Plastic can be found almost everywhere. Businesses across all industries and sectors rely on plastic products to help them provide goods and services to their consumers. Consumers use plastics on a daily basis for a wide range of day-to-day tasks.
Many of the plastic items that you encounter each day started their life as an LDPE sheet. Low-density polyethylene (LDPE) is a unique type of plastic that is extremely flexible and strong. Products from plastic grocery bags to juice boxes are often manufactured from LDPE sheets.
Manufacturers utilize two primary processes when transforming LDPE sheets into the plastic products that you are familiar with: film casting and extrusion.
1. Film Casting
When manufacturers need to produce thin sheets of plastic that will be used to make sandwich bags, protective films, and other thin items, film casting is the manufacturing process of choice.
Film casting requires the use of a specialized machine that feeds molten polymer through a narrow slit. LDPE sheets are melted down to a liquid state, then pushed through the narrow slit. As the LDPE moves through the slit, it cascades much like a waterfall.
A conveyor belt running beneath the slit moves rapidly to catch the cascading polymer and allow it to lay flat.
The conveyor belt moves through a series of cooling chambers, which help the polymer solidify into thin sheets of plastic that can be used in addition to manufacturing processes to create valuable consumer items.
Plastic items that are not completely flat are manufactured using extrusion. A specialized circular die is fitted to the end of an extrusion machine in preparation for manufacturing. Molten polymer is then pushed through the die.
Air is emitted from the center of the circular die, which results in the molten polymer taking on a tubular shape as it is extruded. The tubular bubble continues to fill with air until it becomes as large as the sizing care that surrounds it. The extrusion machine then seals off the bubble and it is moved into a cooler to solidify.
Numerous factors can affect the quality of products manufacturing by extruding melted LDPE sheets. Some of these factors include the stability of the bubble, the consistency of the airflow, and the tension applied to the bubble during extrusion.
Products that are manufactured using extrusion include agricultural films, can liners, and barrier films.
Both film casting and extrusion play an important role in transforming LDPE sheets into usable plastic products. Contact a local LDPE sheet supplier to learn more.