Defect control in bottle-making production lines: Solutions to Bubble and Scratch problems

In the high-speed production of glass bottles, bubbles and scratches are the main factors leading to downgrading and scrapping. For small and medium-sized enterprises, the loss caused by defects can reach 8% to 12%, while for large-scale production lines, it can be reduced to less than 3% through precise control. The bubble problem is mainly concentrated in the melting and feeding sections. Insufficient homogenization of the glass liquid and a temperature difference of over 20℃ between the upper and lower layers of the material can easily lead to the formation of small bubbles and streaks. Raw material impurities, dust and oil stains entering the kiln will form dense small bubbles. Bubbles with a diameter greater than 0.5mm are prohibited in cosmetic bottles. Large fluctuations in the feeding temperature and irregular shapes of material droplets can also bring in gas and cause defects. Scratches are mostly caused by the contact between the mold and the machinery. The billet deviates when entering the die, and the actions of the punching and the jaw clamp arm are not coordinated, resulting in friction scratches. Oxidation, foreign substances or insufficient lubrication on the mold surface can scratch the high-temperature glass surface. Dry friction between the conveyor belt, guide plate and the bottle body can also cause scratches on the bottle shoulder and bottom. Improper operation and maintenance are important contributing factors. Chaotic production change rhythm, inadequate mold debugging, and poor matching between machine speed and air pressure will cause defects to erupt in a concentrated manner. Unreasonable initial mold design and uneven material diffusion can lead to uneven color spots and textures. On-site rectification can yield quick results: stabilize the parameters of the kiln and reduce the temperature difference between materials. Calibrate the blanking mechanism to ensure that the material drops are centered when entering the mold. Maintain the mold, repair surface depressions, and select high-quality lubricating oil spray. Optimize the machine speed, air pressure and cooling sequence to reduce friction and sudden temperature changes; Strengthen equipment inspection and promptly clear clogged and worn parts. After the implementation of a certain production line, the bubble scratch defects were reduced by 70%, and the single-shift qualified product rate increased by 9 percentage points, achieving a remarkable cost reduction effect.