderate loads at high speeds, and a more cost-conscious selection. Where press applications demand the high force, reliability, precision, and longest life, Planetary Roller Screw technology excels. High-force applications that demand high load capacity, rigidity, and durability are key drivers for planetary roller screw selection. The use of alternative cooling methods can further extend the amount of work a planetary roller screw actuator can perform within a given motion profile. When sizing, design engineers must consider the specific requirements of the application, including correct press force, speed, precision, and environmental conditions, to determine whether a ball screw or roller screw is the optimal choice for their high-force electric actuator application.
Though there are many elements to matching a motor to a linear electric actuator, it is important to decide if an integrated actuator (motor integrated into the actuator) or a non-integrated actuator/motor combination will be better in your application. An integrated electric linear actuator, such as the Tolomatic IMA series, is an excellent compact and durable option for lower force press applications. This simplifies the design as only drive and cables are needed to begin operating the actuator. Alternately, an actuator separate from a motor and drive may be beneficial. This allows for gearboxes to be placed between the motor and actuator to leverage mechanical advantage in the actuator assembly for increased force output. Whether sizing a drive for an integrated actuator or choosing a motor and gearbox for a non-integrated actuator, the tools and resources provided by both the actuator manufacturers and the drive manufacturers have made this process much simpler today than even a few years ago. Though determining electrical and mechanical requirements can be calculated long hand, a Design Engineer will be able to save time and minimize errors by using all the available tools and expertise provided by manufacturers.
Non-integrated motor selection is dependent on application specifics such as:
The motor parameters should be an output of a trusted sizing software that can then be used to then size the motor.Integrated actuator motor selection should be directly available in a trusted sizing software as it is part of the actuator assembly. Once an integrated actuator has been selected, matching the actuator assembly to a drive will be the necessary next step. There are a few important considerations that will help ensure a successful drive selection:
These pieces of information will help define drive sizing and selection to the integrated actuator chosen.
Another common design consideration in pressing applications is force control throughout the life of the press application. While force control and what the feedback can be used for is outside the scope of this white paper, understanding the different methods of obtaining force data is pertinent to Electric Servo Press design. Force feedback can be accomplished through multiple methods at varying cost levels. These options include:
Integration of simple strain gauge into fixture
Using a simple strain gauge on a fixture is the most cost-effective method of collecting force feedback. As the strain gauges do not need to be placed in-line with the force, the risk of mechanical failure is extremely low. This method is not as accurate as using a direct load cell in-line with the applied force, but the accuracy is sufficient for a number of general industrial applications.
Use of motor torque feedback
Motor torque feedback is often the next-best, cost-effective method of force feedback. There are two common methods for using motor torque feedback. First, performing a calculation of torque from current via the motor Kt value is a cheap and simple way of achieving accuracy within 10% on actual output force. If increased accuracy is needed, a load cell can be used to calibrate the actuator force output and achieve up to a 2% accuracy on actual force output. It is important to remember that additional components (reverse parallel belt motor mounts, gearboxes, couplers, etc.) and efficiency changes due to &#;warm up&#; can impact the accuracy of motor torque feedback to force output estimations. These should be considered if using this method.
Rod end or fixture integrated load cells
Rod End load cells or load cells integrated into the fixture provide an alternative method for measuring force. Rod end load cells must be selected individually based on the force measurement capacity desired. These strain gage load cells typically have accuracy within 1% and should be recalibrated at regular intervals. They can be purchased as an add-on from a variety of sources and easily installed on the rod end of a linear actuator. An additional consideration when using rod end load cells is the cable must be routed appropriately during operation to prevent damage. Similarly, a pancake style (or low profile) load cell can be integrated into the press table or fixture. This method places the force sensor much closer to the point of force application and results in high accuracies (similar to and often exceeding rod end load cells). Depending on the design of the fixture, this can be relatively easy to replace or recalibrate when needed and cable routing is not an issue.
Actuator integrated internal load cell
The last option is integrating a low-profile load cell internally to an actuator. Generally, these are installed internally near the rear bearing housing of the actuator to be directly in-line with the applied force. Either piezo electric style or strain gauge style can be used internally, but they have tradeoffs. Piezo electric load cells require a special preload on internal components to reach the appropriate force range. Over time, it can be difficult keep a consistent preload as components wear. This can be accounted for to some extent with recalibration, but eventually the system components will need to be replaced if too much preload is lost. Using a strain gauge style largely eliminates the issue of preload, but both styles introduce the issue of service and replacement difficulty. Integrated load cells have an extremely strong advantage in specific applications, such as resistance spot welding, where the ability to truly follow a force profile enables high confidence in welds and reduce the total number of welds needed. In general, industrial and press applications, it is less common to use an integrated load cell due to some of the drawbacks. The load cell and actuator are designed and built together, which generally will require replacement or refurbishment of both components in the event of either an actuator or load cell failure. Integration in the actuator is often the highest cost option as most actuator manufacturers do not have integrated load cells as a standard feature in their product designs.
In many industrial press applications, the advantages provided by Linear Servo-electric press technology can offer substantial process improvements over traditional hydraulic presses. With precise, programmable control and repeatability, energy efficiency, reduced maintenance requirements, compact design, and application flexibility, linear servo capabilities enhance the performance, productivity, and efficiency of press machines, and improve the quality of produced parts and components.
When specifying new press equipment, engineers should evaluate if Linear Servo-electric press capabilities can benefit their production processes. For existing hydraulic press lines, retrofit solutions to convert to Linear Servo-electric operation may offer return on investment and value through numerous performance improvements and savings.
With Linear Servo-electric press technology continuing to advance, the advantages over hydraulic machines will only increase in the years to come. Partnering with a capable, highly-qualified servo-electric press supplier is key to leveraging the benefits for your production environment.
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