In polyurethane spraying operations, excessive wear of the spray gun mixing chamber will not only affect the foaming quality, but also increase the maintenance frequency and use cost. Usually, such problems are closely related to material properties, equipment parameter settings and accessory wear resistance.
1. Materials and daily maintenance factors
Polyurethane raw materials with high viscosity or high filler content will increase the friction and erosion of parts during the mixing and injection process, resulting in a shortened mixing chamber life. To reduce the risk of wear, the following measures can be taken:
Reduce material viscosity : appropriately adjust the A/B component ratio or add co-solvent to improve material fluidity
Clean immediately after each spraying : Use special cleaning agents (such as methylene chloride, acetone, etc.) to thoroughly flush the mixing chamber and nozzle channel to prevent residual material from crystallizing
Regularly replace wearing parts : such as mixing needles, sealing rings, O-rings, etc. It is recommended to check them every 3 to 6 months, and the replacement cycle depends on the frequency of use.
2. Adjustment of spray gun parameter settings
Mismatched spraying parameters will also indirectly accelerate the mechanical wear of the mixing chamber, and reasonable optimization should be made according to the characteristics of the raw materials:
Increase the nozzle aperture : High viscosity raw materials should use a nozzle with an aperture of 0.8~1.2mm to reduce the retention and shear of the material in the mixing chamber.
Balance the raw material supply pressure : ensure that the feed pressure of components A and B is basically the same to avoid bias flow and local erosion caused by pressure difference
3. Recommendations for selection of wear-resistant accessories
In order to extend the service life of the mixing chamber and related parts, it is recommended to pay attention to the following material selection when selecting or repairing:
Mixing chamber material : Stainless steel or chrome-plated steel mixing chamber is preferred, which has higher corrosion resistance and wear resistance;
Seal ring and O-ring : It is recommended to use fluororubber (Viton) material , which is resistant to polyurethane isocyanate system corrosion and has a wider operating temperature range.
If the above optimization measures still cannot improve the life of the mixing chamber, it is recommended to contact the spray machine manufacturer to redesign the spray gun structure, such as replacing it with a dynamic mixing spray gun or introducing a self-cleaning structure.