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Why Are There Weld Lines in the Inner Liner of Vacuum Insulated Cup?

When we buy vacuum insulated cup, we will find that there are two weld lines on the inner liner of vacuum insulated cups, one is straight to the bottom of the cup, the other is round at the bottom of the cup, and there are also some vacuum insulated cups without weld lines on the inner liner. What is the difference between the two? Does it affect the use or insulation effect of vacuum insulated cup? Now let's share the difference with you.


1. Integral stretching process of vacuum insulated cup


In fact, whether there is a welding line on the inner liner of the vacuum insulated cup depends on the productive technology used in the processing of the vacuum insulated cup. In the vacuum insulated cup industry, there are two technologies: overall stretching and seam welding stretching. If there is a welding line on the inner liner of the vacuum insulated cup, it indicates that it adopts the seam welding technology. If there is no line, it adopts seamless welding and overall stretching technology .


The overall stretching technology is a process of directly stretching a vacuum insulated cup liner on a piece of stainless steel seamless pipe material through a combined die. The technology is simple, but it has high requirements for equipment and molds.


If the overall stretching technology is used to stretch the inner liner of vacuum insulated cup, it will cost more materials and cost more. Sometimes, if the height of inner liner is too high, one-time stretching cannot be done, and it needs to be done twice or even three times. The advantage is that there is no welding line, and it will look more beautiful and smooth.


2. Welding and stretching technology of vacuum insulated cup


The welding and stretching technology is completed by cutting, bending, rolling and other processes of stainless steel plate, and then argon arc welding with a special straight seam welding machine. You will see the first straight welding line. The other is argon arc welding between the customized vacuum flask liner and the liner bottom. It needs a special horizontal circumferential seam welding machine to complete. This is the second circular weld. After the process is completed, use the inner liner leak detector of insulated cup to detect whether there is missing welding, and then carry out the next process of compression welding with the outer liner.


For the second welding line, most manufacturers of insulated cups use the horizontal circumferential welding process, so two welding lines can be seen. The bottom of the inner liner has an arc shape, which is easy to see dirt clearly and can be cleaned directly.


The manufacturers of vacuum insulated cup use vertical circumferential seam welding process. The bottom of the liner is a right angle, so we can only see a straight welding line with eyes. The disadvantage is that it is easy to hide dirt at the bottom, which can not be seen by eyes and can not be cleaned. Therefore, the bottom welding seam stretching process can save materials and cost, and the design can be diverse. The disadvantage is to see the welding line. It doesn't look very beautiful, but it doesn't have much impact on the use and thermal insulation performance of the insulated cup.


These two stretching processes do not have much difference in the use and thermal insulation performance of vacuum insulated cups. The only difference is in the purchase price. The overall stretched insulated cup will be more expensive than the welded stretched insulated cup, but this does not affect the use and thermal insulation performance.

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