How to choose between carton BCT test or ECT test？

For cardboard box users, choose cardboard box compressive strength test(BCT test) or edge compression strength test(ECT test)? Let's talk about this issue today.

To know which one is better, we first need to understand the similarities and differences between edge compression strength and compressive strength.

Table of Contents

1、Carton Edge compression strength

• Definition
  
• Testing Principle
  
• Factors affecting edge compression strength
  
• Referenced standards
  
• Testing instrument
  

2、Carton compression strength

• Definition
  
• Testing Principle
  
• Factors affecting edge compression strength
  
• Referenced standards
  
• Testing instrument
  

3、Conclusion

1、Carton Edge compression strength

• Definition
  The edge compression strength of corrugated cardboard refers to the maximum pressure exerted along the corrugated direction on a unit length of cardboard perpendicular to the corrugated direction, in kN/m. Edge compression strength is commonly expressed by ECT in foreign countries, and the edge compression strength of corrugated cardboard is closely related to the pressure resistance of the cardboard box.
  
• Testing Principle
  Place the corrugated cardboard test piece between the two pressure plates of the compression tester, with the edges of the test piece perpendicular to the pressure plate, and then apply a compressive force until the sample is crushed. To prevent premature damage to the edge of the specimen during load application, the stressed edge of the specimen is reinforced.
  
• Factors affecting edge compression strength
  1、Improper cardboard material
  The material of cardboard is one of the important factors affecting the edge compression strength. The raw materials for cardboard mainly consist of corrugated paper and tissue paper. If the thickness of the corrugated paper is insufficient or the strength of the surface paper is insufficient, it will lead to the cardboard edge pressure not meeting the standard. In addition, the density of cardboard is also an important indicator, as low density can lead to insufficient edge compression strength of cardboard.
  Solution: Choosing the appropriate cardboard material is the key to solving the problem. When selecting materials, factors such as the weight, shape, and transportation method of the product should be considered, and corresponding corrugated and face paper materials should be selected to improve the edge compression strength of the cardboard.
  2、Unreasonable production process
  The production process of cardboard is also one of the important factors affecting the edge compression strength. If the production process is not reasonable, such as unclear indentation of corrugated paper, weak adhesion of surface paper, etc., it will lead to unsatisfactory edge pressing of the cardboard. In addition, improper temperature and humidity control during the production process can also have an impact on the edge compression strength of the cardboard.
  Solution: Improving production processes is the key to solving problems. Optimize the indentation process of corrugated paper to ensure that the folding lines of corrugated paper are clear and neat; Strengthen the bonding process of the face paper and improve the overall strength of the cardboard. In addition, reasonable control of the temperature and humidity of the production environment ensures stable quality of cardboard during the production process.
  3、Unreasonable design
  The design of cardboard is also one of the important factors affecting the edge compression strength. If the design is not reasonable, such as the absence of reinforcement structures at the edges of the cardboard, or the size of the cardboard being too large or too small, it can lead to the cardboard edge pressure not meeting the standard. In addition, some unreasonable packaging methods can also affect the edge compression strength of cardboard.
  Solution: Optimizing the design of cardboard is the key to solving the problem. When designing cardboard, the weight and shape of the product should be considered, and reinforcement structures should be reasonably set to increase the edge compression strength of the cardboard. In addition, choose a reasonable packaging method to avoid excessive pressure on the cardboard during transportation.
  4、Improper storage and transportation conditions
  The storage and transportation conditions of cardboard can also have an impact on the edge compression strength of cardboard. If the cardboard is exposed to high temperature and humidity for a long time, or is subjected to excessive squeezing pressure during transportation, it will cause the cardboard edge pressure to not meet the standard. In addition, unreasonable storage and transportation methods can also affect the edge compression strength of cardboard.
  Solution: Reasonable storage and transportation are the key to solving the problem. During storage, the temperature and humidity of the storage environment should be kept stable to avoid unnecessary damage to the cardboard. During transportation, reasonable packaging methods should be adopted to protect the cardboard from the impact of squeezing pressure.
  
• Referenced standards
  TAPPI T811 "Determination of Edge Compression Strength of Corrugated Paper Board (Short Column Method)"
  TAPPI T823 "Determination of Edge Compression Strength of Corrugated Paper Board (Rigid Support Method)"
  GB/T 6546-2021 "Corrugated Paper Board - Determination of Edge Compression Strength"
  ISO3037:2013 "Corrugated board - Determination of edge compressive strength"
  GB/T2679.17-1997 "Corrugated Paper Board - Determination of Edge Compression Strength (Edge Reinforcement Method)"
  GB/T 6546-2021 "Corrugated Paper Board - Determination of Edge Compression Strength"
  
• Testing instruments
  
  
  
  Measuring range: 5~3000N
  Accuracy: ≤±0.5%
  Test force test range: 0.4% ~ 100% FS
  Displacement speed: 100 r/min
  Power accuracy: within ±1%
  Force value resolution: 0.1N
  Test speed benefit ratio: 1:5
  Reduction ratio: 1:40
  Deformation resolution: ≤0.1mm
  Test speed: 12.5±1mm/min
  Platen parallelism: ≤0.05mm
  Operating system: Adopt American AD converter to improve detection linearity
  Human-machine interface: touch screen control, switch between Chinese and English
  Printout: Modular all-in-one thermal printer
  Dimensions: 40*37*56cm
  Weight: 60kg
  

2、Carton compression strength

  ● Definition

     The compressive strength of a cardboard box is to place the sample cardboard box between two parallel pressure plates of the testing machine, and then apply uniform pressure to record the load and pressure plate displacement until the test sample 

     ruptures or the load or pressure plate displacement reaches a predetermined value.

  ● Testing Principle

     Place the test sample between two parallel pressure plates of the testing machine, apply pressure evenly, and record the load and pressure plate displacement until the test sample ruptures or the load or pressure plate displacement reaches the 

     predetermined value.

  ● Factors affecting edge compression strength

     1、The quality of raw materials and raw paper are the decisive factors determining the compressive strength of cardboard boxes, as can be seen from the Kellicutt formula.

     2、The influence of other conditions during the production process of corrugated cardboard cannot be ignored, such as the amount of adhesive used, the change in height of the corrugated cardboard, impregnation, coating, and composite processing.

     3、Moisture: Manufacturing cardboard boxes with corrugated cardboard with high moisture content or storing them in a humid environment for a long time can reduce their compressive strength.

     4、Fiber is a type of material with strong water absorption. During the rainy season and high humidity in the air, the moisture balance between the cardboard and the atmospheric environment is important.

     5、Box type: Box type refers to the type of box and the size ratio of the same type of box, which has a significant impact on compressive strength.

     6、Some cardboard boxes are made of double-layer corrugated cardboard, which significantly improves the compressive strength compared to single-layer boxes of the same specification; Under the same conditions, the higher the box, the poorer its 

     stability and lower its compressive strength.

     7、Printing and punching: Printing will reduce the compressive strength of the cardboard box. Opening holes on the box surface or punching handle holes on the side of the box for products with breathability requirements can reduce the strength of the 

     cardboard box, especially if the opening area is large and biased towards one side, which has a more significant impact.

     8、Processing process deviation: Improper wire pressing, deep grooving, and weak bonding during the box making process can also reduce the compressive strength of the box.

     Referenced standards

     GB/T 4857.4-92 Packaging - Pressure Test Methods for Transport Packaging

     GB/T 4857.3-92 Packaging Transport Packaging - Static Load Stacking Test Method

     GB/T 4857.2 Packaging, Transportation, and Handling of Temperature and Humidity Adjustment of Packaging Components

     GB/T 4857.17 Packaging - General principles for the preparation of performance test outlines for transportation packages

     GB/T 4857.18 Packaging - Quantitative data for the preparation of performance test outlines for transportation packages

     GB 3538 Marking Methods for Each Part of Transportation Packaging

• Testing instrument
  
  
  
  

Test Range: 10KN, 20 KN, 50 KN(Optional)

Specimen Dimension: （600*400*600）mm/（800*600*800）mm

              （1000*800*1000）mm/（1200*1000*1200）mm

              （1200*1200*1200）mm/（1500*1500*1500）mm

Resolution: 0.01N

Deformation error: ≤±1mm

Test force test range: 0.4% ~ 100% FS

Platen parallelism: ≤1mm

Sensor error range: ±1%

Test speed: 5~300mm/min infinitely adjustable, return speed: 100mm/min

Compressive strength: 10±3mm/min

Stacking strength: 5±1mm/min

Unit interchange: N/Lbf /kgf

Data analysis: 7in touch screen, thermal printing integrated

Test function: Determination of compressive strength, measurement of stacking strength, measurement of fixed value strength

Working environment: temperature (20±10°C), humidity<85%

Dimensions: 1000*800*1300 (length*width*height)

Power supply: 220V, 50HZ

Weight: about 250kg

3、Conclusion

Edge compression strength（ECT test）refers to taking a piece of cardboard on a cardboard box and testing its maximum support force, which is edge compression strength. It is a vertical force, and the higher the edge compression strength, the higher its compression value. It tests the material of the cardboard, no matter how many styles the cardboard box has, as long as the material is the same, its edge compression strength will definitely be the same.

Compressive strength（ECT test）is the ability to test the load-bearing capacity of the entire cardboard box. It intuitively expresses how much force the cardboard box can withstand, but its disadvantage is that you need to separately calculate its compressive value for each type of cardboard box, because if there is no such requirement, how much testing is appropriate? If your company produces a wide range of cardboard box styles, and each style changes, then you need to design compressive strength every time, and then test whether the incoming materials meet your requirements. This would be very costly and unscientific.

For cardboard box users, should we use compression testing or edge pressure testing? The author's suggestion is that if the specifications of your company's products are in long-term use and the quantity is large, compressive strength should be determined. After designing the cardboard box, the compressive strength requirements of the cardboard box should be specified. After the supplier delivers it, it is most suitable to test its compressive strength every time,

But if your quantity is small and the specifications of the cardboard boxes change every time, then you should number the commonly used materials and design their edge compression strength according to the regulations. The next time you make a cardboard box, you can ask the supplier to use a certain material for this cardboard box. After selecting the material, you can receive the goods according to the corresponding edge compression strength of the material. Once the edge compression meets the requirements, the pressure resistance will definitely meet the requirements, The quality of the cardboard box can be guaranteed