Uneven cut / sawing problems

After sawing of pipes or profiles, the end face shows burrs, tearing, chipping, or oblique cut surfaces. 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. Comprehensive factors: Saw blade dulled or improperly selected (tooth shape, tooth count mismatch). 2. Process parameter factors: Sawing speed and feed speed do not match. 3. Cooling/environmental factors: Insufficient product cooling causes softening and deformation during sawing. 4. Comprehensive factors: Fixture not firmly secured causes product vibration. 5. 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.

1. Process parameter optimization and adjustment: Select saw blades matching the material and replace regularly. 2. Mold/tooling improvement and maintenance: Adjust sawing feed speed and blade rotation speed according to different wall thicknesses. 3. Equipment inspection and system maintenance: Ensure the product is fully cooled before sawing. 4. Material/formulation optimization: Improve fixture design to ensure the product is firmly secured during sawing. 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 uneven cut / sawing problems 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.