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May 1, 2002

20 Min Read
WEB EXCLUSIVE : Blowmolding is alive and ready to kick


This Hesta Graham dual-station, long-stroke shuttle machine came onto the market three years ago in a monolayer design. It is now making bottles with three or more layers, primarily out of olefins, for food, beverage, personal care, motor oil, and other applications. Depending on the bottle size and the number of heads, production can range from 750/hr (5-liter bottles) to more than 6000/hr on an undisclosed application.

Blowmolding machinery suppliers say the market is still slow. Sales of new blowmolding machinery are off by 50 percent or more compared with a year or two ago. Yet, there is a distinct tone of optimism, albeit guarded, for the future. Processors in both the industrial and packaging markets echo this optimism, though it appears stronger in the latter due to a high level of consumer activity.

SPI statistics put the number of industrial blowmolding machines sold in 2001 at about half the number sold in 2000. In the packaging sector however, the number of new machines installed in 2001 was about the same as in 2000. The dollar value of the total sales was noticeably lower, indicating that smaller machines were moving. Franz Strohmaier, vice president of operations for Bekum America, (Williamston, MD) says this is largely because the economic slowdown has reduced available capital and managers are simply using what they have rather than buying new equipment. He stressed that the slowdown's effects vary considerably by market segment.

Though there is definitely life on the industrial side of the business (see sidebar at bottom), machinery suppliers generally agree there is more activity in packaging markets. Machinery sales slowed in the last 12 months as the economy slid downwards, but processors have continued process and product development.

Consumer marketing companies are constantly looking for ways to differentiate their products from the competition's and to create packages that catch the consumer's eye in busy supermarkets. Tony Hooimeijer of SIG says the range of applications in the PET market is widening, while at the same time there is growth in established market segments.

He splits the market into commodity (high volume) products like soft drinks, and specialty markets where lower volumes provide interesting challenges for the package converter. Besides the challenges of low volume, there's also the wide variety of container sizes, and the limitless variables including shapes, substances being packaged, hot-filling, and labeling.

Production volume has the greatest bearing on whether a PET container is done in a two-step process—injection molding the preform, then blowing it into shape—or a one-step system where the preform is made and blown inline. As a rule of thumb, lower volume applications run on systems that combine the two steps and higher volume applications are done in two steps. Certainly there is overlap, particularly as a specialty product becomes established and its volume increases.

What the market demands of machinery to serve the two principal segments, says Hooimeijer, is what you would logically expect. In the high-volume commodity markets, high value is placed on machine uptime and overall output. Producers want a robust machine so the application can run nonstop at high volumes. Specialist bottle and jar producers have lower volumes of a given product, but speed and fast changeovers are a necessity.

Based on market statistics it appears production numbers are greater in the commodity areas, but Hooimeijer says the growth is in the specialty markets, with the exception of water. In addition, specialty products, assuming they are successful, may grow quickly, perhaps even to the commodity level. Hooimeijer cites Gatorade as an example of a product that has had such growth.

The jump from a one-step integrated bottle making system to a two-step process of separate injection and blowmolding is a big one. Though the outputs of one-step systems vary, SIG's popular Ecomax 10/2 typically produces about 2000 bph (bottles per hour), depending on bottle size and shape. A two-step process can produce up to 40,000 bph—clearly a different realm.


Packaging plays a critical role in consumer marketing, but cost is also a factor. When Bacardi-Martini launched its Tropico drink in 1998, it wanted the plastic bottles to look exactly like its 750-ml frosted-glass bottles. Captive Plastics (Piscataway, NJ) and PolyOne, its colorant supplier, developed an injection stretch blowmolded PET bottle made with a custom-formulated color concentrate called FX Frost, and a finely textured mold surface to achieve the matte look. The process yielded a 40 percent reduction in bottle cost compared to the original solution (a sprayed-on, UV-curable matte coating), and did not change any of the original processing parameters.

There are all manner of variations possible within this enormous range, and many machine manufacturers are moving to serve specific segments. Husky (Bolton, ON), for example, is a major supplier of molds and machine systems for high-volume PET preforms. At the K 2001 show, Husky introduced its first 144-cavity mold for high-volume production. At the same time it presented the Index SB integrated preform injection molding and blowing system for in-line production of lower volume (50 million parts/year) applications.

Husky is very clear that it is not turning away from the high-volume markets, but instead is reacting to the growing need for lower volume machines with high production efficiency. Machinery companies are exerting considerable effort to serve these varying needs. For example, the SIG Group is the combination of long-term blowmolding suppliers such as Krupp Corpoplast, Krupp Kautex, Fischer, and W. Muller, and also includes Simonazzi, a full packing line systems integrator, labeling system supplier Alfa, Hamba Filltec, and SIG Moldtec, which supplies both the injection and blowmolds for PET systems. Joseph Spohr, vp of global sales for the Graham Machinery Group (York, PA) says his company is offering everything from its very small German-made Hesta one- and two-cavity machines, to double-sided Hesta long-stroke machines, to the high-volume rotary wheel systems designed and built in the U.S.

Spohr says that in the ongoing contest between plastics, metal cans, glass, and cartons, plastics are steadily gaining share. Much of this can be attributed to converters having technology they did not have or could not afford five years ago. Multilayer technology is no longer exotic, nor is in-mold labeling. The output, precision, and repeatability of production systems has improved dramatically. According to Spohr, Graham has invested heavily in research and new product development over the past few years, and virtually the entire current product line is different from three years ago. The machines not only offer more cavities, they go faster. Servomotors controlling machine motions offer speed that can be up to 50 percent faster than a few years ago with very precise repeatability. Scrap rates have also been slashed.

PET is not the only important material, by far. Spohr says unless a drink really needs a clear package or has to be hot-filled, the lower cost of olefins is a powerful factor in material choice. The image quality, colors, and gloss of shrink sleeves and labels give marketers the tools they need to create the attraction and image properties they want for their products. This is largely a converter-served market, says Spohr, and in the U.S. the converter base continues to consolidate although the rate has slowed appreciably lately. The number of converter companies now is about half of what it was five years ago.

The market shares of one-step and two-step PET systems are markedly different between the U.S. and Europe. The 15 European Union countries have a combined population larger than the U.S., but they are still 15 countries with at least 15 different cultures and unique food and drink preferences. Therefore, Europe has more one-step systems for its higher number of smaller volume specialties, while the relatively homogenized U.S. culture creates higher volumes for successful food and drink products, allowing more two-step production.

Hooimeijer says the PET container market in the U.S. has matured considerably and overall growth rates have slowed to about 8 percent, but this will vary by segment, sometimes greatly. The high-volume carbonated soft drink market now has relatively flat growth. Bottled water, particularly single-serve bottles, is in high-growth mode—with large players like Coke (Dasani) and Pepsi (Aquafina) involved, the volumes are quickly rising to the commodity level, if not already there. A high percentage of specialty PET packaging is hot-filled, such as Gatorade and the variety of fruit juice-based drinks on the market, and some have already reached commodity volumes.

The food and beverage packaging markets, says Spohr, are moving along quite well considering the depressed state of the economy. Like many others, he cites the single-serve drink market as a driving force—in particular, the emerging categories of dairy-based drinks such as liquid yogurts and flavored milks. The PET producers are contesting this market but many packages are being designed for olefins such as HDPE and to a lesser degree, PP. Hooimeijer notes that the conversion from glass to PET continues and also plays a role in the new milk-based drinks. The dairy industry, he says, would prefer that its products not be perceived as commodities, so it has been creating branded products with higher margins. Most, but not all, of the branded dairy bottles, he says, are being produced in two-step systems.

The oft-discussed market for PET beer bottles is still to be decided. One driving force, the so-called "venue" markets such as athletic fields and arenas, are a lot less sure than they were. Cans are also light and unbreakable, and full plastic bottles can be thrown just like any other object of that weight and size. Given that prices are still higher than glass, there are no major incentives for the breweries to convert. The multi-layer technology used to make beer bottles is closely guarded by the converters, but the machine technology is much the same as for other similar-sized PET bottles.

The steady growth of in-mold labeling (IML) of extrusion-blowmolded consumer packages is the combined result of factors in the market and in the factory. Franz Strohmaier says marketers are extremely attuned to the quality and aesthetics of product labels, including subliminal effects. The look and feel of a product can easily be the deciding factor, particularly in the store, and IML offers a wide variety of aesthetic choices and excellent quality. On the other hand, production specialists want process integration, intending not to let go of the product until it is done. IML supports both factions. Although, strictly speaking, IML brings a cycle time penalty—usually between 1.5 and 2 seconds—downstream decorating adds logistical complications. Further, robotic label insertion systems will align and position labels better than most downstream processes, and adhesion is excellent without the need for an adhesive. Polymer labels are easily matched to the package material in advance.


This selection of various automotive tubes and pipes shows the kinds of twists, turns, and shapes that can be achieved using 3-D/suction blowmolding.These components were made by Miniature Precision Components (MPC) on a suction blowmolding system from the SIG Group (see sidebar below).

IML is currently more accepted in North America than in Europe, where most package decoration is still done downstream. Bekum alone has more than 40 double-sided systems with IML installed in North America. When it is used in Europe, it is on single-sided machines. Strohmaier notes that IML is certainly not new. It has been used on wheel machines since the mid-'80s, however more engineering creativity was needed to make it work on shuttle systems. At this point IML is an integral part of the American market. Hooimeijer says that more of this IML work is in fact moving to shuttle machines for easier positioning of robotics, more precise label positioning, and better overall quality control. Wheel machines like GMG's, however, still account for the largest share of IML activity.

Compared to just five years ago or less, blowmolding machines in general are faster, more precise, and have more cavities for higher output. Naturally, that takes a lot of engineering on drives, shuttles, mold open/close mechanisms—just about everything.

Yet, machine makers say the key to productivity and quality is the power and ease of use in the controls. Maintaining parison thickness is more critical than ever as more packages are designed in six or more layers. While machines have to be able to clamp up on the extruded parison consistently at higher speeds, says Strohmaier, it is the controls that maintain cycle-to-cycle consistency as speeds increase.

Strohmaier was formerly in the injection molding business, which gives him an interesting perspective. Blowmolding, he says, demands a lot more skill and know-how from the operator as compared to injection molding. It is still as much art as science, so skilled operators are critical to success. Fortunately, a lot of progress has been and is being made in automation. It is not easy to find skilled people for every shift when you are running nonstop as most blowmolders are or want to be. To resolve that problem, control systems must be simpler and more intuitive.

The consensus among machine suppliers is that the industrial side of the blowmolding business has slowed more than packaging, but it is poised for recovery, particularly in certain markets. The industrial markets, products, and materials are more diverse than in packaging, and of necessity so is the production technology. According to Wolfgang Meyer, president of SIG Kautex USA, much of the productivity and quality gains over the last few years in automotive, toys, and other industrial blowmolding markets are also based on major improvements in control technology.

One of industrial blowmolding's hallmark applications, automotive fuel tanks, is currently in a state of limbo thanks to new California standards for hydrocarbon emission. More than 60 percent of the fuel tanks in North American cars are now blowmolded in as many as six layers. The impact of the new regulations is not yet clear, but they raise the specter of a return to metal tanks. Automakers do not want the higher production cost, added weight, and design limitations of metal. The possibility of thermoforming the tanks is being investigated by several suppliers. This allows external components that can be sources of hydrocarbon leakage to be put inside the tank, but there is concern about the integrity of the welds between the formed halves. In addition, many producers have relatively new blowmolding machines and do not want to buy thermoforming machinery, despite its lower capital cost.

As in packaging, many processors serving auto markets with air and exhaust ducts, interior knee bolsters, and other similar components are not upgrading their industrial blowmolding machines. Current cash flow does not permit it. Meyer notes a similar situation in other markets. For example, the industrial drum market has also been stagnant in terms of new machinery investment. He describes a scenario where a processor could replace three older generation machines making 30 to 40 drums per hour with a SIG Kautex double-station machine making 80 to 100 drums per hour. The processor could gain a significant market edge with this move in terms of lower cost and higher quality. Machine orders are slow, so as an added bonus a processor can expect faster than normal delivery. Meyer notes that some processors have been upgrading their existing machines, for example retrofitting one of SIG's double heart curve heads made to handle materials as viscous as HDLI 2. This allows a reduction in wall thickness, lower weight, and material savings—all coupled with improved quality.

There may also be some action in 3-D molding on the horizon. Though it has taken hold in Europe, there are still just a few machines in North America. A major reason is that Europe has a large and growing market for the complex-shaped tubes that can be produced using 3-D techniques. Diesel cars and light trucks are popular there for fuel economy, and diesel engines require complex-shaped tubes. In the U.S., diesel engines are used mostly in large trucks and industrial equipment.

The benefits of the 3-D process are not limited to complicated shapes. The 3-D process offers virtually scrap-free production, finished parts without side seams, and can extrude hard and soft materials sequentially to create flexible joints in parts up to 2m long with 18-mm diameters (see photo). Miniature Precision Components (MPC) in Walworth, WI, has a suction blow molding 3-D system working now (see sidebar at bottom).

The ongoing debate in the injection molding world over the relative merits of hydraulic, electric, and hybrid machines has echoes in blowmolding. Bekum's position as a machine supplier is that it only makes sense to switch to another drive technology if there is a noticeable benefit to the processor.

Quiet, precise movement, and a cleaner environment are good arguments in favor of electrics, says Franz Strohmaier, who thinks smaller blowmolding machines will be mostly electrically driven in the mid- to long-term.

In smaller sizes, fully electric machines offer the same benefits of speed, precision, and energy cost savings as they do to injection molders. Strohmaier says economics still rule out electric machines in larger sizes, a position shared by many—though not all—injection machine makers. Bekum showed a fully electric stretch blowmolding machine at K 2001 to demonstrate its commitment to this technology.

In the case of extrusion blowmolding, many machines in the field have had electromechanical extruder drives for some time. That, says Strohmaier, is where energy consumption is greatest. The other main and secondary movements of a blowmolding system have linear movements, making a hydraulic drive efficient, especially if a high level of power is needed. If the hydraulic system is designed and sized properly, he says, movement is produced very efficiently.

Meyer sees all-electric technology making slight inroads in small machines with few cavities. Hybrids are more frequent among the industrial machines. Electric motors are being used for mold closing but the critical final pinch-off requires the higher force of hydraulics. As with injection molding machines, it is an open question as to whether electric motors can be competitive in larger size machines. Servomotors have shown some cost drops recently, but larger ones still carry relatively higher price tags than comparable hydraulic systems.

Editor's note: Robert Neilley is a contributing editor to PA&M and a senior editor for Injection Molding Magazine.

Auto supplier striding ahead with suction blowmolding


Two years ago, Miniature Precision Components (MPC) of Walworth, WI was already using injection molding, extrusion, and other forming technologies to supply a wide variety of components and assemblies to the automotive industry. Among its products are a large number of tubular components of widely varying sizes and shapes for applications including secondary air induction and emission control systems, vacuum systems, and idle air bypass assemblies.

MPC had been looking at blowmolding for some time. When it came across suction blowmolding (SBM) it saw a way to offer auto engineers design freedom in shape creation, high product quality in large-diameter tubular products, and cost savings. Management also viewed SBM as a process that would allow MPC to compete for new products.

The company acquired a BlowTec SB 15 suction blowmolding system from the SIG Group (photo below) and began development projects with several of its auto customers. Some of these developments have gone into production, and according to David Jacques, director of new business development for MPC, several others will begin production soon.

Since MPC already seemed capable of making just about any tubular shape in plastic that one could think of, what is the attraction of SBM? Jacques says it is a combination of being able to produce larger-diameter tubes (in excess of 100 mm) with complex shapes, angles, bends, and tight tolerances (see ejected part, top right), with the added capability of multilayer and sequential coextrusion. Additionally, the finished part holds its shape more consistently than conventional tube-forming processes. Because of the fast cycle times and minimal scrap, the system is very cost competitive.

SBM first surfaced in 1995 and has since taken hold in Europe. Not so in the U.S. One reason is that Europe has a big application for the complex, hollow shapes in which SBC excels: the tubing used in diesel cars and light truck engines. Other than in big trucks and buses, diesel is pretty much a nonstarter in the U.S. market. SIG has more than 70 SBM systems installed across Europe and only a few in the U.S.

MPC has been privately held since its start in 1972 and employs about 1500 people in three U.S. manufacturing locations and a plant in Mexico. Jacques says the company has prototyped many parts on the SBM system in the last two years besides its production runs.



Franz Strohmaier says there is current activity and additional interest in blowmolding in medical supplies and equipment markets. Machines can be adapted relatively easily to Class 100,000 cleanrooms by using the right construction materials and pressurizing the clamp area to remove fumes and small particles. For cleaner environments such as Class 10,000, the machines have to be compartmentalized. Some medical companies, says Strohmaier, are actually putting machines into Class 10,000 environments. He clearly implies that this can be done, saying that the same questions asked about blowmolding now were being asked about optical disk manufacturing 15 years ago. That manufacturing has become normalized. The problems with placing machines in a class 10,000 environment, he says, are not as bad as the problems posed by people being in that environment, and certainly more predictable. It is a question of good machine design and containing, eliminating, or expelling any contaminants.


Consumer marketing is a never-ending search for ways to differentiate one brand from the others and to create a preference for it. Packaging plays a critical role, but cost is also a factor. For example, when Bacardi-Martini launched its rum and citrus drink Tropico in 1998 they wanted the plastic sample bottles to look exactly like their tall 750-ml frosted-glass bottles.

Captive Plastics of Piscataway, NJ, responded with an injection stretch blowmolded PET bottle that was frosted with a sprayed-on UV-curable matte coating. Bacardi was happy with the package but not with the cost. After the initial launch was done, they asked Captive to lower the cost but retain the look of the spray coating. It was not only the cost of the coating—the bottles had to be shipped to the company that did the spraying.

Its colorant supplier, PolyOne, suggested a custom-formulated color concentrate called FX Frost that would provide diffused translucence without a secondary operation. Though the concentrate can be tinted, a colorless formulation was selected to show the product color. Since the colorant does not significantly change the material's surface gloss, PolyOne also suggested a finely textured mold surface to attain the matte look.

The new process yielded a 40 percent reduction in bottle cost. Alfonso Mendez, North American purchasing director for Bacardi-Martini USA, says the frosted effect of this new Tropico bottle allows the company to differentiate the product on the shelf and simultaneously reduces production costs. The new version of the bottles is injection stretch blowmolded on an Aoki blowmolding system. Using the FX Frost colorant did not change any of the original processing parameters.

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