Zinc Alloy Generic Terms
All zinc alloys are not the same be sure to specify correctly to ensure you get what you want.'
The current Zinc alloy chemistry specifications originate from around 1935, from research by The New Jersey Zinc Corporation, who introduced the generic name Zamak to zinc alloys.
Prior to this research Zinc alloys contained many harmful impurities some added to mistakenly to improve casting characteristics. Some of the element metals added had severe effects on the long term properties of the Zinc alloy pressure castings.
It was common for lead, tin and antimony to be added to Zinc alloys and the research by New Jersey Zinc demonstrated that these plus other impurities promoted inter-granular corrosion when present in Zinc/Aluminium alloy pressure castings. As a result of this research the effects of these elements was clearly understood.
Today, all Zinc alloys supplied by reputable producers are made from primary or virgin Zinc which conforms to the SHG (super high grade) or Zn 1 brand which is quoted on the LME commodity market worldwide.
Zinc of this standard is 99.995% pure and has to conform to international quality specifications such as EN 1179. In turn the qualities of the alloys manufactured from this grade of Zinc are controlled to EN 1774 or other international standards thus guaranteeing the chemistry and long term properties of the alloy.
It is therefore in the interest of all users to maintain and support the use of these standards when ordering, specifying and promoting the use of Zinc alloy castings.
Unfortunately, the use of generic terms or descriptions of Zinc alloys have become common and are frequently specified by designers on casting drawings and by purchasing managers on formal orders for parts.
Secondary alloys are still available in the market place; they are of indeterminate origin and variable quality. Their use should be confined to the manufacture of non-critical parts where mechanical properties are not important. Again specifying the EN standard on part drawings will eliminate the use of secondary alloys and protect the user from product liability problems.
The use of names such as Zamak are common. Use of trade names is common as is specifying Zinc on drawings but to ensure that the parts meet the anticipated standard of quality assurance it is wise to use the relevant EN or international standard which in Europe is EN 12844 for Zinc alloy castings.
This will guarantee that the alloy used meets the desired standard and that the castings are supplied to a manufacturing specification designed to optimise the quality and consistency of the parts supplied.
In Europe Zamak has become a common name for all zinc alloys although there are several different grades which fall within this description - Zamak 2, Zamak 3, Zamak 5 etc. Several manufacturers use Zamak as their product description.
'The use of generic names is not uncommon, the name "Hoover" has become synonymous with vacuum cleaners but ultimately if you need a Dyson you have to specify a Dyson.'
Simple explanation of the origins of zinc alloy generic names and the implications of their use.