Havells Factory
Manufacturing CFLs is more complex and expensive than incandescent bulbs.The process begins with cutting of the straight glass shells
By Arnab Pratim Dutta (Reporter, Down to Earth)
Photographs by Meeta Ahlawat)
The mercury can either be in the form of pellets or liquid. The heated cathodes turn the mercury into gas
The tubes are dried and put in a baking machine that maintains a temperature of about 550 degrees centigrade. After three minutes the tubes are taken out and a fluorescent-whitening agent is applied
Havells Factory
The shells are then bent into a U shape
(By Arnab Pratim Dutta (Reporter, Down to Earth)
Photographs by Meeta Ahlawat)
The CFLs are capped with a plastic base and sent for quality checking that involves grading of CFLs based on their luminescence
The filament is slipped inside the tubes
The tubes are washed in chemically purified water at a temperature of 65-75 degrees centigrade
The ends of the glass tubes are cleaned and they are mounted on a sealing machine for locking the filament inside the tube
After the wash the tubes are dried for about 25 minutes at a temperature of about 80 degrees centigrade
The tubes are vacuumed in an exhaust machine and mercury and argon are introduced into the tubes while the cathodes are heated
A coating of fluorescent powder prepared with a binder and purified water is then applied to the glass shells. The fluorescent powder is a combination of phosphor (containing calcium phosphate, aluminum oxide) and polyethylene oxide and dispersion agents
