How to unify the hot melt adhesive particles for mixed line sealing of multi specification cardboard boxes? A packaging factory’s parallel production case

Background: Three lines merge into one, but the glue doesn’t match

A packaging factory in the Pearl River Delta, in order to save manpower, merged the original three sealing lines into a mixed production line, and ran the cardboard boxes from 3-layer small boxes to 5-layer heavy boxes together. In the first week of merging, there was a problem: small boxes overflowed with glue and had dirty surfaces, while large boxes couldn’t be sealed tightly, resulting in thousands of rework per day. The reason is that each of the three lines originally used one typeHot melt adhesive granulesAfter merging, they were forced to unify into one of them, resulting in no one being compatible.

Problem Decomposition

• Large weight span of cardboard boxes: 3-layer boxes have fast adhesive absorption, while 5-layer heavy-duty boxes have hard paper surfaces and slow adhesive absorption;
• Original high initial adhesion fast curing type: The small box is sufficient, and the large box has not been pressed in place before the adhesive solidifies;
• A set of universal parameters for gluing points: if there are too few glue points in the large box, the glue can be directly opened when compressed and stretched.

Resolve actions

The technical personnel from Guangzhou Sunlife Trading went to the factory to do three things: firstly, to switch to universal sealing granules with moderate opening time and wider bonding window, so that both fast and slow substrates can be pressed in place inside the window; The second is to set the glue amount and point position according to the box type – small boxes have 4 points, with 0.3g per point, and heavy boxes have continuous glue strips, with the glue amount increased to 1.2g/box; The third is to change the pressing time from a uniform 1 second to a box type linkage of 1-2.5 seconds. Sunlife hot melt adhesive also provides comparative adhesive test reports for 3-layer and 5-layer corrugations, allowing the production line to directly set parameters according to the table.

Result

Mixing lines is not about randomly choosing a universal adhesive, but about selecting adhesives with wider bonding windows and then grouping them with parameters to adapt to differences.

Three reusable experiences

One is to make a list of the weight, number of layers, and single box weight of all box types before merging, so that the supplier can recommend the most difficult type of adhesive; The second is to set the glue amount, point position, and pressing time for each box type as equipment presets, and call them directly for changing the type to avoid errors in manually changing parameters; The third is to conduct a three-day first article inspection after merging, focusing on whether there is any displacement at the opening of the heavy-duty box. Early detection is much cheaper than rework afterwards.

Frequently Asked Questions

Q1: Do mixed wires have to be unified into one type of glue?
The most convenient way to unify is to choose a universal model with moderate opening hours; If there are extreme differences in box types, production can be carried out in batches according to shifts.

Q2: Do heavy-duty boxes require continuous rubber strips?
It is recommended to use strips for stacking with high stress, as their anti stretching ability is significantly better than glue dispensing.