Creating Prototypes with Sand Casting
The process of sand casting has been the same for hundreds of years. First, a pattern is placed in sand to create the mold and a gating system of some type is incorporated for the molten metal to flow into the mold. The pattern is then removed and the cavity is filled with molten metal. After the metal has cooled, the sand is broken away and the casting is removed.
Although Hoosier Pattern started as a traditional pattern shop—machining and building these patterns while becoming an industry leader—there was more to be explored within the sand casting world. Patterns are reusable and perfect for production use, but what about low volume productions or prototypes?
Back in 2013, Hoosier Pattern bought their first 3D sand printer, expanding their capabilities to more than just hard tooling. Five years later, Hoosier Pattern now has three sand printers in house and is more equipped than ever to provide prototypes.
How It Works
The 3D sand printing process is fairly simple and works as a normal 3D printer would. A CAD file is plugged into the machine and a layer of sand goes across a large job box (70.9 x 39.37 x 27.56"). Binder is then dropped where the part is to be made—the binder joins the sand together and, after layers of this repeated process are bonded together, the mold is formed and extracted from the job box. The created mold is then cleaned and sent to the foundry to be poured within 10 days of receiving the purchase order.
Benefits to 3D Sand Printing
There are two big benefits to 3D printing prototype molds and cores—cost and time.
Traditional pattern making is expensive and it can take months to get your first casting and maybe realize it's not even what you want. Under strict timelines, this may only give engineers and designers a couple of tries to get it right. With 3D printing, a customer can have a casting in a matter of days if needed. Depending on the size of the mold or core, multiple versions of a prototype can be printed at once in the same large job box and sent to the foundry together for maximum use of time.
Hoosier Pattern's method of 3D sand printing allows a customer to print multiple versions of the same prototype at the same time because we aren't committed to tooling. Within a short amount of time, multiple designs can be printed, poured, and tested, allowing for additional alterations or decisions to be made on even a shorter timeline.
Manufacturability is another gain when it comes to 3D printing. Designers are free to castings made true to design and designs don't need to be altered or compromised by manufacturability. Complex cores that would normally need assembly can be printed as one piece. Cores can also be printed with a hollow interior, allowing gas to escape or a core to collapse if need be—this achieves high-quality internal passage systems for castings.
Additionally, 3D printing has the potential to highlight issues that—in situations of traditional tooling—may not normally come up until the molds are moved into production. Finding these issues earlier in the timeline and after fewer resources have been spent help prevent these errors from surfacing for the first time further along in the project timeline, saving time and money in the end.
Every great product started as multiple prototypes that helped shape, adapt, and perfect the final product. Prototypes are essential in detecting problems, testing to see where improvements can be made, and ultimately making the final product more useful to the end user. 3D printed sand is not directed at a certain industry or a particular customer—this technology can be used by a wide range of customers from various backgrounds and industries of all levels.
Hoosier Pattern is a boundary-breaking industry leader—we take pride in elevating ourselves and our customers to top-notch solutions, meaning higher quality castings and quicker turnaround times. Contact us today to learn more or take the first step toward working with us.
The Benefits of 3D Sand Printing
Hoosier Pattern opened its doors in 1997 as a traditional pattern shop. Over 20 years later, HPI has become an industry leader as a premier pattern shop and—as of 2013—an additive manufacturer as well. Hoosier Pattern is one of the only shops in the United States that has both rapid prototyping and hard tooling capabilities. Many customers come to HPI and ask how they can determine whether to 3D print something versus having a tool built for their project.
The difference in benefits between 3D printed sand and hard tooling boil down to two factors—time and money. Hoosier Pattern's 3D printed sand molds take around ten days to craft and cost $0.13 per cubic inch. Hard tooling can take anywhere from a few weeks to several months to complete and costs can climb to thousands of dollars.
On the surface, 3D printing looks like the way to go for every project. However, some projects are better suited for sand printing and some for hard tooling depending on the elements and goals for the project itself. But how can it be determined which method best fits your particular needs? We may have the answers you’re looking for.
When to Use 3D Printing
Sand printed molds and cores can only be used once, which makes them the perfect option for prototypes. If you have more than one design for a potential part, prototyping can be used to determine which mold or casting is the best option. All of the designs can be sand printed quickly, simultaneously, and at a cheaper cost. Each mold will be individually identified, which prevents confusion when it reaches the customer. Since all 3D printed sand parts start with a CAD file, parts can also easily be tweaked and re-printed.
Low Volume Production
The term “low volume” can be defined differently by every company. We define “low volume” as anywhere from 10-500 units per year. It may not be the best choice for a company to invest in the traditional tooling process if a part will only be used for a short amount of time. Sand printing may be the best option for smaller or temporary projects.
Sand printing is the best choice when projects require a fast turnaround. At Hoosier Pattern, many of our employees have a foundry background, so we understand how critical deadlines can be. Our standard turnaround time for 3D sand prints is 10 days. This is 10 days from the time the order is placed to the time the project will be back on the foundry floor.
Our 10-day turnaround time has changed the game for many of our customers. In the past, it could have taken several months for a tool to be completed and reach a foundry. After we receive the CAD file, we plug it into a job box. Our job box is roughly the size of an average refrigerator and takes 20-22 hours to print. Because this turnaround time is so fast, we are sometimes able to do rush orders. Our employees do everything they can to ensure a customer has their product when they need it.
Geometrically Complex Parts
It's not uncommon during the process of conventional patternmaking for engineering changes to appear. Even the smallest change can pose a problem to the castings once the tooling has been produced. Since 3D printed sand begins with a CAD file, engineers are able to design and create geometrically complex casting castings to be manufactured the way they were intended to be.
Compromises don't need to be made in order to have high-functioning manufacturability while maintaining a low cost.
When to Use Traditional Tooling
High Volume Production
Although 3D printed sand molds are more cost and time effective, there are project scenarios in which traditional tooling is a better fit. For example, it doesn't make sense to have single-use molds made for a part that is going to be produced thousands of times—in the long run, a traditional pattern is going to be more cost efficient.
3D printed sand molds and cores can't compete with the lifespan and durability of a hard tool. While 3D printed sand is made for one-time use instances, hard tooling molds are made to withstand thousands—or even hundreds of thousands—of uses.
Still wondering which process is right for you? Our engineers at Hoosier Pattern will help you make the best choice for your specific needs. We will be honest with you and let you know whether your project is best suited for 3D sand printing or traditional tooling.
Contact us today to learn more about our process and how we can use our expertise to benefit your business.
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HPI is having an open house and you are invited! We are opening our doors for the public to come inside and see what we do on a day to day basis. We are proud to be a part of a hardworking community and are excited to share what we do with them.
There will be refreshments, facility tours and even some casting! We will have our 3D sand printers running in our newly renovated sand room. There will be a job box fresh out of a 3D printer where people can extract their own keychain molds from the sand, clean them and then pour molten metal into them! Once the keychains cool, employees will help remove the gating and rough edges so attendees can take home a small keepsake from HPI.
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