The increasing use of a new generation of oil-based die release agents offers a number of advantages – both environmental and economical - over the traditionally used water-based die lubricants, says Ultraseal International.
Popular because of their fire-resistant features, water-based die lubricants nonetheless have many disadvantages, not least of which is that most of the lubricant applied is simply wasted.
This waste is hard to avoid because it arises from the very nature of water-based die release agents themselves, and is in stark contrast to the efficiency of applying modern water-free, oil-based lubricants.
Indeed the differences are spectacular: water-free die lubricants can provide excellent results with only 1/800th of the volume that would be required if a water-based die release agent was used.
The environmental benefits of using water-free die lubricants don’t stop there: applying them requires less electricity, which reduces the carbon footprint of the die casting process. They also produce less wastewater.
The second generation of water-free die lubricants is especially efficient. These have been modified in order to be applied by an electrostatic spray gun which produces a ‘wrap-around effect’ with the spray mist.
One of the major drawbacks with water-based die lubricants is the amount of spray that simply never reaches the die surface at all: in general about one-third of the lubricant misses the target.
With an electrostatic spray, such as Lubrolene WFR-EC, the mist is drawn around to surfaces of the die that were previously inaccessible in the ‘wrap-around effect’. More of the lubricant hits the target, less is wasted, and coverage is better.
Electrostatic water-free die lubricants are especially useful for dies that have complex shapes, as multiple sprayings from different angles are no longer necessary, cutting down on production time.
Another major disadvantage of water-based die lubricants is that they adhere to the die most effectively at temperatures of between 150°C and 250°C, which is well below the temperatures at which some dies operate.
This is because water-based die lubricants are emulsions in which the main oily, active ingredients are heavily diluted with water (in the proportions 0.2wt% to 99.8wt%) and delivered in a spray.
Each tiny droplet of spray contains oil surrounded by water and the idea is that when a droplet reaches the die surface the water will evaporate, leaving the oil to form a film on the die surface.
In practice, this works only if the die surface temperature is between 150°C and 250°C. Below 150°C the water won’t evaporate quickly enough and some of the oil will go down to the floor as waste.
Equally frustratingly, if the die surface is hotter than 250°C, the water based lubricant will rebound from the die surface in an effect called the Leidenfrost phenomenon. That, too, results in poor oil film formation.
As the dies are usually hotter than 250°C, when water-based die lubricants are applied, a large volume of lubricant is used up simply cooling the die to a temperature at which a decent oil film can be formed. This is clearly wasteful.
Another problem inherent to water-based die release agents is that extra electricity is required to blow air over the die to ensure that no water is left in the die cavity. There is not the same need with water-free die lubricants, and the carbon savings can be significant.
For example, about 60 tons of carbon dioxide can be saved a year if water-free die release agents such as Lubrolene WFR-EC, an electrostatic water-free lubricant, were used instead of a conventional water-based lubricant, on a 350 tonne die casting machine (based on evaluation of a Japanese size machine over a three-month period).
The good news is that all these environmental benefits come with significant economic benefits that derive from the fact that water-free lubricants do not significantly cool the die in between castings.
Using the Lubrolene WFR range of water-free die release agents reduces the wear and tear on the die, greatly extending die life and leading to six figure savings annually. So die casters can not only reduce their impact on the planet, they can add profit to their bottom line.
Contact: Ultraseal International
Tel: +44 (024) 7625 8444
email: [email protected]
web: www.ultraseal.co.uk