Manufacturing contact lenses is a volume business and the scale of the operation at CooperVision’s daily disposable manufacturing facility in Gyal, near Budapest’s airport, is impressive. Shail Patel, professional services consultant with CooperVision, explains the centre’s position, in the centre of Europe, makes sense for distribution as does its location close to the airport. The centre has won a prestigious Hungarian architecture award and was conceived and built by Sauflon shortly before its acquisition by CooperVision. Sauflon chose the location for the reasons above and the availability of a skilled and flexible workforce.
Since the impressive, shiny, white facility was set up (Optician 09.12.13) volume at the plant has grown, as has its footprint. Patel says the site now occupies 18,000sqm employing 1,200 people producing 1.7 million contact lenses a day, every day through three eight-hour shifts. The store room contains a buffer of 110 million lenses which would provide two months’ worth of stock. Production currently employs 24 production lines in 12 cells, each cell is housed behind its own firewall and expansion, running at 35% a year, is through the addition of modular replicated manufacturing cells. The scale and modernity of the plant could not be more different from the humble contact lens its produces. ‘When people see contact lenses being manufactured for the first time it changes their attitude,’ says Patel.
Adding to the drama of a visit is that anyone entering the facility has to don protective clothing, a hair net, white coat, booties and, for those with facial hair, a beard snood. Positive pressure clean rooms constantly change the air to keep the environment particle-free. CooperVision also tries to protect the outside environment through recycling of packaging and reuse of materials were possible.
The detail of manufacture takes place behind a blur of pick and place machinery and precision robotics. Many of the simple tasks are automated and some of the many quality checks are carried out by camera. People are used where the firm feels they can improve on quality or maximise outcomes.
At the heart of the process is a plastic mould into which the contact lens monomer is injected. The mould is equally important as it creates the lens shape.
Two polypropylene moulds are made for this purpose one inside the other. Their shape determines the dioptric power, shape and size of the finished lens. Aluminium formers are used to press out the male and female parts of the moulds in an injection moulding process. The moulds are arranged in circular groups of six petals each forming a flower. The female part of the mould provides the dioptric power and the male part the base curve. The petals are shaped so they can be picked and placed robotically, but accurately, throughout the process.
Mark Chatham, professional services consultant, explains how Hungarian ingenuity has been employed throughout the process. He gives the example of this during the polymerisation of the mould monomer. This has to be completed in a nitrogen-rich atmosphere which clogs the heating tubes of the ovens. The local engineering team filters the nitrogen through paraffin oil which prevents the clogging.
Once made the flowers have to be left to rest so the gases created in their production can disperse, they are then stacked in batches which can be robotically handled through the process.
The creation of the contact lens comes through a dry casting process. A precise amount of monomer is injected into the female mould which is then united with its male flower counterpart. Each petal is sealed at three points to create an even edge to the lens which is then heat polymerised.
Polymerisation is closely monitored over a two-day period. The lenses are put into ovens heated to 350ºC (662ºF), which is reduced to 120ºC (248ºF), the lenses are then allowed to cool for the next day and a half. This, says Chatham, allows the quality of the lens to be maintained. The temperature and oxygen levels in the curing atmosphere are continually checked, he adds. Once cured the moulds are separated.
The contact lens, initially left in the female mould, is robotically removed and checked both electronically and by human eye for physical integrity and optical properties, the plant aims for a success rate of between 95 and 98%. At this stage the finished lens is hard and dry so goes through a hydration process during which the lens expands to its final shape and size.
Perhaps the most impressive task of the day is the insertion of the lenses into the blister packs. This task is currently carried out by hand. Banks of women take the lenses with a pair of tweezers a place each one in the bottom of the blister. Saline is then injected into the blister to hydrate it. It is then sealed with a foil wrap which is printed with the relevant power details. The whole unit goes on to be sterilised in an autoclave. Before despatch further quality checking takes place of the lenses and the blister packs.
The lenses are then bulk packed for shipping to CooperVision’s main European distribution hub in Liege.