White fused alumina 1000# 15um for tungsten-containing polymer bushings

Part 1: The Abrasive – White Fused Alumina (WFA) 1000# / 15µm

• White Fused Alumina (WFA):

  • A synthetic abrasive made from high-purity aluminum oxide (Al₂O₃).

  • Key Properties: High hardness, sharp grains, good self-sharpening, and lower heat generation compared to other abrasives. It is known for producing a very clean, high-quality finish.

  • Typical Use: Ideal for fine grinding, honing, and polishing of hard materials (like steel, alloys) or where heat sensitivity is a concern.

• 1000# and 15µm (Microns):

  • These are two standards for measuring grit size, and they correspond closely here.

  • 1000# is a very fine grit according to the FEPA (European) or JIS (Japanese) standard. It is used for final polishing stages to achieve a mirror-like or near-mirror finish.

  • 15µm directly states the average particle diameter in microns, confirming the fine, polishing-grade nature of the abrasive.

Conclusion: This is not for cutting or stock removal. It is specifically selected to produce an extremely smooth, low-micro-roughness surface.

Part 2: The Component – Tungsten-Containing Polymer Bushing

• Polymer Bushing: A sleeve or liner, typically made from a high-performance engineering plastic (e.g., PEEK, PTFE, Vespel, Nylon).

• Tungsten-Filled: The polymer is compounded with tungsten powder to create a composite material with enhanced properties:

  • Increased Density/Weight: For balancing and vibration damping in rotating machinery.

  • Radiation Shielding: Tungsten is excellent for blocking X-rays and Gamma rays, useful in medical (CT scanners) and nuclear equipment.

  • Improved Stiffness & Wear Resistance: To enhance the mechanical properties and longevity of the bushing.

This composite is often very hard, wear-resistant, and can be brittle, requiring precise machining.

Part 3: The Probable Application & Finishing Process

Using such a fine abrasive suggests one of several precision finishing methods:

1. Lapping or Polishing: The WFA is mixed into a slurry or paste. The bushing’s surface (internal or external) is then finished against a soft lap (e.g., cast iron, copper, or even a soft cloth) to achieve a mirror finish and tight tolerances.

2. Abrasive Flow Machining (AFM): This is a highly likely process, especially for finishing the complex inner diameter (ID) of a bushing. A viscous media laden with the WFA abrasive is pumped under pressure through the bushing’s bore, uniformly deburring, radiusing, and polishing the inner surface.

3. Fine Honing: A honing tool with stones containing the 1000# grit could be used to precisely size the bore and create a perfect cross-hatch surface pattern for optimal oil retention.

Part 4: Key Considerations for the Process

1. Heat Management: Although WFA generates less heat, the polymer matrix is sensitive to temperature. Adequate coolant (often a water-based solution) is essential to prevent the bushing from deforming or melting.

2. Cleaning: Post-processing cleaning is critical. Any residual 15µm abrasive particles embedded in the soft polymer matrix can break loose later, causing contamination or wear in the final application.

3. Fixturing: The bushing must be held securely with proper fixtures to prevent distortion during the finishing process, as polymers are less rigid than metals.