You may be convinced that PET is the revolutionary material its advocates say it is, but any choice to bottle with it is more complicated than just that. Paul Gander looks at the options open to producers looking to utilise this fast growing packaging.

Any filler moving into PET, or expanding volumes in the material, is faced with the choice of whether to source the packaging from an outside converter or produce it in-house, either from preforms or resin. A straightforward choice? Evidently not; volume and the proximity of the converter are important issues, but so too are the structure of the bottle and the structure of the end user's own filling processes.

The apparently logic-defying nature of PET supply is most striking in the North American market where converters ship truckloads of empty bottles over hundreds of kilometers of equally empty road to their waiting customers. European sales director at Constar, Francis Jackson is fairly new to the job, but this huge difference between practices on the two sides of the Atlantic is one of the features of the industry that has left the biggest impression on him.

Another international bottle supplier, Amcor PET Packaging, is also puzzled by this disparity. VP sales and marketing Phil Gunning points out that in Europe some 80% of sales are in preforms and 20% in pre-blown bottles, mostly niche containers for barrier, hot fill or other short-run needs. But in North America, these proportions are reversed. "One explanation may be because freight rates are cheaper, but for me it's still a cost," says Gunning. Other possible explanations, he says, might be the greater complexity of packs and the higher number of SKUs.

Different approach
Constar's Jackson is similarly unconvinced that the 'cheap freight' argument fully explains this phenomenon. "It must be largely to do with transport costs, but perhaps it is not that simple," he suggests. "It could also be to do with a different approach to the idea of sticking with your core business."

In other words, the US market believes that converters should convert and fillers fill. Certainly, with even the highest-volume producers such as Pepsi Cola (Constar's biggest customer in the US), adopting this approach, the theory is a convincing one. But it would be even more convincing were it not for the notable exception of Coca-Cola, which for years has pursued a policy of blowing its own PET in-house from preforms throughout its markets.

In any case, North America is the last place in the world to be dogmatic about business practices if they do not add up in terms of cost, both from the point of view of the converter and the filler. Constar has 14 plants around the US where a combination of economies of scale and added value from additional processes such as labelling means that suppliers can reduce their own costs while also limiting those that their customers would have incurred with in-house operations. In this case, the PET converter performs a service little different from that of the glass manufacturer.

There is, though, one big contrast between glass and PET: the scale of the plant needed to produce the bottle. Whether bottles are blown from resin or from preforms, the amount of space and energy required by injection and blow-moulding is a fraction of that needed by glass. Certainly for medium to large fillers, there is little to stop them from investing in their own moulding equipment.

For Gunning at Amcor, one of the issues could be utilisation of equipment. While a converter will ensure that its moulding capacity is kept busy, an end user blowing bottles in-line may average only 20 or 30% utilisation for both parts of the line. "Some people who've done the calculations say it's still worth it: you've got no storage or packaging, and you've got great responsiveness."

In-house tendency
Very often, beverage markets have developed favouring one or other of these approaches - converter supply or in-house manufacture - for historical reasons, and stuck with it largely through inertia. According to Italian blowmoulding equipment supplier SIPA, the UK market is among those that have tended to follow the converter-supplied route, while southern European fillers have, by and large, preferred to invest in the in-house option. In such markets it is even common for medium-sized mineral water fillers, for example, to blow their own bottles from resin - not from preforms. And the company believes the underlying trend is towards increased in-house production, even among as conservative an end user base as the UK.

Not everyone agrees with this analysis of the UK market, though. Amcor's Gunning says he cannot think of any major soft drinks companies in this market which source pre-blown bottles from the company, with the exception of a major soft drinks company which buys the empty bottles pre-sleeved. Meanwhile, fillers such as Coca-Cola in the UK have favoured a hole-through-the-wall supply, such as that operated by Amcor at Sidcup.

SIPA does believe that a volume threshold can be sketched out for the cost-effectiveness of in-house moulding. "In general terms, when you are in the region of 60 to 70 million bottles, or around 20 million for each of three sizes, you are in the area for using in-house production," says a spokesman. "Only a few years ago, the figure talked about was 100 million." One reason for this shift is the increase in the productivity of blowmoulding machines, he explained. In 1999, they could achieve outputs of around 1,000 pieces an hour, whereas now this figure has risen to 1,400 or even 1,500. The capital cost per cavity has, as a result, been reduced by 40%.

When French fruit juice filler Pampryl opted to move from a Barex bottle to multi-layer PET from Amcor, it was able to equal the 12 month shelf life of its previous pack. But it also gained production efficiencies, simply because blowmoulding technology had moved on so much since it had installed seven extrusion blow-moulding machines several years before. These were replaced by a single Sidel SBO 10, which blows the bottles before they are aseptically filled.

Even when the product profile of a particular filling operation is more complex, possibly including seasonal lines, SIPA argues, an in-house solution is still likely to be the best for higher overall volumes. One area where the supplier says there is less certainty is multilayer barrier containers. Of course, even when this barrier layer is required to lengthen shelf life, the bottles can still be blown in-house from preforms. With all these provisos, for any given filler reaching the recognised volume threshold for in-house moulding, any decision will come down to the company's confidence in its ability to handle the technology.

Need to invest
Attempts to cut out the converter altogether by blowing bottles from resin can go wrong, though. Since Amcor's European business makes most of its money from pre-forms, it is hardly surprising that Gunning sounds a cautionary note about fillers which reject the preform route.

Injection moulding technology has leapt ahead in the last 10 years, with today's 96-cavity machines dwarfing those of only a few years ago, Gunning explained. Unlike a filler, a converter like Amcor can keep up with this evolution. "It's our business; we have to invest to stay ahead in the technology race," he says.

For SIPA, the real struggles over the costs involved in PET filling will in future focus not so much on the issue of whether bottles are blown in-house or out-of-house, but on the question of uptime. "The crucial point from an engineering point of view is whether there is an opportunity to de-couple the blowing stage from the filling." Shutdowns at the filling stage - whether short or long - are not a major problem; but at the blowmoulding stage they can be very costly, since a moulding machine cannot start and stop in the same way.

Of course, productivity may not be the filler's greatest concern and, as SIPA points out, the in-line systems made popular by suppliers such as Sidel may turn out to offer significant benefits in terms of space limitations or hygiene. "There's no solution which optimises everything," the supplier warns. "It just depends where you want to compromise."