What If The Thickness Of The Film Is Not Uniform? Common Faults And Solutions Of Single Layer Membrane Blowing Machine

In the production process of plastic film, uneven thickness is one of the most common and influential problems affecting the quality of finished products. Many manufacturers using single-layer diaphragm blowers have encountered such difficulties. Thickness deviation will not only directly reduce the uniformity of the film, but also affect subsequent heat sealing, printing and other processes. In serious cases, it may even lead to the scrapping of the entire product, causing unnecessary loss of production. To solve this problem thoroughly, it is necessary to investigate from multiple dimensions such as equipment, technology and raw materials, find the root cause and adjust it in a targeted way.
First, we need to start working on the core module system. The uniformity of die clearance directly determines the initial distribution of molten extrusion. If the gap is large or small in different parts of the mold, the amount of molten extrusion will be different, and the resulting film will naturally have different thickness. In many cases, if the mold head are used for long periods of time, residual material accumulation in places, which can also take up space and lead to local thinning. In this situation, we can first stop the machine, and then use a pure copper scraper to clean the mold mouth of the accumulation. Then, by adjusting the bolts around the mold head, we can gradually adjust the clearance of each position to ensure that the clearance of the entire feed ring is completely uniform. The mold head's heating system also needs to be checked. Uneven temperature distribution around the die mouth is also a common cause. At higher temperatures, the melt is more fluid and the discharge volume is larger, resulting in thicker films. Conversely, at lower temperatures, the number of discharges decreases, leading to thinning of the film. At this time, it is necessary to check the thermocouple values of each temperature field of the mold head, adjust the heating power and keep the temperature of the whole die mouth uniform. If the radiator is found damaged, replace it in time.
Then there is the impact of cooling systems. The cooling air ring is the key part to determine the film film bubbles shaping. If the air supply is not uniform around the gas ring, the cooling speed of the film bubbles will be different at different locations. In the area with faster cooling rate, the film formed earlier and the thickness of the film be thinner after stretching. Films in slower cooling regions are still in a highly elastic state, and the thickness of the films increases after stretching. In daily production, dust and residual plastic debris need to be regularly cleaned from the inside of the air ring, and the air inlet hose of the air ring needs to be checked for damage or distortion to avoid air pressure bias at different locations. Before starting, the air outlet angle of each part of the airlock should be adjusted to ensure that the airflow can be evenly distributed around the film bubble, allowing the membrane bubble to cool and form in sync around the membrane bubble. At the same time, attention should also be paid to the stability of compressed air. If the supply pressure fluctuates frequently, the diameter of the membrane vesicle will fluctuate, directly causing the thickness of the membrane to change with the degree of tensile strength. It is necessary to install pressure stabilizers at the supply end to maintain the stability of air pressure.
The mismatch of process parameters is also a high frequency cause of uneven thickness. An unreasonable combination of inflation ratio and traction ratio can cause the membrane vesicle to be unbalanced in its tensile state. For example, when the inflation ratio is too large, the membrane bubble is prone to shake from side to side, and the tensile degree of different parts fluctuates greatly, making it difficult to control the thickness. At this time, the inflation ratio can be adjusted appropriately to maintain the stable state of the membrane bubble. You also need to check the performance of the traction system. If the speed of the traction roller is not constant, the transmission components will slide and the longitudinal stretching of the film will change, directly affecting the uniformity of the thickness. The mechanical transmission device of the traction roller needs to be maintained regularly to ensure that the speed of the traction roller is stable. At the same time, the pressure at both ends of the traction roller should be adjusted to ensure that the clamping force on the surface of the roller is consistent and to avoid uneven pressure on the film due to deviation.
In addition to these core factors, the maintenance of everyday details can greatly reduce the problem of uneven thickness. Before replacing each material, check that the material is dry. Raw materials with more than 0.3% moisture content can bubble during extrusion, disrupting the continuity of discharge and causing local thickness deviation. Periodically replace the extruder filters to prevent impurities from clogging the flow path and disrupting the flow state of the melt. Secondary heating is used every time the machine is turned on to avoid sudden changes in melt flowability due to temperature overshoot.
The problem of uneven thickness of single-layer plastic film blower is never caused by a single factor. Every step of the way, from moulding, cooling, molding to hauling and winding, requires the operator to carefully adjust and periodically maintain the film thickness to maintain it within the qualified range and improve the overall quality of the finished product.