Industrial cores may be just one component in a much larger production process, but their performance can have a significant impact on efficiency, product quality and downtime.
Whether a core is used to wind film, textiles, paper or wire, it must be strong enough to withstand the forces placed on it throughout winding, handling and storage. If it collapses or deforms under pressure, the consequences can extend far beyond the cost of replacing the core.
That is why crush testing is an important part of quality control at Industrial Packaging.
What is crush testing?
Crush testing measures a core’s ability to withstand compressive force without collapsing or becoming permanently deformed.
During testing, a sample core is subjected to controlled pressure to establish the level of force it can withstand. The result provides a measurable indication of the core’s structural strength and helps confirm whether it meets the required specification for its intended application.
A core may appear perfectly suitable from the outside, but appearance alone cannot show how it will perform under pressure. Crush testing helps identify potential weaknesses before the finished cores leave our facility and reach a customer’s production line.
Why does crush strength matter?
During winding, a core can be exposed to considerable tension and pressure. The material wound around it adds weight, while handling, transportation and storage can introduce further compressive forces.
If the core is not strong enough for the application, it may buckle, flatten or become distorted. This can lead to production line stoppages, damaged material, waste, additional labour and costly reruns.
In a high-speed production environment, even a short interruption can have a wider impact on output and efficiency. Selecting a core with the correct crush strength therefore helps protect both the wound material and the wider manufacturing process.
The appropriate strength will depend on how the core is being used. A core carrying lightweight material at relatively low tension will have different requirements from one used for a heavy roll or a high-tension winding process. The objective is not simply to manufacture the strongest possible core, but to produce one that is correctly specified for the demands of the application.
Radial crush and flat crush testing
Different testing methods can be used to assess how a core responds to particular types of pressure.
In a flat crush test, a section of core is placed horizontally between two flat surfaces. Pressure is applied across the sides of the core until it begins to deform, measuring its ability to resist a concentrated compressive load.
Radial crush testing measures a core’s resistance to pressure applied around its circumference. This more closely represents the inward pressure created when elastic materials such as film or textiles are wound under tension.
The most appropriate testing method depends on how the core will be used and the forces it is expected to encounter. In some applications, more than one measurement may be relevant when establishing the required specification.
You can learn more about our testing procedures in our previous article, Radial Crush Testing with Ibrahim Darwish.
How wall thickness and board grade affect performance
A core’s crush resistance is influenced by its construction, including its wall thickness and the grade of coreboard used.
Generally, increasing the wall thickness or selecting a stronger board grade will improve crush resistance. However, these factors must be considered as part of the core’s overall specification.
Understanding the application from the outset helps ensure the core provides the required performance without adding unnecessary material or cost. Getting the specification right at this stage is far more efficient than responding to failures once production has begun.
Why moisture must be controlled
Moisture is another important factor in core performance. Paper-based coreboard naturally responds to moisture in its surrounding environment. If the moisture content becomes too high, the fibres can soften, reducing the stiffness and crush strength of the finished core.
At Industrial Packaging, moisture levels are closely monitored during production. A batch with moisture content above the required specification will not leave our facility.
This control helps ensure greater consistency and reduces the risk of cores performing differently once they are placed under load.
Not all cores are equal
Two cores with similar dimensions may perform very differently depending on their board grade, wall construction, moisture content and manufacturing quality.
A cheaper core may appear to offer an immediate saving. However, if it fails during winding or elsewhere in the production process, the resulting downtime, material waste and reruns can quickly outweigh the initial price difference.
The real cost of a core is therefore not simply its unit price. Its reliability and effect on the overall efficiency of the production line must also be considered.
By selecting the right specification and verifying its performance through crush testing, businesses can reduce uncertainty and minimise the risk of costly failures.
At Industrial Packaging, we work with customers to supply cores that are suited to the demands of their applications. To discuss your requirements or review your current core specification, contact our team.