Pneumatic or electric actuator?

Question

Hi!
I'm designing a tribometer to test materials to wear impact (for example to test teeth impact while chewing).
At the university, we have a tribometer that does that but needs an improvement because it doesn't work properly. It is used a linear pneumatic actuator to promote the impact, but the compressed air net is very instable, which means the tribometer needs a compressor individually, and that's not viable.
I'm not sure if a linear electric motor has the speed and force needed for this application.
The specifications we need to achieve are:
-max. load: 500N (variable in time in a controlled way)
-25 mm stroke

Can you suggest any linear electric actuator, or other, that fulfils this requirements?

Thank you!

P.s. Sorry about any mistakes, english is not my native language : )

Answer 1

It is not clear what the problem is that requires a dedicated sir compressor. Is the problem simply a limited air supply? If so, why not use an accumulator to build up sufficient volume to make the system work?



Secondly, why have you not considered a hydraulic system?



Sounds like you don't want a simple low tech solution but really want a new system just because it seems sexier. Not a good approach.

Answer 2

It seems like you need an accumulator. This is an air reservoir (pressure tank) near the actuator. It has a function similar to the reservoir capacitor on a DC electrical supply. It smooths the pressure variations, and the discharge pipe can be sized to make sure the actuator gets sufficient flow to perform the task. If this is a commercially produced unit you should be able to get a spec for pressure and flow, presuming it is run within its ratings. Also check the operation is correct, e.g. lubrication, gumming up lubricants, worn or loose components, dirty or kinked pressure or discharge lines, etc.



Electric linear actuators are probably not ideal for this (in my thinking), unless the speed is slower than I think. The rating of 500N is fine, equivalent to lifting 110 pounds or 50kg weight, some are much bigger. Look up the link below for either products, or application analysis form. These work by using a motor and screw thread, and some sort of feedback. They are servos. The feedback is from a sensor like a potentiometer etc. Potentiometers have a short life in repetitive cycling. There is a voltage signal driving of appropriate frequency and shape to get stroke and oscillation speed. A sine wave oscillator.You will need to specify:



Expected lifetime (total operations or strokes at rated force)

Maximum continuous force in N (often in pnds or kg weight).

Peak force.

Stroke

Speed (strokes per minute etc.)

You will need a power supply with sufficient reserve capacity just as for the air line. ALso the electric actuator may be noisy.



There are other linear actuators, but less suitable. Voice coil actuators also work with servos, but have a smaller force than you require.



If this is a 12 or 24V unit, the power supply alone probably costs nearly as much as a compressor, and must be carefully specified to handle the peak currents. It seems a decent compressor or accumulator tank with the air system is a far simpler solution, probably cheaper, and you just buy in a local shop somewhere, fixed today.

Answer 3

Use an eccentric drive (like a crank shaft , or drive wheel on a steam locomotive)to convert rotary motion to linear motion. Using a gear head motor will slow the speed in increase the torque to usable range. If you need a speed control us a DC motor and send PWM power to the motor to control speed. PWM is pulse width modulation, a micro controller like an Arduino sends control pulses to a solid state relay which in turn operates the motor.



If you need a longer amount of linear travel you can use a lead screw. Basically a threaded rod is turned by a gear motor. A nut threaded on the rod is then driven along the lenght of the rod as it turns. A small platform is attached to the nut and is guided by rails.

Answer 4

Use Linear actuator which is used for Dampers opening various type available Pl.choose suitable one from the below links Link

Answer 5

attempt a Morin or Keystone pneumatic a million/4 turn actuators with LSO and LSC digital alerts seem on ebay or Tyco valves. They make a speedy launch exhaust for instant closed and a electric 2 way solenoid valve via fact the valves are spring closed.