Deburring titanium alloy necklaces with white fused alumina

Why White Fused Alumina (WFA) is a Good Choice for Titanium

1. Hardness:​ WFA has a Mohs hardness of about 9.0. Titanium alloy has a hardness typically in the range of 5-6.5 (depending on the specific alloy and heat treatment). This significant difference in hardness means the WFA can effectively abrade the titanium without breaking down too quickly.
2. Friability:​ WFA is a sharp, blocky abrasive that fractures to create new sharp edges. This “self-sharpening” property helps maintain a consistent cutting action.
3. Chemical Purity:​ The “white” designation means it has a high purity (over 99% Al₂O₃). This is critical for jewelry as it minimizes the risk of iron contamination (which can cause rust stains on the final product). Brown fused alumina (BFA) has lower purity and is not recommended for titanium jewelry.

Recommended Methods for Deburring

1. Vibratory Tumbling (Most Common for Small Parts)

• Media:​ Use pre-formed plastic or ceramic media in a triangular or pyramid shape. The media carries the abrasive and provides a gentle rubbing action.
• Process:
  1. Load the titanium parts into the vibratory tub.
  2. Add the plastic/ceramic media to about 70-80% of the tub’s volume.
  3. Add the White Fused Alumina Abrasive:​ Use a fine grit size. A good starting point is #80 to #120 grit​ for aggressive deburring, followed by a finer grit (#220 to #400) for a smoother pre-polish finish. A ratio of about 1 part abrasive to 10 parts media by volume is a common starting point.
  4. Add a small amount of water​ and a drop of liquid compound (a “burnishing compound”) to keep the slurry from becoming too pasty, reduce friction, and prevent rust on the machine.
  5. Tumble for several hours (2-8 hours, depending on the amount of burr and desired finish). Check periodically.

2. Barrel Tumbling

• Best for:​ Pendants or more robust components.
• Process:​ Similar to vibratory tumbling, but media selection is critical to prevent parts from tangling or impinging on each other.

3. Blasting (For a Matte Finish or Specific Textures)

• Abrasive:​ White Fused Alumina, typically in a finer grit (#80 to #220).
• Equipment:​ Use a dedicated pressure blast cabinet​ or a suction blaster.
• Key Parameters:
  • PSI (Air Pressure):​ Keep it relatively low, around 30-60 PSI. High pressure can etch or peen the surface too aggressively.
  • Nozzle Distance:​ Keep the nozzle moving at a consistent distance (4-8 inches) to avoid creating uneven spots.
  • Angle:​ Blast at a 45-degree angle for effective deburring; a 90-degree angle is more for general surface finishing.

4. Hand Finishing (For Precision and Delicate Pieces)

• Tools:
  • Abrasive Papers/Sponges:​ Sanding sponges or sheets coated with WFA.
  • Brushes:​ Use small, stiff nylon or natural fiber brushes with a slurry of WFA powder and water.
• Technique:​ Always sand with the grain of the metal if possible. Move from coarser to finer grits progressively.

Critical Considerations and Safety

1. Contamination is Your Enemy:​ THIS IS THE MOST IMPORTANT POINT.
   • Iron Contamination:​ Never, ever use equipment that has previously been used for steel or iron parts.​ Titanium is highly sensitive to iron contamination. Embedded iron particles will rust and create ugly red stains on your jewelry, ruining the piece. Use dedicated tubs, media, and blasting cabinets for titanium.
   • Cross-Grit Contamination:​ Use separate media for different grit sizes. If you use the same media from a #80 grit run for a #400 grit run, the leftover coarse abrasive will scratch the finish.
2. Grit Progression:​ For a smooth, polished finish, you must progress through increasingly finer grits. You cannot jump from a #80 grit finish to a mirror polish. A typical progression might be: Deburr with #120 -> Smooth with #220 -> Pre-polish with #400 -> Then proceed to polishing compounds.
3. Titanium’s Low Thermal Conductivity:​ Titanium heats up quickly during grinding or aggressive hand sanding. Excessive heat can alter the color of the titanium (creating heat tints like straw, blue, or grey) and affect its temper. Use light pressure, keep the piece cool, and use coolant/lubricant if possible.
4. Safety Gear (Non-Negotiable):
   • Respirator:​ When blasting or doing any dry abrasive work, you MUST​ wear a NIOSH-approved respirator with P100 filters. Inhaling fine abrasive dust is extremely harmful to your lungs.
   • Eye Protection:​ Safety glasses or, better yet, a full-face shield.
   • Gloves:​ Cut-resistant gloves are recommended.

Summary Workflow

1. Clean:​ Start with clean, grease-free parts.
2. Choose Method:​ Select vibratory tumbling for batches/blasting for a finish/handwork for precision.
3. Deburr:​ Use WFA grit #80-#120​ in your chosen method.
4. Rinse:​ Thoroughly rinse the parts in water after each step to remove all abrasive residue.
5. Progress:​ Move to a finer grit (#220-#400) to refine the surface and remove scratches from the previous step.
6. Final Clean:​ Perform an ultrasonic clean to remove any embedded particles.
7. Polish:​ Proceed to your standard polishing techniques (e.g., with diamond compound or specialized titanium polishing pastes) to achieve the final luster.