How cardboard boxes are made
Made from renewable resources & easy to recycle
Making corrugated cardboard boxes involves a number of processes, which can be quite interesting. Would you like to learn some of the basics?
Trees into Kraft paper
One of the first steps is that trees have to be converted into Kraft paper. The most common trees used for this process are pine, spruce, fir and silver birch. These kinds of trees have long fibres, which gives the Kraft paper a high tear, split and burst resistance – which are all good qualities for stronger paper, aren’t they?
Trees such as these above are natural and renewable resources, which means they can be replenished over time. Responsible management involves planting new trees when existing trees are harvested, and that means less harm to the environment, doesn’t it?
The look and colour of Kraft paper can depend on the trees it’s made from. It can vary from light to dark brown and even a yellowish colour at times.
The process of making Kraft paper involves pulping wood chips, which starts with the tree trunks being stripped of bark and torn into small chips. These chips are then placed in a large high pressure tank and cooked in a solution of mainly alkaline based chemicals. The wood chips convert to fibres after the pressure is released. Quite amazing, don’t you think?
In trees there’s a glue like substance called lignin which binds the individual fibres of the tree trunk together. This lignin is no good for making paper, so it needs to be removed.
The alkaline solutions used in cooking help dissolve the lignin and increase the strength of the pulp. This is often referred to as the sulphate process and is where the name Kraft comes from, as it’s the Swedish word for ‘strength’.
After various other steps, the fibres are made into heavy rolls of Kraft paper ready to be made into cardboard.
Kraft paper into corrugated cardboard
Corrugated cardboard usually has at least three layers – an inner and an outer liner with a wavy corrugated section sandwiched in between. This corrugated section helps give the cardboard its strength and impact protection, which is important when packing, isn’t it? The corrugating process occurs on machines called corrugators which can be as large as football fields. Picture that!
Some rolls of Kraft paper can be used for the corrugating medium in between, and other rolls can be used for the inner and outer lining. In the corrugator the various rolls of paper are crimped and glued together to form the corrugated cardboard which is ready to be made into new cardboard boxes, some of which you can buy here.
Corrugated cardboard into boxes
After the Kraft paper has been converted into corrugated cardboard a slitter scorer then scores and cuts the continuous sheets of cardboard into large box blanks ready to go to other machines for further processing, which commonly includes trimming, gluing and printing.
For instance, various machines fold the boxes along the scored lines and then glue or stitch (staple) the blanks in the appropriate places. The sections are folded together to form the finished product which is a corrugated cardboard box, something you’ve probably used many times before, right?
The finished flat boxes are then banded together and stacked ready for shipping. You can easily buy new cardboard boxes on our site.
We’re pleased to say that environmentally friendly processes, such as recycling, have continued to grow in importance and it’s very common these days that instead of virgin fibres from trees being used in the manufacture of cardboard, that most of the content of cardboard is recycled material – which seems like a step in the right direction, wouldn’t you say?
In Australia most, if not all, new cardboard boxes have a percentage of recycled cardboard in them. Even with boxes predominantly made from virgin Kraft board, the corrugation in between the liners is usually made of recycled board.
Today many boxes are made from 100% recycled material, sourced from existing cardboard, such as second hand boxes, and also from other second hand paper products. Instead of tree fibres, the recycled materials are the starting point and they go through processes such as de-inking and removal of other impurities and then continue through many of the same processes that virgin Kraft does when it’s made into cardboard boxes.
Recycled board is usually distinguishable by the minor imperfections in its appearance when compared with virgin Kraft.
One of the qualities that makes cardboard so simple and environmentally effective to recycle is that the fibre has already been processed. According to Planet Ark, using recycled material to make cardboard boxes means that,
“…large amounts of water (up to 99% less) and energy (up to 50% less)” are saved
In addition, there are also less by products and wastes associated with recycled cardboard, which also seems great for the environment, doesn’t it?
A win for the environment
Another incentive for manufacturers to make cardboard from recycled material is that it’s much cheaper to make. Recycled material doesn’t have to be cooked or washed to have the lignin removed and this means reduced costs.
As a result of both its ease of recycling and the cost savings involved, it’s likely that the use of recycled material to make cardboard boxes is only going to continue to grow in the future – and isn’t that a tremendous win for the environment?