Transfer Plunger Crawling

The plunger exhibits crawling, discontinuous motion when advancing. When this defect occurs in products of Process No. 4, it is usually related to a specific process parameter range or equipment status. If it persists, it will directly affect the product qualification rate and production cycle, increasing material loss and rework costs. Timely diagnosis and elimination is a basic requirement for ensuring stable production.

1. Equipment factors: air mixed into the hydraulic system, large friction resistance between the plunger and barrel, hydraulic oil contamination, and overly tight seals. 2. Runner and gate design factors: In transfer molding, the material must enter the cavity through runners and gates; the runner length, cross-sectional shape, and gate size directly affect pressure loss, fiber breakage, and filling balance; unreasonable design is the root of many quality problems. 3. Feeding factors: The volume of the loading chamber, the loading amount, and the preheating state of the material directly determine the transfer pressure and filling effect, and are key variables unique to transfer molding.

1. Process parameter optimization and adjustment: Bleed air from the hydraulic system, improve lubrication between the plunger and barrel, filter and replace hydraulic oil, and adjust seal fit. 2. Systematic troubleshooting method: Troubleshooting of transfer molding problems follows the order of "runner -> feeding -> parameters -> mold". First check whether the runners and gates are blocked or worn, then verify the loading amount and material preheating, then adjust the transfer pressure and speed, and finally check the mold venting and temperature uniformity. 3. 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.

This problem is a typical manifestation of transfer plunger crawling in transfer molding. The core of the solution lies in the reasonable design of the runner and gate system, the effective transmission of transfer pressure, and the uniform control of mold temperature. It is recommended to start troubleshooting from the runner system and transfer parameters.