Air Bearings seals a longer operating life

Edited by the Engineeringtalk editorial team Aug 11, 2003

Replacing quad-ring seals with Ceetak's O-ring energised PTFE rod and piston seals has helped Air Bearings extend the operating life of its tool-changing mechanism.

Replacing quad-ring seals with Ceetak's O-ring energised PTFE rod and piston seals has helped Air Bearings extend the operating life of its tool-changing mechanism.

Air Bearings (ABL) introduced its latest tool-changing mechanism three years ago.

The new design forms an important part of the company's renowned air-bearing spindle range, which is used principally by OEMs in the printed circuit board industry.

The mechanism's lubricant-dependant seals could, however, experience stick-slip, as Stuart Hughes, General Manger at ABL, explains.

"Our ongoing product improvement programme identified that the seals used in the cylinder could, in time, lead to stick-slip.

If this were to occur, it could lead to inconsistent operation of the tool changer.

We eliminated the possibility that this could occur two years ago when we changed to seals supplied by Ceetak".

The company originally specified quad-ring seals to safeguard the axial movement of the pistons, which are attached to a push rod which opens a collet to facilitate tool changes.

Because of the seals' relatively large contact area and materials used, lubrication was required, which over time could degrade.

"The seals play an important part in the tool-changing mechanism", Hughes acknowledges.

"We found that the stick-slip on the quad seals could cause problems.

Although we lubricated the quad rings, the level of lubrication would deteriorate over time and, potentially, the pistons could stick".

ABL contacted a number of seal suppliers to help them find a solution.

"We had to find something that was more freely running and provided long-term performance", Hughes recalls.

Ceetak "came up with the right product" and won the contract.

Ceetak's piston seals were ideal as they combine a PTFE piston sealing ring and an O-ring in a single unit with a small contact area.

More importantly, the low-wear characteristics provide minimum breakout and reduce dynamic-slip friction, which ensures steady movement even at low velocities and a complete lack of stick-slip.

The Ceetak rod seals were also specified as they are compatible with nearly all media due to the high chemical resistance of the rod sealing ring and the wide selection of O-ring compounds.

Combining a PTFE rod sealing ring and an O-ring, these seals are suitable for a variety of applications including rods in control cylinders, servo-assisted equipment, machine tools, quick-acting cylinders and construction machinery.

In total, three Profil ON rod seals and three Profil OE piston seals are used to safeguard the mechanism's pistons and cylinders.

By specifying Ceetak seals, ABL has been able to extend the operating life of the tool-changing mechanism used in its high-performance spindles.

Stuart says: "The Ceetak seals don't need lubrication - they go in dry.

So in the long term, there is no degradation in the performance.

Because of this, we knew that long-term improvements were achievable".