In actual coating production, even with stable‑running equipment, common issues affecting product quality are almost inevitable. The ability of a coating machine to quickly and accurately identify and resolve these problems directly determines the effective operating time of the production line and the product qualification rate. Based on practical experience, Nanjing sumino  Machinery Co., Ltd. has summarized a systematic set of troubleshooting and solutions.

Coating Bubbles: Systematic Inspection from Slurry to Drying

Bubbles in the coating layer are one of the most frequent defects during coating production. Possible causes include insufficient defoaming of slurry, air ingress in the feeding pipeline, and solvent bumping caused by excessively high drying temperature.

During troubleshooting, first check whether the slurry viscosity is too high and if sufficient defoaming time is provided. Next, inspect the feeding pipeline for air‑leakage points. Finally, verify that the drying curve is gentle and the temperature of each section is within a reasonable range.

Coating machines manufactured by Nanjing sumino are equipped with an on‑line defoaming system and feeding pressure monitoring system, which can effectively reduce bubble generation.

Uneven Thickness: Targeted Inspection from Feeding to Coating Head

Uneven coating thickness will lead to performance fluctuation of functional coatings. Causes of uneven thickness are generally located in two key areas: the feeding system and the coating head.

For the feeding system, check whether the metering pump is worn out and whether the feeding pipeline is blocked or leaking air. For the coating head, confirm that the gap is uniform and check the lip for damage or attachments.

The coating machines of Nanjing sumino Seiko adopt an on‑line thickness gauge paired with an automatic adjustment system, enabling real‑time monitoring of thickness deviation and automatic fine‑tuning.

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

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

Common causes for substrate breakage include excessive tension, foreign objects on roller surfaces, and inherent defects of the substrate itself.

For troubleshooting, sequentially check temperature settings of each zone, clean air nozzles and the coating head, and verify tension‑set values and roller‑surface conditions for all sections.

Regular Maintenance is the Foundation of Problem Prevention

Nanjing sumino provides customers with detailed maintenance manuals and on‑site training to help establish a preventive maintenance system covering key items including periodic coating‑head cleaning, tension‑sensor calibration and oven‑air‑nozzle cleaning. This eliminates potential faults at an early stage and guarantees long‑term, stable operation of the coating machine.