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Common problems affecting the quality of bag making

Update time : 2020-12-01

Source : Zhejiang Deguang Machinery Co.,Ltd

Views : 159

Common problems affecting the quality of bag making
The bag-making process is simple while revealing complexity, because any small details may become a big problem that affects the quality of the bag. When using the bag making machine to make bags, you need to pay attention to some matters. This article lists the four major bag making quality problems and the corresponding solutions for your reference.
 
Poor heat sealing strength: means that the strength of the sealing position is lower than the standard requirement
1. Cause
① The adhesive in the composite film has not been fully hardened.
②The heat sealing conditions are inappropriate.
③The distance between the heat sealing knife and the cooling knife is too long.
④There is a problem with the inner sealing layer film.
⑤The heat-sealability of the ink is poor, resulting in a decrease in the composite strength of the film at the heat-sealed part.
⑥Dust, spray powder and other substances adhere to the hot cover.
⑦The composite strength is low or the composite strength of the heat-sealed place drops too much.
2. Solution
①Through heat preservation and aging to promote the hardening of the adhesive (curing, curing), improve the composite strength and heat resistance of the composite film.
②Select the best heat-sealing conditions (temperature, time and pressure) according to the structure of the composite film, heat-sealing state, etc., or improve the heat-sealing method, and cool down immediately after heat-sealing.
③Check the shelf life and storage conditions of the heat-sealing layer film. If the heat-sealing layer uses the old batch of film and the film that has been heat-sealed, pay special attention.
④Increase the thickness of the heat-sealing layer film or check the degree of treatment of the heat-seal.
⑤ Change the type and grade of the heat-sealing layer film, and use an inner-sealing layer film with anti-pollution heat-sealability.
⑥Check whether the grade of the adhesive meets the requirements (the exudation of low-molecular-weight substances in the resin may sometimes affect the composition of the adhesive).
⑦Improve the heat-sealing performance of the heat-sealing layer (substrate), control the content of slip agent, and use MLLDPE film.
⑧ Control the monomer content of MDI in the composite adhesive.
⑨ Change the ink (two-component ink is best).

⑩Change the printing pattern of the packaging bag so that the part printed with ink avoids the heat sealing part, or change the heat sealing method (pay special attention to the metal ink not to be printed on the sealing part).

 bag making quality problems

Size error

1. Cause
①The system error of the bag length fixing of the bag making mechanism is too large.
②The electric eye tracking is not accurate.
③The influence of the processing speed of plastic composite film bag making.
④Operating factors, such as improper tension control, insufficient pressure setting of the pressure cylinder of the film rubber roller, etc.
2. Solution
①Adjust the fixed-length system.
②Adjust the working status of the electric eye.
③Check whether there are cursor printing problems or spacing problems, and adjust them.
④Check whether the compression degree of the compressed film ruler and the friction coefficient of the composite film are appropriate.
⑤The preset film feeding length (when adjusting the white bag) and the actual bag size should be as accurate as possible.
⑥ Reduce the bag making speed, and adjust the bag making speed slowly.

⑦Adjust the pressure of the film rubber roller, the cylinder pressure and the tension of each part.

 quality of bag making

There are spots and bubbles on the cover: it means that the sealing surface is not flat

1. Cause
① When heat-sealing on a structure containing hygroscopic materials such as nylon film, the hygroscopic film will generate air bubbles when it absorbs moisture.
②The heat-sealing knife or heat-sealing silicone pad is uneven.
③The heat sealing pressure is insufficient.
④ Use single-component adhesives, such as neoprene adhesives, when heat-sealing bags. The hot cover is prone to small bumps.
2. Solution
①Keep the raw materials and semi-finished products properly to avoid moisture absorption.
②Check or adjust the heat-sealing knife and heat-sealing silicone pad.
③Replace the adhesive.
 bag making quality problems
Misalignment of the upper and lower pieces: refers to the problem that the front and rear sides are not aligned when making the bag
1. Cause
①The thickness of the composite film is uneven, with lotus leaf edges.
②The tension of the double floating roller is too small.
③Some rollers rotate unevenly.
2. Solution
①Adjust the tension of the double floating rollers.
②Check and adjust the relevant guide rollers (such as compensation rollers, deflecting rollers, etc.).
 
Zhejiang Deguang is a professional supplier of bag making machines. We are familiar with any detail in the bag making process. Here, you can know more about the causes and solutions that affect the quality of bag making.
 
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