Construction Machinery Coating Line
Construction Machinery Coating Line –- India Structural Parts Coating Line Project
In this India structural parts coating project, the production line is designed for large welded structures used in construction machinery, including excavators, loaders, and mining equipment. The entire line is engineered around heavy-duty corrosion protection and long-term durability. By adopting a “shot blasting + multi-layer liquid coating system” process route, combined with manual precision operations and a continuous conveying system, the line ensures stable coating quality and reliable mass production capability.
Process Flow
1. Loading & Shot Blasting Pretreatment
After loading, the workpieces first enter the shot blasting process for intensive surface preparation. Shot blasting or sandblasting removes mill scale, rust, and welding residues while increasing surface roughness to provide a strong mechanical bonding foundation for subsequent coatings.
In this project, blasting intensity and coverage were optimized to ensure thorough treatment across all areas of large structural components.
2. Chemical Pretreatment
According to product requirements, processes such as degreasing, rinsing, and phosphating or phosphate-free treatment are applied to further clean and chemically treat the surface.
By enhancing cleaning efficiency and controlling conversion coating quality, this stage improves coating adhesion and overall corrosion resistance, providing a stable foundation for subsequent painting processes.
3. Putty Application, Drying & Sanding
To address weld seams and surface imperfections, manual putty application is used for surface leveling. After application, the workpieces undergo drying, forced cooling, and fine sanding.
This process plays a critical role in improving substrate flatness and surface quality, ensuring an ideal foundation for primer and topcoat application.
4. Primer Application & Flash-Off
The workpieces enter the painting area where primer is applied manually. For complex structures, spray angles and spray paths are carefully adjusted to ensure complete coverage of weld seams, inner corners, and other critical areas.
After primer application, a flash-off and leveling stage allows solvent evaporation and coating stabilization, improving intercoat adhesion and coating uniformity.
5. Topcoat Application & Flash-Off
Topcoat is applied over the primer layer using manual spraying to accommodate large and complex structures. By optimizing spraying parameters and operational rhythm, a consistent overall appearance is achieved.
A subsequent flash-off and leveling stage further improves film quality, reducing defects such as sagging and orange-peel texture while ensuring a high-quality final finish.
6. Curing
After coating, the workpieces enter the curing oven for final curing. By optimizing temperature distribution and curing profiles, the thick coating system is fully cured to achieve excellent adhesion, hardness, and weather resistance.
The curing system is specifically designed for large structural components to ensure uniform heating and avoid performance variations across different areas.
7. Forced Cooling, Finishing & Final Inspection
After curing, the workpieces undergo forced cooling before entering the finishing stage, including masking removal, thread reworking, and touch-up painting.
A comprehensive final inspection is then carried out to verify coating appearance and performance. Only qualified products are released, ensuring stable and reliable delivery quality.
