PRIME MOVER™ Metal Bellows Linear Actuators

Linear actuation for:

• Ultra-clean environments or
• Actuation through a pressure boundary

There are many applications for linear actuators in ultra-clean or vacuum environments. The challenge for equipment designers is how to provide linear actuation through a pressure boundary while maintaining the hermetic integrity of the process.

Conventional actuator technology

Conventional means of linear actuation include air cylinders, ball screws, or cables and pulleys. These conventional actuators require the equipment designer to also consider a means of providing a hermetic, dynamic seal. Given that these actuators are required to perform millions of cycles without failure the most common means used for this dynamic seal is a welded metal bellows. The welded metal bellows can be designed for a great variety of stroke length and diameter and can last for the millions of cycles required.

PRIME MOVER technology

A linear actuator has been developed that combines the actuation and dynamic sealing functions into one unit. This is the metal bellows type PRIME MOVER actuator. With the PRIME MOVER actuator the welded metal bellows is integrated into the device to act as the hermetic seal as well as the actuation force generator.

The metal bellows is essentially a hermetic spring. When a pressure differential is applied across the bellows, the bellows will compress and thus drive the actuator. When the pressure is removed the bellows spring force will retract the actuator. The all welded construction provides a completely hermetic seal.

Comparison of PRIME MOVER to conventional actuator

As compared with conventional actuator technologies, the metal bellows type PRIME MOVER actuator offers many unique advantages. These advantages are in both cost and performance areas.

Compact

The metal bellows type PRIME MOVER actuator is very compact because it combines both the sealing and actuation functions into one device. This allows for an overall more compact equipment design.

Simplifies Integration

The PRIME MOVER can be made to be adjustable but that is not necessary. These actuators can be factory preset to specific actuation requirements. This feature can greatly simplify installation into the system as no adjustment or calibration is required. With conventional actuators, system integration involves careful adjustment and calibration, which extends manufacturing time and drives up costs.

System level integration is greatly simplified and the system component count is reduced. With conventional actuators the system component count is higher, which increases logistics costs, increase system assembly time, and reduces overall system reliability.

Features

• Provides pure axial motion – No rotational forces are introduced. With conventional actuators like air cylinders some small amount of rotational force can be transmitted.
• All metal construction – PRIME MOVER actuators can be used in temperature extremes, cryogenic to 450F. Additionally, the all-metal construction makes it compatible with the harshest chemicals, plasmas and fluids. Conventional actuators with elastomeric seals are temperature limited and have seals that can degrade in harsh environments
• Accurate and repeatable positioning
  • Up and down stop Z-axis positional accuracy is +/- 0.001”
  • Lateral positional accuracy is +/- 0.005”
  • Repeatability is +/- 0.0005”
  • Unit-to-unit uniformity is within 0.005” over the entire stroke
• Ultra smooth actuation – No wearing seals. Bellows provides smooth consistent actuation over entire stroke.
• No dynamic elastomeric seals – With no wearing seals PRIME MOVER actuators are completely maintenance free and can operate for millions of cycles without failure. Because there are no wearing components, there is no degradation in performance over hundreds of thousands of cycles
• Clean actuation – PRIME MOVER actuators meet ISO 14644 Class 1 requirements, which specify £ 10 particles per cubic meter of air ³ 0.10 micron.
• Pressure range – The typical pressure range that PRIME MOVER is designed for is 60-90 PSID. This produces actuation forces on the order of 40 to 80 pounds. With larger diameter actuators, actuation forces of up to 1000 pounds can be achieved.
• Reliability – Because there are no wearing seals, PRIME MOVER actuators can be designed for 10 million cycles or greater.
• Position sensing – In some actuation applications the position of the actuators needs to be determined and electronically signaled to a controller. In these applications there are a few options. Optical and magnetic position sensors can be easily integrated in to the PRIME MOVER actuator

Applications

• Pneumatic and hydraulic linear actuation
• Actuation across a pressure boundary
• Actuation in ultra clean environments
• Semiconductor/vacuum processing
  • Pin Lifters
  • Wafer handling
  • Shutters
  • Shadow ring positioning
  • Valve actuators

PRIME MOVER data sheet (PDF)

PRIME MOVER Brochure (PDF)