Blow Molding

Southeastern Container Blow Molding Process

Preforms are dumped into a hopper and are transported to an unscrambler by way of an overhead conveyer. The unscrambler orients the preforms upright and single file into feed rails where they are gravity fed into the blow molding machine. Once the preforms enter the machine, an infeed wheel spaces the preforms and then loads them onto oven spindles. The spindles travel through the oven while rotating the preform in front of oven banks which contain six to eight infrared lamps. The infrared lamps heat the preforms uniformly to transform them physically into a stretchable, moldable state, and ready to be formed into a bottle.

Preforms are removed from the ovens by way of conveying tables and preform transfer arms (PTA’s). The PTA’s load individual preforms into bottle molds which rotate around the blow wheel. Once the preform is in the mold, a long steel rod stretches the heated preform toward the bottom of the mold while low pressure air is introduced to keep the side walls of the preform from touching the stretch rod. The preform is now in a preblow stage and resembles a partially inflated balloon. High-pressure air is then introduced which causes the balloon to stretch out and take the shape of the bottle mold. The stretch rod retracts, the mold opens, and the finished bottle is pulled from the mold by bottle transfer arms (BTA’s). The BTA’s send the bottles to the exit wheel and out of the blowmolder to an airveyor. The airveyor sends the bottles to the palletizer where they are stacked, strapped, and wrapped for shipment to the customer.