Racking
Confirm part orientation, contact points, masking areas and loading density to reduce handling damage, trapped liquid and poor electrical contact.
MAGNESIUM SURFACE ENGINEERING
Magnesium Cleaning & Passivation Process
A nine-stage route from racking and oil removal to controlled conversion coating and drying for magnesium alloy parts.
The nine-stage process
The objective is not simply to add more tanks. Each stage has a defined purpose and helps control oil, salts, drag-in, trapped liquid and rinse-water variation before film formation.
Ultrasonic Degreasing
Ultrasonic cavitation and a controlled degreasing system remove machining oil, rust preventive oil and particulate contamination, including in cavities and blind holes.
Water Rinse
Remove displaced soils and residual cleaner to reduce chemical carryover and surface contamination.
Spray Rinse
Use targeted spray action to rinse external surfaces, holes and edges more consistently.
DI Water Rinse
Reduce ionic and mineral residues before purification and conversion coating.
Surface Purification
Condition or activate the magnesium surface according to alloy grade and incoming surface condition.
Conversion Coating
Form a controlled passivation film designed around corrosion resistance, adhesion and downstream coating requirements.
Final DI Water Rinse
Remove unreacted residues and control final-rinse cleanliness to reduce water marks, stains and corrosion risk.
Drying
Control temperature and time for the part geometry and coating system while avoiding trapped water, overheating and secondary contamination.
Common pretreatment risks
- Die-casting release agent or heavy oil causing local non-coating
- Trapped liquid in blind holes and cavities causing carryover or water marks
- Over-cleaning causing excessive surface reaction or dimensional risk
- Ionic residues affecting conversion-coating consistency
Information we need
- Alloy grade, forming process and heat-treatment condition
- Drawing, critical appearance surfaces and prohibited rack points
- Oil type and any existing surface treatment
- Corrosion, adhesion, appearance and delivery targets
FREQUENTLY ASKED QUESTIONS
Technical FAQs
Process parameters, test methods and acceptance criteria are confirmed against representative samples, drawings and the agreed quality specification.
Why use water, spray and DI-water rinses?
Each stage has a different function: removing cleaner, flushing complex features and reducing ionic residue before film formation.
Are purification and conversion coating the same stage?
They are separated here for engineering clarity. Purification conditions the surface; the following conversion stage forms the passivation film.
Can all magnesium alloys use the same parameters?
No. AZ91D, AM60B, AZ31B and different casting or machining conditions require sample validation.
REQUEST AN ENGINEERING REVIEW
Send your part details and drawing
Please include the alloy grade, application, target process, estimated volume, appearance standard and corrosion requirements. For confidential drawings, contact us before transfer.
Phone / WeChat: +86 13724861913