Melt-blown Fabric Mould

How to manufacture high-quality mold for melt-blown fabric

---- Experience sharing from masters of melt-blown equipment

Introduction: The manufacturing of melt-blown equipment is not complicated, and the main problem that needs to be overcome is the process. Because the parameters of temperature, air pressure, mold, and speed are involved, it needs continuous running and debugging to achieve the best results.

01. Methods to increase product strength:
a. Increase the hot air flow (fine fibers, many winding nodes, uniform fiber stress, increased strength, but after a certain degree, it will decline)
b. Raise the temperature of hot air (same as above);
c. Appropriately increase the weight of the product (within the range of internal control);
d. Raise the temperature of the die head (die tip) and other areas (same as a);
e. Appropriately reduce output;
f. Appropriately reduce the DCD (not too small, but the brittle strength will decrease, combined with other parameters);
g. Increase the suction at the bottom of the net (large gram is more obvious); h. Use raw materials of low melting index.

02. Methods to increase product elongation:
a. Appropriately reduce the hot air flow or temperature (the slippage path of the node becomes larger and the feel becomes harder);
b. Reduce the working temperature of the die head (die tip) (same as above);
c. Appropriately reduce the output;
d. Increase the DCD (more effective when used in conjunction with a or b);
e. Reduce the ambient temperature (spinning ambient temperature);
f. Increase the suction of the bottom of the net (the effect is not obvious, the large grammage is better);
g. Change the fiber angle (change the structure of the fiber mesh, not commonly used)
h. Properly increase the output (this method will cause the reduction of other physical indicators, not commonly used).

03 Ways to reduce resistance:
a. Reduce the hot air flow or temperature (fiber becomes thicker, the porosity is larger, the resistance is small, and the efficiency becomes worse);
b. Increase DCD (increasing the bulkiness of the fiber, the porosity is large, and the efficiency becomes poor);
e. Reduce the spinning environment temperature (the fiber is cooled sufficiently, the structure is fluffy, the porosity is increased, and the hot air can achieve the purpose of reducing resistance and improving efficiency);
f. Reduce the suction at the bottom of the mesh (the fiber changes from dense to fluffy, the porosity becomes larger, and the large grammage is more obvious);
g. Lower the working temperature of the heating area such as the die head (die tip) (the fiber becomes thicker and the porosity becomes larger);
h. Increase the metering pump (the extrusion volume becomes larger, the fiber becomes thicker, and the porosity increases, generally used when the order is quickly transferred);
i. Appropriately reduce the weight (within the range of internal control).

04 Ways to improve filtration efficiency:

a. Increase the hot air flow or temperature (increasing the fineness of the fiber, reducing the porosity, improving the catching ability, but the resistance increases);
b. Increase the electrostatic voltage (current) (polarized fiber, increase the electrostatic field energy of the fiber and improve its adsorption capacity);
c. Add powder or other electrets to the raw materials (improve the fiber's power receiving capacity and storage time, let the fiber carry more charge and charge time);
d. Increase the suction at the bottom of the net (increasing the density of the fiber and improving the catching ability of the fiber. The large grammage is obvious and not commonly used)
e. Properly reduce the output (under the same process, the extrusion volume becomes smaller, the fiber becomes thinner, and the resistance increases);
f. Raise the working temperature of the die head (die tip) and other areas (melt fluidity becomes better, fibers become thinner);
g. Increase the spinning ambient temperature (fibers become thinner, generally when the room temperature increases, the resistance increases significantly, and other physical indicators decrease);
h. Properly increase the amount of powder added.

05 The method that can both reduce resistance and improve efficiency:
a. While increasing the DCD, increase the hot air flow or temperature appropriately and reduce the bottom suction (increasing the fineness and bulkiness of the fiber);
b. Improve the fiber fineness and reduce the spinning ambient temperature (such as adding cold air device);
c. While increasing the bulkiness of the fiber, increase the electrostatic voltage (current), and appropriately increase the amount of powder added;
d. Improve the fineness of the fiber and reduce the weight (not commonly used).

06 Ways to improve both strength and elongation:
a. Properly reduce the hot air flow or temperature, reduce the DCD, and appropriately increase the bottom suction (used for the physical temperature is too high and the raw material melting index is too high to cause the physical index to fail);
b. Properly increase the flow or temperature of the hot air, increase the DCD, and appropriately reduce the air suction at the bottom of the net (used to be unqualified due to too low ambient temperature and too low raw material melting index);
c. Reduce output;
d. Increasing the fineness of the fiber while reducing the spinning ambient temperature.

07 Method of reducing product CV value:
a. Correspondingly change the working temperature of each area of the die head (the temperature is increased if the gram weight is small, and vice versa)
b. When the local efficiency and resistance conflict with the CV value, a baffle can be added to the position (increasing the local spinning ambient temperature);
d. The CV value of longitudinal grammage is mainly related to the stability of the speed of the web-forming system.

08 The reasons for "Shot":
a. Improper setting of working temperature (too high or too low, generally too high is easy to appear);
b. The raw material or masterbatch is too dirty (generally appears on whole cloth surface, or in a large area);
c. After the die head is used, the die tip is dirty (sometimes it is a poor thread or a large area appears, you can use a scraper to scrape the die tip);
d. There are carbonized substances or dirty plugs around the die tip that cause poor wire output (usually caused by abnormal shutdown. Generally, a small amount occurs locally, which can be solved by scraping the die tip);
e. The air knife is partially dirty or has physical damage to the air knife (affecting the uniformity of the normal spinning airflow, which appears locally and is accompanied by longitudinal thin grooves);
f. The output is too high or too low (generally appears in large areas, reduce or increase the output to solve);
g. Raw material melting index is too high or too low (usually too high is easy to appear);
h. There is water in the raw materials.

09. Reasons for "fly waste":
a. The hot air flow is too large or the temperature is too high (too many broken fibers);
b. The working temperature in each area is too high (too many broken fiber);
c. The DCD is too small (the cloth is too dense, which affects the suction efficiency);
d. The spinning environment temperature is too high (same as a);
e. When adding recycled materials, the amount of recycling is too large.
f. The output is too low;
g. Improper setting of the suction parameters of the bottom of the net or the screen is too dirty (small suction, the fiber cannot be fully absorbed on the screen and detach from the screen)
h. The raw material melting index is too high.

In summary, the various methods mentioned above need to be selected and used in accordance with the actual production situation and in accordance with the principle of process optimization in the actual application process. Every process parameter and every method in our process adjustment process are not isolated, they are complementary and mutually restrictive. If you want to achieve the improvement of a certain physical index without affecting other indexes, you need a variety of methods to achieve the goal. As for the increase of the product index, the optimal method and parameter combination are mainly selected according to their own working experience. Although there are multiple combinations to complete a product, an excellent combination of process parameters can achieve the simultaneous improvement of various physical indicators of the product. Only a craft that achieves this goal is a perfect craft! It is also a measure of whether a process is qualified or not. Therefore, in our future work, we should adjust in order to improve product quality, reduce energy consumption and reduce costs.

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