Influencing factors of carton compressive strength
The main factors that affect the compressive strength of cartons are:
① the quality of raw materials;
③ box and flute type;
④ printing and opening;
⑤ processing technology.
A, the quality of raw materials Kellicutt formula is based on the ring compressive strength of corrugated cardboard to calculate the compressive strength of the carton, which is an indicator of the compressive strength of the carton. The ring compressive strength is the bonding strength of the core paper and the face paper or the inner paper. The raw material is the main factor that affects the ring compressive strength. It is related to the basis weight, tightness, and moisture of the raw material. The grades of boxboard and corrugated base paper are mainly A, B, C, D, E, etc. Under normal circumstances, the principle of grade matching should be followed when selecting materials. The grades of boxboard and corrugated base paper should be similar. At the same time, boxboard The basis weight of paper and corrugated base paper should be kept within 21, so as to ensure the overall quality level of raw materials and the quality of corrugated cardboard. Of course, corrugated cardboard is volatilized by the bonding of the face paper, the core paper and the inner paper. Therefore, the factors of the adhesive and the core paper should also be considered. The proper moisture content and tightness of the core paper and the uniformity of the core paper are conducive to the adhesion of the face paper and the lining paper. The better adhesive properties of the adhesive and the appropriate thickness of the adhesive layer are all conducive to improving the compression resistance of the corrugated box. strength.
B, moisture, carton production environment, storage environment, use environment, weather, climate and other factors will affect the water content of the carton. In order to ensure the compressive strength of the carton, the external environment should try to avoid the influence of the water content of the carton. The initial moisture content of corrugated base paper will directly affect the quality of corrugated cardboard. High moisture content will soften the base paper, but the tensile strength will be relatively reduced; low moisture content will dry the base paper and the corrugated top will easily crack during corrugation. In the production of corrugated board, the moisture content to obtain the best strength value is generally 6% to 8%. The traditional method of moisture determination is the drying weighing method at 105°C, using an oven and a balance, this method is the standard method.
C, box type and flute type, box type refers to the type of box and the size ratio of the same type of box. They have a significant impact on the compressive strength. Some carton boxes are made of double-layer corrugated cardboard, and their compressive strength is significantly higher than that of single-layer boxes of the same specification; under the same conditions, the higher the box, the worse the stability and the lower the compressive strength. In people's consciousness, it is often believed that the larger the flute, the higher the compressive strength of the carton, and it is easy to ignore the influence of flute on the amount of deformation. The larger the flute type, the greater the compressive strength of the carton and the greater the deformation; the smaller the flute type, the smaller the compressive strength of the carton and the smaller the deformation. If the carton is too large and the corrugation is small, the carton will be easily crushed during the compression test; if the carton is too small, the corrugation is large, and the deformation will be too large during the compression test, and the buffering process will be long and effective. The force value deviates too much from the final force value.
D, printing and perforation, printing will cause certain damage to the corrugated cardboard, which will reduce the compressive strength of the carton. The size of the pressure and the size of the bearing area are the main factors that affect the compressive strength of the carton. If the printing pressure is too large, it is easy to crush the corrugation and reduce the corrugation height. Especially when printing at the press line, in order to perform forced and clear printing at the press line, the entire cardboard will be crushed and the compressive strength of the carton will be greatly reduced. Therefore, try to avoid printing here. When the carton is full or surrounded by graphics, in addition to the pressing roller on the corrugated cardboard, the ink also infiltrates the paper surface, which in turn reduces the compressive strength of the carton. When a general carton is fully printed, its compressive strength drops by about 40%. For products that require ventilation, opening holes on the surface of the box or punching the handle holes on the side of the box will reduce the strength of the carton, especially if the opening area is large and it is biased to one side, the effect is more obvious.
E, processing process deviation, through the test, under the same conditions, every time the horizontal pressure line of the carton is widened by 1mm, the compressive strength of the carton will decrease by 90N-130N, and the deformation will increase by about 2mm. If the pressure line is too wide, the force value of the carton during the compression test will increase slowly, the effective force value will be small, and the final deformation will be large. In order to ensure the compressive strength, we should try our best to improve the production process and reduce the influence of each process on the compressive strength of the carton. In the process of box making, improper line pressure, too deep grooves, weak bonding, etc. will also reduce the compressive strength of the box.
So what can test the box?
Box Compression Tester Computer Model GT-N02B
Computer Model Box Compression Tester with multi-function and high precision is designed to test the compressive strength of standard size corrugated box, or packages and containers made of other material with a compressive strength smaller than 100kN. With advanced mechanical structure of a pair of threaded shafts & guide pillars and imported motor for control, the testing machine has the following salient features: good parallelism, reliable measure precision and high return speed.
1.Strength test which belongs to a destructive test is mainly used to measure the deformation when the sample is loaded with maximum pressure or crushing strength.
2.There are two parameters which are to be set in the constant value test: load force value.
3.Stacking Test is used to check up that whether the sample can endure a constant pressure in a given time period. Set up two parameters: compressive strength and testing time (hour).
4.The overall system is in good parallelism, stationarity and high return speed.