Sand 3D Printing – How Additive Technologies Are Changing the Game in the Foundry Industry

From Ancient Craft to Digital Precision

Sand casting, a technology proven over millennia, has always been a cornerstone of industrial manufacturing. However, the traditional approach, which requires the creation of physical pattern tooling, inevitably faces limitations: long lead times, high tooling costs, and, most importantly, compromises in part geometry dictated by the need to extract the pattern from the mold. Engineers were forced to design not the ideal part, but a part that could be manufactured.

Today, the foundry industry is undergoing a technological shift comparable in significance to the industrial revolution. Sand 3D printing, based on Binder Jetting technology, is not just an improvement but a complete paradigm shift. It eliminates the most expensive and time-consuming stage – pattern tooling production – by allowing foundry molds and cores of any complexity to be created directly from a digital CAD file. This marks a transition from “Design for Manufacturability” to “Manufacturability for Design.” Complex bionic structures, topologically optimized parts, and internal channels, previously unimaginable for casting, are now becoming a reality.

This article provides an in-depth analysis of sand 3D printing technology, its implementation in foundries across Europe and America, the key market players, and the strategic prospects it opens for the entire industry.

Binder Jetting Technology – How Molds Emerge from Sand and Glue

At the heart of sand 3D printing is the Binder Jetting process, which builds a physical object layer by layer from a digital model.

The Step-by-Step Process:

1. Digital Preparation – the process begins with a 3D model of the casting mold, which is digitally “sliced” into hundreds of thin horizontal layers.
2. Spreading a Layer of Sand – a special mechanism (a recoater) evenly distributes a thin layer of foundry sand across the printer’s build platform.
3. Selective Binding – an industrial printhead moves over the sand layer and, much like an inkjet printer, deposits droplets of a liquid binding agent precisely onto the areas corresponding to the digital model’s cross-section. The binder penetrates the sand, bonding the particles together.
4. Building the Mold – the platform lowers by one layer’s thickness, a new layer of sand is applied, and the process repeats. Layer by layer, the mold “grows” inside the build chamber, surrounded by unbound sand that serves as natural support for complex features.
5. Cleaning – upon completion of the print, the mold is extracted from the sand bed. The unbound sand is removed, typically with compressed air, and can be reused, making the process economical. In most cases, the mold is ready for metal pouring almost immediately.

The materials – sand and binder – play a crucial role in the quality of the final casting. The sand can be standard silica sand or special ceramic sands for working with high-temperature alloys. However, the true “heart” of the process is the binder system. Furan resins are the most common, providing high mold strength for ferrous and non-ferrous metals. A major innovation, particularly in Europe, has been the shift to water-based inorganic binders. These emit virtually no harmful volatile organic compounds during pouring, replacing them with water vapor, which dramatically improves working conditions and reduces environmental impact.

Who Creates the Equipment for Digital Casting

The market for industrial sand 3D printers in Europe and the US is primarily represented by two pioneers of Binder Jetting technology.

• ExOne (part of Desktop Metal), USA – one of the founders of the technology with over 20 years of experience. ExOne’s systems, such as the S-Max® Pro, are known for their reliability and focus on serial production, including full automation capabilities. Despite the recent financial difficulties of its parent company, ExOne’s technological expertise remains undeniable.
• Voxeljet AG, Germany – the company is famous for producing the world’s largest sand 3D printing systems. Its flagship VX4000 model, with a build area of 4×2×1 meters, can print massive, single-piece molds for the energy and heavy machinery industries. Voxeljet focuses on scale and speed, offering solutions for large-format and cost-effective production.

Both companies, despite market challenges, remain technological leaders. For foundries, this means that when choosing a supplier, it is essential to evaluate not only the technical specifications of the equipment but also the long-term stability of the manufacturer.

How 3D Printing Solves Real-World Production Challenges

The advantages of the technology are best seen through real-world examples from leading global companies.

• Automotive Industry: BMW Group. To produce high-performance engines, BMW required sand cores with extremely complex geometries for cooling water jackets, which were impossible to manufacture traditionally. In collaboration with Voxeljet and Loramendi, the world’s first fully automated production line for 3D printing these cores was created, enabling their serial production and improving the engines’ thermal performance.
• Heavy Industry: GF Casting Solutions. When manufacturing a hydraulic gear reducer, the company faced a challenge: the core assembly consisted of 12 separate parts. Manual assembly was labor-intensive and resulted in a high scrap rate. Using an ExOne S-Max 3D printer, the entire assembly was printed as a single, monolithic core. This completely eliminated assembly errors, improved quality, and reduced labor costs.
• Prototyping and Repair: Waupaca Foundry. As one of the largest producers of iron components in the US, Waupaca Foundry experienced chronic quality issues in the production of a turbocharger housing. The three-part core assembly was a “true nightmare in terms of scrap.” Installing their own ExOne S-Max® Pro printer to print the core as a single piece completely solved this problem.

These examples demonstrate that one of the main advantages of 3D printing is the elimination of manual assembly of complex core packages. Every joint and glued connection in the traditional process is a potential source of defects. 3D printing creates a perfectly accurate, seamless core, physically eliminating the root cause of scrap.

Advantages and Limitations

Like any technology, sand 3D printing has its strengths and weaknesses.

Key Advantages:

• Drastic Reduction in Lead Times – mold production is reduced from weeks to a few days or even hours.
• Zero Tooling Costs – expenses for designing, manufacturing, storing, and repairing patterns are completely eliminated.
• Unlimited Geometric Freedom – the ability to create highly complex internal channels and bionic shapes to reduce weight and improve part performance.
• High Precision and Quality – eliminating assembly errors results in castings with tighter tolerances and fewer defects.

Limitations and Challenges:

• High Capital Investment – the cost of industrial 3D printers is a significant investment.
• Surface Finish – the surface of a printed mold can be rougher than with some traditional methods, which may require additional finishing of the casting.
• Skill Requirements – the technology requires trained operators and a deep understanding of the processes to achieve consistent results.
• Mold Strength – printed molds require careful handling before pouring. Finding the right balance between strength and core collapsibility (shakeout) is a key engineering challenge.

When is Sand 3D Printing Profitable?

Evaluating the return on investment (ROI) for sand 3D printing must be comprehensive. The technology is most cost-effective for:

• Prototyping and pilot batches.
• Low- to medium-volume production, where the cost of traditional tooling is prohibitively high.
• Manufacturing highly complex parts that are impossible or too expensive to produce otherwise.

For the mass production of simple parts, traditional methods may still be cheaper. However, a full ROI analysis must consider not only direct savings on tooling but also strategic benefits: faster time-to-market, the ability to produce innovative high-value-added parts, flexibility in producing spare parts on demand, and, most importantly, a drastic reduction in scrap and rework costs.

Towards the Smart Digital Foundry

Sand 3D printing is not an endpoint but a foundation for further digitalization. In the next decade, we will see:

• Full Automation – integration of 3D printers with robots for cleaning, assembling, and transporting molds.
• New Materials – the emergence of binders with improved properties and the development of multi-material printing to create molds with locally defined characteristics (e.g., with integrated chills).
• Faster and More Accessible Printers – the technology will become more productive and affordable, opening it up to small and medium-sized enterprises.
• Integration with Simulation Software – the creation of a closed-loop digital cycle where the mold is designed, simulated, and printed correctly the first time, minimizing physical trials.

These trends are leading to the creation of the “smart digital foundry,” where data and flexibility are paramount. Foundries will transform from suppliers of raw castings into high-tech partners capable of co-developing advanced products for the aerospace, automotive, and energy industries. Sand 3D printing is the key to this future, enabling the foundry industry to remain competitive and innovative in the 21st century.