Centrifugal Casting

Centrifugal Casting – A Beginner’s Guide

Document Owner: Tonia O’Neal
Version: 1.0
Last Updated: July 6, 2025

1. Purpose

This SOP outlines the step-by-step process for performing centrifugal casting using a small-scale casting machine. It is intended for beginners working with metal casting in a workshop, makerspace, or educational environment.

2. Scope

This procedure applies to the creation of small metal objects using centrifugal casting, including rings, pendants, and other small components. It assumes the use of a horizontal casting machine with a spring-driven arm.

3. Responsibilities

• Operators must follow all safety protocols and complete safety training before use.
• Supervisors are responsible for ensuring equipment is maintained and properly set up.
• Observers must stay clear of the casting area during operation.

4. Required Equipment & Materials

• Centrifugal casting machine (spring-loaded)
• Investment mold (pre-burnout)
• Metal to be cast (e.g., silver, bronze)
• Crucible (appropriate for metal type)
• Casting torch and fuel (e.g., acetylene or propane/oxygen)
• Safety gear: gloves, face shield, apron, closed-toe shoes
• Tongs and quenching container
• Fire-safe work surface

5. Safety Precautions

⚠️ Always wear full PPE (personal protective equipment).
⚠️ Ensure no flammable materials are near the casting area.
⚠️ Use the machine on a stable, fire-safe surface and ensure the spring arm is secure before releasing.
⚠️ Do not stand in line with the spinning arm.

6. Procedure

Step 1: Prepare the Mold

• Ensure the investment mold is fully burned out and dry.
• Mount it securely in the casting cradle.

Step 2: Load the Metal

• Weigh and place the appropriate amount of metal into the crucible.
• Attach the crucible adjacent to the mold, ensuring a smooth pour path.

Step 3: Wind the Casting Arm

• Wind the centrifugal arm until the spring mechanism clicks into place.
• Double-check the safety pin is engaged.

Step 4: Heat the Metal

• Use the torch to evenly heat the metal until it reaches a full, fluid melt.
• Remove any slag with a carbon rod if needed.

Step 5: Release the Casting Arm

• Quickly remove the safety pin and step back.
• The arm will spin and force the molten metal into the mold.

Step 6: Cool and Quench

• Allow the mold to cool for 5–10 minutes.
• Use tongs to transfer the mold to the quenching container.
• Once cooled, break away the investment to reveal the casting.

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7. Post-Operation Cleanup

• Turn off the torch and return all tools to proper storage.
• Wipe down the casting machine and surrounding area.
• Safely dispose of any leftover investment material.

8. Troubleshooting

Issue	Possible Cause	Solution
Metal didn’t fill mold	Inadequate heat / too little metal	Re-melt and add more metal
Porosity in casting	Improper burnout / gas trapped	Check burnout timing and temperature
Flashing or overflow	Overfilled mold or too rapid spin	Adjust weight and ensure proper cradle fit

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9. References

• Workshop Safety Manual
• Manufacturer’s Manual for [Your Machine Brand]
• Jewelry Casting by Murray Bovin (for further reading)