Casting Aluminum is an excellent method of manufacturing metal components. However, there are several factors to consider before making a decision. It would be best if you learned about the different types of aluminum alloys, sand casting versus die casting ejector marks on castings and the Rockwell hardness of aluminum.
Approximately 85% of all aluminum products today are wrought aluminum alloys. These alloys are formed by smelting pure aluminum ingots and combining them with other metals to form the final shape. Wrought aluminum alloys are then cast into large slabs or billets. These aluminum alloys have good tensile strength and corrosion resistance. They are often used in recreational vehicles, aircraft fuselage, general sheet work and electronics.
Wrought aluminum alloys are classified in series based on the main alloying elements. For example, alloy 413.0 is often used in aircraft applications due to its high corrosion resistance. These aluminum alloys are then heat treated to remove residual stress. Aluminum alloys are classified by the amount of alloying metals added. These alloys are divided into a number of groups, which have different physical properties and applications.
8000 series primary alloys for casting aluminum are aluminum alloys containing 0.01% to about 0.05% by weight of rare-earth elements (REE) as the principal alloying element. REEs are added to aluminum alloys to improve the stress relaxation resistance of aluminum alloys. The addition of REEs also maintains the electrical conductivity of the aluminum alloy.
Typical aluminum alloys have low creep resistance and low-stress relaxation resistance. 8000 series aluminum alloys exhibit improved creep resistance. They can also be used to form conductive elements inside power receptacles. The tensile stress relaxation time of 8000 series aluminum alloy is 660 seconds at room temperature. At a stress of 75 MPa, it can reach 85% of its initial stress. The electrical conductivity of 8000 series aluminum alloys is substantially unaffected by rare-earth elements.
Choosing between die casting and sand casting can be a tough decision. There are many factors to consider, including cost, design, and the product’s functionality. Understanding the key differences between these two processes can help you make the right decision. Die casting is a process that uses a metal mold to produce parts. It is designed to hold the molten metal and force it through a pattern. The metal mold is made from steel, and is usually coated with a protective coating.
Sand casting, on the other hand, is a process that uses sand as a mold. This method is a very cost-effective manufacturing method. It is also extremely versatile and can be used for a wide range of alloys. Both processes can produce large, complex components. However, sand casting is more suitable for larger designs and unusual shapes.
Using ejector pins to eject the aluminum casting from the mold can be a critical part of the die-casting process. Ejector pins are small steel pins that push the casting out of the die cavity. They work with a plate that moves forward simultaneously with force applied to the ejector pins.
There are three main ways to reduce ejector marks on the casting:
- Design your part so that it does not create a tight spot where the ejector pins are located.
- You can use machining to remove the ejector pin marks from the casting.
- You can use hand scraping to remove the marks.
One of the biggest design considerations in aluminum die casting is the ejector parting line. This parting line is where the two die halves meet.
Whether you’re testing aluminum, plastics, or another material, you must know how to read a Rockwell hardness number. The Rockwell Hardness number is a numerical value derived from the indentation depth difference between the indenter’s initial and final depths. The Rockwell hardness equation is commonly used in metallurgy and engineering. The equation is H R = N – h d. The equation has three stages: preload, major, and minor.
A preliminary test force is applied to the specimen, causing it to breach the material’s surface. Then a major load is applied, causing it to stabilize. After a specified amount of time, the indenter is removed. The measured distance is then calculated. The difference in the indentation depth measurements is transferred to the Rockwell C scale chart.