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Device stops cylinders precisely at intermediate points
Published:  22 October, 2014

Festo has announced a module that can be positioned anywhere along the stroke length of a pneumatic actuator to create stops where they are needed. A “unique” follow-through function is claimed to allow faster cycle times after such stops.

Festo says that its DADM intermediate position module will bring new levels of flexibility and efficiency to pneumatic guided slides, rodless cylinders and self-built drives. It is aimed at handling, assembly and pick-and-place applications and, according to the company, will save machine-builders time and money.

The easy-to-install, off-the-shelf module is said to be smaller and cheaper than other methods used to create mid-position stops – such as “piggy-backing” two cylinders on top of each other, which is expensive and bulky, or using an electric drive, which may be more complex and expensive than is necessary.

“The travel-through feature of the DADM is unique, eliminating the need to ‘back-off’ to continue along the stroke,” explains Steve Sands, Festo’s product manager in the UK. “For high-speed production machinery, where the aggregation of marginal gains is a key focus, each fraction of a second saved makes a significant impact on the overall cycle time.

“Previous intermediate stops required the thrust of the cylinder to be reduced to enable the stop mechanism to be retracted before the movement could be completed,” he continues. “Through careful design of the geometry, we have been able to provide a robust stop cam that can be retracted under load, saving valuable cycle time and simplifying the controls and programming.”

A Festo pneumatic cylinder fitted with the DADM module (on the right)

The module can be mounted at any position within the stroke length and includes position detection for safety and reliability. Shock absorbers cushion the stop with a metal-to-metal final position, assuring a repetition accuracy to within ±0.02mm.

Initially the device is available in two sizes ­– 10mm and 16mm – with corresponding maximum impact forces of 500N and 1kN. It can be reversed, allowing it to be used on either the out or return strokes.

“The intermediate position module has been designed and exhaustedly tested for an operating life in excess of 20 million operating cycles,” Sands reports. “This convenient, off-the shelf item has often been requested as it will save machine-builders a phenomenal amount of design effort and expense, engineering bespoke mid-stop solutions. Now there is a ready-tested solution with guaranteed reliability.”