Engineering Plastic Compounding is the main application for twin screw extruder. It is used in a wide variety of application.
USEON SAT-X serial Extruder with high torque gearbox is special designed for this application.
There are several different processing methods:
The Basic Formula
|General Engineering Plastic||Advanced Engineering Plastic||Additives|
|PA6, PA66, PA46, PPA||PBI||Glass fiber|
|POM-C, POM-H||PEEK||Flame retardant|
- Automotive (Intake manifolds, Header tanks, Filters, Fans and Shrouds, Engine covers, etc.)
- Electrical (Terminal block, Cable ties, Connectors, Power tools, MCCB, relay, light, etc.)
- Blow Moulding (Medical & Cosmetic container, Lubricant & Paint container, etc.)
- Film & Pipe Extrusion (BOPA, BOPET, PET Sheet , Pipe , etc. )
- Fiber (PA fiber, PSF, FDY, PSF, etc.)
- Other Industrial (Construction, House wares, Furniture, Toys, etc.)
Processing of Engineering Plastic
Engineering plastic is sensitive to over heating and hydrolytic degradation.
Our SAT-X serial Extruder with 13Nm/cm3 specific torque and 800rpm speed can get higher output with less residence time, better dispersion, more accurate temperature control.
a) Technical Specifications of Extruder
b) Heating System
Instead of traditional casting heater (outside the barrel), we use cartridges heater (made in Germany) inside the barrel, it will save energy and Polymer will be melt mostly by heating, not kneading elements, so the working life of screw and barrel is longer and the quality of the compounding is better.
c) Cooling System
With two input and output on each barrel, more uniform cooling and fast cooling.
d) Supporting Frame
The supporting point of traditional barrel is in the underneath. When heated, its thermal expansion is upward with the value 0.2～0.5mm (difference up to the size of extruder), and uneven gaps in the upper and lower between screw and barrel.
The supporting point of barrel of SAT extruder is in the middle, When heated, its thermal expansion is upward and downward uniformly, ensuring the center height is on the horizon and the constantly even gaps in the upper and lower between screw and barrel.
e) Under Water Strand Pelletizing System
The the strands go into the pelletizer automatically by the water flow, even the strands break during changing the filter. So there will be almost no waste during the manufacturing process.
If the strand number more than 25 pieces (the output about 800kg/h), it will be more difficult for operator to handle the hot strand to pelletizer manually.
Several Different Processing Methods
1) Short Fiber Reinforce Compounding
Add the roving shape or chopped glass fiber into twin screw extruder directly and compounding with polymer, you will get 4mm length pellets with glass fiber length 0.2~0.3mm.
a) Roving glass fiber
Locate 20 pieces of roving fiber on the support frame with weighting transducer- Mettler Toledo.
Put the fiber into the venting port on the fifth barrel. They will be taken into the barrel by twin screw.
With weight controller to indicate the feeding rate (kg/h). You can adjust the feeding capacity by increase/decrease the screw speed or number of fiber.
b) Chopped glass fiber (with length 4~6mm)
Feed into the fifth barrel by two stage side feeder:
The top stage is loss-in-weight feeder with output control.
The bottom stage feeder works with fixed speed for force feeding.
2) Long-fiber Thermoplastic (LFT)
LFT parts are typically manufactured using one of three different processing methods as the following Figure 1.
① Glass Mat Thermoplastics Sheet
Add the roving shape glass fiber into the T-die, then coating by the melting polypropylene PP or PET from extruder. You will get the sheet with width 600~1000mm and the thickness 0.3~1.4mm. It is used for wall panels of Truck/Trailer Vehicles.
- For PP base sheet, single screw extruder is ok.
- For PET base sheet, it should be twin screw extruder with the following advantages:
- Pre-drying-free technology
- High efficient vacuum system keeps IV drop minor
- Optimized screw design avoids yellowing
② LFT-G (Long-fiber Thermoplastic Compounding for Indirect Moulding)
Add the roving shape glass fiber into the impregnation mould, then coating by the melting polypropylene (PP) from Twin screw extruder. You will get the 6-16mm pellets with the same length glass fiber inside. The pellets will be used for any product by injection molding machine.
The modulus of LFT-G is double than that of Short fiber reinforce thermoplastic, while impact tension is four times, can keep its function without any change under the temperature of minus -30°C.
③ Direct LFT technology
Involves combining the raw materials (fiber and matrix) immediately before entering the molder and avoids the production of an intermediate. This gives the manufacturer the ability to enhance the properties of the resin as required for the application by adding fillers, fire retardants and additives ,while also significantly reducing material costs and only establishing a single heat history of the matrix. This direct process can be separated into two process:
a) LFT-D-IMC (Long-fiber Thermoplastic Injection Molding Compounding Process)
Melts the polymer and mixes it with the fiber, is attached to an injection molding machine.
b) LFT-D-ECM (Long-fiber Thermoplastic Extruder Compression Molding)
Uses two extruders system for the polymer melting and fiber dosing coupled with hydraulic press for compression molding.
There are two primary advantages to LFT-D-ECM over the other two technologies.
First is that the compounding and fiber mixing steps are separated and therefore both extruders can be individually optimized for their specific functions.
Second, the material is not subjected to the same high levels of stress as in injection molding, which helps to maintain fiber length. This is critical because the mechanical properties of fiber reinforced thermoplastics are strongly dependent on the fiber length. Therefore, LFT-D-ECM process gives a maximum degree of freedom in terms of optimizing material choice, polymer modification, and process parameters, which is important for automotive applications.