Deco Products uses the highest quality certified alloys. Our production alloys include the entire range of hot chamber zinc alloys (No. 2, No. 3, No.5, No. 7, and ZA8). Let our highly experienced team of engineers guide you in selecting your alloy choice. We can also use proprietary alloys designed by our suppliers which may meet your needs.
No. 3 alloy is usually the first choice when considering zinc for die casting. Its balance of desirable physical and mechanical properties, superb castability, and long-term dimensional stability are the reasons why over 70% of all North American zinc die castings are in No. 3 alloy. ZAMAK No. 3 also offers excellent finishing characteristics for plating, painting, and chromate treatments. It is the “standard” by which other zinc alloys are rated in terms of die casting.
No. 5 alloy castings are marginally stronger and harder than No. 3. However, these improvements are tempered with a reduction in ductility which can affect formability during secondary bending, riveting, swaging, or crimping operations. No. 5 contains an addition of 1% copper which accounts for these property changes. The alloy is widely used in Europe and does exhibit excellent castability characteristics, as well as improved creep performance over No. 3.
Because of No. 3’s wide availability, material specifiers often strengthen components by design modifications instead of using No. 5. However, when an extra measure of tensile performance is needed, No. 5 alloy castings are recommended. The alloy is readily plated, finished, and machined, comparable to No. 3 alloy.
No. 7 alloy is a modification of No. 3 alloy in which lower magnesium content is specified in order to increase the fluidity. To avoid problems with intergranular corrosion lower levels of impurities are called for and a small quantity of nickel is specified. Alloy No. 7 has slightly better ductility than No. 3 with other properties remaining at the same level.
The alloy is therefore popular for those special cases where the die caster is making thin walled components requiring a good surface finish. However, research testing has shown that metal and die temperatures have a bigger effect than changing alloys. Close attention to control of die casting process parameters is important so as to eliminate defects and achieve consistent quality.
No. 2 is the only ZAMAK alloy which is used for gravity casting; mainly for metal forming dies or plastic injection tools. This alloy is sometimes referred to as KIRKSITE.
For die casting, No. 2 offers the highest strength and hardness of the ZAMAK family. However, its high copper content (3%) results in property changes upon long term aging. These changes include slight dimensional growth (0.0014 in/in//after 20 yrs.), lower elongation and reduced impact performance (to levels similar to aluminum alloys) for die cast products.
Although No.2 alloy exhibits excellent castability, it has seen limited use by die casters in North America. It does, however, provide some interesting characteristics which may assist designers. Its creep performance rates higher than other ZAMAKS and No. 2 maintains higher strength and hardness levels after long term aging. Also, preliminary investigations suggest No. 2 alloy is a good bearing material, and may eliminate bushings and wear inserts in die cast designs.
A good gravity casting alloy, ZA-8 is also rapidly growing for pressure die casting. ZA-8 can be hot chamber die cast, with improved strength, hardness, and creep properties over ZAMAKS, with the exception of a No. 2 alloy which is very similar in performance. ZA-8 is readily plated and finished using standard procedures for ZAMAKS. When the performance of standard No. 3 and No. 5 is in question, ZA-8 is often the die casting choice because of high strength and creep properties and efficient hot chamber castability.
Visit our Knowledge Base for more technical specifications of the various alloys.