What affect PET plastic bottle quality?
- Preform quality Recycling materials should not exceed 10%. The number of recycling time should not exceed two. Preform cools for more than 48 hours. Storage time can not exceed 6 months. We can not mix different production dates preform, especially preforms with too long storage time
- PET Plastic Bottle Machine Pre-heatingThe PET Plastic Bottle Machine heating temperature usually set at 85-120℃. Transparent preform should be higher, and the colored preform should be lower. Too high or too low will cause product defects, such as tearing, white fog, etc. Each area has indepent temperature controller. The output power has a great influence on the heating preform, which controls the heat output of the entire oven. When the machine turns off for a long time and turns on again, the initial output power should be set higher accordingly. Then gradually reduce to the normal state. The output power is generally about 80%.
- PET Plastic Bottle Machine Pre-blowingPET Plastic Bottle Machine Pre-blowing makes the preform take a genral shape and increase its longitudinal strength by the stretching rod. If the pre-blowing position is advanced, bottle bottom will be skewed , thin, uneven and white. Inversely, bottle center will be thickr and sink. singel-way valve controls air flow. Generally 3-4 turns are appropriate. The pre-blowing pressure should be 0.8-1MPa.Bottle bottom and center point has the greatest impact on the quality of the bottle. Improper adjustment often causes fatal defects such as bottle burst (under normal experimental conditions) and leakage.
- stretching rodThe stretching rod must move vertically and steadily during the blowing process. Driving pressure 0.55-0.8MPa. Gap with the bottom mold 2.3-2.5mm. If the gap is too large, the center point will shift; if the gap is too small, the center point will become thinner.
- High-pressure blowThe high-pressure blowing pressure is generally 3.7-4MPa. There are two positions,high pressure gas and exhaust. The length of this time has a great influence on the stability of the bottle volume. Insufficient high-pressure air may cause improper bottle molding and insufficient bottom blowing.
- Bottle mouldDuring the production process, keep the mold constant temperature, clean, and unblocked vent. When the mold heating and cooling system fails, the bottle neck will be tilted. The volume and height will change, and the bottom will become heavier. Maintaining the mold constant temperature can also prevent condensation on the mold surface.After PET molding, the shrinkage rate is relatively large, generally 1.8%, and it is slightly reduced after adding glass fiber reinforcement, but it still reaches 0.2%-1.0%. Under normal circumstances, high mold temperature shrinkage rate is large, low mold temperature shrinkage rate is small, in order to maintain the stability of PET bottle volume, mold temperature must be strictly controlled. Generally, the temperature of the bottle body is slightly higher, which is 20-45℃, and the bottom requirement is lower, which is 6-15℃. High bottom temperature will make the bottom heavier and the center point thicker. Experts of automatic blow molding machine concluded that there are nozzles in actual production that will affect the forming of PET bottles.