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Zinc Painted Steels

Zinc Painted Steels. Resistance Welding . Learning Activities View Slides; Read Notes, Listen to lecture Do on-line workbook. Lesson Objectives When you finish this lesson you will understand:. Keywords. Zincrometal Coating. Dacromet Application. Zincromet Application. Dryer.

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Zinc Painted Steels

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  1. Zinc Painted Steels

  2. Resistance Welding • Learning Activities • View Slides; • Read Notes, • Listen to lecture • Do on-line workbook • Lesson Objectives • When you finish this lesson you will understand: Keywords

  3. Zincrometal Coating Dacromet Application Zincromet Application Dryer Dryer Dacromet = Fine Zn Dust in Chromic Acid: Dries to a Zinc Chromate Zincromet = Zinc Powder in Epoxy

  4. Epoxy Zincromet Dacromet Steel Current

  5. Pre-Painted Steels Chromate, Phosphate, Phosphate-Chromate Surface Electro-Chemical treatment is dilute solutions provides an adherent coating for subsequent painting

  6. Painted Steels Organic Paint Spray Laminated Film a. polyvinyl chloride b. Teflon, etc.

  7. Weldability Considerations

  8. Zincrometal Epoxy Zincromet Dacromet Steel Current Takes Time for Coating “Burn Through” Higher Electrode Forces Reduced Electrode Life

  9. Peel-Test Results for a Zincrometal-Coated Steel -- Containing 0.07C and 0.08P 30 25 20 Button Diameter, in. 15 10 5 6 7 8 9 10 11 12 13 14 15 Current, kA [Reference: “Spot Weldability of High-Strength Sheet Steels”, Welding Journal 59 (January 1980), Baker & Sawhill]

  10. Zinc Phosphate • Thin Coats for Paint Adhesion • Appear to have no effect on Spot Weldability • Thick Coats - “Parkerized or Bonderized” • High Resistivity • Need High pressure to Break Coating • Adverse effect on Electrode Life

  11. Painted Steel Welding • Organic Coating • Heat Sensitive, Will Scorch or Burn • Electrical Insulators • Intended to be Used Without Post Weld Finishing • Film Coating • Film Tends to Separate From Sheet • Bubbles & Blisters • Solutions • Used One Side Coated Material • Provide Local Bare Areas

  12. Series Weld on Bare Material

  13. Series Spot & Projection Weld

  14. Projection Weld - Through Painted Surface

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