Custom Sand Casting Frequently Asked Questions

LB Foundry specializes in non-ferrous sand castings and pours a broad range of alloys, including:

• Aluminum alloys: 319, 356, A356, and 535 (Almag 35)
• Brass alloys: Yellow brass, red brass (C83600), and lead-free red brass
• Bronze alloys: Silicon bronze, aluminum bronze, and manganese bronze

If you have a specific alloy requirement not listed above, contact us and our team will advise on its suitability for sand casting.

Both are Al-Si-Mg casting alloys with similar chemistry, but they differ in allowable impurity levels — particularly iron content:

• 356.0 permits higher iron content (up to 0.6%). It is a cost-effective general-purpose alloy suitable for moderate mechanical property requirements.
• A356.0 limits iron to 0.2% or less, significantly improving ductility, elongation, and fatigue resistance. Commonly specified in T6 temper for structural and safety-critical applications.

The premium for A356 over 356 is typically modest. Our team can help you evaluate whether the performance benefits justify the upgrade for your application.

Almag 35 (Alloy 535) is an aluminum-magnesium casting alloy that stands apart from common Al-Si alloys by offering:

• Excellent corrosion resistance — especially in saltwater and chemical environments
• No heat treatment required — achieves properties in the as-cast condition
• Good machinability — clean chip and excellent surface finish
• Anodizing response — accepts anodizing well for decorative or protective finishes
• Good ductility — higher elongation than most Al-Si alloys in comparable tempers

Almag 35 is the right choice when corrosion resistance, appearance, or elimination of heat treatment are priorities. Visit our 535 Almag Sand Casting page to learn more.

We use two primary molding methods, selected based on part geometry, size, and volume requirements:

• Green Sand Molding: The most cost-effective and widely used process. Sand is blended with clay and water to form the mold. Ideal for high-volume production and a broad range of part sizes.
• Air-Set (No-Bake) Molding: A chemical binder cures the mold without heat, producing tighter dimensional accuracy and a superior surface finish. Well-suited for larger, more complex castings and lower-volume orders where surface quality is a priority.

Our team will recommend the best process for your project based on alloy selection, casting design, and required quantities.

As a general design guideline, the minimum wall thickness for aluminum sand castings is approximately 3/16" (about 5 mm). Achievable minimums vary by alloy, part geometry, section length, and molding process — air-set molding can sometimes achieve slightly thinner walls than green sand.

Designing at or near minimum thicknesses increases the risk of defects such as misruns and cold shuts. We strongly recommend involving our engineering team early in the design process to optimize wall sections for both castability and structural performance.

Yes. LB Foundry operates an in-house machine shop capable of performing secondary operations directly on finished castings — including milling, drilling, turning, tapping, and other standard CNC and manual machining operations.

This single-source capability simplifies procurement, tightens quality control, and shortens overall lead time compared to splitting work between a foundry and an outside machine shop.

Yes. LB Foundry can work with 3D printed (rapid prototype) patterns. This allows customers to produce prototype castings at low tooling cost before committing to permanent production tooling — ideal for design validation, fit checks, or producing a small number of pre-production parts on an accelerated schedule.

Contact us to discuss your prototype casting requirements and the most suitable approach for your timeline and budget.

Sand casting tolerances follow ASTM and ANSI/SFSA standards. For aluminum sand castings, typical linear tolerances begin at approximately ±0.030" for the first inch, adding roughly ±0.005" per additional inch of dimension. Brass and bronze castings follow similar guidelines.

Air-set molding generally achieves tighter tolerances than green sand due to the increased rigidity of the chemically bonded mold. For dimensions requiring tighter control, our in-house machine shop can bring castings to net or near-net shape after casting.

Visit our Sand Casting Tolerances page for a full reference guide.

Yes. We provide pattern tooling and design assistance services. Our experienced team can review your part drawings for castability and recommend design modifications that improve yields, reduce scrap, and lower your total cost per casting.

Engaging us early — even during the concept or prototype phase — is the most effective way to ensure your design is optimized for the sand casting process before permanent production tooling is built.

Castings typically offer important advantages over weldments:

• No joints or seams: Castings are monolithic — no weld seams that can be a source of weakness, porosity, or leak paths.
• Consistent part-to-part quality: Each casting is produced from the same mold, reducing dimensional variation.
• Design freedom: Complex internal passages, bosses, and undercuts can be incorporated into a single casting.
• Lower labor cost at volume: Once tooling is amortized, sand castings are generally less labor-intensive per piece.
• Reduced part count: Consolidating multiple weld-fabricated components into a single casting simplifies assembly.

For a detailed comparison, visit our Castings vs. Weldments page.

Sand casting cost is driven by several factors:

• Pattern and tooling: A one-time upfront investment. Simple patterns can cost a few hundred dollars; complex multi-core tooling may run into several thousand.
• Part weight and alloy: Metal cost is tied directly to finished casting weight and current commodity pricing.
• Order volume: Higher quantities spread tooling amortization over more pieces, reducing per-piece cost significantly.
• Molding process: Air-set molding typically carries a higher per-piece cost than green sand for comparable parts.
• Secondary operations: Heat treatment, machining, pressure testing, and other finishing steps are quoted separately.

To receive pricing specific to your part, submit a Request for Quote with your drawing or 3D model.

• New tooling + first article: Tooling fabrication typically adds 4–8 weeks for simple to moderately complex patterns. First article castings are generally produced immediately after pattern approval.
• Repeat orders (existing tooling): Production lead times generally range from 2–6 weeks depending on casting complexity, alloy, and quantity.
• Prototype / rush orders: Expedited lead times may be possible for prototype quantities using 3D printed patterns. Contact us to discuss your timeline.

For a specific lead time estimate, submit a Request for Quote or call us directly.

The fastest way to receive pricing is to submit our online Request for Quote form. To produce an accurate quotation, it helps to include:

• A part drawing or 3D model file (PDF, DWG, STEP, or IGES accepted)
• Alloy specification (or request our recommendation)
• Annual estimated quantity and desired delivery frequency
• Any special requirements — heat treatment, machining, pressure testing, marking, etc.

You can also reach us through our Contact Us page. We typically respond to quote requests within 2 business days.

Quality is foundational to our operation. LB Foundry maintains a documented Quality Management System (QMS) that governs our entire casting workflow — from incoming material verification through molding, pouring, shakeout, finishing, and final inspection before shipment.

Our in-process and final inspection capabilities include dimensional verification, visual inspection for surface defects, and metallurgical testing of alloy chemistry. We work with customers to establish appropriate quality hold points and inspection criteria for their specific requirements.

LB Foundry serves a broad range of industrial markets that rely on reliable, precision non-ferrous castings, including:

• General industrial and heavy equipment
• Pumps, valves, and fluid handling systems
• Marine and offshore
• Electrical and power distribution
• Agriculture and construction equipment
• Food and beverage processing
• Defense and government (prototype and limited production)

If you are evaluating whether your application is a fit for sand casting, contact our team and we will review your requirements.