CASTINGS
Zinc die casting technology as practiced by E. Toman & Company is leading the way in creative and cost-effective solutions to some of the toughest problems faced by design engineers. The elimination of many secondary operations, as well as the ability of E. Toman & Company to create castings of unsurpassed detail and complexity, favor the selection of Zinc over aluminum, brass, bronze, or iron castings, and steel fabrications, as well. Durability and surface options, including chrome plating, brushed-metal effects, and high-quality painting, often make Zinc preferable to molded plastic parts.
But no manufactured part can be truly cost-effective unless quality and consistency are at the core of its design and creation. At E. Toman & Company, the latest in die casting technology and statistical process control is brought to bear on each job. This results in unmatched uniformity and quality in each part we ship.
Of course, no matter how technologically advanced our product is, it is our customer service that is the critical link between customer and supplier. Personal attention to each of our customers is the hallmark of our company.
METALLURGICAL REVIEW
The amount of undesirable elements in your zinc castings can give you big headaches; a departure from specified limits in the failure to get strength and stability the alloy was designed to give.
- Lead in excess promotes subsurface corrosion at the minimum levels of magnesium.
- Cadmium is detrimental to the mechanical properties and adversely affects hot shortness and castablility.
- Tin is controlled to inhibit dimensional growth and subsurface corrosion.
- Silicon adversely affects the mechanical properties of zinc alloy.
- Chromium contamination, usually resulting from melting back plated scrap, can form intermetallic compounds and have a deterioration effect similar to iron.
If lead, cadmium, tin and iron are the bad guys in our metallurgical story, aluminum, magnesium and copper are the heros. In fact, the inclusion of carefully controlled amounts of these elements make modern zinc die casting possible....
- Aluminum is added to increase strength. However, impact strength drops off with amounts over 4.5% until you approach 8%. Some loss of castability and other properties occurs below 3.5%.
- Magnesium is added to alloys to prevent the harmful corrosive effects of the normal impurities. The minimum limits prevent the formation of subsurface corrosion. A higher content lowers fluidity, affecting castability and promotes hot shortness in castings.
- Copper is not added to #3 alloy. When added, strength and hardness are improved as in #5 alloy; however, properties and growth are adversely affected when copper exceeds 1.5%.
That's it for our metallurgical review. We hope you can use this information to impress your customers, particularly when you discuss the “off shore” castings being used today. Like the old saying goes, “you get what you pay for.”
Please review our ZINC ALLOY SELECTOR section.
Let E. Toman & Company help you choose one of the five listed zinc alloys for your next project.
