Is there any other solution besides replacing a rusted caster axle?

Rust and corrosion don't necessarily require replacement. Targeted treatment options are needed based on the severity of the rust (mild, moderate, or severe) and the axle material (e.g., steel or galvanized). Prioritize repair through cleaning, rust removal, and protective measures. Replacement is only necessary if the rust causes structural damage (e.g., axle deformation or excessive wear). The following are specific solutions, categorized by rust severity:

1. Mild rust (surface pitting, no sticking or deformation)
If only a small amount of pitting rust remains on the axle surface, with no rotational resistance or axle deformation, restoration can be achieved through "Rust Removal + Rust Protection." The steps are as follows:
Cleaning and Dust Removal: First, use a dry brush to remove dust and grit from the axle surface. Then, use a cotton cloth dipped in diesel or kerosene to wipe the axle and bearing gaps to dissolve oil and remove loose rust. If stubborn debris (e.g., sand embedded in the gaps) remains, gently remove it with a thin toothpick or cotton swab to avoid scratching the axle. Gentle Rust Removal: Use 200-400 grit fine sandpaper (or a rust removal sponge) to gently sand the rusted area, sanding along the length of the shaft (avoiding horizontal scratches) until the natural metal color is exposed. If the shaft is coated (such as galvanized), use gentle sanding to remove only the rust to avoid damaging the coating.
Rust Protection: After rust removal, wipe the shaft dry with a dry cloth and spray a thin layer of rust inhibitor (such as a thin layer of rust-proof oil or clear rust-proof paint) or apply a small amount of lithium-based grease (which provides both rust prevention and lubrication). If the axle has a seal (such as a rubber seal), apply the rust inhibitor/grease evenly to the inside of the seal to enhance the seal.

2. Moderate Rust (Surface Rust, Slight Sticking)
If the rust is flaky and there is slight resistance when turning the axle but no noticeable deformation, "Deep Rust Removal + Component Repair" is required. The steps are as follows:
Disassembly and Cleaning: First, remove the rubber wheel (if the wheel and axle are connected by snaps, gently pry them apart with a flat-blade screwdriver; if they are bolted, remove the setscrews). Remove the axle and bearings (completely remove the sealed bearings to avoid damaging the seals). Soak the axle and bearings in diesel fuel for 10-15 minutes to soften stubborn rust. Then, scrub the axle surface and bearing raceways with a fine-bristle brush. Rust Removal and Repair: Use 180-grit sandpaper to sand away any flaky rust on the shaft, focusing on the bearing mounting area (ensure there is no noticeable wear on the shaft diameter). If there is rust inside the bearing raceway, gently wipe it with a cotton swab dipped in a rust remover (such as a diluted oxalic acid solution, 5%-10% concentration). Rinse with clean water and wipe dry to avoid residual corrosion. Inspect the shaft for minor scratches. If any, polish and repair with 600-grit sandpaper.

Lubrication and Assembly: Apply waterproof grease (such as lithium-based composite waterproof grease) to the axle surface and bearing raceway, ensuring full contact between the bearing balls and the raceway. Reinstall the bearing and wheel, tighten the set screws (with moderate force to avoid shaft deformation), manually rotate the wheel to test, and after ensuring there is no sticking, reapply rust inhibitor to the exposed areas of the axle.

3. Severe Rust (Rust Deep into the Axle, Jamming/Deformation)
If the axle exhibits the following conditions, repair may pose a safety hazard and immediate replacement is recommended:
The axle's diameter is worn beyond the specified value (e.g., original diameter 10mm, worn ≤ 9.5mm), resulting in excessive clearance with the bearing (play exceeding 0.3mm);
The axle is bent (using a ruler to compare, the clearance between the axle and the ruler exceeds 0.5mm), or the bearing raceway is severely rusted (the ball bearings are jammed and cannot rotate);
The axle shows signs of rust penetration (small holes in certain areas, significant thinning), making it prone to breakage under load. If temporary repairs are necessary due to limited conditions (for emergency use only), first remove the rust according to the "Moderate Rust" procedure. Then, fill any worn/dented areas on the axle with a metal patch (such as epoxy patch). After curing, sand the axle to the desired size and finally apply grease. However, please note: temporary repairs are only suitable for short-term use (1-2 weeks). Replace the axle as soon as possible to avoid equipment failure.

4. Post-Repair Protection: Preventing Re-Rust

Whether the repair is minor or moderate, further protection is required to prevent recurrence of rust:

Environmental Control: Avoid contact between the axle and water or humidity. If the axle is used in a high-humidity environment (such as a food processing plant), wipe the axle with a dry cloth regularly (every two weeks) and re-lubricate.

Enhanced Seals: If the axle seal is deteriorating, replace it with a new rubber seal or dust cover to reduce dust and moisture intrusion into the axle.

Regular Inspections: After repair, check the axle rotation weekly. If minor rust is found, wipe it with a cotton cloth dipped in grease to prevent rust from developing. In summary, mild to moderate rust can be repaired through "rust removal + protection", which saves costs and extends the life of the axle; only when rust causes damage to the shaft structure and the fit clearance exceeds the standard, a new axle needs to be replaced to ensure the load-bearing and rotation safety of the caster.