Engineering Competence

Packaging solutions benefit from sophisticated design approach

Following a review of its packaging for larger bearings, SKF decided to embark upon the development of an improved design that would meet demands for robustness, safety and recycling and would reflect the high quality of the contents.

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Following a review of its packaging for larger bearings, SKF decided to embark upon the development of an improved design that would meet demands for robustness, safety and recycling and would reflect the high quality of the contents.


Both customers and SKF staff were involved in the consultation process and first evaluations of a new packaging solution, the SKF ProofBox, which took place in Sweden in mid 2000. The design team developed a set of broad criteria for the new packaging that covered safety, environment, product protection, handling, production and branding.

From a user point of view the new packaging needed to enable safe handling with minimal risk of injury to those handling the package or damage to the contents. Environmental friendliness and the ability to recycle and dispose of the packaging safely was another user requirement, as well as tamper detection to identify if the package had been opened.

To protect its contents, the packaging needed to be robust and to keep bearing rollers in place to avoid damage from vibration during transport. It needed to seal securely and not include any packing material that might pollute the bearing with loose particles. It also had to allow the bearing to be transported “ready for use,” and thus not be wrapped in plastic or oilpaper. And the packaging had to meet SKF rust protection demands and stand up to air transport in a non-pressurized cabin.

The design needed to take into account movement and storage, including the ability to transport the package using a forklift truck, to load it efficiently on a half pallet, and to stack packages both symmetrically and asymmetrically. It had to be possible for the bearing to be safely lifted out of the packaging by using, for example, a lifting strap.

Production demands were equally strict, with the goal of mass manufacturing series of more than 100,000 per year on automated production lines. The empty packaging had to be stackable, able to accommodate some 45 different bearing sizes in the weight range of 30 to 96 kg and not create additional waste problems within the factory.

Finally, the packaging needed to support SKF branding by reinforcing the group image. It needed to create a clear visual identity of the content – and be difficult for competitors to copy.

The first model was produced on a scale of 1:1 in laser-hardened acrylic plastic. The model showed clearly the need for a design to achieve the desired image and the problems involved in producing packaging that would be able to accommodate a number of different bearing sizes. The packaging principle that satisfied all the demands presented was a hard, injection-moulded protective shell. The best choice of material turned out to be transparent polypropylene. The material is easy to inject and is impact-resistant, environ-mentally friendly and relatively cheap. Injection moulding is rational and cost-effective and well suited to mass production of this type of product.

Through computer modelling, using a bearing as a template, it was possible to work out the best packing solution. In addition to the practical issues, the design needed to reflect SKF’s image and core values. Ideally, the packaging needed to be as close to the size of the bearing as possible. Transporting air is an unnecessary cost, although approximately 15 mm of air around the bearing is necessary to provide space for deformation zones.

Two different appearances were developed: a circular shape and a square shape. The most natural shape for a bearing is a circular packaging, although there was a great deal in favour of square packaging, such as labelling, closing, etc. Industrial design is a balance between creativity and limitations imposed by the requirements of the packaging system.

The packaging was divided into two halves and joined horizontally using tape.

The tape had two purposes: to keep the packaging sealed and to indicate whether someone had opened the packaging. The labelling was large and clear, to make it easy to read but also to keep the two halves of the packaging together.

Apart from the SKF team, GEJI Industri AB, a plastics manufacturer, MBS-Plastic, a supplier of raw materials for plastics, and an industrial designer were involved in the project.

The packaging needed to be able to accommodate around 45 different bearing sizes in the SKF Explorer class, with a variation in outside diameter of 270 to 420 mm and weights of between 30 and 96 kg. The original idea was to solve this using different inner shapes for the packaging. This could be done but required the addition of loose inserts to the main tool. Each bearing size would have its own unique packaging.

The problem was to find a package that could cope with 45 different bearing sizes without the tool costs being excessive. The solution was an outer shell with loose inserts that were unique and that gripped the different bearing sizes. The idea of loose inserts was based on the fact that it is cheaper to produce smaller plastic tools than to produce large, costly ones. It is also cheaper to injection-mould small parts with shorter work cycles and at lower pressure than larger parts. The plastics manufacturer could use smaller injection-moulding machines and reduce the manufacturing cost. The inserts could be designed as a thin supporting “skeleton,” with minimum requirements with regard to finish, and at the same time low-cost tools could be used.

Handling all bearing sizes with a single shell, however, did not prove to be practical. By creating three different outer shell sizes, all size variants could be handled and good economy could be retained. In the development process, the focus was on a packaging for bearings in the size range of 270 to 340 mm. If the solution functioned in practice, it would be simple to scale up to a larger packaging shell using larger inserts and, in doing so, handle larger bearings.

The evaluation of loose inserts proved that the idea was viable. The work that ensued was to see if all the demands in the specification could be met.

One important demand was stacking, with the requirement of being able to stack to a height of three packages placed with a base of four on a half pallet. When stacked, these could be secured with a strap. The solution for stacking was the creation of an indentation in the top half of the package that fitted into the feet on the bottom half. In doing so, the packaging on top was prevented from sliding off. During the evaluation it was shown that the idea was functional.

The packaging needed to clearly show whether someone had opened it, and it had to be difficult to re-seal. The solution was a box divided horizontally into two halves in the middle. These halves overlap and the slit is sealed with tape. The tape cannot be removed without it being destroyed. To make it even more difficult for an unauthorized person to open the packaging, the product labels were placed across the tape. To make sure that the packaging could not be opened unintentionally, four straps were placed crosswise around the packaging.

With the new packaging it was envisaged that a packaging line with robots could be introduced. When samples became avail-able, it was possible to prepare production for the introduction of the new packaging.

Before the SKF ProofBox was launched, an intensive test programme was initiated:

Rust protection in climate chamber.
Transportation tests (truck, train, boat and aeroplane).
Loading tests.
ASTM handling tests by external packaging and transportation institute.

A comprehensive life-cycle assessment was also made by an external packaging and transportation institute to safeguard environmental friendliness.

The SKF ProofBox has been in production since mid 2002. An evaluation has also been done with a box for large bearings up to 250 kg. Currently more than 100,000 SKF ProofBoxes are handled per year on three production lines. The box covers bearings in the size range of 270 to 420 mm outside diameter. Forty-five inserts cover the different bearing sizes.

The project has been very successful. A survey showed that SKF’s customers are very positive about the new packing system.

The success of the SKF ProofBox can be attributed to the fact that SKF set up a project group at an early stage and brought in expertise from different sectors, adding creativity to the process. SKF invested in tools to test whether the packaging idea functioned in reality. With the aid of the sample packaging, all the weaknesses could be traced and rectified before costly investments were made.

The SKF ProofBox is design protected in most industrial countries.

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