In actual coating production, common issues affecting product quality may occur even when the equipment runs stably. The ability of a coating machine to identify and resolve faults quickly and accurately has a direct bearing on the effective uptime of the production line and the qualified‑product rate. Drawing on practical experience, Nanjing Sumino Precision Machinery Co., Ltd. has developed a systematic set of troubleshooting procedures and solutions.

Coating Bubbles: Systematic Inspection from Slurry to Drying

Bubbles in the coating layer rank among the most frequent defects in coating production. They may stem from insufficient slurry defoaming, air ingress in the feeding pipeline, or solvent boiling‑over caused by excessive drying temperature.

During troubleshooting, first check whether the slurry viscosity is too high and whether defoaming time is adequate. Next, inspect the feeding pipeline for air‑leakage points. Finally, verify that the drying curve is gentle and the temperature of each zone falls within a reasonable range. Coating machines from Nanjing Sumino Precision Machinery are equipped with an on‑line defoaming system and feed‑pressure monitoring system, which can effectively minimize bubble formation.

Uneven Thickness: Targeted Inspection from Feed System to Coating Head

Uneven coating thickness will trigger performance fluctuations of functional coatings. Root causes are generally located in two sections: the feed‑supply system and the coating head.

For the feed system, check whether the metering pump is worn and if the feeding pipeline is clogged or leaking. For the coating head, confirm uniform gap clearance and inspect the lip for damage or adhered contaminants. The coating machines of Nanjing Sumino Precision Machinery adopt an on‑line thickness gauge coupled with an automatic adjustment system to monitor thickness deviation in real‑time and perform fine‑tuning automatically.

Surface Defects & Substrate Breakage: Rapid Diagnosis from Environment to Tension

Surface defects such as orange‑peel texture and scratches are commonly caused by skin formation on the coating surface due to over‑high drying temperature, dust or foreign debris accumulated on air nozzles, and contaminants stuck to the coating‑head lip.

Substrate breakage usually results from excessive web tension, foreign objects on roller surfaces, or inherent defects of the substrate itself.

Carry out troubleshooting by sequentially checking temperature settings of each zone, cleaning air nozzles and the coating head, and verifying tension set‑points as well as the surface condition of all rollers.

Routine Maintenance: The Foundation of Fault Prevention

Nanjing Sumino Precision Machinery provides customers with detailed maintenance manuals and on‑site training to help build a preventive‑maintenance system. It covers key items including periodic coating‑head cleaning, tension‑sensor calibration and oven‑air‑nozzle sanitation, eliminating potential faults at an early stage and ensuring long‑term, stable operation of coating equipment.