The sand casting process can be the simplest and most cost-effective type of metal casting.
Explore the casting process and how Precise Cast’s approach to sand casts gives our customers faster parts, smoother finishes, and quality sand casting.
Sand Cast Design
All sand castings start as CAD models. We review all CAD models or similar files submitted by our customers for any design flaws upfront.
Then Finite element analysis (FEA) is performed to test mechanical stress, heat transfer, fluid flow, and many other simulation behaviors.
We can also use this time to simulate parts and pour. Identifying shrink and rigging during this tooling phase.
If you haven’t built a CAD model for your parts, our team of highly skilled engineers can work with your product developers at any stage of your development process to aid in this stage.
What is a Match Plate in Casting?
After the CAD model has passed simulations, a match plate will be created to resemble the CAD model.
This type of mold is more cost-effective and quicker to produce parts compared to die casting. This saves our customers weeks of time and can help get products to market faster.
The process with sand mold casting is faster because the mold can be made of various materials, including plastic and wood.
You can learn more about the differences between sand casting vs die casting here.
What is a Match Plate Molding?
Match plate molding ensures a double-sided pattern that can be used in the cope ( top) and drag ( bottom) of a sand casting enclosure.
The match plate pattern is inserted into the cop and drag and then sand is mixed with the proper chemicals for binding is compacted against the match plate.
Metal Casting Sand
We do something most foundries do not- we use fine-grain sand to meet our customer’s needs of Ra 120-220 finish. Saving you additional cost on machining and smoother surface finishes.
The sand mixture is allowed to harden and after the appropriate amount of time the match plate is removed, leaving an indentation
What is Green Sand Casting?
The reference of “green sand casting” is that the sand is recyclable and doesn’t contain chemical additives.
Sand Cast Parts
Several additional aids are required for sand casting. This includes an ingate ( A gate to pour in the molten metal), a runner ( to carry the molten metal to the cavity of the casting), and a riser ( designed to help with shrinkage of the metal casting). Also, a core may be needed to help shape the inside of the cast.
What is Gravity Sand Casting?
Most times a crucible is used to heat the metal and a gravity pour technique is used to carry the molten metal down through the ingate, through the runner, and into the cavity of the casting. Using “gravity” to fill the mold instead of highly pressures machines like one would do with die casting.
When is the Sand Casting Ready to be Removed From The Mold?
Variables of metal temperature, cooling rate, riser size, mold temperature, and other variables are controlled using rotary degassing, a continuous melt furnace, and a reduced atmospheric testing system to ensure flawless results.
Removing the Cast From the Sand Mold
When working with a mature foundry, we know from experience and formulas when a casting should be pulled from the mold.
The temperature needs to be low enough so differential cooling takes place to prevent cracking.
The proper timing also helps reduce residual stress on the casting, wrapping, or distortion of the casting.
When the optimal temperature has been achieved, you need to remove the sand core, ingates, rummers, and risers.
This can be done by knocking or hammering the casting to remove these parts. Another technique is hydro blasting with a water jet.
Determining the proper time and temperature to “break out” the casting is the most crucial factor and required for a casting shakeout.
What is Casting Shakeout?
Another method for removing aided cast parts and sand is called “casting shakeout.”
Much as the name entails, this is a vigorous agitation and shaking technique to remove the added parts and the unwanted sand around the cast.
The cast is placed on a vibration table that agitates and shakes the cast while helping dislodge the sand from the casting. The loose sand falls between holes on the table and into a box below. This way the sand can be reused for future casting, saving more cost and offering recyclability options.
What is the Linishing and Fettling Process?
After the cast has gone through the “shakeout” process there may still be some attached sand, risers, and seam lines from the sand casting process affecting the casting surface.
Fettling helps remove those imperfections and finishing involves sanding or grinding the part to improve the surface texture. This process removes excess material and divide lines leaving a “raw” casting.
Does Machining or Sand Casting Give a Better Surface Finish?
At Precise Cast, we offer a unique fine-grain sand casting method. This helps our sand castings achieve a Ra surface finish of 120-220. Most other foundries castings will require machining, but because of our unique approach to sand casting, we help save machining costs and time.
Machining of Castings
Final machining is often used to create high-tolerance geometries that are either beyond the capabilities or not economical to incorporate into the casting process.
We have a machining department dedicated to the machining of castings. Our technology includes multi-axis capability and probe technology to ensure consistent and accurate machining of each casting.
Metal Sand Castings
Aluminum and Magnesium Sand Castings
Precise Cast specializes in quality aluminum and magnesium sand casting. We carry an A+ rating with the BBB and are a long-standing sand casting company in the USA.
You can learn more about our sand casting services
The team at Precise Cast is ready to answer your sand casting process questions!
Contact us to get started on your project.