ASO Co., Ltd.

The complaints are mostly due to poor sealing. This seal failure can be broadly divided into two types of complaints.

・The first is insufficient heat during sealing.
・The second is over-heating, which is excessive heat.
 

 In short, under-heating can be a cause of complaint, and over-heating can also be a cause of complaint.
Failure of the seal makes the bags unusable, so this is the most important process point to consider.

  The seal part can be easily peeled off when tearing vertically along the sealing part. The seal can also gradually peel off when it is pulled.

 This symptom is particularly frequent in the central part of the seal.
On the other hand, if too much heat is applied, the seal can easily ‘snap’ or bottom out when the contents are filled.
 In the case of a hot plate seal, distortion of the seal bar can even cause a mixture of the above situations.

 Seal failure is the minimum requirement for a poly bag to fulfill its basic function of “filling,” but it is also the most frequent complaint.
This is due to the dependence on highly skilled personnel in factories, and the techniques are not always shared.
  The reason for the system seems to be the lack of standardized procedures.

 Japanese industrial standards, JIS Z-1711 ‘For polyethylene film bags used as light packaging bags for commercial and household use,’ stipulate seal strength, length, etc. However, these stipulations are so low that they are not practical for industrial use.

(1) Thickness unevenness (thickness variation)
The second most common cause of bag-making complaints is thickness unevenness (variation in thickness).
 The thickness of polyethylene tubes fluctuates due to the following factors:

(2) Width defects
 Defects related to width (folded diameter) are classified into the following two types:

These problems are mainly caused by machine trouble or operational errors.

(3) Blocking (poor opening performance)
This is a phenomenon in which the bag opening sticks together and becomes difficult to open.
 It is caused when overheating of the resin promotes bleed-out of additives.

(4) Powdering (blooming)
This is a phenomenon in which powder adheres to the surface of the bag.
 It is caused by:

　To prevent these defects, it is important to thoroughly manage the production process, perform regular machine maintenance, and establish standardized manufacturing procedures.
　In particular, by strengthening the inspection system for base film and optimizing sealing conditions, it is possible to suppress the occurrence of complaints.