Pneumatic cylinder in an affair of the heart

A new polymer vascular prosthetic graft is proving so popular that production is being further automated to keep up with increasing demand.

A new polymer vascular prosthetic graft for the treatment of diseased and damaged arteries is proving so popular with vascular and cardiovascular surgeons that production is being further automated to keep up with increasing demand.

Key elements in the automation system include a rodless pneumatic cylinder and a precision slide, both built to clean room specification from mechatronics specialist Hoerbiger-Origa.

The graft, developed and manufactured in Scotland by Vascutek, is essentially a highly flexible, microporous tube, in lengths ranging from 100 up to 800mm.

It is made of a sophisticated expanded PTFE fluoropolymer reinforced with an expanded PTFE bead.

Due to increased production of the recently introduced Unity ePTFE graft, the need of a mechanical aid for the removal of the graft from processing mandrels was necessary.

The aim of the aid is to mimic the grip and physical pull down strength of the operator.

Therefore a soft and controllable grip coupled with a linear motion air powered supplied by Hoerbiger-Origa for clean room compatibility was designed.

This is achieved by a custom-made pneumatic clamp that is moved into position by the Hoerbiger-Origa rodless cylinder, which traverses between a rest position and the end of the mandrel, the stroke length of 200mm providing adequate clearance without making the overall size of the system overly large for the busy production clean room.

The cylinder is set in motion by the local operator, using a joystick controller provided by Hoerbiger-Origa as part of the macro-solution package.

"We are currently semi-automated", explains Vascutek Development Engineer Fabien Lombardi, "which suits our batch manufacturing process".

"But the system is designed such that we can switch to fully automated continuous production when demand dictates".

"When we first introduced the new graft our production processes were largely manual".

"As demand grew there was a danger that our operators would suffer from repetitive strain injuries, so we implemented the plan to shift to semi then full automation".

To maintain the necessary precision motions Hoerbiger-Origa incorporated its Proline linear guide into the system for load bearing due duties, the clean running characteristics and clean room rating of which were ideal for the task in hand.

"The whole macro-solution is bench mounted so can easily be re-positioned or re configured to accommodate predicted increases in production".

"The simplicity of the final design is a great bonus".

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