Comparison of technical performance between friction gun and high-pressure gun

The technical performance of friction gun and high-pressure gun is compared
1, the performance of two kinds of guns
the performance of the gun is closely related to the electric field, to know the difference in the performance of the two guns, first compare the differences between the two gun electric field. The electric field of the friction gun is formed by the space charge of the powder particles, and because the distance of the gun can be very small, the electricity is more uniform. The electric field of high-voltage gun is a typical uneven electric field
the
. The electric field near the pole needle is very strong, the potential gradient in the direction of the pole needle is very large, and the electric field is very weak near the work piece. In addition, the electric field range of the high-voltage gun is much larger than that of the friction gun.
2, the current of the spray gun
electrostectrectrectectrectrectrative spray, the current output of the electrostectrectrectrectrative generator is not completely increased by the powder belt or brought to the work piece, or by the powder to the earth. And a part of the current does not use powder as a medium to flow to the space outside the work piece, the earth, the formation of so-called ion wind current. Ion wind currents are different from gun to gun. For friction guns, the charge generated by friction is brought to the work piece or earth in a powder medium, while the high-voltage gun has a strong ion wind current. This is one of the reasons why spraying with a high-voltage gun is not very effective, although the spray current is large.
3, the spray effect of the two
it is difficult to fully compare the spray effect of the two guns. Only a few major indicators are compared here. These comparison results are inferred from the difference between the electric field of the two guns and have been proved by practice.
(1) coating thickness
even coating can be sprayed with both high-pressure and abrasive guns. However, it is difficult to spray a thick coating with a high-pressure gun. When the high-pressure gun is sprayed, anti-ionionation (also known as reverse knock-through) occurs when the powder layer thickens. A spray experiment with a high-pressure gun showed not only pits and spots on the surface of the powder layer, but also several "snowflakes" with a diameter of 1 cm. The anti-ionization phenomenon of the powder layer destroys the gloss of the coating after surface flattening and curing and even leaves pinholes. Anti-ion ionism is caused by the electric field of high-voltage guns. There is no such strong electric field in the friction gun, so there is no anti-ionation phenomenon. A thick coating of high surface quality can be sprayed with an abrasive gun.
(2) adhesion
the uncarified powder layer requires sufficient adsorption between the powder, otherwise the powder will fall off the powder layer. This adsorption force between powders is not the same as the coulomb force produced by free charges, but is the gravitational force between binding charges produced by polarization of powder particles. The size of this gravity is determined by the strength of powder polarization. High-voltage gun electric field is strong, powder polarization strength is high, the resulting binding charge density is large, the gravity between powders is large, the powder layer adhesion is large. The powder layer sprayed with a high-pressure gun is placed for seven days, ten days or longer before it is cured, and the powder does not fall out of the powder layer. The powder layer sprayed with friction gun has less adhesion, but can also fully meet the needs of spray production, which has been confirmed by engineering practice.
(3) Powder deposition rate
Powder deposition rate is a technical indicator determined by a variety of factors, and is not a constant in spraying, the deposition rate will decrease as the powder layer thickens. There is no uniform specification of sedimentation rate in our country, and it is not strict to say that the sedimentation rate is high or low in general. In order to correctly evaluate the advantages and disadvantages of electrostectrectrectrectrative spraying equipment, we should formulate a unified, recognized technical specifications. The powder deposition rate of the two guns is not easy to compare carefully. However, it can be said that in the small amount of powder spray, close spray, the powder deposition rate of the friction gun is higher than that of the high-pressure gun, especially in the spray small parts, complex surface shape of the work parts.
(4) coating capacity
which is a technical indicator that reflects the production capacity of the spraying equipment and is determined by the deposition rate and the amount of powder sprayed. If the amount of powder spray of the two guns is similar, the coating ability of the friction gun can be compared with the high-pressure gun of the workman at 40-60KV and the spray distance of 200-300 mm.
the comparison between the two guns, it can be said that the friction gun has many advantages, but the friction gun can not completely replace the high-pressure gun. Both guns have their own advantages and scope of application, designers should pay attention to this when choosing electrostectrectrectrectrectrative spray guns.