Due to advances in technology over the last ten years and changes in environmental, safety and ergonomic requirements, motion control system capabilities have developed, increasing the complexity of choice.
Recognised motion control methods include:
• Hydraulic Powered motion – used in the Agricultural industry
• Pneumatics – used in the Process industry
• High precision Stepper motors and linear guides – used in the Automation industry
One motion solution that has seen a rapid increase is the incorporation of electric actuators in new applications, as well as, a replacement in applications that formerly used Hydraulics, Pneumatics, Stepper motors and even manual operation. The growth of electric linear actuators is due to substantial research and development over the last decade, with major technological advancements in regards to force and load capabilities, ruggedness, speed, duty cycle, control, and other key factors have allowed actuators to surpass alternative solutions.
These developments have also helped overcome misconceptions about the limitations of electric actuators that exist in the minds of both manufacturers and end users.
Examples of how electric linear actuators compare to alternative motion solutions can best be shown through comparison of some aspects of the basic motion requirements areas.
1. Technical specifications:
Actuators can be configured to lift loads in excess of 2200lbs; these applications are now common in the market, with more specialised solutions available that can lift significantly more. New designs, stronger components, and advances in manufacturing techniques have allowed manufacturers to gradually increase the maximum load capabilities of each new product. Electric actuators continue to replace hydraulics in applications that require high load capacities.
Travel distances (a.k.a. stroke length) have also seen exceptional increases in electric actuators. In applications where stroke lengths in the range of 48″ to 60″ are required, examples include RV slide-outs or electrically powered bollards, linear actuators have become a viable option in replacing alternative solutions.
In the past, power input options for electric actuators have been limited to 12V and 24V
DC. However, newer solutions in actuators are changing to meet the requirements of applications that utilise 36V and even 48V DC power. In applications where these higher voltage, lower amperage combinations are desired, such as electric/hybrid mowers, fork trucks and utility vehicles, linear actuators are now available.
2. Performance specifications:
Constant improvements to actuators have allowed for speeds of six inches per second and sometimes more. This innovation has allowed electric actuators to be a superior solution in many applications that require faster travel speeds.
A motion control system must meet the lifetime and environmental conditions of its application. Corrosion from cleaning solvents, fertilizers, salts, or exposure to moisture or dust can limit the lifetime of some systems. Electric linear actuators are engineered for these tough environments. Using corrosion resistant materials and better seals to prevent moisture and dust from entering the housing, actuators can last longer than ever in the harshest of environments. This has made electric linear actuators a viable choice for harsh outdoor environments, like combine harvesters and fertilizer spreaders, as well as indoor applications requiring exposure to cleaning solvents such as food processing.
Thorough climatic, electrical and mechanical testing has shown that the more robust design of electric actuators are able to withstand vibration, shock and the impact of extreme hot and cold temperatures and can sustain long lifetimes in such environments. The performance and lifetime of alternative solutions can be greatly affected by such conditions; therefore, linear actuators have proved a more stable performance across a wide variety of conditions.
Linear actuators can offer precision with many types of feedback including Analogue Potentiometers as well as Digital Reed and Hall Effect signals.
3. Safety needs:
Safety is a high priority in any application, whether the person at risk is the operator, bystander or maintenance worker. While risks of exploding hoses or other components in high pressure systems like hydraulics and pneumatics can be reduced with certain designs and frequent maintenance, the risk still remains. A major safety benefit of electrically powered systems is that once the power is cut-off the actuator does not move and integral braking systems lock the load in position so it does not drift. Comparatively, in many cases, hydraulic and pneumatic systems can remain charged even though the equipment is not being operated and power is removed.
Personnel safety cannot be addressed properly without a discussion of the more long term injuries occurring from poor ergonomics. Recent trends show an increasing need to address diversity in industrial applications; for example, workstations that adjust from the 5′ -3″ first shift employee to the 6′ -3″ second shift employee. This type of motion control can pay dividends and provide a return on investment in improved worker performance, attendance, and moral.
In addition, worker compensation costs that result from repetitive strain injuries can be reduced simply because electric actuators allow the position of the worker, or work surface, to be adjusted to meet the needs of the individual.
Environmental safety should also be considered a criterion when selecting a motion system; because of this many companies and industries are re-evaluating their use of hydraulics.
4. Control Specifications:
The level of complexity of electric actuator control systems is diverse and can range from a simple toggle switch, to raise and lower a snow plough, to a sophisticated control system involving multiple actuators in a factory automation setting.
Many of today’s electric actuators are designed to integrate electronics into the actuator, this is a concept commonly referred to as mechatronics. Electric actuators now offer a level of electrical control and information feedback never before seen; and while positioning feedback has long been a feature of linear actuators, now even more information can be provided from the actuator to the control system.
5. Economic Factors:
Most electric actuators are maintenance free and are generally installed by inserting mounting pins and plugging in a connector. Electric linear actuators only consume power when in operation and use no power when not in operation, unlike hydraulic or pneumatic systems.
For more information contact LINAK UK Ltd
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