🎨 Professional Spray Painting Workshop Planning (QLQ System)
Target Product: Zinc Alloy Zipper Pulls (Complex shapes), Buckles.
Capacity: 500 KG / Day (1 Shift).
Methodology:
Tumble Spray (Barrel Painting): 80% of volume (Small zipper pulls, buttons). Efficient, low labor.
Rack Spray (Hand/Spindle): 20% of volume (Large buckles, high-gloss items).
Key Requirement: Pantone Color Matching & 5-Grade Adhesion.
Part I: Workshop Layout & Infrastructure (The "Clean Room")
The workshop CANNOT be an open shed. It must be an enclosed, positive-pressure environment to prevent dust from ruining the paint.
1. Facility Requirements
Total Area: 200 - 300 Sq.M
Cleanliness Class: Class 100,000 (ISO 8).
Mechanism: A Fresh Air Supply Unit (MAU) pumps filtered air into the room, forcing dust out through the exhaust.
Flooring: Epoxy Anti-Static Flooring (Conductive).
Zoning:
Zone A: Paint Mixing Room (Explosion Proof).
Zone B: Tumble Spray Room (3 Machines).
Zone C: Rack Spray Booth (1 Unit).
Zone D: Curing Oven Area.
Zone E: QC & Packing.
2. Equipment Configuration (For 500 KG/Day)
| Equipment Name | Specs/Quantity | Purpose |
| Auto Tumble Spray Machine | 3 Sets. (Drum 600mm). Heated drum capability. | Mass painting small pulls. 3 machines allow running 3 colors simultaneously. |
| Spare Drums (Barrels) | 6-10 Sets. | Crucial: Dedicated drums for White, Black, Red, Blue series to prevent cross-contamination and speed up changeover. |
| Rack Spray Booth | 1 Unit (Water Curtain type). 2.4m wide. | For large buckles or "Rubber Paint" that cannot be tumbled. |
| IR Tunnel Oven / Batch Oven | 1 Set (Temp up to 180°C). | For curing Rack Spray items. (Tumble machines usually cure inside the drum). |
| Air Compressor | 20HP Screw Compressor + Refrigerated Dryer. | Paint requires Oil-Free, Water-Free air. |
| Paint Mixing Station | Explosion-proof Mixer + Viscosity Cups. | Color matching and thinning. |
Part II: Process Flow & SOP (QLQ Standard)
Phase 1: Pre-Treatment (Critical for Adhesion)
Zinc alloy is "slippery." Paint will peel off if not primed correctly.
Degreasing: (Same as plating) Ultrasonic Clean --> Rinse.
Phosphating / Chromating (Conversion Coating):
Chemicals: [QLQ Product] Zinc Adhesion Promoter (ZAP).
Purpose: Creates a microscopic "roughness" for the paint to grip.
Drying: Parts must be 100% Bone Dry before painting. Moisture = Blisters.
Phase 2: Paint Preparation (The "Chef's" Work)
Sourcing:
[QLQ Product] Polyurethane (PU) Enamel Paint: (High hardness).
[QLQ Product] Soft-Touch Rubber Paint: (Matte feel).
[Purchase Locally] Thinner / Hardener: To save shipping costs.
Viscosity Control:
Use a Ford Cup #4. Target: 16–22 seconds.
Rule: Too thick = Orange Peel. Too thin = Sagging/Runs.
Phase 3: Tumble Spraying (The Bulk Process)
Load: ~15 KG per drum.
Step A (Pre-Heat): Rotate drum at 50°C for 5 mins.
Step B (Spray):
Gun Speed: Auto-reciprocating.
Atomization Pressure: 2–3 Bar.
Time: 15–20 mins (Multiple thin coats are better than one thick coat).
Step C (Cure): Drum heats up to 120°C–150°C while rotating. Time: 30–45 mins.
Phase 4: Rack Spraying (The Manual Process)
Load: Manually mount buckles on jigs.
Spray: Hand spray or Spindle rotation.
Flash-off: Let sit for 10 mins (Solvent evaporation).
Cure: Move rack into the Oven (150°C for 30 mins).
Part III: Safety & Environmental (Mandatory)
Paint shops are high-risk zones for Fire and VOC (Smell) pollution.
1. Fire Safety (ATEX Standards)
Electrical: All lights, switches, and motors in the spray room must be Explosion Proof (Ex d IIB T4).
Grounding (Earthing): All spray guns and machines must be grounded to prevent static sparks.
Fire Suppression: CO2 or Foam extinguishers at every station.
2. Exhaust & Filtration (VOCs)
The System:
Stage 1: Water Curtain / Dry Filter (Traps paint mist).
Stage 2: UV Photolysis or Activated Carbon Tower (Removes the solvent smell).
Requirement: Exhaust fan must maintain negative pressure in the spray booth area so fumes don't drift to the office.
Part IV: Quality Control Lab (The "Testing Zone")
To match Gap/H&M/Zara standards, you need these instruments:
Color Matching Box (Light Booth):
Check colors under D65, TL84, CWF light sources.
Cross-Cut Tester (Adhesion):
Cut a grid (1 X1 mm) into the paint. Apply 3M 600 tape and pull.
Standard: ISO Class 0 (0% Peeling).
MEK Rub Test (Cure Check):
Rub the surface with Methyl Ethyl Ketone (solvent) soaked cloth 50 times.
Pass: Paint does not dissolve or dull.
Thickness Gauge:
Magnetic induction type. Target: 20–30 microns.
RCA Wear Tester: For "Rubber Paint" abrasion resistance.