Here is some background information about the manufacturing standards employed by AE METALS, my sole supplier of recycled metals. This information has been taken directly from their website.
We use only the highest grade silver and gold possible. Most of our pure gold and pure silver comes from recycled products. Our website shows the products that are made from recycled raw materials.
To melt and cast silver and gold wire and sheet we use brand new continuous casting and static casting equipment. The means that firstly we use much less power than older style melting equipment, and secondly that we always melt under inert atmosphere or with vacuum. Melting without oxygen present is very important for achieving good results in many gold alloys, and is very important when melting and casting silver alloys. To cast sterling silver alloys without this technology has always been a very hit and miss operation, but with this latest equipment and the controls in place to make sure that we always use the correct raw materials, this is no longer the case. We have also been able to apply this to the melting and casting of other traditional products such as Shibuichi and Shakudo which have previously been done on a small scale by hand. This has meant that they have been very unreliable and difficult to make, but by using de-oxidised silver and copper and by melting and continuous casting these alloys have been greatly improved.
Sheet and Strip Rolling
This is where we have kept to the age old traditions and have acquired high quality rolling mills from around the world. Our mills are in various formats to enable us to roll many different types of sheet and strip, from 12mm down to 0.2mm, and sheet up to 280mm wide. Also we can produce many different embossed strips and fancy profiles. We have eight different rolling mills, from small ones for doing special order gold jobs, to big mills with 300mm diameter rolls for breakdown of silver concast sheet. We also have high precision rolls for mirror finish rolling of thin sheet down to 0.2mm, and special embossing rolls for making many different patterns and profiles.
Traditionally this process was very time consuming as the cast wire or billet was rolled square on traditional wire rolls, and it would take many hours to do each batch. With our new wire rolling machines we can achieve the same result in only a few minutes before the wire is then drawn to final size. These machines use a series of rolls to roll from concast wire down to the first anneal. The wire once annealed then goes to the second machine that then rolls down to the final size before annealing and drawing to size.
Our brand new wire drawing machines are capable of drawing fine wires down to 0.2mm diameter spooled. Here we only use diamond dies for the best finish and accuracy. Normal tungsten carbide dies which most other manufacturers use wear quickly with use, so the wire becomes dull and oversize.
Our bright annealing furnace is brand new and the only one in the country. It is able to provide even heat throught, which stops hot spots occurring in the furnace. Hot spots leads to uneven hardness. It is large enough to anneal anything we can produce in inert atmosphere, which means that all our annealing is done with no oxygen present. This means that we do not have any fire scale on our silver products, which is of course very important to the silversmith. Some other manufacturers do not anneal in atmosphere, so they have to pickle their wire products in acid afterwards, and then draw the wire to make it bright. This method is not good enough for our quality control as it can result in fire scale that does not become obvious until the jeweller or silversmith works the metal, or until it is left for a while to tarnish. Also this tends to draw oxides into the surface of the metal further increasing the problem. We know how important this is as many of our staff are practicing jewellers and silversmiths.
The Environment In Manufacturing
Because most of our equipment that uses any significant power is new we use in total a very small amount of power to run our manufacturing operation. Manufacturers with older style melting and annealing equipment that use very significant power to run. Our bright annealing furnace is also much more energy efficient than using other forms of annealing, such as belt annealing, which wastes a huge amount of heat and covering gas in the process. Because our furnace is sealed it does not waste heat and gas and is thus better for the environment. As almost all our products are bright annealed we do not have to pickle them. Therefore we use very little acid, and what we do use is a very weak form rather than the sulphuric acid solutions that people have traditionally used. We make sure that even this is all reclaimed, so that none ends up in our waterways or landfill. All our cooling water for our melting and annealing processes is recycled and filtered so that we do not use any significant volume of water in our production process. We are continuing to work on new ways to further improve our manufacturing both in terms of producing new products and in producing them in the most cost effective and environmentally responsible way possible.