Pattern making is a critical component in the casting manufacturing process, serving as the blueprint for casting metal parts. The selection of tooling methods and the evolution of pattern-making technologies significantly influence the efficiency, accuracy, and cost-effectiveness of the casting process. This article is part two of our Foundry 101 Series and provides an overview of tooling method selection, traditional and next-generation tooling, and best practices for pattern storage.
Tooling Method Selection
Tooling methods vary from traditional wood or polyurethane patterns to next-generation options like robotically milled or 3D-printed patterns. Selecting the appropriate tooling method for pattern making depends on several factors, including the complexity of the design, production volume, material properties, and cost considerations. Key criteria for tooling method selection include:
• Complexity and Precision: The intricacy of the part design and the required precision dictate the choice of tooling method. Complex geometries may benefit from advanced technologies like 3D printing.
• Production Volume: High-volume production often justifies the initial investment in durable tooling materials, like wood or polyurethane. Low-volume or prototype production are typically better suited to next-generation methods.
• Material Properties: The material being cast influences the choice of pattern material. For instance, wood patterns might be suitable for certain metals, while poly patterns are preferable for others.
• Cost and Lead Time: Budget constraints and project timelines also play a critical role. While traditional tooling has a higher set-up cost and lead time, it offers a lower variable cost-to-cast over time for higher volumes. Next-generation methods can be a great choice for short runs and prototypes, where they can offer reduced lead times and lower overall costs for many geometries.
For a deeper dive into the advantages and disadvantages of various tooling methods, please read our whitepaper or contact Brad Moore, Director of Sales Engineering, at bradm@badgeralloys.com.
Traditional Patterns
Traditional pattern making has been the backbone of the foundry industry for decades. The primary materials used for traditional patterns are polyurethane and wood.
Poly Patterns
• Durability: Polyurethane and other poly patterns are known for their durability and ability to produce high-quality casts over extended production runs.
• Precision: These materials offer good dimensional stability and can achieve high levels of detail, making them suitable for complex designs.
• Cost: While more expensive than wood, poly patterns provide a longer lifespan, which can offset the initial investment over time.
Wood Patterns
• Cost-Effective: Wood is a more affordable material for pattern making, especially for low-volume production or prototype development.
• Workability: Easy to machine and modify, wood allows for quick adjustments and refinements.
• Limitations: Wood patterns are less durable and can degrade over time, particularly with repeated use or exposure to moisture and temperature variations.
Next-Generation/Rapid-Response Tooling
Advancements in technology have introduced innovative methods in tooling for castings, offering enhanced precision, flexibility, and efficiency.
Patternless Tooling
• Direct Molding: This method eliminates the need for physical patterns by directly creating molds from digital designs. It is highly efficient for custom and complex shapes.
• Flexibility: Ideal for prototypes and short runs, patternless tooling reduces lead times and allows for rapid iterations.
• For Consideration: Robotically milled molds tend to produce a rougher surface finish than traditional tooling.
3D-Printed Molds and Cores
• Precision and Complexity: 3D printing enables the creation of highly intricate and precise patterns that are difficult or impossible to achieve with traditional methods.
• Design Flexibility: 3D-printed molds eliminate the need to consider draft angles when designing parts and tooling.
• Material Versatility: Various materials, including resins and metals, can be used in 3D printing, catering to specific casting requirements.
• Cost and Speed: While the initial setup cost can be high, 3D printing significantly reduces lead times and is cost-effective for low to medium production volumes.
• For Consideration: 3D-printed molds and cores may produce a rougher appearance, particularly on gently curved sections. This is due to the minimum layer height achievable by 3D sand printers.
Hybrid Tooling
• Combining Methods: Hybrid tooling integrates traditional and modern methods, such as using 3D-printed components with poly or wood patterns to achieve the best of both worlds.
• Optimized Performance: This approach leverages the strengths of each method, enhancing overall performance, cost-efficiency, and production flexibility.
Pattern Storage
Proper storage of patterns is essential to maintain their integrity and ensure they remain ready for future use. Best practices for pattern storage include:
• Controlled Environment: Store patterns in a clean, dry, and temperature-controlled environment to prevent warping, cracking, or degradation.
• Labeling and Cataloging: Clearly label and catalog patterns for easy identification and retrieval. Digital records can help track usage history and maintenance needs.
• Regular Maintenance: Inspect and maintain patterns regularly to address any wear and tear, ensuring they remain in good condition for subsequent production runs.
• Protective Measures: Use protective covers or cases to shield patterns from dust, moisture, and physical damage during storage and handling.
By understanding and leveraging these many available patternmaking methods, OEMs can work with foundries to enhance the casting manufacturing process. The ultimate goal is to create the best value casting for an OEM’s needs.
At Badger Alloys, our engineers work with our customers and our highly skilled pattern makers to create custom patterns based on exact specifications. Because our pattern shop is dedicated solely to serving our foundry and customers, customers receive the highest quality patterns. Our engineers are readily available to work with each customer to analyze which methods and materials will result in the best quality, highest value casting. To learn more, contact Brad Moore, Director of Sales Engineering, at bradm@badgeralloys.com or 414/258-8200.