This is the "Rack Plating Pre-Polishing Workshop Operations Manual".

The Hard Truth: Plating does not hide defects; it magnifies them. A scratch on raw zinc becomes a canyon after bright nickel plating.

The Mission: To transform a rough die-cast surface into a "Class A" Mirror Surface (Roughness Ra < 0.05 µm) without destroying the sharp lines of the logo.

Here is the Master’s Standard for the Polishing Department using the [QLQ System].

💎 Metal Polishing Workshop Manual (Pre-Rack Plating)

Target: High-End Belt Buckles, Luxury Logo Plates, Bag Hardware.

Goal: Mirror Finish, No Pits, Sharp Edges (No "Rolled" logos).

Material: Zinc Alloy (Zamak) or Brass.

Part I: The Process Workflow (The "Cut & Color" System)

Polishing is divided into three stages: Grinding (Shaping), Buffing (Leveling), and Coloring (Shining).

Step 1: Emery Grinding (Deburring)

• Goal: Remove the "Parting Line" (Mold seam) and "Gate" (Inlet).

• Tool: Abrasive Belt (Sanding Belt) or Flap Wheel.

• Grit Sequence:

  • #240 Grit: Remove the heavy flash.

  • #400 Grit: Smooth the scratch marks.

• Master's Rule: Do not touch the main face of the buckle. Only touch the edges. If you grind the face, you create deep scratches that are hard to remove later.

Step 2: "Cutting" (Rough Buffing)

• Goal: Remove the "Orange Peel" (die-cast skin) and pores. Level the surface.

• Wheel: Treated Sisal Wheel (Hard fiber) or Stitched Cotton Wheel (Hard).

• Compound: [QLQ] Purple Cutting Compound (Fast Cut) or Grey Wax.

• Speed: 2400 – 2800 RPM.

• Technique: High Pressure. Cross-hatch motion.

Step 3: "Coloring" (Final Mirror Finish)

• Goal: Remove the swirl marks from Step 2 and bring out the deep gloss.

• Wheel: Loose Cotton Wheel (Soft, Air-flow type) or Flannel Wheel.

• Compound: [QLQ] Green Rouge (Chromium Oxide) or White Polishing Paste.

• Speed: 1800 – 2200 RPM. (Slower speed prevents "clouding").

• Technique: Light Pressure. Let the compound do the work.

Part II: Consumables & Equipment Setup

Using the right wheel is 50% of the job.

Part III: Operational Rules (The "Hand Skill" Standard)

Rule #1: The "Cross-Polish" Technique

• The Error: Polishing in only one direction. This digs trenches.

• The Master's Way:

  • Step 2 (Cut): Polish Horizontally ($\leftrightarrow$).

  • Step 3 (Color): Polish Vertically ($\updownarrow$).

  • Why? The vertical pass cuts across the horizontal scratches, erasing them completely.

Rule #2: Logo Preservation

• The Error: Pressing a logo plate hard against a soft wheel. The wheel deforms into the letters and rounds off the sharp edges ("Washing out" the logo).

• The Master's Way:

  • Use a Harder Wheel (Stitched Cotton) for logos.

  • Use Light Pressure. "Kiss" the surface.

  • Never dwell on the text. Keep moving.

Rule #3: The "Drag" Zone

• Safety: Always polish on the lower quadrant of the wheel (spinning downwards).

• Quality: Polish off the edge, not into the edge.

  • Into the edge: The wheel grabs the part (Projectile hazard) and rounds the corner.

  • Off the edge: Keeps the corner sharp.

Rule #4: Wax Management

• The Error: Applying too much wax. The part looks black and greasy.

• The Result: The wax gets impacted into the logo recesses. It will NOT wash out in the ultrasonic line, causing plating failure (blisters).

• The Fix: Apply wax to the wheel, not the part. Apply small amounts frequently (every 5-10 parts).

Part IV: Quality Control (The "Light Box")

You cannot inspect polishing under dim factory lights.

1. Inspection Station: Must use D65 Daylight or High-Intensity LED Strip.

2. The "Reflection" Test:

   • Hold the polished buckle up to a piece of text (e.g., a newspaper).

   • Pass: You can read the small text clearly in the reflection.

   • Fail: The text is blurry or distorted (Orange Peel).

3. The "White Glove" Check:

   • Wipe the part. If grey dust remains, the polisher is using too much compound or the ultrasonic cleaning will be difficult.

Part V: Master’s Troubleshooting (Real Experience)

Part VI: Efficiency & Safety (The Boss's Concern)

1. Dust Extraction (Fire Safety)

• Danger: Zinc and Aluminum dust is explosive. Cotton lint is flammable.

• Requirement: Every station must have a high-velocity Vacuum Hood.

• Maintenance: Empty the dust bags daily. Never smoke in the polishing room.

2. Automatic vs. Manual

• Manual: Essential for complex shapes and high-end detail.

• Rotary Table Auto-Polish: Good for high volume, flat rounds.

  • Strategy: Use Auto-Polish for Step 2 (Cut), then use Manual Polish for Step 3 (Final Color). This saves labor while keeping quality high.

3. Rack Prep

• The "Clean" Handover: Polished parts are sensitive.

• Rule: Polishers must place parts neatly into Foam Trays or Egg Crates.

• Never throw polished parts into a bin. They will scratch each other.

🌟 Featured Album: The "Mirror Maker" Series

Description for the Blog/Guide Album:

💎 The "Mirror Maker" Album: Pre-Plating Perfection

Plating is only as good as the surface underneath it. This album is the training manual for turning rough metal into liquid chrome.

What you will master:

• 🔄 The Cut vs. Color: Understanding why you can't skip the Sisal Wheel. (Hint: The Cotton wheel shines the bumps; the Sisal wheel removes them).

• 🔍 The "Drag Line" Danger: How to hold the buckle against the wheel to ensure the edges stay "Razor Sharp" instead of looking like a melted candle.

• 🧴 Compound Chemistry: Why [QLQ Purple] is designed specifically for Zinc Alloy to prevent "Clogging," while Standard Grey Bar is for Steel.

• 🔥 The Heat Limit: How friction heat changes the surface structure of Zinc, causing "Cloudy" plating later, and how to polish cool.