Cast Film Machine

A: Business owners are increasingly shifting away from traditional blown film extrusion and choosing the cast film extrusion process instead. With improved efficiency and sustainability standards, cast film is used by around 70-80% of the industry globally. Here are the main differences between Cast film extrusion vs blown film extrusion.
Direction and type of die: Blown film extrusion process extruded resins vertically with a circular die, creating a thick layer of film with bubbled shape. Cast films are made by melted thermoplastic horizontally through a flat die to create a fine sheet of film.
Cooling speed: The cooling process of blown film extrusion is much slower because the bubble-shaped film is gradually cooled. While the instant cooling technology of cast film extrusion enables faster production line speeds.
Clarity: Cast film tends to be clearer and shinier, whereas blow film gives less clarity due to crystallization that occurs during manufacturing.
Resistance to stretch: Blown stretch film is very resistant to puncture while cast films are not as good as the former.
Unwind noise: Cast film extrusion makes less noise unwinding than the other.
Usage: Factories usually preferred blown film for wrapping sharp-edged products and heavy loads, and cast film for lighter products.

A: Thanks to modern technology, the cast film extrusion process is done automatically. This process consists of 3 steps:
Melting the thermoplastic materials, Flattening and solidifying, and Trimming and rolling.
In the cast film extrusion process, the molten materials are extruded through a slot die onto an internally cooled chill roll. Then, it goes through a set of rollers that determine the qualities of the cast film such as thickness. After this step, the cast film is trimmed and rolled.
Melting the thermoplastic materials
The process starts with the feeding of plastic resins using a gravimetric feeding system to one or more extruders. The materials are subsequently melted and mixed into a consistent mixture by the extruders. The most commonly used materials for cast film extrusion are polyethylene (PE) and polypropylene (PP).
Flattening and solidifying
Once molten by the extruders, the materials travel to a flat die to be flattened into a thin film. This film is drawn to the surface of a cold roller, where it is cooled and solidified by using an air knife or vacuum box.
The main two rolls subsequently cool both sides of the product. This step helps the fine film rapidly quench, which improves its mechanical features and clarity. The thickness of the film might range from less than 10 microns to 200 microns. The cast film can be monolayer or multilayer, with a maximum of 5 layers.
Trimming and rolling
In the final stage, the film is then passed through a sequence of cold, polishing, and nip rolls to help form the desired thickness. It is then trimmed and wound into a drum for storage by a winder.

A: The machine is mainly used to produce Three layers LLDPE, LDPE, PE, and other cast film. The machine adopts the top intelligent industrial control system to ensure the operation is safe and easy, winding is more solid and smooth. Therefore, it ensures top product quality and the productivity; reduce the production cost to create bigger value. The main unit installed a shaking device to improve the smoothness of the web roll and appearance quality and make the products more competitive.

A: T-Die Extruder machine can produce waterproof PE film for baby diaper, sanitary napkin, folders, table cloths, medical film, etc.
Film thickness 0.03~1 mm.
Equipped with a fully automatic winder with cutting and changing rolls functions.
Hydraulic screen changer for short maintenance stop.

A: The cast film machine is a special equipment for making cast film. The high-precision electronic ceramic casting machine utilizes alumina as the main raw material for ceramic casting. First, the crushed powder is mixed with binder, plasticizer, dispersant, and solvent to form a slurry with a certain viscosity. Flowing down from the hopper, it is scraped and coated on the special base tape with a certain thickness. After drying and curing, the film is peeled off from the top to become the green tape, and then the green tape needs to be punched based on the size and shape of the finished product. Lamination and other processing treatments are carried out to form the finished blank product that will be sintered. It has the advantages of low cost, high quality, no toxicity, and a simple production process.

A: The main features of a casting machine: the surface gloss of the produced film products is good, the flatness is high, the thickness tolerance is small, the mechanical extension performance is good, the flexibility is good, and the transparency is higher than that of the blow molding method. Cast film is a non-stretch, non-oriented film produced by melt casting quenching, while blown film is oriented. This is the fundamental reason for the significant difference in conductivity between the two films. Due to the orientation of blown film, carbon black, graphite, etc. form an orientation structure, which has good conductivity in the machine direction, but poor lateral conductivity, forming the so-called conductive anisotropy. Because the cast film does not have obvious orientation, it does not present an advantage in electrical properties in any certain direction, and the conductivity is not significant. Another problem is that the pressure of the calender roll on the cast film during the casting process has a damaging effect on the structure of the permanent conductive filler (for example, the aspect ratio decreases), which will also cause the material to lose a lot of conductivity.

A: At least once a year, a flat extrusion die for film, sheet, or coating must be disassembled for standard maintenance--a procedure called a "split and clean." Typically, a falloff in production quality indicates that a split and clean is required. The purpose of the procedure is to remove polymer buildup from the flow surface inside the die, lubricate all moving parts of the adjustment system, and inspect the die for possible problems requiring part replacement or repair of critical surfaces like the flow areas. This protects your investment in the die and helps maintain optimal productivity and end-product quality.
To make a complete cleanout of polymer possible, most dies have to be hot. Working with a hot, heavy die can raise safety issues as well as expose the die to possible damage resulting from mechanical impacts. To minimize these concerns, it is important to carefully follow the recommended steps for carrying out a split and clean.

A: Before lifting the die, it is a good time to inspect the eye bolts. Make sure they are not bent or cracked, and if they are, do not use them. They can break when lifting the die, causing injury to people and damage to the die.
It is strongly recommended that the die body bolts be loosened while the die is still online, leaving four body bolts hand-tight, one on each end and two toward the center. This will prevent the die from cooling during offline disassembly. Once the die bolts are loose, you can unplug the electrical components.
When working around the die, pay close attention to avoid impacting it, especially the front edges, the pilot, or the ends. Always use the protective cover when transporting the die or when torquing the die body bolts. No power tools should be used. No matter how carefully you handle them, damage will occur to the flow and seal surfaces.
Disassembling the Die Offline
Once the die is placed onto the working surface, remove the end plate and seal plate assemblies. Use the Allen wrenches to remove the die body bolts—remember that these will be hot. Underneath each bolt (except on some older dies) is a washer that must also be removed. Places the bolts and washers on a heat-proof surface and clean each one.
Before separating the die bodies, attach the lifting device to the eye bolts and make sure that the lifting chain is drawn tight in a perfectly vertical position so that the upper die body will be lifted straight up. Next, apply a generous coating of anti-seize to the jack bolts and insert them into the jack bolt holes (designated by the letters JB) on the die body. Hand-tighten all of them, turning each approximately the same distance.
At this point, remove the protective cover from the front of the die and insert brass, aluminum, or high-temperature plastic shim stock—slightly smaller than the lip opening—between the lips. This will protect the lip surfaces in case the surfaces bang against each other as the die is taken apart.
Continue tightening the jack bolts. Some will loosen as others are being tightened, and the lip gap will start to open up. Check on the back of the die to make sure that the splitting of the die is even. If the opening on one side is narrower than the other, you need to apply more pressure to the jack bolts on that side. As the die bodies separate, the lifting chains become loose and have to be periodically readjusted as you apply more tension to the jack bolts. Keep turning the bolts evenly, keeping an eye on the gap between the die bodies to make sure that the bodies are parallel. Do this several times until the upper die body clears the dowel or guide pins that align the die bodies. At this point, you can use the lifting device to raise the upper die body.
Cleaning the Die
As the die body is raised, you can cut the molten polymer strands that stretch between the die bodies. Then move the upper die body away from the other half, remove the jack bolts so that they do not seize up, lay the upper body down on a clean protected surface, and turn it over.
Once the bodies are separated, they will start to cool quickly, so you will need to remove the polymer as quickly as possible. Having a coworker (or coworkers if it is a large die) clean one of the die halves while you clean the other is a good idea. Using an assortment of brass scrapers, remove all of the polymer from the flow surface, the front lip edge, and the seal surface. Scrape the die lengthwise where possible.
Next apply the die soap to all of the above surfaces, working on one section (about two feet) at a time. The soap will melt as it is applied. Using steady pressure, rapidly clean away the die soap with the copper gauze, being careful not to let the hot soap splatter onto you or a colleague and also avoiding getting the soap into the threaded body bolt holes, where it would be very difficult to clean out. You will need to change to fresh gauze periodically. Now is the time to inspect the flow surfaces and front edges of the die to see if there are nicks, dents, or dings that need repair. It may be possible to minimize the damage while the die is on-site at your plant, but in general, it is not possible to do a full repair. Consult your die supplier. Many variables affect the severity of the damage and the type of repair that is required. You may need to send your die to the supplier for rework, although the supplier’s service team may be able to polish out dings at your facility—or, for a short-term fix, fill in a ding with nickel.
Reassembling the Die
Before placing the upper body over the lower one, apply a thin coat of anti-seize to the dowel pins and place the shim stock on the die lip surface of the lower body.
You will need to work with a colleague as you lower the upper body onto the lower one. One of you will hold the upper body straight, using a straight metal bar, as it is being lowered into position, while the other person closely monitors the positioning of the upper body onto the dowel pins and uses a steel handle to keep the die halves completely parallel. Once the upper body has been lowered onto the pins and the lift chains have become loose, it often happens that there is still a gap between the bodies. To remedy this, take two body bolts, coat them with anti-seize (on the head and threads, as well as on both sides of the washers), insert them into the center of the die, and, using the Allen wrenches, hand-tighten them. When doing this, make sure the die halves are parallel as they are being squeezed together. You may need more than two bolts for longer dies. Once the die bodies are together, start from the center to insert the remaining body bolts (each should be similarly prepared with anti-seize).
Torquing of the body bolts should be done after the die has been put back online. Before torquing, place the protective cover over the lip area. Refer to your Operation & Maintenance Manual for the body bolt torquing sequence and specifications. Using smooth movement of the torque wrench, begin with the four center bolts, using a crisscross pattern between the four. Then, move on to the next outer bolt on each side, and so on until all bolts are tightened.
Finally, install the end plates onto the die with cleaned and anti-seized bolts, followed by the end seals and the end seal push plates. Note, the end seals should be replaced with new ones every time the die is taken apart. The end plate bolts should not be torqued until the die has been brought up to operating temperature and the lip gap has been set. At that point, your die is ready to go back into production.

A: In the cast film extrusion process, the molten materials are extruded through a slot die onto an internally cooled chill roll. Then, it goes through a set of rollers that determine the qualities of the cast film such as thickness. After this step, the cast film is trimmed and rolled.