A workcell measuring 0.8m by 1m, with an ABB IRB 120 robot hanging upside-down from the ceiling, is used at global contact lens manufacturer CooperVision’s R&D facility in Southampton. The cell provides a reduced cycle time of 30 percent by enabling the faster transfer of contact lenses between the moulding and curing processes.
“I wanted to make the most of the available space and suspending the robot from the ceiling seemed the best way to minimise the footprint,” said Rod Mitchell, technical director of Midlands-based machine builder Notio. His company specialises in bespoke solutions for applications where production equipment is not readily available. Mitchell integrates solutions involving mechanical engineering, electronic engineering and software to find a suitable design to fit the application and the budget, aiming to bring a creative perspective to machine design. “We are specialists at solving quirky problems for unusual applications, typically the ones that larger companies are reluctant to tackle because there is too much engineering and not enough sales involved,” he said.
Notio does the whole job – drawings, sourcing of parts, documentation and everything else up to commissioning. In fact the name of the company, Notio, is Latin for notion or concept, indicating the company’s investigative approach to manufacturing problems.
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.
“Controlling the cell is a fairly simple job and this solution offered the lowest cost,” commented Mitchell.
The cell at CooperVision is used to transfer contact lenses from moulding 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. “Apart from that, the cell came out pretty much as we had expected. We have worked with Notio for some time and set them a challenge to find a solution for this application. It has now been in operation for a couple of months and we are very happy with its performance. Notio has the knowledge and skills to meet our critical quality specifications and develop applications that we can successfully introduce into manufacturing. They also help source components, enabling us to work with the manufacturers and platforms that best suit our needs. The cell will be used for about a year here, but it’s quite an adaptable cell so we will probably reconfigure it and get more use from it somewhere else.”
CooperVision is a soft contact lens manufacturer that develops, manufactures, and markets a range of contact lenses to a worldwide market. CooperVision produces both spherical contact lenses and specialty lens products. The company is headquartered in California and its products are sold in over 100 countries.