First CoEx fuel tank blow molding system still in use

The sale of the first fuel tank extrusion blow molding machine, the KB250, with 6-layer coextrusion process in 1992, signified Kautex Maschinenbau’s breakthrough into the US market and marked the start of its global market leadership in the area of fuel tank blow molding machinery. At the same time, innovative multi-layer technology laid the first foundation stone for the commercial success of the manufacturer, Walbro Automotive Corp (now called TI Automotive Group).

In the 70s and 80s, plastic fuel tanks were manufactured in the USA using a single layer of polyethylene. After being blow molded, they were fluorinated on the inside in order to prevent petrol vapor from diffusing through the tank’s wall. As there was a tightening of the limits for gas emissions from car fuel tanks in the pipeline in the mid-80s, Kautex Maschinenbau developed a process to manufacture multi-layer tank systems to integrate a barrier layer. The first industrial blow molding machine with CoEx process was presented at the trade fair for plastics in Dusseldorf in 1989. The type KB250 machine was further optimized in subsequent years and converted from the discontinuous accumulator head process to a continuous process. In 1992, the manufacturer, Walbro Automotive, purchased the test machine, which had been modified several times, for its plant in Ossian, Indiana in the USA.

Six-layer tanks prevail

The CoEx process does not need fluorination. Instead, the blow molded tanks reduce Petrol. Vapor emissions thanks to a so called barrier layer, which is made from a special plastic and located within the tank wall. An adhesion promoting layer is integrated on both sides of the barrier layer. A reclaimed regrind layer enables the reuse of production waste. Finally, another external layer and internal layer made from polyethylene are required so that the new tanks have a six-layer wall. In this respect, the resulting vapor barrier is better than a coating with fluorine as it reduce the diffusion of gases through the tank wall to a minimum and remains in place for the entire product life

of the tank. The decision by Walbro Automotive to get into the business of CoEx tanks was an important milestone in Kautex’s corporate history. The KB250, which was delivered in 1992, was the first multi-layer CoEx tank blow molding machine on the American market. Just six months later, the Ford Works in Milan, Michigan commissioned the first use of the machine, for which the machine has been specifically designed. During the same year, other machines (types KB250 and KB400) followed for Ford and the Belgian company, Fina, and again for Walbro Automotive in 1994. Kautex Maschinenbau built another KB250 type machine for itself for its Bonn Technology Center (Technikum) for developmental work with regards continuous six-layer coextrusion.

KB250 – A machine goes around the worldKB250

“After introducing the six-layer technology, business really took off for Walbro Automotive,” recalls retrofit manager René Vanmarcke, who personally installed the machine in the USA over 20 years ago.“ In October, the plant accepted the production of the first CoEx tanks in Ossian for several Ford models. A milestone for the company, especially since Ford manufactured all other plastic parts in its Michigan plant at the time.” The six-layer tanks were then exclusively produced on the KB250 that was purchased in 1992 and which proved to be extremely reliable and was able to produce 500,000 tanks a year. Furthermore, as a double shuttle machine, it was possible to run two different shapes simultaneously. The success continued and there were many subsequent orders. The KB250 was constantly improved and additionally equipped with a robot for the parison transfer. This technology enabled the plastic parison, which runs out from the extruder, to be laid in the desired shape without it having to be moved. “The KB250 was, so to speak, our pioneer

machine on the US market,” recalls Kautex expert, René Vanmarcke. “And it has proven to be extremely reliable and durable: When Walbro was taken over by the TI Automotive Group in 1999, the very first KB250, which was delivered to the USA, was relocated from Ossian to Great Britain. At the end of 2001, it was moved to the TI plant in Belgium due to short notice expanded production, where it today still produces fuel tanks.”

“The KB250 has an extremely stable extruder platform. In 2006, we invested in a new control system and reconditioned the closing unit. We are very satisfied.“
Michel de Clerq, TI Automotive Group

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