Hanging robot minimises footprint

CooperVision's Southampton facility, where the new workcell is installed, develops production processes for introduction in serial manufacture in the company's plants worldwide. The workcell has been set up to develop a process for manufacturing a wide range of contact lens mouldings with total backward traceability in a cleanroom environment.

The robot used, the ABB IRB 120, is a small multipurpose industrial robot that weighs just 25kg and can handle a payload of 3kg, certified for ISO 5 cleanroom areas (Class 100). The robot was selected for its small size and speed; the requirement was eight parts in ten seconds.

To make the cell even more cost-effective, the robot's built-in controller is used to manage the whole cell, eliminating the requirement for a PLC as well as a HMI.

The cell at CooperVision is used to transfer contact lenses moulded to curing. Initially, a mould consisting of two pieces, one for the front and one for the back of the optical surface, is made up. The space between the two halves of the mould is filled with monomer.The assembly is cured and the mould is then discarded. The process requires high precision as well as high volume.

The robot cell has been introduced to remove a manual step from the process, aiming to save time and free up staff. The reduction in cycle time has been achieved by using the robot to transfer parts from the injection moulding process that arrive in batches of eight, to a tray with over two hundred parts, which are placed and orientated to a specific pattern ready to go into the cure process.

As the target tray is fairly large, this impacted on the footprint of the installation and the solution was to suspend the robot from the ceiling of the cell.
"Operating the robot from the ceiling of the cell was a novel idea to us. It's a creative approach that saves space, which is important to us, so the whole cell now takes up no more footprint than the robot baseplate," says Robin Frith, R&D project engineering manager at CooperVision.