Polyethylene Bag Manufacturing Process

Film Extrusion

Clear LDPE (low density polyethylene) plastic resin in pellet form is vacuum fed from storage silos and blended with various additives as required for specific product applications. These mixes transform the plastic polymer to improve their basic mechanical, physical and chemical properties into a commercial product.

Additives combine to create the desired proprietary blends of clarity, strength, stretchability, sealability, scuff and tear resistance, UV protection, bacterial protection, surface appearance, slip resistance and other properties required for the finished product. If coloured film is to be made, coloured pellets (called "Master Batch") are added in blends from 1% to 25% to achieve different opacities and virtually any colour imaginable. Numerous resins, both LDPE and Linear LDPE, are kept in stock to allow for the many diverse applications that are manufactured daily.

The blended resins are then fed into extruders and melted at 380F. Screw drives force the molten mixture through a precision die where air is introduced and a 'bubble' is formed. This process is known as "blown film extrusion". Adjustments to wall thickness and diameter are made in this continuous bubble or tube. As it rises some 20 feet, it cools and is flattened and wound under tension into 50 - 200 lb. rolls.

Our line-up of extruders gives us the flexibility to regularly produce custom film orders. This allows also for quick order fulfillment where tubing may be available in as little as 2 or 3 days.