Know about Corrugated Boxes
All You Need to Know About Corrugated Boxes: A Comprehensive Guide
- What is a Corrugated Box?
- How Corrugated Boxes are Made
- Fiberboard in Manufacture Corrugated Boxes
- Types of Corrugated Boxes
- And much more
What is a Corrugated Box?
A corrugated box is a disposable container whose sides are made up of layers of material that include an inside layer, outer layer, and middle layer. The middle layer is fluted, which means it is styled in rigid, wave-shaped arches that provide cushioning and support for weighted materials placed in a corrugated box.
The common cardboard box has been around for over 200 years. The practice of adding flutes for corrugation began in the middle of the first industrial revolution. Over the years since its development, the corrugated box has become the most common form of shipping container and is found in every aspect of material management and transport.
How Corrugated Boxes are Made.
Though the construction of a corrugated box may seem to be a simple and easy process, various elements have to be considered prior to beginning manufacturing. As with all manufacturing and shipping equipment, corrugated boxes are designed and engineered to determine what they can hold, how much, and their strength.
The first step in box manufacturing is to examine the various elements of the box, which are construction, flute size, burst strength, edge crush strength, flat crush strength, the heaviness of the cardboard sheets, weight of the paper, and types of surface treatments.
Elements of a Corrugated Box
Single Wall - This is the simplest corrugated wall design, with a single outer layer and inner layer with fluting between the two layers.
There are five common types of corrugated flutings, which are A, B, C, E, and F. Though these are standard, manufacturers and designers can create and construct customized versions, which can be combinations of the standard versions or unique, unusual designs.
Aside from the five above flute styles, there are specialty flutes that are combinations of the above flutes or that fall between the regularly used flutes, such as D flutes. Other special flutes include EE, EF, and BC, which are used with double wall flute profiles. Flutes such as N and O are rarely used and are extremely small at less than half a millimeter.
- A – is the original type of flute at 36 flutes per foot and is used for double wall applications and thick corrugated padding.
- B – has the second highest arch size with 49 flutes per foot and has stacking strength and crush resistance.
- C – most commonly used flute with 41 flutes per foot for cushioning, stacking, and printing properties.
- E – second common flute, environmentally friendly with 90 flutes per foot.
- F – has small, tighter flutes, and is environmentally friendly with128 flutes per foot.
Mullen Test (Burst Strength)
The burst strength of a corrugated box refers to the amount of force that can be applied before the material ruptures, cracks, or falls apart. The Mullen Test, which was developed over 130 years ago, applies force to the face of the corrugated material until it bursts. The results of the test are given in pounds with a rating. For example, a box rated at 200# can withstand 200 pounds (90 kg) of force per square inch. The results of the Mullen test offer data regarding the amount of force per square inch required to burst through the paper on a corrugated box.
The Mullen test is an indicator of how a box will endure its treatment when it is being shipped individually and subjected to the rough handling of assembly operations and mail carriers. As it moves through the multiple distribution channels, the contents of the box are more likely to move inside and possibly cause a puncture.
The flaw with the Mullen test is that the fluted medium doesn't add to the bursting strength of the box. This isn't to say the medium isn't important because 50% of the stacking strength of a box comes from the medium. This is where the Edge Crush Test comes in.
Edge Crush Test (ECT)
The ECT test measures the vertical compression strength of a box and serves as an indicator as to how well a box will react to being stacked for shipping or placed on a pallet. It is a sensible and reliable test to determine how well a box will hold its form during transit and while being handled. The ECT test is a "performance-based" property test rather than a "material characteristics" test. The ECT of a box can be influenced by several factors, which include humidity, amount of time a box remains stacked, amount of crush from going through a production machine, and the stacking pattern. A box that tests with an ECT of 55 will be able to withstand 55 lbs (25 kg) of pressure.
The basis weight is a measurement of the weight of cardboard sheets before being made into boxes and is the weight, in pounds, of a ream of paper. Since paper comes in different sizes and widths, the basis weight can vary and must be calculated by measuring and weighing a piece of paper
The weight of cardboard is dependent on how thick the cardboard paper is. The weight of the paper to make the sheets of corrugation is measured in pounds, which can vary from 26 lbs. to 42 lbs (11.8 to 19 kg).
During the production of corrugated boxes, coatings and finishes are applied to protect the stability of the box and give it a certain appearance. There are two basic types of coatings, which are aqueous and UV
Producing Corrugated Board
The machine that produces the corrugated board for corrugated boxes is called a corrugator. The main elements of corrugated board are liners that are the flat facing of the board and come from various grades of paper. This central element is made from the long fibers of softwood trees.
The fluted portion is made from shorter fibers found in hardwood trees. Huge rolls of paper are combined in a single facer that produces the fluted form. To create the flute, the paper is steam heated to 338 ° F (170° C). The fluted paper is attached to a single sheet of the liner by the application of glue at a controlled temperature to the peaks of the flutes and pressed flat by pressure rollers. This produces the single faced web.
Finalizing Corrugated Boxes
The scored, printed, and cut corrugated boards are fed into a trimmer that perforates the boards to create flaps and handles. This process can complete as many as 90 boxes per minute. Once the boxes have been sufficiently formed and trimmed, they are sent on to the folding machine that bends the box along the score lines and applies glue to the sections that will be joined together to complete the forming of the box.
Uses for Corrugated Boxes
What we consider to be the common shipping box is one of the most used shipping tools available to manufacturers for use in shipping their products. Since corrugated boxes can be designed and produced to fit nearly every shipping need, they are one of the most omnipresent and accessible logistical devices.
Corrugated boxes are famous for their structural rigidity and protective cushioning for shipping fragile and delicate items. There are countless advantages to using corrugated boxes that can be customized to fit any type of shipping need.
An important reason that corrugated boxes are used by the industry is the ability of box manufacturers to print on the boxes and place a company‘s logo. A clean image of a company‘s logo goes a long way to promoting its brand and making it recognizable. Boxes are an inexpensive way of making a company‘s image unique and distinct.
Fiberboard for Corrugated Boxes
he material used to make corrugated boxes is corrugated fiberboard, which comes in different thicknesses and grades. To produce the highest quality corrugated box, the fiberboard used in the process has to include the best paper and fluting. Corrugated fiberboard is a packaging material made by gluing fluted corrugated sheets to flat linerboards. The advantages, structure, and eco-friendly nature of corrugated fiberboard have made it an essential part of the supply chain for many industries.
Single wall fiberboard is one row of fluting pressed between two liners. The most popular flute profiles for single wall fiberboard are A, B, C, E, and F, with B and C being the most common.
Basically, double wall corrugated fiberboard is a double version of single wall fiberboard. Instead of one set of fluting, it has two that are positioned between two liners or facings with a medium positioned between the flutes, which are normally AC, BC, and EB.
As the name implies, triple wall fiberboard has three lines of fluting. Though it may be assumed that the three lines are similar to the lines of double and single fiberboard walls, in triple wall fiberboard, the fluting lines can be the same or of different sizes with varying numbers of flutes. The paper on the outside of the flutes is referred to as liners or facings. The paper between the flutes is called the medium.