In Sweden’s national environmental quality objective ‘A non-toxic environment,’ lead is described as a hazardous substance for both people and the environment. The use of lead has been regulated for a long time, but still there are many items that use lead in their production.
Lead is added to steel to produce precision parts in watches for example. New materials available today offer the possibility of phasing out lead altogether in the manufacturing of precision parts.
There are many products around us with small mechanical parts and where the demands are high on durability. This includes everything from ABS brakes, dental tools, probes, and instrument panels to the clockwork in our timepieces. In addition to weathering wear and tear, these small mechanical parts that are all around us must be light, easy to cut, turn and mill to the desired shape. Traditionally, steel is mixed with lead to achieve these characteristics.
The picture changed a number of years ago when the Swiss watch industry began to see changes in the EU requirements on products with lead content. And they expected cost increases as a result. The Swiss watch industry subsequently contacted the Swedish tooling company Sandvik. Their solution was Finemac – a new high carbon steel without any lead content that fitted perfectly into the watch industry’s specifications.
In tests, Finemac has been confirmed to be as good or even better than its lead-containing precursor. The new, lead-free steel has a wider temperature and time span and therefore need not be cooled as quickly after curing.
It is advantageous for component manufacturers because steel that is cooled too quickly often must be scrapped. Using Finemac is easier and generates less scrap, which also means better resource management.
The secret in the manufacturing of the new steel is revealed by Pär Berglund, director of marketing for Finemac at Sandvik Materials Technology: “We have simply replaced the addition of lead with a mixture of mainly sulfur, which yields the same good machining qualities of the steel. It allows us to avoid the development of lead-containing gases that are dangerous to humans and the environment.”
As a material, Finemac is only a few years old but its prospects to replace leaded steel look good.
“Our hope is that we can show that there is now a lead-free and environmentally friendly alternative and that more and more industries can now replace the steel they use. The trend in steel mills is to take an active stand and say ‘no’ to leaded steel,” says Berglund.
The article was published in October 2011.