Corrugated Cardboard and Case Packing: Introduction and Review

Abstract:

The modern theory defines packaging as “the process of providing a protective and informative covering to the product in such a way that it protects the product during material handling, storage, and movement and also provides useful information to all the concerned parties about the content of the package.” [1]

From primary packaging to secondary and tertiary packaging, we basically need various layers of protection with different materials and forms of packaging to keep our commodities safe from any damage during the processes long the supply chain until the location of sales and distribution.

Despite the primary packaging and secondary packaging like the flexible bag and carton boxes that already provide protection for the products contained, the distribution and transport between the location of manufacturing and the place of sale usually engage moving the commodities in bulk and the loading, trucking, forklifting, and discharge are all of them potential factors that may leave damage to the packaging. Case packing, with regard to these challenges, is the most extensively used option to either pack primary or secondary packaging in bulk and to provide protection.

In this article, we will look into the features and benefits of case packing and why it is accepted as the standard tertiary packaging for products from all industries.

The study will include a mathematical analysis to analysis the strength and elasticity of corrugated cardboard to look into why it is a ideal material for tertiary packaging.

Keywords: 

Case packing, tertiary packaging, corrugated case, case packers

Introduction

By case packing, we usually refer to the approach of keeping products in bulk in corrugated box containers as packaging and for transporting. [2]

Corrugated box and case packaging have been a well-accepted option of containers for freight transport ever since 1903 when it was first acknowledged by freight classification organizations, the packaging has been following since then the trend of growing consumer demand and has seen a wider use and application thanks to its advantages with regard to facilitating the movement of goods as well as the function of protection.

Corrugated Paper
Credit: Materials Today: Proceedings

In China, according to the statistics of the Paper Committee of Shanghai Packaging Technology Association [3], it was estimated that the use of corrugated boxes reached 80% of all uses of external packaging since the 1950s since they were introduced to the market back in 1930 when they only took 20% among the use of external packaging while back then the mostly used was wooden box.

And now, corrugated boxes have evolved as the preferred option for packaging, transporting, industrial supply, e-commerce, food and healthcare products due to their excellent durability, recyclability, and shock resistance. [4]

The Manufacturing of Corrugated Cardboard Boxes

Corrugated cardboard has several varieties according to the flute profile and faces, the structure is no more than laminating and attaching paper materials called “liners” over the “corrugated medium”. [5] The corrugated medium is also referred to as the “flute” that provides cushioning and improves the cardboard’s ability to withstand external pressures or impacts. 

Profile of Corrugated Cardboard
Credit: ELITER Packaging Machinery

To take the example of single-face white corrugated cardboard, the manufacturing process engages rolls of white sheet and packaging board (corrugated box board) being stretched and passed through their corresponding rollers and then being pasted with a 3rd roller to form the corrugated cardboard with liner, then being processed by the die which contains blades for fine cutting and ridges for crease marks and to punch the paper.

The manufacturing process of single-face white corrugated cardboard
Credit: ELITER Packaging Machinery

What are the Different Kinds of Corrugated Cardboard?

Corrugated cardboard can be identified and classified with regard to the fluting profiles and how many layers are used to form the structure.

By Layers – It is just like OREO

The corrugated cardboard is just like OREO and is an orthotropic sandwich with surfaces piled and a corrugated core (fluting) to provide bending and shear stiffness. They are glued togerher and along the edges of the facking plates (liners)  to form a wide sandwich panel.

If you are a freak of OREO it would not be difficult to understand the structure of corrugated cardboard which is no more than a layer of cream over (RE) a piece of biscuit (O) and then another piece of biscuit (O).

OREO
Credit: Know Your Meme

[SINGLE-EACE CORRUGATED CARDBOARD]

[SINGLE-WALL / DOUBLE FACE CORRUGATED CARDBOARD] 

[DOUBLE-WALL CORRUGATED CARDBOARD]

By Flutting Profiles

The fluting profile is basically about the height and shape of the corrugated medium.

[A FLUTE CORRUGATED CARDBOARD] 

[B FLUTE CORRUGATED CARDBOARD] 

[C FLUTE CORRUGATED CARDBOARD] 

[E FLUTE CORRUGATED CARDBOARD] 

Why is Corrugated Cardboard Preferred for Case Packing?

Ever since the 1930s and even now in 2023, corrugated cardboard is still the best material of choice for bulk and external packaging of all kinds of goods and is accepted in shipping and transport.

Imagine that you are a company that is looking for the ideal way to pack and contain your products with either quantity and safety and to launch them along the supply chain with an improved cost-effectiveness and reliability, there would not be any better choice than case packing basically due to the unmatched advantages of corrugated cardboard including:

The OREO-ish Structure Provides Excellent Durability and Strength

The multilayer and OREO-ish structure with liners and fluting just like a sandwich provides excellent strength and durability and allows the material to support heavy loads and protects the packaged products during handling, transportation, and storage.

Corrugated Cardboard Boxes are Impact-Resistant

The air pockets formed by the fluted layers of corrugated cardboard act as a cushioning material to absorb shocks and protect the products contained from impacts and vibrations – an ideal feature for securing fragile or sensitive items during transit.

Corrugated Boxes are Versatile in being Designed and Manufactured

Corrugated cardboard can be easily customized and designed to fit various product shapes and sizes. It can be die-cut, scored, folded, or glued to create specific packaging configurations, making it versatile for a wide range of applications.

It is Lightweight and Saves Logistical Cost

Despite being strong and durable, corrugated cardboard is relatively lightweight compared to alternative packaging materials such as wood or metal. This not only reduces shipping costs but also makes it easier to handle and manipulate in a packing or manufacturing environment.

Corrugated Cardboard Can be Recycled Multiple Times

Corrugated cardboard is highly recyclable and made from renewable resources, primarily wood pulp. It is often manufactured using recycled materials and can be recycled multiple times, reducing the environmental impact associated with packaging waste.

What are the Different Forms of Corrugated Boxes for Case Packing?

Case packing is similar to cartoning but varies in the sense that it involves a large packaging size and things to be loaded tend to be stacked. And just like cartons that come in different shapes and are automated by cartoner with various patterns and from different packaging styles.

RSC Box – Regular Slotted Cases

RSCs (Regular Slotted Cases) or American Cases are pre-glued corrugated cardboard boxes that can easily assembled by hand from folded blanks into a box with open ends.

Regular Slotted Cases are designed with four flaps of equal length and meet at the center of the box when folded. The flaps on the top and bottom can be taped or sealed with glue for added strength and security. This construction style makes RSCs highly efficient for stacking, storing, and shipping goods.

RSCs can either be handled manually for packaging now that it is easy to assemble or be automated by a case packer by top-loading or side-loading.

Flat and Unglued Corrugated Box Blanks

Flat and unglued corrugated cardboard boxes are essentially board blanks. It is a typical corrugated cardboard box (blank) for use on case packing machines and, to be specific, on wrap-around case packers. Although a wrap-around case looks like an RSC box when fully formed and sealed, it has unique advantages over an RSC case and it is perfect for industrial packaging.[6]

With regard to the sealing method of corrugated cardboard boxes, the only two methods are:

• Sealing with hot melt glue: Using adhesive or glue to seal the flaps of the box can be done with a machine or manually by applying glue to the flaps and pressing them together until the glue sets
• Sealing with tapes: The most common method is using packaging tape to seal the flaps of the box. This can be done with a handheld tape dispenser or an automated taping machine. It is important to use strong and durable tape to ensure a secure seal.

Why are Corrugated Cases Reliable? – Shear-Resistance Test

To study the stiffness of the corrugated cardboard box, we will evaluate the material in terms of shear and bending resistance.

To begin with the test, we have to define the geometrical parameters of the corrugated cardboard specimen with which we will carry out the study.

Geometrical parameters of the cardboard panel

• H: Overall thickness
• Hc: Height of Flute, core thickness of the sandwich
• p: flute step
• CD: the cross direction that coincides with the y-axis
• MD: the machine direction that coincides with the x-axis
• Flute density: 125 flutes per meter
• Liner thickness: 0.16 mm

Shear-Resistance Test of Corrugated Cardboard

The shearing test is carried out by applying transverse shearing: \( G_\text{xz} \) and \(G_\text{yz}\), with limits relative to the geometry of the tested corrugated cardboard panel which is as follows:

• \(hc \lt b/2 \), where b  is the width of the specimen
• \( hcs \lt l/12\), where l is the length of the specimen
• and hc stands for the core thickness

The corresponding effective shear moduli along MD (Machine Direction) and CD (Cross Direction) are defined with the following formula:

$$ G_\text{iz} = \frac {\tau_\text{iz}} {\gamma_\text{iz}} = \frac {\theta \cdot H} {b\cdot l\cdot} $$

where

• i=x,y;
• \( \tau_\text{iz} \) is the shear stress;
• \(\gamma_\text{iz} \) is the shear strain;
• \(\theta\) is the slope of the liner part of the load-displacement curve;
• H is the sandwich thickness;
• b is the panel’s width;
• l is the length of the panel;

The shear-resistance test is done by load-displacement test along MD and CD direction to check at which level of force loaded will the corrugated cardboard panel fails or gets deformed.

Given the experimental fact that 1 newton is more or less 0.1kg mass, we can find out that the corrugated cardboard panel engaged in this test can withstand a weight of up to some 600~1200 kg, Note the point of failure as follows:

• 6000N with regard to MD shear resistance – equivalent to 600 kg
• \(12×10^3\) with regard to CD shear-resistance – equivalent to 1200kg

Bibliography

• [1] What is Packaging? Definition, Types, Functions, Types of Packaging Material, https://www.geektonight.com/what-is-packaging
• [2] An Overview of the Reducing Principle of Design of Corrugated Box Used in Goods Packaging, Jing Chen, Yao-li Zhang, Jian Sun, Procedia Environmental Sciences 10 ( 2011 ) 992 – 998, https://doi.org/10.1016/j.proenv.2011.09.159
• [3] Gao Meifen, Wang Ninghong, Wu Guorong.History, Status and Development of corrugated box industry. Mechanical and electrical information , 2004; (05): 31-34.
• [4] Automatic corrugated box making line, Materials Today: Proceedings, Vivek Kumar Verma, Amit Agrawal, 23 November 2022, https://doi.org/10.1016/j.matpr.2022.11.116
• [5] What is Corrugated Cardboard? Different Uses And Types? 2021-02-01, Kinghome, https://kh-pack.com/sustainable-packaging/corrugated-cardboard/
• [6] Wrap-around case packing VS RSC, Enoline, https://enoline.solutions/en/articles/wrap-around-vs-rsc/