Sand Casting vs Die Casting
Two metal casting processes go head-to-head for “Best in Cast”. Explore the pros, cons, and everything in between in these two metal casting methods.
Since the ancient Chinese learned you could cast metal in the 4th century B.C, this age-old process of heating and molding metal became crucial for armor, weapons, and architecture. In today’s world, many companies and industries still rely heavily on the metal casting industry. specifically for aviation, automotive and medical devices.
According to “Casting Source Magazine,” the metal casting industry is expected to grow 7.5% by 2025, and according to the American Foundry Society (AFM) “Metal casting companies are responsible for over 110 billion dollars in economic output… creating almost 500,000 jobs in the industry,” and that is just in our niche of sand and plaster mold castings.
Metal Casting Processes
Not many companies know which is the best selection for their project, simply from a lack of understanding the differences in casting methods.
Both metal casting methods are productive in their own way, but many times these two casting methods go head-to-head for who is better for metal casting projects.
So what are some things to consider when comparing sand casting vs die casting? Maybe you need to know which metal casting process is faster? Or if sand casting is more cost-effective than die casting? let’s match up these two heavy hitters and see who takes home the belt in “Best in Cast.”
Lets’ Get Ready to Rumble!
Matching these two heavy hitters up.
Ladies and gentlemen, these two contenders have battled for best casting processes for years and all that tension has built up into an all-out brawl of metal casting choices.
Before we see who takes home the title “Best in Cast” let’s match them up head-to-head and toe-to-toe!
Comparing these two metal casting methods can be a bit tricky because you will soon realize it’s like comparing apples to oranges. They both have their own benefits and limitations. It will come down to what is needed for your project and the budget to help decide who the winner is for you.
Sand Cast vs Die-Cast
To select the best casting method, we need to understand casting limitations, process difficulties, and price.
There are some major differences in these casting processes so let’s explore each individually and thier price to help us get a better scope of the competition.
In the left-hand corner, we have the heavy hitter Die Casting. “Dies” are built from steel or aluminum, which is why Die casting comes with a heavy upfront cost, but benefits high volume manufacturing. The cost can be less for tooling when over the threshold of 1000+ units compared to Sand Casting.
Cost of Die Casting vs Sand Casting
There is quite a big difference in cost between die casting and sand casting. You will see from this article, cost importance is going to reflect back to units and size of parts. While sand castings are most cost-effective for low-volume manufacturing, die-cast becomes more reasonable for high-volume castings. Tooling costs for die cast vs sand casting is also something we will cover. Read through their match-up to see what best fits your metal casting needs.
Lead Time for Metal Castings
Round 1… ding, ding, ding! Lead time and cast time.
Lead Time for Die Cast– Slow
This is the time prior to production it takes to get the tooling ready for your cast.
Die casting lead time takes the most time because the cast must be formed from steel or aluminum prior to production. This can take 6 -8 weeks.
Time to Cast – Fast
About 30 sec – one minute. Die casting may be slow to draw the first punch, while it waits for its “Die,” but soon will pick up momentum by casting time. Getting metal castings done in about one minute.
After the “die” has been produced, a die casting machine injects highly pressured metal into the mold or “Die” and then it is allowed to solidify.
The steel mold or “Die” gives the caster the opportunity to use the Die again and again after the part has been removed, saving additional tooling costs for future castings.
But, because the initial die has to be created from steel, the upfront tooling cost is high and very time-consuming. This won’t make the best casting method for companies looking for fast, low-volume production parts.
The picture below is a Die-cast machine.
Next, let’s explore the time and process for sand casting.
Lead Time Sand Casting – Fast
For sand casting- 1-2 weeks. Sometimes even less.
Time to Cast – Fast
1 minute. Sand casting is fast up from and throughout the processes. Getting your products or prototypes done quicker, without the heavy price tag from die casting.
Sand Casting Process
A core or pattern is made from a CAD model and tested through a digital simulation prior to pouring. This pattern can be made of many types of materials, including wood or plastic which help keep cost low.
The pattern is molded into what is called a match plate. The match plate is placed inside a two-sided enclosure. The top half is called the cope and the bottom half is called the drag.
Sand is filled and pressed around the match plate that was added to the top and bottom enclosures. Then they are pressed together and clamped into place to form the pattern from the match plate. Once the sand is compacted, the enclosure is opened and the match plate is removed, leaving an indentation of the mold. Think reverse sandcastle. Instead of filling the pattern with the sand, you are pressing the pattern into the sand.
Then molten metal is poured with a ladle or gravity pour into the cavity by a core, filling the mold. The metal is left to solidify and then the cast is removed by breaking the part of out the sand or by water jets.
The picture below is what sand casting looks likes.
The Benefits of Sand Castings
Cheaper tooling doesn’t mean cheaper products. You still get incredible results for your sand casting if done by the professionals here at Precise Cast Prototypes and Engineering. Because you don’t have to invest in steel mold castings like with a die-cast, modifications to your cast can be simple and less costly. Also, as long as Precise Cast is producing your part you won’t pay for new tooling for worn-out parts.
Round One winner is…
You can see each process has its benefits and limitations when it comes to time. Sand casting is faster upfront but will depend on how many units are required. But if we look solely on time, this round goes to Sand castings.
Round 2…Ding, ding, ding! Metal cast parts, surface finishes, and quantities.
When it comes to size in castings, we aren’t talking just about shape- we also need to focus on quantity size.
Size of your part
Sand casting and Die casting can handle small precision and complex parts, but sand casting offers a wider range for larger castings. Especially if you want to save on the cost of the “die” for a large metal cast.
Sand castings offer more design flexibility and weight ranges. From grams to tons, or small precision parts to large items for aviation, automotive, or agriculture. Complex shapes are achievable and have tight tolerances. “The process has high dimensional accuracy, with a tolerance of ±0.010 in for the first inch and ±0.002 in/in thereafter. Cross-sections as small as 0.090 in (2.3 mm) are possible.” (wiki)
With Die casting, it’s also possible to obtain smaller, complex parts with this type of casting method. Making it ideal for medical devices or small, thin-wall parts.
Sand castings offer the best solutions for low-volume production ( under 1,000 a month), rapid prototyping, and prototype castings.
This is best suited for die casting as you will pay a higher tooling cost upfront but becomes a more cost-effective choice if you are over the threshold of 1,000 quantaties.
Surface Finish Die Cast vs Sand Cast
When comparing Sand vs Die casting surface finish, die castings typically deliver a smoother finish, but not at Precise Cast. Because we use a special type of fine-grain sand that creates a smoother finish than the green sand process many other foundries use. It results in a Ra- 120-220 finish. This can save time at the end of castings if your part requires a smooth finish.
The above picture is a Die cast part showing a smooth surface finish.
The above picture is a Sand Cast part showing a more granular surface.
To conclude best cast for parts, finishes and tolerances, Die casting has a little more advantage for its smaller complex parts and smooth finish if not using fine grain sand. But again, if those don’t matter to your part, sand casting is best is cast for this process.
Round Two Winner is…
As I said before, its like comparing apples to oranges. I hope you are starting to see they both have benefits and limitations based on the project needs. So the only way to call a winner for round 2 is to discuss your needs with a metal casting expert. Our team is standing by waiting to answer your questions!
Alloys for Metal Castings
Round 3! Ding, ding, ding! Which can handle the most variations in alloys?
Die casts are best produced with aluminum, zinc, and magnesium alloy combinations. This can be restrictive on the type of alloy for your part.
With Sand casting, you can produce parts with almost any alloy or metal. This provides greater combinations and options for metal cast parts.
Round Three Winner is…
For me, this means Sand Casting takes the best casting process for alloy combinations or choices.
Best in Metal Castings
Each metal casting process walks away today with a “participation award” for their part in metal casting.
As you have learned more about the differences and similarities between die casting vs sand casting, I hope it has become clearer that both champs are victors in their own field.
The best solution is to talk with our experts about your project. This way we can fine-tune the details and find the best metal casting process for your part.
Precise Cast is a leader in sand casting and plaster mold castings serving the North American market. We have helped many fortune 500 companies like Ball Aerospace, Tesla, and John Deer with their metal casting needs.