Iron & Stainless Steel Buttons

Professional Barrel Plating Workshop Planning: Iron & Stainless Steel Buttons (QLQ System)

Application: Jeans Buttons, Snap Fasteners, Rivets, Eyelets.

Base Materials: Iron (Carbon Steel) and Stainless Steel (304/316).

Capacity: 1 Ton/Day (High-Throughput Semi-Automatic Line).

Key Challenge:

• Iron: Preventing rust and ensuring leveling (smoothing out rough stamping marks).

• Stainless Steel: Breaking the "Passive Layer" to ensure the plating doesn't peel off.

Sourcing Strategy:

• Commodities (Acids, Anodes, Base Salts): [Purchase Locally] to save costs.

• Core Technology (Additives, Activation, Finishes): [QLQ Product] for performance and technical guarantee.

Production Line Overview

• Barrel Configuration:

  • Iron: Standard PP Hexagonal Barrel ($\phi300 \times 600$mm).

  • Stainless Steel: High-mesh PP Barrel (to prevent small buttons from sticking).

• Rectifiers: 12V/1000A (Iron needs higher current density than Zinc).

• Filtration: 10 Tons/hr continuous filtration for Copper and Nickel tanks.

Phase I: Pre-treatment (The "Split" Process)

Iron and Stainless Steel require different activation paths. The line should be designed to handle both.

Step 1: Hot Soak Degreasing (Common for Both)

• Purpose: Remove heavy stamping oils and polishing compounds.

• Chemicals:

  • [QLQ Product] Steel/SS Degreasing Powder: 60–80 g/L (High alkalinity).

• Parameters: 70–80°C, 10–15 mins.

Step 2: Anodic Electrolytic Degreasing (Common for Both)

• Difference from Zinc Alloy: We use Anodic (+) cleaning here. Iron/SS does not dissolve like Zinc, and Anodic cleaning removes smut better.

• Chemicals:

  • [QLQ Product] Anodic Electro-cleaner Salt: 50–70 g/L.

  • [Purchase Locally] Sodium Hydroxide: (If needed for pH adjustment).

• Parameters: 60–70°C, Current: 5–8 A/dm², Time: 1–3 mins.

• Polarity: Workpiece as Anode (+).

Step 3: Acid Pickling / Activation (The Critical Divergence)

• PATH A: For Iron (Carbon Steel)

  • Purpose: Remove Rust and Scale.

  • Chemicals: [Purchase Locally] Hydrochloric Acid (HCl): 30–50% concentration + [QLQ Product] Acid Mist Inhibitor.

  • Time: 1–3 mins (Until surface is clean and grey).

• PATH B: For Stainless Steel (The "Woods Nickel" Strike)

  • Purpose: Stainless steel is passive. Standard acid won't work. You must use a Woods Nickel Strike to bond to the surface.

  • Chemicals:

    • [Purchase Locally] Nickel Chloride: 200–240 g/L.

    • [Purchase Locally] Hydrochloric Acid: 100–120 ml/L.

    • [QLQ Product] Woods Nickel Additive: (Improves coverage).

  • Parameters: Room Temp. High Current Impact (5–10 A/dm²) for 2–5 minutes.

Phase II: Base Plating (Leveling & Protection)

Step 4: Cyanide Copper Strike (Mandatory for Iron)

• Note: Acid Copper cannot be plated directly onto Iron (it will create loose "immersion copper").

• Chemicals:

  • [Purchase Locally] Copper Cyanide: 40–50 g/L.

  • [Purchase Locally] Sodium Cyanide: 60–70 g/L.

  • [QLQ Product] Copper Grain Refiner: Consult QLQ.

• Parameters: 50–55°C, 20 mins.

Step 5: Acid Copper Plating (High Leveling)

• Crucial for Buttons: Buttons often have rough stamped edges. QLQ Acid Copper provides "Mirror Leveling."

• Chemicals:

  • [Purchase Locally] Copper Sulfate: 200–220 g/L.

  • [Purchase Locally] Sulfuric Acid: 50–70 g/L.

  • [QLQ Product] Acid Copper Brightener (B) & Leveler (A): Use automatic dosing.

• Parameters: 25°C (Chiller required), 3–5 A/dm², 40–50 mins.

Step 6: Bright Nickel Plating

• Chemicals:

  • [Purchase Locally] Nickel Sulfate/Chloride/Boric Acid.

  • [QLQ Product] Nickel Brightener System: Consult QLQ.

• Parameters: 55°C, pH 4.0–4.5, 20 mins.

Phase III: Color Finishes (QLQ Specialty Processes)

Iron/SS buttons are often fashion items, requiring specific trends.

A. Imitation Gold (Brass Alloy)

• Description: Replaces real gold. Matches 18K/24K color.

• Chemicals: [QLQ Product] Imitation Gold Salts.

• Parameters: 35°C, 30-60 seconds.

B. Gunmetal / Black Nickel (Tin-Alloy)

• Description: High wear resistance for jeans buttons (which go through washing machines).

• Chemicals: [QLQ Product] Gunmetal Salts.

• Parameters: 60°C, 8–10 mins.

C. Antique Copper / Bronze (Vintage Look)

• Process:

  1. Plate Thick Copper (Cyanide or Acid).

  2. Blacken with [QLQ Product] Antique Blackener.

  3. Tumble/Burnish: Use a tumbling barrel to wear off the black from the raised logos/text, revealing the copper underneath.

D. Nickel-Free Finishes (EU Standard)

• Important: If the client requires "Nickel Free," replace the Bright Nickel (Step 6) with [QLQ Product] White Bronze (Copper-Tin-Zinc).

Phase IV: Post-Treatment

Step 7: Passivation

• Chemicals: [QLQ Product] Anti-Tarnish Dip.

Step 8: Baking (Hydrogen Embrittlement Relief)

• Note: Only necessary for High Carbon Steel or Spring Steel parts. Standard low-carbon iron buttons do not usually require this.

• Temp: 200°C for 2 hours.

Step 9: Lacquering

• Chemicals: [QLQ Product] Water-based Clear Lacquer.