What Is a Blown Film Machinery?
Inflation molding is a type of extrusion molding that specializes in bag-shaped films.
The extrusion mold has a ring-shaped opening through which the molten resin is extruded into a thin film. While extruding, cooling air is blown in to expand the film to a specific size and form it into a bag.
Not only single-layer films but also multi-layer films can be formed at the same time.
Uses of Blown Film Machinery
The machine produces films such as food wrap film and plastic bags.
It is also used to form multi-layer olefin films to produce films used in agricultural greenhouses, rice bags, fertilizer bags, general coating films, and food packaging films.
Highly functional films can be molded by adding additives such as pigments, antistatic agents, and AB agents that prevent films and products from sticking together to polyolefin materials such as polyethylene (PE) as well as polyvinyl chloride resin (PVC).
Principles of Blown Film Machinery
The general configuration of an inflation molding machine is as follows.
First, there is an “extruder” that extrudes molten resin, a “round die” which is a mold with an opening of the shape (cylindrical) to be molded, an “inflation and cooling section” that inflates the extruded, film-like resin with air and cools the inflated resin by air to make it solid, a “clamping roll” that tightens the air inside the film. In contrast, the film is then rolled up, cut to the required length with a cutter, etc., and one side is thermally welded to form a pouch.
While inflation has the advantages of a simple structure, low tooling cost, low unit cost due to continuous molding, and the ability to produce thin-walled molded products, it has the disadvantages of not being able to produce thick-walled products and not being suitable for small-lot production.
In addition, it should be noted that products molded with inflation molding machines may have uneven thicknesses and surface defects such as streaks.