Casting 101
Buyers of outdoor cast elements (streetlamps, decorative street signage, curbside mailboxes, cluster box units, and benches) are often looking for a beautiful product that is durable and budget friendly. Many don’t know the role the material and casting process play in the quality, cost, and consistency of the finished cast product.
Aluminum, for example, offers the durability and corrosion resistance that provides a low-maintenance outdoor installation that will last for many years. This lightweight material also keeps freight costs low and does not require any special equipment to lift the cast products into place.
Types of Casting
The way an aluminum casting is manufactured has a significant impact on its quality, consistency, and cost. There are three methods commonly used to produce aluminum castings. They are sand casting, gravity casting with a permanent mold, and die casting.
Sand Casting is considered the oldest and most widely used casting process in the world. Skilled craftsmen create an aluminum sand casting by pouring molten aluminum into a single-use mold made of sand. Then they literally “break the mold” to reveal a hand-crafted look that you cannot get with mass production machinery. Because this process requires a new mold for each product, no two pieces will look exactly identical. Sand casting also tends to produce products that are thicker and heavier, which can make them suitable for structural use, like a lamp post base. For non-structural components the extra weight only adds cost. Surfaces tend to be more porous. Surface imperfections, such as pitting, may shorten the life of the paint finish if great care is not taken in the finishing process.
Gravity Casting with Permanent Molds uses highly polished metal plates rather than sand to form the molten metal. Depending on the shape, a sand core may still be used in the process. Though the tooling cost is higher, the metal plates produce a casting with a cleaner surface and a more consistent look from one piece to another. This improves production times and reduces postproduction modification labor. The smoother outer surfaces found on permanent mold gravity cast products can improve the life of a properly applied paint finish.
Die Casting relies upon expensive, high-strength metal tooling and machinery designed to withstand the high-pressure injection of molten aluminum. They produce virtually identical precision castings with very tight tolerances and smooth surfaces. Components machined from a die casting process consistently fit together better and are less brittle than products cast by other methods. Thinner walls and shorter production cycle times help to reduce the cost of the individual castings but require large production runs to justify the investment.
While some projects require identical and blemish-free castings produced by the die casting method, others need thicker walls for structural purposes, which is why it is important to know that there are options.
Brandon Industries—Casting Experts
You want access to the best products at the best prices. Brandon Industries has been producing high-quality outdoor cast products since 1987. Their expertise, quality control, and continuous investment in appropriate production methods gives you that access. They offer you a wide selection of aluminum castings, ensuring you will find the solution that best meets your desired aesthetic, expected lifetime and price point.
