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Diesel Powered

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Diesel engines are on the march. Refinement, economy and now even performance have been so incredibly enhanced that the penetration of diesel engines is starting to make a big impact in most European countries. For example, so rapid is the growth in France and Germany, as well as Spain, Italy and Belgium that a 40% penetration is predicted within the decade. This compares with 27.6% across Europe in the first 10 months of 1999, which itself was up from the 24.8% of the previous year.

It is against this background that output from the biggest diesel engine factory in the world is set for a massive rise over the next few months as leading diesel engine manufacturer PSA Peugeot Citroën moves to step up the volume of its new-generation HDi (high pressure diesel injection) power unit.

Introduced only 18 months ago in the Citroën Xantia, the acclaimed common-rail direct injection engine is proving such a commercial success across European markets that demand has already overtaken maximum available capacity at Tremery, the French group's principal source of power units.

Despite achieving a daily production total of around 7,000 engines—which is currently being increased to 8,000—the huge complex is unable to keep pace with the flow of orders for the fast-expanding range of HDi-equipped Peugeot and Citroën cars and light commercial vehicles. The output of diesel engines now represents 80%, up from 75% four years ago and 50% in 1979, the first year of operations. Fortunately, there is no shortage of space for expansion as the site's 32 hectares of buildings in rolling countryside 10 miles north of Metz in the north-eastern corner of France is surrounded by another 87 hectares of available land.

"We are operating flat out and HDi assembly is at saturation point, but because demand is so high, we're forced to constantly look for ways to raise our efficiency," says Pascal Damien who is responsible for HDi production at Tremery. Altogether there is a workforce of 3,600, more than 1,500 specialised machines, 2,200 programmable robots, 500 digital controls and 580 manipulators, robots and gantries to minimise manual effort.

As a result of this highly automated and computer-controlled operation that continues around the clock on an eight-hour, three-shift rotation Monday through Friday, new petrol and diesel units arrive at the end of the lines at the rate of one every 30 seconds. On Saturdays and Sundays, though, extra volume of the 2.0-litre and 2.2-litre diesel engines is gained from special 10-hour shifts worked by teams of part-time employees.

"With 11 assembly operations to supply in France, Spain, the UK, Portugal, and Italy, along with the group operation that sells engines to power vehicles made by other companies, we are always busy. We are delighted with the success of HDi, but this has brought a special challenge," says Damien.

"At the peak of its popularity, XUD engine production ran at 4,000 per day. As next-generation engines are progressively replacing the existing XUD, output of this range has been scaled back. However, it is difficult to predict when production will finally come to an end because it is still required for the C15 van and some other low-volume applications. Meanwhile, it is clear that HDi is only at the start of its life and it's obvious that this family has a great deal of potential under the bonnets of future products.

"We have taken several steps to raise efficiency, but the most significant alteration to our production system has been the addition of the facility we describe as the ‘common-rail room.' It occupies an area of 600 square metres and covers the 11 workstations that assemble and fit the injection system.

"Because this operates as an enclosed area, we are able to control the atmosphere and create a sterile environment where this equipment is put together. The facility cost FF12 million ($1.5 million), but is proving to be worth the investment by ensuring the quality and absolute accuracy that delivers perfect performance."

Each cylinder head is subjected to 1,800 checks for dimensional accuracy, 300 governing its shape and 200 monitoring surface finishing at quality control stations. However, visual checks are still carried out by two operatives before each unit is released from the section.

A sled is designated to carry each engine through the assembly process. On it is the unit's computer identification chip containing the specification details needed to ensure it is fitted with the correct components as it progresses through dozens of automatic, semi-automatic and manual work stations. Should an operative select the wrong part for the unit, the mainframe computer automatically shuts down the section.

"This is an essential back-up facility. In order to comply with all the different legislative requirements of the different markets in which our vehicles operate, we have to produce 122 different versions of our diesel engines and 91 different petrol engines. It is therefore no surprise to find that mistakes can sometimes happen," says Damien.

Despite the size of the plant, just the main engine components such as crankcases, crankshafts, flywheels, cylinder heads, camshafts, oil and water pumps, and heating systems are completed at Tremery. As a result, a large number of pre-machined parts are received on a JIT basis from more than 200 suppliers for assembly. Stock for three days' production is stored near the assembly lines.

The rapid increase in output has resulted in the temporary appearance of a 2,000 square metre marquee on the lawn outside the main assembly hall. "We need this structure to provide additional storage space. At the moment, it is holding components in 1,800 large containers, but we're planning to provide the space for these parts inside the factory in the near future," says Damien.

While the HDi engine is being a runaway success, the French group's petrol engines are also set to receive a boost with the introduction of the next-generation of high-torque, fuelefficient HPi units. These new high-pressure direct-injection gasoline engines will also be built at the Tremery plant, before being progressively introduced across a broad spectrum of the Citroën range. 

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