Method for manufacturing coated article

1. A method for manufacturing a coated metallic article, comprising the steps of:

performing an electrostatic powder coating process to form a primary powder layer in at least a region of the metallic article to be coated, said region having projections and depressions;

removing the primary powder layer from a tip portion of each projection by a specified thickness;

after said removing the primary powder step, performing electrostatic powder coating process to form a secondary powder layer over said region from which the primary powder layer at the tip portions of the projections has been removed by the specified thickness; and

after the secondary powder layer has been formed, melting the primary and secondary powder layers by induction heating to form a coating film on the article.

2. The manufacturing method according to claim 1 , wherein the step of removing the primary powder layer includes scraping the primary powder layer while removing the scraped powder by suction.

3. The method according to claim 1 , wherein in performing an electrostatic powder coating process, a powder coating material having a mean particle size of 5 μm to 100 μm is used.

4. The method according to claim 1 , wherein in performing an electrostatic powder coating, a thermoplastic resin-based powder coating material is used.

5. The method according to claim 4 , wherein the thermoplastic resin is a nylon resin.

6. The method according to claim 1 , wherein in the step of removing the primary powder layer, the thickness by which the powder layer is removed is set such that the coating film to be formed has a substantially uniform film thickness at any portion thereof.

7. The method according to claim 6 , wherein the film thickness is within a range of from 100 μm to 300 μm.

8. The method according to claim 1 , wherein a ratio of a coating weight A (g/m 2 ) of the primary powder layer to a coating weight B (g/m 2 ) of the secondary powder layer falls within a range of A/B=20/80 to 80/20.

9. A method for manufacturing a coated metallic gear, comprising the steps of:

depositing a powder coating material having a particle size of 10 to 70 μm onto a metallic gear by an electrostatic powder coating process to form a primary powder layer on a surface of the gear;

removing the powder layer from crests of teeth of the gear by a specified thickness by scraping the powder layer with a scraper while sucking up the scraped powder;

after said removing step, further depositing a powder coating material having a particle size of 10 μm to 70 μm over the surface of the gear by electrostatic powder coating process to form a secondary powder layer; and

after the secondary powder layer has been formed, melting the primary and secondary powder layers by electromagnetic induction heating to form a coating film having a thickness of 150 μm to 200 μm.

10. A method for manufacturing a coated metallic spline shaft, comprising the steps of:

forming a thermoplastic resin-based primary powder layer on a surface of a toothed portion of a metallic spline shaft by an electrostatic powder coating process;

removing the powder layer from crests of teeth in the toothed portion of the spline shaft by a specified thickness by scraping the powder layer with a scraper movable in an axial direction of the spline shaft while sucking up the scraped powder by a suction means;

after said removing step, further coating the toothed portion of the spline shaft with a thermoplastic resin-based secondary powder layer by electrostatic powder coating process; and

after the secondary powder layer has been formed, melting the primary and secondary powder layers by electromagnetic induction heating to form a coating film.