Rotary Drives
Magnetically-coupled Rotary Drives - MRD Series
Differentially Pumped Rotary Feedthrough - DPRF Series
Rotating Platform - RP Series
Many vacuum processes require a sample or other component to be rotated. This can range from something as simple as spinning an attenuating chopper wheel, to accurately moving a sample to face from one analyser to another. VG Scienta have a wide range of rotary drives to fulfill most customer requirements.
There are several different methods of achieving rotation in vacuum. The two most common arrangements are:
A vacuum-tight seal on a mechanical drive that moves through the vacuum wall
or
A magnetic coupling that transfers motion from air-side to vacuum-side.
The more standard versions are discussed in this section but please bear in mind that we create a large number of custom rotary drives for many different applications, so please contact our sales department if you feel you have a requirement that is not covered in this section.
All the drives contained in this section cover different aspects of in-vacuum rotation. These range from simple manual drives with relatively low resolution and torque capacity to high performance drives that are capable of carrying high loads or have high speed or torque specifications. Many of these can be motorised with stepper or DC motors; they are listed as order code options where available.
Magnetically-coupled drives use a high strength rare-earth magnetic coupling to transfer the rotational forces into the vacuum envelope. This is achieved without any dynamic seals or bellows. The vacuum enclosure, complete with Conflat flange, can be machined from a single billet of material. Thus many of the problems associated with conventional stainless steel drive bellows, such as leaks to atmosphere, are completely eliminated.
The use of high strength rare-earth magnets gives exceptional levels of torsional rigidity. However, if the recommended input torque is exceeded, the magnetic coupling will simply 'cog' over to the next position. As there is no actual mechanical connection, the drive will not be damaged. All magnetically-coupled drives are extremely robust and utilise large, highly specified, bearings to ensure long service life. All drives are fitted with magnetic shielding as standard.
Bellows sealed drives can be mounted in any orientation and are the most widely used form of actuation. A vacuum-side shaft extends into the air-side space within a vacuum enclosed metal sheath. A 30o bend is put in the shaft on the actuation side (but still under vacuum). This bend is contained within a sealed bellows unit and welded into the sheath and capped at one end. Between the cap and shaft is a ball socket joint that allows the bellow to 'wobble' when rotational force is applied to the shaft. The bent shaft connection on the actuation side causes the bellows to wobble allowing a rotational force to be applied to shaft within the vacuum envelope.
The 'wobble' method of actuation is more than capable of handling lighter workloads that do not require high torque or continuous high speed (see individual drive specification for details).