Metal powder flame spraying (welding) spray welding process typical surface spray characteristics
The geometry of the part has a certain effect on the effect of spraying (welding), such as the outer surface of the spray, when the coating is cooled, there is a tendency to shrink tight; the inner surface of the surface coating
cooling from the workpiece, the simple surface spray The powder is easy to deposit; the complex surface of some tortuous parts of the spray powder is difficult to deposit.Therefore, the research and excavation of various types of parts surface spray (welding) characteristics, the correct use of spraying (welding) process, to ensure the quality of spraying is very practical.
1, the axis of the surface of the spraying process points:
(1) spray the surface before the preparation to be strict control purification treatment, roughening treatment according to the process requirements to do, handle the surface to avoid contact with the moisture or hand touch.
(2) strict control of spray specifications, control the workpiece temperature rise can not exceed 250 ℃, when the coating is thick, the workpiece is small, continuous spray temperature rise may exceed 250 ℃, should be intermittent spraying method cooling, but the residence time can not Too long, otherwise the coating will be caused by pollution caused by poor layer.
(3) grinding over the angle and edge, with holes or keyway of the journal, the hole should be blocked and the edge of the keyway polished into rounded corners, pay attention to spray the edge.
(4) the outer surface of the substrate preheating temperature should take the lower limit, the spraying process should control the substrate temperature, thereby reducing the matrix shrinkage.
2, the plane spraying process points:
(1) pay attention to repair the edge, edges and corners; ⑵ preheat requirements uniform, large pieces can be used at both ends of the warm-up.
(2) spraying from the edge of the dust from the edge, and then lead to the plane, repeated powder, the time should be followed by a spray and the previous direction perpendicular to each other.
(3) In order to prevent the edge of the coating tilt, before spraying can be grooved at the edge of the workpiece, and by sand blasting can reduce the stress.
3, the mouth surface spray process points:
⑴ spraying should be sprayed before the cylindrical part of the spray after the plane part.
⑵ spray gun powder spray direction along the circumference of the workpiece into a 45-degree angle injection is good, this may make the powder deposition rate is low, but it can spray a clear edge of the spray operation Note that the gun can not be sprayed perpendicular to the corner, This will cause the corners of the coating to be loose or sandwiched.
⑶ spraying edge such as burr, Alice, should be promptly removed and then spray.
4, the local serious damage parts of the spraying process points:
⑴ the local damage at the polished clean, first spray or repair with other methods, and then spray all the plane.
⑵ for the deeper, wider local defects can be seen, can also be used to fill the welding, and then fully sprayed.
⑶ on the local defects with cracks must first find the crack from the end, and in the place to play a hole, open the groove, the cracks will be cleaned up all the clean or fill the welding fill the defect site, and finally spray to be sprayed surface.