Testing Lab: On-site Board Testing
Board Analysis Method
Board analysis can be used to determine the weight of the board, the thickness of the board and the weight of the component papers of corrugated board after separation. This test method provides the weights of the constituent papers. The weights given should be considered alongside other performance related test methods.
This is due to papers of the same type and weight from different sources typically have differing performance values, causing board grades of the same weight to differ dependent on the paper origin.
Performance Characteristics of Paper
Performance, runability and ease of conversion of corrugated packaging are to a large extent defined by paper properties. Paper properties are broken into three elements, optical, surface and physical properties. Optical properties are primarily related to the visual element of paper. Surface properties are important for corrugated board manufacturers, specifically the bonding process. While physical properties are of most interest to board performance.
As paper performance contributes to box performance there are several tests that are key in determining the required structural specifications. These include SCT (compression strength of paper), ECT (compression strength of board) and BCT (compression strength of box).
Box Compression Testing
BCT is used to assess the compression strength of a glued corrugated case and to determine a maximum load a box can withstand when palletised.
It is typically used to calculate the force being applied to the bottom case within a stack on a pallet and the strongest indication of whether a case will be suitable for palletising.
Performance Factors
In an ideal world, every box would be the same size and would carry the same weight, to the same place in the same climatic conditions throughout the length of the journey. This would also happen without any vibrations or movement in transit.
Unfortunately, this is not the case and there are a variety of factors that can affect box compression strength. Paper attributes can be used to predict case performance to an extent. Key considerations should include case length/width/depth ratios, palletisation, logistics and environment.
Case Sizes Matter
Typically theoretical Box Compression Test (BCT) performance is reliant upon a formula, which uses the perimeter of the case rather than the individual length:width:depth measurements.
However, a square case and a rectangular case can have the same perimeter but will not have the same BCT performance due to the length to width ratio, consequently when tested they will crush and buckle in different places and at a different rate.
Re-assessing Board Grades
Corrugated board serves a lot of purposes, making it the ideal packaging material. Once a board grade is assigned to a specific job it is rarely reassessed unless it is not performing sufficiently.
However reassessing board grades and understanding the variable elements of packaging can influence its strength, performance and cost. Therefore, considering board grade is not just for new specifications it can provide valuable information on existing specifications. Exploring the purpose of the box can help identify scope to trial an alternative board grade which could provide beneficial outcomes.
Supply Chain Considerations
To help establish the required Box Compression Strength of a case, there are several questions which can assist with calculating an appropriate board grade, for instance the case size, number of cases per pallet, transportation conditions, how long the cases are stored, what the ambient conditions are.
Some of the above points assist the calculation of the case performance and others help establish the safety factor, which attempts to appreciate climatic and environmental effects within the supply chain. A full list of questions to determine theoretically performing board grade can be obtained by contacting Board24.
Changing Flutes
Changing the board flute type offers two key benefits: performance and logistics.
Performance benefits; for instance, improved print finish, perforation tear or board strength.
Logistics benefits can offer improved loadfill, reduced warehouse space, reduced number of forklift truck movements, lower storage costs and lower delivery costs.
