There are many types of coolants. Water is a good coolant, but is a poor lubricant. By adding extreme pressure soluble oil to water, you can have a very good coolant. However, this type of coolant can leave stains on the strip, which is not acceptable for many products. It is best to use a coolant that will not burn. It is very common to use an extreme pressure oil like gear lube on low speed mills. Kerosene mixtures are very common for aluminum because they make a beautiful product without stains. However, a water based lubricant is still used for aluminum rolling. The problem with kerosene lubricants is the possibility of a fire. Aluminum rolling mills are equipped with many CO2 automatic valves. With rolling mills that run aluminum at high speeds, a bearing or friction could cause a spark and start a fire. When you use a kerosene based lubricant, it is very common to use a good CO2 system. There are many different types of coolants with product mix. A good coolant lubrication system uses a good filter system and heat exchangers to keep the coolant temperature constant. Certain products that are cladded, require little or no coolant, especially with stand alone, high reduction rolling mills or rolling mills that are in a continuous casting line.
Coolant Fume Control
With a special type hood, the coolant fumes are used to produce a high velocity of fume input to withdraw all of the fumes into the hood. The material is sent from the hood through a large fan that extracts the fumes. The fumes go through a scrubber system so the oil vapor or fumes do not go into the environment. You will notice these mills are totally enclosed to prevent fumes from going into the factory. All good fume systems require a large vacuum fan and scrubber system.