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                        What are the problems with screw barrel refurbishment?

                        Date:2018-07-18

                        In order to improve production efficiency and reduce production costs, plastic processing enterprises often buy new barrels and screws. In fact, the screw after renovation is as durable as the new one and the production capacity will not be reduced.


                        Question1: How to distinguish if the screw barrel heat treated by nitriding?

                        The color of the screw barrel after nitriding heat treatment will become grayish white, with texture, different from the color of the previous rust. Some factories deceive people with fire burning so the color is pure black with no texture. A barrel can be carried out at most 4 times of nitriding heat treatment because the internal structure has changed because the iron of the barrel has been denatured. Since the nitriding furnace requires one or two hundred screw barrels to be opened at a time, there is no nitriding furnace in the place where the mechanical hardware is not developed. Only Guangzhou, Zhongshan, Shunde have a nitriding furnace! If without nitriding the barrel, the absolute time is not long. In this case, The old barrel material determines the length of use.

                         

                        Question 2: What is the degree of wear on the screw and barrel?

                        The degree of wear of the barrel and the screw is different for each set of screw barrels. Different materials have different wear and tear. Generally, since the screw is active and the friction position is screw edge, the friction area of the screw edge is smaller than that of the barrel, so the degree of wear of the screw is larger. Generally, the degree of wear of the screw is 3 :1, but if the material hardness of the screw far exceeds the barrel, the barrel is much worn out.


                        Question 3: what if the barrel not be nitrided?

                        No! All the new screw barrels are subjected to nitriding treatment, and the thickness after treatment is about 40-50 filaments. When the first screw is worn out, the barrel is also worn out, and the degree is different. However, if the output drops drastically, the nitride layer of the barrel will not exceed 20C (filament), and the thickness of the nitride layer of each barrel is different, so some refurbished plants can use it for more than half a year at the first time but when the second time, three months. The reason is that when the first time the nitride layer has a layer of nitride layer thickness, so it can be used for more than half a year, but when the second time The nitride layer is completely gone. Nitriding heat treatment is the key to ensuring the length of use of the screw barrel! But in order to save costs, some plants do not use it.


                        Question 4: What are the ways to refurbish?

                        1. Spray welding: use special—made "Alkyne & mdash; Oxygen" spray gun to spray alloy powder (30-50yuan/kg)

                        Disadvantages: weak wear resistance, air holes, the alloy may partially incompletely melted during the spray welding process. In the process, there will be alloy powder coming out, which causes the material to leak and the mold to be damaged.


                        2. Electric welding: welding with alloy electrode (20-30yuan/kg)

                        Disadvantages: weak wear resistance, more likely to appear pseudo soldering, the surface is not smooth, there will be air holes, the pellets will stay in the screw, resulting in yellow small coke and black spots.



                        3. Surfacing: Use "Alkyne & mdash; Oxygen" to completely melt the 300 yuan/KG imported alloy electrode on the screw.

                        Advantages: Because of completed melt, there is no pseudo soldering or air holes.

                         

                        Question 5: which is better between the old screw barrel refurbished and the old barrel refurbished with a new screw?

                        If your factory’s business is about old material (recycled material), there is no difference between the two methods. The time for refurbishment is a little longer than the other one, because the imported alloy on the screw is very wear resistant but not change the hardness of the barrel. If your business is about new material, it is better to use the refurbished old barrel with a new screw, which is exactly the same as the new one! But the price is less 50% than the new! Now the steel price has risen sharply, many factories do not use alloy materials, because of the price


                        Question 6: Why some factories refurbished products are very cheap? How long does the screw barrel last after refurbishment?

                        Each factory has different positioning, and some factories are positioned to obtain customers quickly by low price and low quality. Therefore, the price is very cheap; some factories rely on quality to obtain long-term customers, and the cost is high, so the price is relatively higher. But if the factory wants to survive, it must have a profit to survive. The low—price product is made of domestic alloy, the barrel is not nitrided and heat treated, just deceiving with fire! If the screw barrel is made of imported alloy and the nitriding heat treatment of the barrel is refurbished, the use time is about two years at least, or 30% higher than the previous use time. The screw barrels made of good materials all have been used for more than half a year!

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