Cast vs Blown Stretch Wrap - What's the Difference?

How Cast Stretch Wrap Is Made？

Cast stretch film is a common plastic film production process. The following is the usual manufacturing process:

1. Raw material preparation:

Polyethylene (PE) is usually used as raw material, which can be divided into low density polyethylene (LDPE), linear low density polyethylene (LLDPE) or high density polyethylene (HDPE). These feedstocks are usually supplied in granular or pellet form.

2. Melt extrusion:

Feed the raw material particles into the extruder, melt the raw materials through heating and extrusion, and extrude them through the extrusion head to form a preliminary film.

3. Casting and molding:

The initial film is cooled through a cooling roller or a cooling water tank, so that it is quickly cooled and solidified, and then pulled to the appropriate size and thickness by a traction roller.

4. Stretching:

The cast film is fed into a stretching machine and stretched through a series of rollers or clamps to improve the strength and transparency of the film.

5. Winding:

The stretched film is rolled up through a roller or winder to form a roll-shaped finished film roll, which is convenient for storage and transportation.

How Blown Stretch Wrap Is Made？

Blown stretch film is a common plastic film production process. The following is the usual manufacturing process:

1. Raw material preparation:

Polyethylene (PE) and other plastic particles are also used as raw materials.

2. Blow molding extrusion:

The plastic particles are fed into the screw barrel of the blow molding machine, melted by heating and extrusion, and then the melted plastic is extruded into a hollow tube.

3. Blown film molding:

Air is blown into the inside of the tube through the die, causing it to expand and extend into a wide film shape. At the same time, the film is rapidly cooled and solidified through rollers or coolers.

4. Stretching:

The cooled and solidified film is stretched twice through a stretching machine to improve the strength and tensile properties of the film.

5. Winding:

After finishing, the final film is rolled into a roll by a winding machine to form a finished film roll.

The manufacturing process of blown stretch film is relatively simple and efficient, and it is widely used in food packaging, agricultural covering films, industrial purposes and other fields. Film products with different properties and specifications can be produced by adjusting different raw material formulas and process parameters.

Which one is better, Blown Stretch Wrap or Cast Stretch Wrap?

Blow molded stretch film and cast stretch film each have their own advantages and applicable scenarios. You need to choose the appropriate product according to specific needs:

1. Blown stretch film:

Advantages: high production efficiency, relatively low production cost, good film uniformity, and high dimensional stability.
Applicable scenarios: Suitable for general cargo packaging, pallet packaging, logistics and transportation, etc.

2. Cast stretch film:

Advantages: better tensile properties, strong impact resistance, high transparency, smooth surface.
Applicable scenarios: Suitable for items with higher packaging requirements and better protection properties, such as high-value fragile goods, food, etc.

Taken together, if the product has higher requirements for appearance quality and better protective performance, cast stretch film may be more suitable; and if more attention is paid to production efficiency and cost control, and the general performance requirements of the product are higher, Blown stretch film is a good choice. The final choice should be comprehensively considered based on specific usage scenarios and needs.