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July 25, 2002

7 Min Read
Seed of idea spawns big-machine cell

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The Lechuza range of plant containers (top) now includes three designs in eight colors and a variety of sizes, each with a built-in irrigation system. At left is a sample showing the foamed PP core inside the transparent PP outer layer.

Although qualities such as marketing instinct and entrepreneurial spirit are often applied to younger people in smaller businesses, it's the exception that makes the rule. Horst Brandstätter is exceptional. He heads the Brandstätter Group, which is not small—$250 million-plus in sales and more than 2000 employees. Nor is it new: It was founded in 1876 to make locks and metal fittings.

Horst Brandstätter has been in the business "only" since the 1950s. One of his first steps in 1958 was to create machinery and molds to bend plastic hose into a hoop—a Hula-Hoop, to be precise. It was a success, and when the fad passed, the company employed the technology it had developed to begin making simple toys. In 1974, Brandstätter used an intensive and highly strategic marketing campaign to launch what has become the company's flagship product: the Playmobil line of figures, vehicles, and other toys for small children that is now a nearly global phenomenon.

None of this, however, was on Brandstätter's mind when he searched for a way to keep his plants alive while away on long trips.

Can't Find It? Let's Make It
The self-watering planters Brandstätter saw on the market either would not keep plants healthy long enough or had an unattractive appearance—or both. So, at around the age when most people are thinking of retirement, he created the basic concept for a line of self-watering planters and a separate business to market them. He then harnessed the design, moldmaking, and molding experience within the group to make it a reality. The Lechuza line of planters is already on the market across Europe and growing well.

The move from making toys to planters carried the staff of the geobra Brandstätter production group into another, much larger dimension. Prior to entering the planter business, geobra's molding machines—185 in Dietenhofen, Germany and about 370 total worldwide—were small to medium, only a few near 500 tons and most much smaller.

Since the upper end of the Lechuza product line features planters that measure 27.5 inches across and weigh up to 8 kg, a much larger machine was clearly in order. Moreover, it had to be a two-component press.

In the end, the new machine needed a new production hall of its own at Brandstätter's manufacturing complex in Dietenhofen. Robert Benker, geobra's technical director, says, "We literally built the hall around the [2200-U.S.-ton] injection molding machine." Existing halls had height limitations and limited available floor space. The dimensions of the new building could be specific to the machine and the crane needed for the large molds.


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The 2200-ton Battenfeld HM hydraulic molding machine has two injection units mounted in parallel. The complete production cell, including the Unirob R25 linear robot, was supplied by Battenfeld.

The new facility consists of a 14,000-sq-ft molding production hall with 39-ft ceilings and an 18,000-sq-ft warehouse space for planter production. Two 275-ton machines and one 550-ton system are also in the production hall to make smaller planters. The components of the irrigation system are molded on some of the toy-molding machines located nearby. Forty-five molds were acquired to produce different components of the horticultural system such as the pot, water level indicators, bottom inserts, filling shafts, shaft covers, and screw caps. In all, geobra invested $3.25 million in the new facility and its equipment.

With New Technology, Support Rules
The larger size of the products and machinery was not the only challenge geobra faced in making the planters. Benker says, "Molding this particular pot is not exactly easy and straightforward. Following the design requirements, we need to inject from the thin wall into the thick wall. The 70-cm container starts with a wall thickness of 4 mm at the injection point at the bottom of the pot. Along the flow path, the wall thickness grows, culminating in 15 mm at the top edge of the pot."

To compensate for the sink marks likely with walls that thick, the pots are sandwich molded. The inner core is chemically foamed PP structural foam. The cosmetically critical thin outer layer is made from transparent, nucleated PP for a smooth, glossy finish.

The molding cell for the production of large planters is built around a fully hydraulic Battenfeld HM 20000/14400+9200 molding machine. The two injection units are mounted parallel and are a bit unusual in that they are of similar size. (Most multicomponent machines of this size have one large main unit and a smaller additional unit.)

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An 18-lb pot (left) is held by suction from the bottom to avoid cosmetic problems caused by touching the planter walls while warm. Air is fed into the pot during the demolding process to maintain its shape. The Unirob handling device (right) has an additional swivel and rotational axes on the gripper arm and a four-step vacuum gripper for demolding and positioning on the cooling belt.



During initial development the geobra technical team tested a wide range of injection molding techniques including physical foaming, internal gas, and external gas technology. Benker notes that Battenfeld provided help with gas injection technology, even though there was no promise that a machine would be purchased.

"The support included not just technological details, but also contacts that allowed us to exchange information with other companies with relevant expertise," says Benker. "Even during sampling at the Portuguese moldmaker, Battenfeld's telephone support really helped us." In the end, Battenfeld was chosen as geobra's supplier.


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Two melt streams converge in this coaxial nozzle installed between two injection units and the mold.

Quality that Conquers Markets
Benker says the core competence geobra has developed over a quarter century of plastics molding was the critical element in developing the new product and technology. Equally important, however, was providing the same high level of quality as that found in its toys. It was clear from the outset that Lechuza production would have to use the high degree of automation and minimal personnel found in the production of Playmobil components.

Consequently, the large machine is at the center of a cell, with all components integrated and supplied by Battenfeld. Benker points out that while the containers are still warm, the glossy surfaces can be easily scratched. Battenfeld's Unirob robot is equipped with tooling that allows it to grip only the bottom of the 18-lb pot, automatically cut the sprue, and then transport the pot to a conveyor that also adds cooling time—all without contacting the planter's surface. Benker says geobra wanted a line with as much automation as possible, which the Battenfeld system provides.

The impact- and weather-resistant Lechuza planters have received an enthusiastic reception in the interior landscaping market in Europe, with negotiations for distribution in the U.S. and other markets in process. The line includes three pot varieties in eight colors with diameters from 8 to 28 inches. A long-term study by the Bavarian State Institute for Wine & Horticulture confirmed that the irrigation system minimizes maintenance requirements while optimizing plant growth conditions. We can only wonder what Horst Brandstätter might be shopping for and not finding right now.

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In the Lechuza self-watering planter, water is stored in the base of the pot and absorbed by the plant as needed.

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Horst Brandstätter has grown the Brandstätter Group mostly on the worldwide success of Playmobil toys such as the one in the foreground. He decided to use the company's moldmaking and molding expertise to fill a gap in the plant container market with products such as the Lechuza Quadra model shown. The electric irrigator visible in the pot was one of many designs developed and not used in the final products.


Contact information 
geobra Brandstätter
GmbH & Co. KG
Zirndorf, Germany
Judith Schweinitz
+49 (911) 9666 144
www.lechuza.de

Battenfeld of America Inc.
West Warwick, RI
(401) 823-0700
www.battenfeld.com

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