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Precision Dippings Marketing, which makes dip-moulded rubber and latex products, has used linear actuators from Parker-Origa to upgrade a semi-automated line to full automation.

Bristol-based Precision Dippings wanted to retain an existing transfer and handling system feeding the dipping tanks.

It called in consultant engineers from Parker-Origa to design and develop a system to dip the moulds or forms into the tanks.

Parker-Origa’s Nigel Smith said: ‘The need was to vertically lower the moulds into the tanks, then lift them out again.

‘But a wide variety of precision mouldings was to be made on the line, each requiring a unique dipping procedure.

‘Some products require a single dip, others multiple dips to build up depth of material; some go in and out quickly, others slowly; some go in and out in steps; some need variable speed.

‘It was clear that we’d need an intelligent controller and Precision Dippings was keen to retain the transfer system controller, so we had to interface to that too.’ Because it was a harsh working environment, a totally enclosed linear actuator was desirable and eventually a suitable electric actuator was proposed.

The OSP-E range of actuators was identified as ideal; these are robust and self-supporting, although in this case they were fitted with a guide to ensure precision motion.

They can be fitted with a belt or screw as the internal-drive mechanism, with a trapezoidal screw being chosen for the dip-moulder because there is no back driving.

A range of motors can be fitted to the OSP-E.

In this case servos were chosen for the vertical axes, as they are the best option for precision motion-control options.

Actuators were also used on horizontal axes to transfer the moulds to and from the dipping tanks.

These were powered by stepper motors, because the precise accuracy of servos was not necessary and their open-loop control simplified system design and installation.

Smith added: ‘The vertical dipping-motion has to be programmable for each type of product, so we needed an intelligent controller for that.

‘The horizontal transfer movements are not so precise, but they can be complex to account for the need for different dipping patterns.

‘Also, different production volumes and speeds are addressed by using one, two or three tanks in parallel; so sometimes the lines each handle different products.

‘We retained the original controller on the existing handling system, so use signals from this to initiate sequences on the new controller.

‘It is actually quite an elegant solution and was the way we minimised disruption to production during installation.’ Precision Dippings currently uses the new system on a 14-hour working pattern, but it can run 24 hours a day if necessary.

Products made include seals for divers’ dry suits, boots for vehicle gear-levers, industrial seals, medial devices and consumables such as condoms and surgical gloves.

Productivity and product quality has improved as a result of automation.

Parker-Origa, a division of Parker Hannifin, is a leader in the innovative design and manufacture of pneumatic and electric actuation and control solutions for industrial automation.

The Origa System Plus range of rodless pneumatic cylinders provides a modular approach to linear automation with the easy integration of guides, controls, position sensing equipment and other accessories. An extensive range of electric linear drives capitalises on this system modularity and extends the scope of application with respect to loads, speeds, precision, positional accuracy and path control.

With annual sales exceeding 12USD billion, Parker Hannifin is the world’s leading diversified manufacturer of motion and control technologies and systems, providing precision-engineered solutions for a wide variety of commercial, mobile, industrial and aerospace markets. The company employs approximately 62,000 people in 48 countries around the world. Parker has increased its annual dividends paid to shareholders for 52 consecutive years, among the top five longest-running dividend-increase records in the S&P 500 index.

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