In Depth Cost Comparison of Pneumatic Cylinders and Industrial Linear Motors

Application Example: In a pick and place application, a 15kg load is run at 30 cycles per minute with a 400mm stroke.

Linear Motor Solutions

The required positing time of 500ms for the task given above is achieved with an acceleration of 10m/s² and a travel speed of 1m/s. The acceleration time, during which the linear motor does useful work, is 100ms. This means that the effective motor losses (other than friction) occur during only one-fifth of the positioning time. The kinetic energy from braking is also converted into electrical energy and stored in the servo controller, so this is available again for the next cycle. The task can thus be accomplished with less than 100W power consumption, and annual energy costs of less than $144.00 USD ($0.17 USD /kWh).

Pneumatic Cylinder Solution

Due to the load mass of 15kg, and the required maximum speed of 1m/s, the pneumatic cylinder must have a piston diameter of 50 mm (2”). In contrast to the linear motor , the energy (compressed air) must be provided throughout the entire motion. The kinetic energy from braking must also be absorbed by dampers, and cannot be stored for the next move. Based on the cylinder volume and cycle time, the annual air consumption is 24,000m³ of compressed air at 6 bar. This energy cost is in excess of $4,580.00 per year.

Analysis of the investment and energy costs in this example application shows that the savings from the use of an industrial linear motor, compared to the use of a pneumatic cylinder, are $2,520 and $6,696 at 12 and 24 months of service respectively.

Total Cost Calculation of Linear Motor vs Pneumatic Actuator

Considering the difference in the energy cost of the linear motor versus the pneumatic actuator, the initial investment cost becomes less and less significant in relation to the total cost. The energy savings in our example typically offset the lower investment costs for the pneumatic cylinders after just a few weeks. The significantly longer service life, compared to pneumatic cylinders, means lower maintenance costs whenever industrial liner motors are used. View the full Cost Comparison-Air vs LinMot Linear Motors Brochure.