Let battle commence

For centuries, regular cans consisted of three components: body, bottom and top. Developments in deep drawing technology and in raw materials enabled the creation of two-piece cans, either in tinplate or aluminium. The technical and commercial developments for the two can geometries varied considerably as a consequence of the various market demands and the technical potential of the raw materials.

For three-piece tinplate cans, the replacement of soldering by welding technology in the 1970s was a major breakthrough. For two-piece cans, the development of the Drawn Wall Ironing technology in the 1960s was crucial for the creation of countless applications in two-piece cans and the starting point of a constant battle between two-piece and three-piece can making technology. The food and aerosol can markets in particular shows that this battle is still not over.

Food Can Market

The market research institute Smithers Pira valued global food can sales for 2014 at $19.2 billion. In its study, The Future of Metal Cans to 2019, it found that food can sales still increase year after year, even with the impact of the global economic crisis on the food industry crisis during the last few years. This increase is mainly the effect of the positive performance of food cans in Asia.

North America and Western Europe are today still the largest markets for food cans. In spite of threats to food cans, including the high degree of saturation of the food can market and the substitution in favour of fresh food products in countries with high incomes, a major increase in demand in developing countries is preventing a decline in global food cans sales. In particular, meat and canned fishery products are forecast to make the biggest gains in these developing countries. Within this global market for food cans, there has been some turbulence in the last few years as operations director Aerosols Europe of the Ardagh Group, Cees Verboom, observes:

“What we have seen in the last few years is a considerable shift from three-piece food cans to two-piece food cans in the USA and Western Europe for segments in which this transition was justifiable. Be aware that you need a considerable amount of uniform can volumes to justify the investments in a DWI line.”

Over a five year period, Ardagh installed several new DWI can making lines in the USA, France, the Czech Republic and the Netherlands. “The most important rationale for our customers and for us is the huge downgauging potential of the next generation can (Nemo) versus modern three-piece cans, leading to significantly lower material costs,” said Verboom. “The application of our innovative NEMO technology, based on liquid nitrogen injection of cans, further extends the potential for a shift to two-piece cans.

“In the US we manufacture DWI cans ranging from diameter 65mm to 83mm and looking at the market size, we see a future in Europe for a further shift from three-piece to two-piece DWI cans. On the other hand, there are of course metallurgical limits to the degree of deep drawing in the DWI process, so not all can geometries, like diameter 99 mm cans, lend themselves for the DWI process.

“Of course there will always be many, particularly in the food can market, for which the three-piece can is the best possible format,” commented Verboom. “In emerging markets, the can quantities are not large enough nor usually uniform enough to justify the huge investments in DWI lines, not to mention the so-called nutrition cans, infant formula, milk powder, coffee and other powders and the quite differentiated general line cans for non-food products. Therefore the search for further downgauging of three-piece cans is certainly worth pursuing.’’

Three-piece aerosol cans

Aerosol cans owe its success primarily to the excellent convenience they offer to the user. Invented in 1927, the aerosol can began as a three-piece tinplate can, though the top end had the special shape of a dome to allow for the dispensing system. Later on, two-piece extruded aluminium cans appeared on the market. The global market grew to a total production of over 12 billion cans in 2015; within this, Europe still leads in aerosol production with more than 5.5 billion cans produced per year. Aerosol can production is still growing year after year and there is lots of development.

For decades there has been competition between three-piece tinplate aerosol cans and two-piece aluminium aerosol cans. Most producers create aerosol cans in either tinplate or aluminium, but after its takeover of the Boxal Group some years ago, the Ardagh Group, one of the major aerosol can producers in Europe, uses both materials. It gives Ardagh a very valid insight into the developments for aerosol cans in both materials as Verboom observes:

“In the last few years, monobloc aluminium aerosol cans seem to be fashionable in Western Europe. However, this impression is somewhat false, commented Verboom. “In fact, the personal care segment, where products like deodorants and all kinds of sprays are mostly packed in aluminium aerosol cans, has a much higher growth rate than the average rate in aerosol cans. Both materials have printing possibilities, but in fact the most modern printing technology for tinplate aerosol cans, which are printed on flat tinplate sheets, is superior.

“There is however one unique design feature for aerosol cans, which weighs heavily in its favour, particularly in the personal care segment and that is the fact that brand owners are able to design an excellent integration of the plastic spray cap and the aluminium aerosol can for their up-market brands. More than once the big brand owners have registered this total product proposition worldwide as proprietary designs. In three-piece steel aerosol cans, such integrated designs are much more complicated.”


In the past, aluminium was more expensive than tinplate as a raw material for aerosol cans. This barrier has disappeared as prices for aluminium can stock are at a historically low level. The process used to produce monobloc aluminium aerosol cans is extrusion. The extrusion ratio diameter x height has clear limits and therefore certain market segments, like for instance Poly Urethane with its can heights of up to 300 mm, will always need tinplate aerosol cans.

“For these quite big market segments, it remains important to enable downgauging by making the existing tinplate harder, like the tinplate producers are doing,” said Verboom. “Whereas the requirements for aerosol cans regarding the burst pressure they have to withstand go up from 15 to 18 bars and may be even 21 bars, we have been able to downgauge aerosol cans, that were earlier produced in 0.18 mm tinplate, to lower gauges today by using the new harder materials. I would say, such drastic downgauging is even more important in cost terms than upspeeding the machinery to make the can.”

In this context, Verboom points at an interesting innovation in the aerosol can market, namely the introduction of a two-piece polymer-coated steel aerosol can.

“In the US, the company DSC produces a kind of a DWI process two-piece steel aerosol cans. The company uses steel from Tata Steel that is coated with a PET layer, called Protact. It is such a success that Tata Steel is expanding its capacity in Belgium for this Protact steel. North American companies like Conagra are using these two-piece steel aerosol cans on a large scale for whipped cream. The company DSC is a Japanese-American partnership, in which the Japanese company Daiwa Can applies the technology, developed for its new ‘Bottle Can’.

“As you can see, the competition between the raw materials steel and aluminium, and between two-piece and three-piece can making technologies, carries on in food cans and aerosol cans,” said Verboom. “I don’t think there will ever be a dull moment in this battle.”

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