Do you know what items need to be tested for honeycomb cardboard?

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Next, everything will definitely be crystal clear at a glance.

1. Appearance

Perform an appearance inspection (visual inspection) of the sample under natural light— the surface of the honeycomb cardboard should be clean and free from any obvious contamination (such as oil stains, water marks, discoloration, or adhesive residues).

Xiaomin on Testing: Use tests to determine whether the honeycomb cardboard is free from visible contamination, with no cracks, thin edges, soft or fractured corners, or any other defects allowed. Additionally, the surface paper of each square meter of honeycomb cardboard must remain intact, without damage or holes.

2. Dimensional Deviation

The dimensional deviations of honeycomb cardboard primarily refer to length, width, and edge-length variations, all of which should remain within the specified tolerance ranges.

Xiaomin on Testing: This test allows you to verify the specifications of the honeycomb cardboard you produce and confirm whether it meets the technical requirements of the reference sample.

3、 Aperture Ratio

The aperture ratio is the ratio of the cell pitch to its inner diameter.

Xiaomin on Testing: This test is designed to ensure the structural integrity of honeycomb cardboard. The tensile strength of the honeycomb core must be thorough, uniform, and well-organized, with an aperture ratio ranging between 0.7 and 1.1. A higher aperture ratio means fewer honeycomb wall panels per unit area are contributing to load-bearing capacity.

4. Debonding Area

Honeycomb cardboard and paper cores require a certain adhesive for bonding, and the glue application on all contact surfaces should be even, thorough, and ensure a strong, durable bond.

Xiaomin on Testing: Poor adhesion—caused by improper quality or dosage of honeycomb cardboard adhesive, excessive drying temperatures leading to brittle adhesive layers, or other factors—can result in large-scale delamination between the upper and lower paper layers, ultimately compromising the flat compression strength of the honeycomb cardboard. Importantly, the total area of delaminated surface per square meter of honeycomb cardboard should not exceed 20 cm².

5. Moisture Content

Moisture content testing refers to the amount of water present in raw paper or cardboard, expressed as a percentage.

Xiaomin on Testing: This test allows you to determine the moisture content separately for both the surface paper and the core layer of honeycomb cardboard. If the moisture level is too high, the cardboard will feel soft, lack stiffness, and exhibit poor bonding quality. Conversely, if the moisture content is too low, the material becomes overly brittle. Therefore, it’s crucial to maintain the moisture content within a reasonable range—specifically, the ideal moisture level for honeycomb cardboard is (12 ± 4)%.

6. Flat Crush Strength

Flat crush strength is an important indicator for measuring the ability of honeycomb cardboard to maintain its original thickness without collapsing, and it is expressed in units of kPa. This property is related not only to the flat crush strength of the honeycomb core but also to the bonding strength between the face paper, linerboard, and base paper.

Xiaomin on Testing: Flat crush strength primarily affects the cushioning performance of honeycomb cardboard—higher flat crush strength leads to better cushioning properties in the resulting honeycomb boxes. In fact, the flat crush strength of honeycomb cardboard is significantly higher than that of corrugated cardboard. Beyond its use in making honeycomb boxes, honeycomb cardboard also serves as an excellent protective and cushioning material for various products.

7, Static Flexural Strength

Bending strength refers to the maximum stress a material can withstand before fracturing or reaching a specified bending moment under bending load—this stress corresponds to the material’s maximum tensile stress during bending, measured in MPa (megapascals). It reflects the material’s resistance to bending and is used to evaluate its overall bending performance.

Xiaomin on Testing: The static bending strength should meet either the relevant product standard requirements for this test or the usage specifications provided by the customer. When honeycomb cardboard is bent, during the elastic phase, wider-span specimens exhibit better cushioning performance; however, once the yield plateau is reached, narrower-span specimens demonstrate superior cushioning capabilities.

8、 Food Safety Performance

The food safety performance of honeycomb cardboard that comes into direct contact with food must comply with relevant national food safety standards and legal regulations (GB 4806.8 — National Food Safety Standard for Paper and Paperboard Materials and Products Used in Food Contact).

Xiaomin on Testing: You can refer to the testing items previously used for disposable paper products—specifically, heavy metals, fluorescent substances, microorganisms, total migration, potassium permanganate, and formaldehyde.