Pretreatment Audit Checklist: The 40 Points That Decide Adhesion — 前处理 40 项审计清单：决定结合力的全部检查点（可打印）.
This is a working reference, not theory: every table and checklist here is designed to be printed and used at the line. It complements the failure case studies published in the Technician Hub with the standard documents those cases eventually produced.
Common Mistakes and How to Avoid Them
| Mistake | Why It Happens | Practical Fix |
|---|---|---|
| 1. Topping up cleaner without titration | Build-up of oils and soil defeats chemistry | Titrate free alkalinity each shift; dump on schedule |
| 2. Rinsing in still water too long | Loaded rinse drags soil into next stage | Overflow or counter-flow; check conductivity |
Best Practices
- Titration log at the tank, not in the office
- Basket loading diagram posted above the tank
- Weekly conductivity check on every rinse
Tank Care Sequence
- Shift titration - Free alkalinity vs control band (Never top up without titrating)
- Load baskets per diagram - Parts do not shadow (Overloading kills cavitation)
- Check final rinse conductivity - <50 µS/cm (High reading = change/overflow first)
Log at the tank | Escalate 2 out-of-band readings in a row
Bath Control Reference Data
Typical control points for alkaline soak and ultrasonic lines.
| Parameter | Reference | Why It Matters |
|---|---|---|
| Soak cleaner concentration | Titrate free alkalinity 1-2 points | Below range = poor wetting; above = carryover |
| Ultrasonic bath temperature | 50-65 °C | Best cavitation for zinc alloy parts |
| Final rinse conductivity | <50 µS/cm | Higher values drag salts into plating |
| Tank dump schedule | Per titration trend, not calendar only | Built-up soil defeats chemistry |
Ten-minute titrations ended blister season
Scenario. Summer blisters were blamed on weather while cleaner strength drifted.
Action. Per-shift titration with a posted control band and escalation rule.
Result. Blisters fell to near zero without adding a single tank.
Frequently Asked Questions
How often should I titrate the cleaner?
Every shift for soak cleaners. Topping up without titration is how tanks drift out of control.
What conductivity means the rinse must change?
Above 50 µS/cm on the final rinse, start overflow or change water. Higher values drag salts into plating.
Can I extend tank life beyond the dump schedule?
Only with titration trend data showing chemistry still holds. Soil build-up defeats the chemistry before visible failure.
Implementation Roadmap
| Step | Frequency |
|---|---|
| Titration kit at tank and log live | Day 1 |
| Rinse conductivity limits set | Week 1 |
| 40-point audit first run | Week 2 |
| Audit review and fix cycle | Monthly |
What Would You Like to Solve?
If you would like this checklist or template adapted to your own line and part mix, contact QLQ — we supply the full equipment and chemistry package along with the working documents that make it run.