Bursting Factor Formula & Bursting Index Formula

Bursting strength is a very important aspect of quality and strength of many materials that are used in different industries. In many industries where there is use of materials that are prone to rupture, the bursting strength is very important to calculate and control. The industries where such materials are used include paper industries, packaging industries, textile industries and so forth. The paper, cardboards, corrugated sheets and fabrics can be easily ruptured when there is a bursting force applied on them. With more and more quality savvy people being aware of the importance of high quality products and materials, the manufacturers of the products are also understanding the fact that in order to increase the brand value. The quality is the major perspective to be focussed nowadays to grab the attention of customers. Selecting the best quality test machine for paperboard is an important assignment for the manufacturer. Choosing an appropriate device will develop quality standards further. To assess the bursting quality of a sample one must pick an appropriate machine. It is not possible for the manufacturers to have a strong customer base without focussing on the quality part of the products. The best method to preserve the quality of the products is using high-quality packaging material to save the inner content of packaging during transportation and warehousing. With the best quality of assurance of packaging materials, we not only ensure the ease of storage and handling but we also ensure that the products packaged inside have the best safety.

Bursting strength of Materials

The bursting strength of material is termed as the maximum amount of rupture force that a material can bear if the rupture force is applied on them by a uniform source from uniform directions. Different materials have different bursting strength. As there is different usage in the industries for different types of materials, hence there is a different level of strength is required for them. Paper is used for wrapping purpose and it is essential that it is able to withstand the forces that it faces during handling. Although the forces that paper has to face during handling and storage are very low hence the paper is needed to have a comparatively low bursting strength than other materials. The cardboards and corrugated sheets are used in industries to prepare the external packaging of the products and hence they need to bear the maximum force that is applied during the storage, handling and transportation. These materials need to be tested for the bursting strength with great accuracy and precision. This is important because any error in calculating the bursting strength of these materials can not only compromise the integrity of the packaging of the products but can also cause huge damage and ruin the quality of the products packed inside as well. Textile fabrics are normally used in industries where there is a requirement of very high bursting strength and the fabric has to bear a continuous application of high magnitude of bursting force. Due to this reason, the manufacturers of the industrial fabrics must ensure that they test the bursting strength of the fabrics with great precision. Any negligence of the strength of the fabrics can not only compromise the quality of the fabrics but it can also lead to fatal accidents as they are used for some very critical applications.


With the help of the bursting strength test aka Mullen Test, one can determine the capacity of the packaging boxes with great ease. This test does not tell you how much to put in a box per square inch, it is (more than anything else) a requirement of construction not a performance requirement. For example, if we are talking about a 200 Mullen box, it must have a minimum of 84 lbs/msf of liner. Furthermore, these liners of the box need to be virgin and not recycled. ECT, on the other hand, is also a performance requirement that needs no prescribed construction. As long as you receive at least a minimum of 32 lbs per lineal inch of crush resistance strength, you are good to go as a 32 ECT (regardless of the material that is used for construction). Recycled paper versus virgin paper has no major difference as they’re both manufactured to give the same Ring Crush (RCT) value.

Calculation of Bursting Strength

Calculation of Bursting Strength

The bursting strength of the materials that are used in different industries such as paper, cardboard, corrugated sheets, textile fabrics etc. need to be tested to the best level of accuracy to ensure best quality of the products that will be sued in industries. The manufacturers as well users of such products need a very sophisticated mechanism that could allow them to apply the required amount of uniform force on the test specimen from all the directions in a uniform manner so that the bursting strength of the specimen could be calculated correctly and accurately. The manufacturers also need to ensure that the mechanism they use for testing the bursting strength should be able to repeat the testing results with great precision. One such testing instrument that is vastly used in industries for the purpose of testing the bursting strength of various materials is the Bursting Strength Tester. The bursting strength tester is the most accurate and precise testing instrument that can be used for testing the bursting strength of the various materials and ensure their best strength and quality delivered to the products. The testing instrument is very easy to operate and can be used under extremely harsh working conditions for rugged test results.

Bursting Factor Formula & Bursting Index Formula

Bursting factor is the property of the material that decides its strength, quality and endurance. The bursting factor is expressed in terms of the bursting strength per unit Grammage force applied on the surface of material. In order to use the bursting factor formulaof the materials, first it is essential to calculate the bursting strength of the material being tested which can easily be done by performing the Mullen test or Bursting Strength Test using the bursting strength tester. Once the bursting strength of the material is calculated, the bursting index formula is used and bursting factor of the material can be calculated with the help of the following formula:

Burst factor = Burst strength (gf/cm2) / Grammage (grams/m2)

Burst Index = Burst strength (kPa) / Grammage (Kg/m2)

In this formula, kPa is kilopascal (pressure applied on the specimen)
Kgf is kilogram force (the force applied on the specimen)
Gf is Gram Force (the force applied on the specimen)
Grammage GSM of the material or the Grams per meter square weight of the material.

The bursting index formula is expressed in the units of kPa which is kilo Pascal. By calculating the BF and BI from these formulae, one can easily get important information about the quality as well strength of the materials such as paper, cardboard, corrugated sheets and textile fabrics. The more is the value of bursting factor and bursting Index of the materials, the better will be the quality of the materials. In the paper industries this bursting factor formula is also used for deciding the price of the paper in the market. But as we know to calculate the bursting factor we need to perform the Mullen test or bursting strength test with the help of Bursting Strength Tester.

Performing the Bursting Strength Test

In order to perform the test, it is essential that all the preparations are done in advance according to the prescribed methods in the ASTM D-3876 and ISO 1060 standards.

  • First of the specimen is prepared by cutting a circular disc from the larger piece of material. The dimensions of this disc have to be larger than the size of the annular clamps provided with the instrument. It is important to keep the dimension as prescribed so that there is no slippage of specimen during the application of force in the testing procedure.
  • Plug in the instrument to the required electrical socket.
  • Clamp the specimen in an appropriate way to the annular clamp. Keep in mind that the sample is clamped firmly so that there is no chance of slippage of the sample. To avoid slippage, serrated holding clamps can also be used.
  • The test can be started by starting the machine. For that, push the button that starts the application of hydraulic pressure on the specimen. Normally, this button is labelled as “Push to Burst’
  • The rubber diaphragm present in the machine is inflated with the increase in the hydraulic pressure in the machine.
  • Let the hydraulic pressure increase to apply the force on the sample until it burst or rupture.
  • When the sample bursts, the hydraulic pressure is stopped and the bursting strength of the specimen is recorded in the instrument.
  • Normally, the machines come with a digital display or an analogue gauge which display the test result.
    To test the bursting strength of another material, just replace the specimen and repeat the procedure.
  • The value that is displayed in the digital or analogue display of the instrument gives the bursting strength ofthe material being tested. This is the maximum value of the force that the material can bear before its rupture. This value can be very helpful for the manufacturers in deciding the quality level of the materials and can also be used for calculations of bursting factor and bursting index.

    Importance of Bursting Strength and Bursting Factor

    Packaging is one of the most important aspects for the safety and quality of products in any industry. The packaging is responsible for providing protection to the products from the external factors like forceful impacts, moisture, environmental factors, dirt, dust and so forth. This is why, it is the responsibility of the manufacturers of the packaging materials to ensure that the packaging materials they are providing to the industries are of the best quality. These materials need to have enough strength so they are not deformed and damaged during the time of storage, handling or transit by application of any type of unwanted force on them. Aldo for the industrial fabrics that are in industries for different critical and crucial applications, it is important that the fabric is able to survive the harsh working environment of the industries without facing any rupture or damage. Any negligence of the quality or property of the fabrics can be very dangerous for the safety of eth products, machines as well as the workers in the industry. This makes the determination of strength and quality very important for the packaging materials. The manufacturers must know the available strength of the materials and make the necessary changes in the physical and chemical composition of the packaging materials to make them stronger for the applications where they will be used.

    In order to calculate the most accurate length of the packaging materials, the manufacturers need to perform the highly accurate bursting strength test. With the help of bursting strength test, the manufacturers can easily calculate the bursting strength and bursting factor of the packaging materials and containers. With the help of this, they can easily estimate whether the material appropriate for the proposed usage. Also this helps them in deciding the right price of the materials according to the quality.

    Increasing the strength of packaging containers with the help of Bursting Strength

    The bursting strength of the packaging materials not only gives you information about the quality of the products but it can also be used for improving the strength and quality of the containers as well. The corrugated sheet that is the major material used for making the packaging containers has different layers of plies that can contribute to the strength of the box. The corrugated sheets come in different types that are single faced sheets, double faced corrugated sheet with single wall, three ply corrugated sheet. The strength of the corrugated sheets can be increased with the help of adding more layers or plies to the sheets. Now the main problem is how to decide how many layers are to be added to make it stringer enough for usage purpose. The calculation of bursting strength can help in that. When we know the bursting strength of each play that is added to the sheet and also we know the required strength of the final products, then we can easily calculate how many layers are needed to be added to the corrugated sheets to obtain the required bursting strength. There are also many other factors that must be tested and measured in order to ensure the best strength of the corrugated fibre sheets such as puncture resistance, Edge crush strength, Ring crush strength and so forth.

    Bursting Strength and Quality Assurance

    With such a huge demand of very high quality products in the markets by the customers, the packaging quality is also a very important aspect in ensuring the best quality of the products. The manufacturers of the packaging materials also play an important role in ensuring the safety of the products during storage and handling. This is why, the manufacturers test each and every aspect of quality of the packaging materials before delivering it to the customers. The bursting strength is one of the easiest ways to determine the strength of the products and hence determine the quality level of the packaging. With the determination of bursting strength, the manufacturers can easily make the necessary changes required in the materials to reach the required strength and quality level. In this way, the manufacturers can easily ensure that the quality of packaging delivered to their industrial customers is of best level and the packaging is capable of providing the utmost level of safety and protection to the products that have been packaged in the containers. Additionally, with the determination of bursting strength, the manufacturers can have a controlled manufacturing process that helps them in putting exactly the right amount of layers and materials in the packaging sheets and containers and hence maximize the profits with optimization of the materials.

    Bursting Strength Tester Formula

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    Pacorr’s Bursting Strength Tester

    Pacorr is amongst the best bursting strength manufacturers and suppliers that offer a very highly accurate testing machine to the paper and packaging industry that is very helpful in ensuring the best quality of packaging materials along with maximization of profits by reduction in rejection. The instrument offered by Pacorr is designed in accordance with standards prescribe by the international standardization authorities. The machine comes with different variants of analogue model and digital model for the convenience of the users and accuracy of the test results. The lab is made from very high quality mild steel with powder coating which ensures a longer service life of the instrument and ability to perform in even the harshest working environments. The machine uses industry grade glycerine for applying uniform force on all the sides for accurate testing results. The equipment is best for testing the bursting strength of a variety of materials such as corrugated sheets, cardboards, industrial fabrics, paper and so forth. With the help of this highly precise laboratory apparatus, the manufacturers can easily assess the quality of the products they produce and deliver to the customers in various industries.