1. Stubborn Contaminants on Die-Cast Housings

1. Residual die-casting release agent, drawing oil and cutting oil

2. Aluminum scraps, dust and burrs hidden in inner cavities, screw holes and blind holes

3. Surface oxide dirt and black stains

4. Easy to get water marks, white spots and corrosion after cleaning

2. Most Reliable Cleaning Solutions (Ranked by Cleaning Effect)

Solution 1: Vacuum hydrocarbon / modified alcohol ultrasonic cleaning (Top Recommended)

• Thoroughly clean blind holes, deep holes and inner cavities; flush out hidden aluminum scraps and dust

• Fully sealed vacuum drying, completely dry directly after cleaning, no water marks or surface fading

• No corrosion, whitening or discoloration on aluminum alloy

• Solvent recyclable by distillation, low consumable cost

Solution 2: High-pressure spray cleaning (Mass production for standard die-cast housings)

• Aluminum scraps easily remain in screw holes and blind holes

• Water cleaning with poor drying easily causes water marks and white mildew

• Passivation treatment is required for anti-oxidation

Solution 3: Water-based ultrasonic cleaning (Low cost with limitations)

• Hard to completely remove scraps from deep holes

• Inadequate drying inevitably causes water marks and mildew

• Aluminum parts prone to corrosion, darkening and surface graying

3. 5 Key Points for Perfect Cleaning

1. Use special cleaning agent for die-cast aluminum

   Strong alkali will corrode aluminum and cause powdery white surface; choose neutral / weak alkaline special aluminum degreaser.
2. Combine ultrasonic + high-pressure spray

   Ultrasound loosens oil and scraps; high-pressure spray flushes out debris. Single process cannot achieve perfect cleaning.
3. Targeted spray & turnover for screw/blind holes

   Do not place workpieces flat; use customized tooling to align holes toward spray nozzles.
4. Ensure thorough drying

   Residual moisture causes damp mildew easily. Vacuum drying is preferred, followed by hot air circulating drying.
5. Anti-oxidation passivation after cleaning

   Bare die-cast aluminum is easy to oxidize and darken after cleaning; add sealing passivation to prevent discoloration and fingerprint marks.

4. Equipment Selection Advice

• High standard (no water marks, clean inner cavity, no whitening) → Bark multi-station vacuum hydrocarbon cleaning machine

• Mass ordinary parts & cost-sensitive → High-pressure tunnel spray cleaning line

• Small batch workshop use → Single/tank ultrasonic cleaner + drying oven