2 Mar 2021 
This is part three of the “Engineers’ guide to metalcasting”, from the Batesville Products Inc. webinar series. Click here to watch the complete webinar.
Permanent mold castings are less prone to failure and defects than other casting options.
They can also include thicker cross sections because of the cavity fill and solidification process.
Sand and die casting have more porosity and shrink potential. Sand molds have low dimensional accuracy than steel molds and poor surface finish. Forcing molten metal into die molds causes more turbulence and air pockets in the molten metal, which can cause similar issues.
Permanent mold casts really stand out due to their density and tight granular structure, so it’s the way to go for pressure-tight and explosion-proof parts.
While most of the high-volume automotive parts are die casted, wheels, structural components and some transmission parts are created with permanent molds, because they need to be strong and pressure-tight.
With permanent mold casting, molten metal is poured into the mold through a gating system. Gates control the feed and flow of molten metal into the mold cavity. The system also serves as a reservoir for the molten metal needed to supply the thick sections of the part as they shrink during solidification.
The tilt-pour method introduces metal by tilting the mold in a controlled fashion. This reduces turbulence, provides shorter cycle times and less metal for feeding the part, which helps reduce issues like gas porosity, pinholes and shrinking.
Permanent mold casting is the best option for cast-in inserts where required.
Cast-in-place inserts allow for a wide range of securing methods. Steel tubing can be added inside the mold to provide a path for electrical wiring within the part.
Sand casts often aren’t stable enough to add an insert into the molding process without an increased risk of sand particles breaking loose and contaminating the metal. Die casting operations are usually heavily automated and placing an insert into the die slows the process down dramatically.
Alloy A356 as our primary metal for its increased purity over other alloys.
This alloy offers great elongation, strength and ductility. It’s corrosion resistant, easily weldable and can be mechanically finished to a shine.
A356 is best used in large, low-volume molds, such as structural and aerospace applications. It’s also used as an alternative to 6061 aluminum alloy, one of the most common general use alloys.
Zinc is a heavier metal often used in household appliances, telecommunication devices and decorative finishes.
No. 5 is an ideal alloy for making small yet heavy parts. It’s widely die cast in Europe and exhibits excellent characteristics, as well as improved is less likely to deform or creep compared other zinc alloys.
ZA12 is the most versatile zinc alloy, combining high-performance properties and ease of fabrication for gravity or pressure die casting. It offers a sound structure with high die cast elongation and impact properties.
It is important to remember that the casting qualities offered by a specific combination of casting alloy, foundry practices, gating designs and thermal treatments aren’t always repeatable under different conditions. So creating a consistent process is paramount to produce high-quality parts.
From here, we’ll explain how we work with clients to create minimalistic designs for timely production and optimal part performance.
Subscribe to learn more about permanent mold casting, such as our industry webinars and other content that will help you navigate the world of metalcasting.
"*" indicates required fields
1-800-758-2372
Guides