Film Extrusion and Why Is It Important

Plastic fim extrusion is one of the most significant procedures in sipping and product manufacturing industries. It produced about 25% of all the thermoplastics used in the industry, especially food packaging while the rest of the extruded films are uilized in construction and agricultural machinery. During the process of plastic film extrusion, the molten polymer is pushed through a circular die. The process is repeated regularly and produces products of the same quality and precise gauge.The production of very thin gauge films involves blown film extrusion or cast film extrusion. Different types of high-quality stretch films are produced in Malaysia. Blown extrusion is similar to the simple extrusion, except for the fact that it produces verythin films. It involves extruding a tube of molten polymer through a die and expanding it multiple times to produce a thin film bubble. The bubble is then molded into different shapes. Numerous types of polymers can be used in this process. However, the majority of the stretch film manufacturers in Malaysia use polyethylene in film extrusion.

• Blown films have more balanced in mechanical properties than simple or extruded films because it passes through various machines and traverse directions. Stretch film manufacturers also make sure that the thin film produced is tensile, flexible, and robust.

• A large film, two smaller thin films, or other shapes of the film can be produced via blown filmextrusion.

• Excessive trimming is not needed after the film is manufactured, and a single die can be used to make different shapes and sizes of the film.

• Compared to the cast extrusion, the lower melting temperature is required in blown film extrusion. It reduced the cost of manufacturing

The aforementioned application shows how important film extrusion is to various industries, especially when it comes to the packaging, shipping, manufacturing, construction and agriculturalmachinery.

WHAT IS BLOWN FILM?

Blown Film is a manufacturing process that produce films of plastic sheeting and tubes. These sheets or tubes can either be fully cylindrical, or have other object inserted into them so they form useful objects like shopping bags, rubbish bags or cling wrap. In this article, we will explore what the process of blown film is and how and why you would use it. The process of blown film is reasonably simple. First you must take plastic pellets and heat them to their melting point (like injection moulding). The plastic is then forced through a cylindrical die and forms a thin walled bubble. This bubble is sustained by air, and is fed up through a scaffold where the tube continues to rise. Over this length, the plastic begins to cool. Once it has cooled enough, it is collapsed down on itself, forming a flattened tube. This tube is passed through various rollers and spun onto a spool. The edges of the tube can be trimmed and it can also be punched, cut or printed on before going on the spool. Blown film manufacturing is great for producing products that require uniform properties along the length and width of the product. It’s also a great high volume production method, however it requires massive capital cost to purchase a blown film machine. Blown film can produce up to 130 metres of products in a single minute. The sheets and film they can produce can be as fine as 10-20 microns (0.01mm – 0.02mm) to 250 microns (0.25mm) thick. Most Blown film is either High or Low Density Polyethylene (HDPE or LDPE) but there are exceptions. The downside to blown film is that it can only product sheets or tubes.

What makes ABA machine special for bag production?

Technically, in ABA type film, the outer and inner layers will be of the same material fed by the same extruder and a middle layer will be of a different material that will be fed by a second extruder. A higher percentage (up to 50-70%) of calcium carbonate compounds or recycled material can be used in the middle layer of the film, thus cutting down the usage of virgin raw material and reducing production cost. This drawing of an ABA die head shows how the middle (B) layer is covered by the (A) inner and (A) outer layers. A high percentage of recycled material is usually put in the middle layer and “sandwiched” by the inner and outer layers using better quality materials. Besides reducing a significant amount of raw material used in the formula, another advantage of the ABA machine is that the 3-layered film that it produces is 30% stronger than the mono-layer film produced by a single extruder. ABA has only two extruders whereas ABC has three extruders. In most bag applications where producers can use the exact same materials in the outer (A) and inner (A) layers, ABA can achieve the same result as ABC (in terms of film strength and material cost reduction) while saving on the machine investment and electricity cost. For products such as industrial film or liner bags in which very less or no recycled materials are used, some producers use ABA machines rather than mono layer machines simply to produce film with higher strength of the same thickness. Here are some features of it:

• Cost saving : Virgin material is applied mainly on the outer (thin) layers which is relatively a small percentage of the film composition. These thin layers can cover the middle layer well enough for shiny film surface and good sealing.

• Stronger : higher resistance comparing to single layer film products of the same thickness.

• Better material mixing : with co-extrusion process to produce better quality film (in which the material is more evenly distributed on the surface), especially when using recycled materials. The effect is very similar to ABC for bag applications.

Features of Ab Blown Film Extrusion Machine

This AB Film Blowing Machine is used for blowing the various kinds film of HDPE, LDPE, LLDPE etc, referred as to low density polyethylene (LDPE), high density polyethylene(HDPE)and linear low density polyethylene(LLDPE) etc, which are widely used for printing, agricultural,packing industrial, garments , textile, and making plastic bags, like T-shirt bag, flat bag, and other daily usage bag, etc. The produced film is very flat,reel is high-quality by the use of reversing haul-off units.The film can meet the demand for the high-speed printing. the film producted by this machine is very strong, can use a
as liquid package bag, like milk, joice and so on.1. Blowing film can be used either in tube form (e.g. for plastic bags and sacks) or the tube can be slit to form a sheet. Blown film extrusion can be used for the manufacture of co-extruded, double-layer or multi-layer films for high barrier applications such as food packaging.
2. Industry packaging (e.g. shrinkable film, stretch film, bag film or container liners).
3. Agricultural film (e.g. greenhouse film, crop forcing film, silage film, silage stretch film).
4.Consumer packaging (e.g. packaging film for frozen products, shrinkable film for transport packaging, food wrap film, packaging bags, or form, fill and seal packaging film).
5. Barrier film (e.g. film made of raw materials such as polyamides and EVOH acting as an aroma or oxygen barrier used for packaging food, e. g. cold meats and cheese), films for the packaging of medical products.
6.Laminating film (e.g. laminating of aluminum or paper used for packaging for example milk or coffee).

What is the features of ABC Two-layer Co-extrusion Blown Film Machine

The production line of 2-layer co-extrusion blown film machines can be used for the production of a wide range of general packaging films, and can be used to produce symmetrical film, including liquid packaging film, shrink/stretch film, electrostatic protection film, waterproof film in ponds, heavy packaging film, etc. Forced feeding main machine: All main machines of PLASTAR adopt dual-alloy forced-feeding screws that feature excellent hardness and wear resistance. It can still plasticize a large number of particles under the environment of high speed and high pressure. The service life can reach 3-5 times of ordinary screws.Cone stacking mold: The production line of two-layer co-extrusion blown film machines adopts a two-layer cone stacking mold. We optimize the layout by virtue of thermofluidics and observe the fluid condition with the help of 3D simulation software. We are sure that after a high degree of polishing and coating, each runner has the ability to clean itself under the high pressure and high speed scouring of PLASTAR’s high-speed screws. It will reduce waste in the particle replacement process and shorten the downtime of maintenance. Advanced automation module: The production line of two-layer co-extrusion blown film machines has advanced automation functions, such as centralized feeding, batching, weight control, IBC internal cooling, automatic thickness control, and automatic central winding. All functions are integrated on the touch screen, thus simplifying operations and increasing productivity.