Investment Casting Vs Sand Casting: Differences and Advantages

Investment casting and sand casting are reliable, cost-effective, quality manufacturing processes that allow for flexibility in budgets, timelines, and design. The pattern used to make casting molds lasts through thousands of impressions and years of use, producing the exact same measurements every time. Patterns also are easily replicable when needed.

When manufacturers choose casting to mass produce complex parts, they have the option of choosing investment casting, which is also called the lost wax process, or a sand casting. The following is a breakdown of the two distinct processes and their advantages.

Investment Casting Process

1. Inject wax into die to create a wax pattern version of the casting.
2. Assemble patterns to a wax gating system to create a mold.
3. Dip the mold in ceramic slurry and sand to create the shell.
4. Melt wax out of the shell.
5. Pour metal into the shell.
6. Finish casting to meet customer requirements.

Investment Casting Process Visual Outline

Sand Casting Process

1. Add sand to “Box” created with the combination of pattern on board and flask.
2. Assemble the top half (cope) of mold to the bottom half of mold (drag) after adding cores.
3. Pour metal into the mold.
4. Finish casting to meet customer requirements.

Sand Casting Process Visual Outline

Investment Casting Advantages

1. Castings from ounces to 150 pounds
2. Can hold tighter tolerances
3. Can cast thinner walls
4. Better surface finish
5. Less machining required
6. Can cast more complex designs
7. Easier to run prototypes

Sand Casting Advantages

1. Castings up to 6,000 pounds (depending on configuration) Gross Weight
2. Lower cost to produce
3. Shorter lead times

While investment casting is ideal for highly complex designs – it can cast 1/8-inch walls at the thinnest and work with both ferrous and non-ferrous metals – investment casting does have weight and size limitations. It is typically more costly than sand casting. It also requires longer lead times, however this is relative since Stainless Foundry & Engineering offers some of the lowest lead times in the industry.

Sand casting achieves net shapes within a quarter of an inch and has a rougher surface finish. Parts can be machined to achieve the exact tolerance and look for the finished part. Sand casting is more versatile with size and weight capabilities than investment casting.

Any manufacturer, prior to requesting a quotation, should consider all of the advantages of each process and decide in the end which process will yield a finished product to the desired quality at the lowest cost. An investment casting may cost more upfront, but when calculating secondary costs of sand casting it may be a wash.

If you are considering the design of a new part to be cast, or weighing the options of sand or investment casting, please contact us. Our sales and engineering team can assist in determining which process would work best for you.