Static electricity problem

Product surface carries static electricity, attracting dust, making winding/collection difficult. When this defect appears in extrusion molded products, it is usually closely related to process links such as die design, screw plastication state, cooling and sizing system, or haul-off stability. Persistence of the defect will lead to out-of-tolerance product dimensions, unqualified appearance, or decreased mechanical properties, increasing scrap rate and rework costs. Timely diagnosis and troubleshooting from both extrusion process parameters and equipment status are basic requirements for ensuring stable continuous production.

1. Mold/tooling factors: Friction between product and guide rollers, haul-off rollers, etc. generates static electricity. 2. Comprehensive factors: Air humidity too low. 3. Material/formulation factors: The material itself has high insulation resistance. 4. Die design factors: The geometry of the die flow channel, the land length, and the outlet dimensions directly affect melt flow stability and product dimensional accuracy. Unreasonable flow channel design (presence of dead corners, excessively large convergence angle) is an important root cause of melt fracture, material buildup, and flow marks, and must be addressed starting from optimization of the die structure. 5. Cooling and sizing factors: The cooling rate and uniformity of extruded products determine crystallinity, internal stress level, and dimensional stability. Uneven cooling causes pipe ovality, profile deformation, and internal stress concentration; the cooling water circuit layout and water temperature control must be optimized.

1. Process parameter optimization and adjustment: Equipment well grounded. 2. Mold/tooling improvement and maintenance: Install static eliminators (ionizing air bars) at appropriate positions. 3. Equipment inspection and system maintenance: Increase workshop air humidity to above 50%. 4. Material/formulation optimization: Add antistatic agent to the formulation. 6. Preventive management: Establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or 5Why analysis to trace the root cause, and solidify countermeasures as PFMEA control points. Establish a regular equipment maintenance system and implement life management for key tooling such as dies/spinnerets/calender rolls/coating heads.

This problem is a typical manifestation of static electricity problem in extrusion molding. The core of the solution lies in eliminating the root cause of the defect through systematic optimization of process parameters (temperature, speed, pressure) and precision correction of the die/sizing system. It is recommended to start with parameter adjustment and gradually go deeper into the equipment and tooling levels.