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ZHOUSHAN XINLU PLASTICS MACHINERY CO., LTD.
Zhoushan Xinlu is a professional OEM & OD of screw and barrels for extrusion and injection molding machines who provide high-quality & competitive burst-sales single and twin screw barrel economically and efficiently for nearly16 years!
At present,we produce high-quality series screw and barrel products such as filmblow, waste recycling granulation, extrusion pipe,plate, super-large parallel twin screw conical twin screw, micro-medical instrument screw barrel, food processing screw, and so on, which have received many favorable comments.
We must deal with and solve the various needs of clients in terms of quality, price,delivery time and after-sales service to seek for long-term partners. XINLU welcome to cooperate with you!
LATESTT NEWS
1.1 Thermal Spraying Repair
Thermal spraying offers surface strengthening for repairs, characterized by high-quality wear-resistant coatings, low cost, high efficiency, and wide applicability. Its basic process involves: melting spraying materials (metals, ceramics, plastics, etc.) into a liquid or molten state, refining them into particles ranging from tens to hundreds of microns, and spraying these particles onto the base material to form a coating.
For example, stainless steel corrosion-resistant steel powder is often used to spray the screws of single-screw plastic extruders for PVC processing. The sprayed coating consists of rapidly quenched particles, which exhibit high hardness. During spraying, a supersaturated alloy state and an oxide film form, further increasing the coating’s hardness—beneficial for enhancing wear resistance. To ensure coating properties and quality, porosity must be controlled by maximizing particle temperature and spraying speed.
Key process parameters for thermal spraying:
Heat Source: Flame spraying typically uses acetylene as fuel, with a temperature of ~3,100°C; arc spraying reaches 5,538–6,649°C; plasma spraying achieves up to 11,093°C. Plasma spraying is optimal for rapid heating and particle transport, followed by arc spraying and oxy-acetylene flame spraying.
Spraying Material: For arc and flame spraying, the diameter of the metal wire must match the heat source power to obtain the best coating.
Spraying Distance: This refers to the distance between the spray gun and the workpiece. Typical values: 100–200 mm for flame spraying, 50–100 mm for plasma spraying, and 180–200 mm for arc spraying.
Spraying Angle: The angle between the central axis of the spray jet and the substrate surface should ideally be 90°, but must not exceed 45° to avoid shadowing effects.
1.2 Chrome Plating
Chrome plating layers exhibit excellent wear resistance, anti-friction, and corrosion resistance, significantly improving the quality of repaired parts—particularly surface wear resistance.
1.3 Cladding Repair
Vacuum fusion alloy coating technology is a modern surface metallurgy technique that modifies the composition and structure of the substrate’s working surface to meet requirements for wear resistance, corrosion resistance, etc. The process occurs under vacuum: concentrated heat melts a pre-applied alloy coating on the substrate surface, allowing it to infiltrate the substrate. Upon cooling, the coating and molten zone recrystallize, forming a strong bond with the substrate. This entire process of melting, infiltration, diffusion, intersolution, and recrystallization constitutes a surface metallurgical reaction.
引自-朱玉明.双螺杆挤出机螺杆机筒的耐磨处理和修复[J].科教文汇(下旬刊),2015,(24):180-181.
Main cause of wear of the screw extruder
The normal wear of the screw and cylinder of the screw extruder mainly occurs in the feeding area and the metering area. The main wear reason is caused by the dry friction between the slice particles and the metal surface, and the wear is reduced.
Screw and cylinder abnormal wear will occur in the screw knot and foreign body stuck, ring refers to the screw condensation material, if the screw extruder lack of good protection device, powerful driving force may twist the screw, stuck will produce extraordinary huge resistance, causing serious damage on the surface of the screw and barrel serious scratches, barrel scratch is difficult to repair.
From the design principle, the service life of the cylinder is longer than the screw. For the normal wear of the cylinder, it is generally no longer repaired. The method of repairing the screw thread is often used to restore the radial clearance between the inner hole of the cylinder and the outer diameter of the screw.
Solution to screw wear
The local damage of screw thread is repaired by overwelding special abrasion anticorrosion alloy. Inert gas protective welding and plasma argon arc welding are generally used, and metal spraying technology can also be used for repair.
First, the surface of the worn screw is ground to a depth of about 1. 5 mm, and then the alloy layer is welded to sufficient size to ensure sufficient processing allowance. Finally, the outer size of the outer circle of the screw and the side of the screw to the screw are the original size.
引自-沈兵.螺杆挤出机的维护保养要点[J].聚酯工业,2011,24(06):49-51.
How to install and adjust the screw extruderInstallation of the barrel
When the barrel deviation, the screw may be difficult to load, barely loaded The screw will be squeezing noise, or damage the screw shaft And shaft sleeve, or scraping screw and barrel, causing disallowed damage. The way to adjust the deflection position of the barrel is to use the front end setting of the barrel The bracket, adjust the height and the left and right deviation.
Installation of screw
When installation, heat the extruder to the operating temperature while the screw is cold The installation is more convenient. When loading the screw is more difficult to the head of the screw shaft, the screw key or the groove are carefully adjusted to the consistent position, generally the flat key at the upper end, and then pushed into the screw.
The installation process is absolutely not to impact and force loading, and carefully check, to confirm that the screw reaches the required position, and turn the screw to check the installation status of the newly mounted screw.
Here is the general installation method for the conical twin screws of a plastic extruder:
1. Preparation Work
Clean relevant components of the extruder, including the barrel, screws, coupling, etc., to ensure there is no debris or dirt.
Check whether the new screws meet the specifications and whether there is any damage or deformation.
Prepare required tools, such as wrenches, screwdrivers, micrometers, etc.
Ensure the extruder’s frame is level with the ground, and adjust it if necessary.
Release all heaters on the screw barrel and connectors.
2. Installing the Screws
Insert the two screws symmetrically into the barrel, first pushing the screws tightly toward the small end of the barrel. Observe the position of the screws; typically, the screw heads should be flush with the barrel, or may be 1-2mm longer or shorter than the barrel.
Push the tails of the screws tightly backward toward the gearbox side and measure the backward distance (assume this distance is 22mm). Determine the thickness of the screw plug based on the relative position of the screws and the barrel in the first step:
If the screws are flush with the barrel in the first step, the screw plug thickness should be 17mm (22mm – 5mm).
If the screws are 1mm longer than the barrel, the screw plug thickness should be 18mm (22mm + 1mm – 5mm).
If the screws are 1mm shorter than the barrel, the screw plug thickness should be 16mm (22mm – 1mm – 5mm).
Generally, set the screw plug thickness to 17mm first, then adjust it according to actual conditions.
Tighten the screw plug into the screw shaft, then install the large nut onto the barrel. Reconfirm the screw position to check whether it has retracted by 5mm (4-6mm is acceptable).
Observe the gap between the two screws from the feed inlet to ensure it is uniform.
3. Final Inspection
Before starting the machine, reconfirm that the screws have retracted toward the gearbox side. Otherwise, when the machine starts, the screws will move forward to the small end of the barrel, which may cause issues such as immobility.
Do not operate the extruder without feeding material, as this may cause the screws to move forward and get stuck.
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18-20 JUNE 2024ICROCUS EXPO,MOSCOW,RUSSIAPAVILION 1,HALL 4F110
In 2018, words such as “green, environmentally friendly, and recyclable” became hot words in the plastic industry. As plastic gradually integrated into every aspect of our lives, it also posed a significant threat to the ecological environment and even us.
So far, humans have produced 8 billion tons of plastic, and the plastic straws flowing into the ocean alone weigh 8 million tons each year. Whether it’s the whales and turtles swimming in the ocean, the seafood on our dining tables, or the salt in the seasonings on our tables, they are all affected by plastic pollution, and ultimately humans themselves are not immune.
What are the impacts of using a large amount of plastic products? Nowadays, more and more research is attempting to solve this puzzle, and many insider information is gradually being exposed to the public eye. Consumers and manufacturers are eager to pay attention to alternatives to plastics, and bioplastics seem to be emerging as a potential option.
What is bioplastics? Simply put, bioplastics refer to the use of biological materials such as plants as raw materials to replace petroleum, hence they are also known as bio based plastics. Specifically, it requires polylactic acid (PLA) from plants such as corn and sugarcane; Or polyhydroxyalkanoic acids (PHAs) synthesized by microorganisms. PLA plastic is commonly used in the food packaging industry; PHA plastics are more commonly used in medical equipment, such as sutures and cardiovascular repair materials. Due to the fact that PLA plastic is mostly produced by large factories producing ethanol and other products, it is currently a cheap and common bioplastic, and many plastic bottles, containers, and textiles on the market are made from it.
Although both the market and consumers favor this plastic as a substitute, does bioplastics have inherent value in reducing carbon emissions? But it has always been the focus of debate. In the eyes of some proponents of bioplastics, 8% of the world’s oil is used to make plastics. When plastics are discarded, it signifies the beginning of carbon emissions. However, during the degradation process of bioplastics, the carbon content released into the atmosphere is much lower because most of the carbon is absorbed by growing plants.
However, the matter is not so simple. In 2011, a research report from the University of Pittsburgh reported that some plants planted for the production of bioplastics were related to environmental pollution incidents, involving fertilizer and land use. In this world where resources are increasingly scarce, how to allocate the only resources is also the focus of verbal debate, and using corn as a plastic production material instead of food is the center of the debate.
In terms of post-processing, according to data, discarded bioplastics in reality face various fates, some of which, like most petroleum based plastics, are thrown into waste landfills, while others are sent to industrial composting plants.
In industrial composting, it is necessary to apply a sufficiently high temperature to allow microorganisms to complete their degradation. Without high-intensity heating, bioplastics cannot be effectively degraded on time, which is no different from sending them to landfills or composting them in their own backyard. In addition, if they eventually enter the marine environment, their impact is no different from that of petroleum based plastics, both of which will decompose into tiny fragments. This slow process will continue for decades and pose a deadly threat to marine life, just like any other.
“If PLA bioplastics are released into the ocean, they will not be effectively degraded. At that time, they will become a cancer of the ocean like all industrial polymers,” said a scholar.
Although there is still controversy in the current academic community and some organizations regarding the benefits of bioplastics, in recent years, under the framework of circular economy, many governments, enterprises, and researchers have been optimistic about the prospects of bioplastics and continue to explore in this field.
