The pneumatic versus electric debate

25 October, 2016

The rise in popularity and availability of electric actuators over recent years has been the source of much debate and seems to have in some instances divided opinion. Electric actuators are without doubt a significant breakthrough which, at first glance, may appear to offer a more accurate and effective solution over their pneumatic counterparts, but before making any decisions prospective users need to examine the respective merits of both systems.

One of the main arguments made in favour of electric actuators is an ability to offer high precision control and accurate position, velocity, and acceleration of the axis in environments where highly tuned performance is paramount. Such accuracy often comes at a price though, and the associated design and build costs might prove prohibitive to many potential users.

Pneumatics by contrast, may be unable to offer such fine tolerances and are more prone to excessive wear when used at high speeds over time. In general, pneumatic actuation tends to be best suited to simple handling of medium-heavy loads, where extreme accuracies or particular motion profiles are not critical. The design and maintenance of such circuits are relatively simple, thereby reducing the total cost of the project over its lifespan.

There will almost certainly be a greater financial outlay associated with installing electromechanical solutions, when compared to more affordable pneumatic systems, but the lifespan of the electrically powered solution is likely to be greater, so costs will be recovered over time; sometimes making electric the more economic long term choice.

The ability to withstand temperature is one factor where pneumatics is often the only choice, due to its ability to operate safely in extremes of heat and cold; environments which may not be recommended for electric actuation.

The downtime factor

Downtime is another factor that users need to give careful consideration to. Replacement pneumatic parts are usually quick and easy to obtain, resulting in speedy repairs and minimal disruption. By contrast, safe servicing of electric actuator breakdown requires an entirely different skill set and may be dependent upon external resources and out-sourced expertise, which can prove costly both in terms of time and money.

Electric is often viewed as a cleaner technology as it has a self-contained unit, with only a cable connecting to the actuator. This is particularly relevant when used in applications where hygiene is a key consideration such as pharmaceuticals or food and drink packaging; where a possible lubricant leak from a pneumatic cylinder seal could result in a major compromise to health and safety.

Both technologies are excellent at achieving a smaller carbon footprint, a factor which is at the forefront of many of today’s spending decisions. Energy consumption is kept to a minimum in slower moving pneumatic applications, whilst noise pollution can be minimised when switching to electric.

In applications where a load is lifted and a continuous movement is required then electric implementation is better suited, but if the load in addition to being moved needs to remain locked in a given position for any length of time, on balance the pneumatic actuation solution will work out cheaper.

 ‘Horses for courses’

Considerations and similar analysis must also be given to factors such as TCO (total cost of ownership), the motion profiles required, loads to be handled, health and safety regulations and industry sectors. When assessing pneumatic versus electric performance therefore, it is still very much ‘horses for courses’, and both systems have a variety of strengths and weaknesses that need careful consideration when electing for one system over the other.

www.camozzi.co.uk