Quality on view

Visual and automated checks are made throughout the production of Opel’s new three-cylinder Ecotec engine. David Fowler reports

The inauguration of Opel Austria’s production facility for its new three-cylinder Ecotec-Compact engine on St Valentine’s day this year was the culmination of six years of continuous improvement at the company’s plant at Aspern near Vienna.

The plant began operations in 1982. General Motors’ Opel subsidiary was persuaded to build there by a subsidy from the Austrian government. It was a controversial decision with many saying the money should have gone to small Austrian companies. But at the Ecotec inauguration, Austria’s federal chancellor Viktor Klima praised the `political courage’ of the decision. Up to 1996 the factory had produced five million engines and seven million gearboxes, earning Sch113bn (£5.8bn) in exports.

But six years ago far-sighted managers at the Aspern plant recognised the need to improve efficiency to win future investment in competition with other GM plants. The process of continuous improvement and reducing inventory began.

`One reason Aspern got this job was they didn’t have to extend the factory,’ says Martin Cray, Opel adviser on lean manufacturing, who joined from Toyota UK. `We made 16,000m2 available by reducing space from other lines.’ All the time three shift production of Opel’s older 1.2 and 1.4 litre Family 1 engines continued as normal.

The award of the Ecotec-Compact assembly job, a Sch4.9bn (£254m) investment, came 18 months ago. The new one-litre engine made its debut at the end of last month in the facelifted Corsa. When the current single shift of 90 workers is augmented to full three shift production next year, Aspern will turn out half a million of the engines annually.

The production line, comprising 108 machines, is as innovative as the engine itself. Six operations are carried out: machining the engine block, cylinder head, crankshaft, camshaft and connecting rods, plus final assembly.

The block and head are machined on a series of computer controlled transfer lines, with one station per operation, such as drilling a hole or inserting a screw thread. The transfer lines are connected by shuttles rather than fixed conveyors, which improves access to the machines for maintenance.

Crankshafts and camshafts are produced in a single operation on cubic boron nitride grinding machines. Quality is such that the normal separate finishing operation is not necessary. Tolerances are measured to within 1 m.

Valves, springs, camshafts, pistons and connecting rods are assembled into the cylinder head and engine block by machines – the cylinder head is even placed on the block automatically.

Though there is more automation than on Family 1 lines, final assembly, which includes fitting of components such as the oil filter, is mainly manual. `Too much automation takes away the ability to improvise,’ says Cray.

Each worker has a 1.5m wide area alongside the line, limiting storage space. The parts inventory on the line, stored in racks behind each worker, has been cut by about 50% compared with a conventional line.

Bob Harvey, GM Europe executive director for powertrain and chassis development, says that two fundamental principles underlie the production process: being able to manage the entire process visually, and checking quality on each group of stations on the line.

The first was achieved by limiting the height of the machines to 2.5m, which allows easier communication between workers. It also makes possible one of the most striking features of the facility – the Andon boards suspended from the roof structure at a height of 5m.

Andon is a Japanese technique whereby boards display the status of all the machines. The machine number can be lit up in three colours. Red indicates it has stopped, yellow that a quality check is due and white that a tool change is needed. From a number of vantage points on the factory floor, team leaders can see all the Andon boards.

Under the system, tool wear and projected tool life is monitored and logged automatically by each machine.

Sophisticated measuring equipment checks that parts are within tolerance after each sequence of operations, so it is virtually impossible to produce substandard parts. There are two Leitz 3D measuring devices with 24 ruby tipped probes that measure to an accuracy of 2 m and 100 measuring points for the crankcase alone.

The principle of involving suppliers at an early stage of design was taken one step further in this project, says Werner Hackl, GM Europe manufacturing engineering director: `The suppliers were involved in the engineering side.’

GM’s design engineers consulted the foundries producing the castings for the block and head, as well as the machine tool manufacturers. The suppliers worked together so that both casting and machining could be optimised.

Also, critical component suppliers were invited to the plant to go over Opel’s processes and quality plan. They were asked to point out anything that had been overlooked and could have an effect on quality. Problems were resolved jointly.

Cray says there is still work to be done `to get the people side right’. The workforce took to some new practices more easily than others – Andon more readily than Kanban, for instance. But the success of the continuous improvement initiative was not due to the management alone: `There’s a lot of talent in the factory.’ The process was underpinned by a mutual commitment from the unions and employer, with Opel guaranteeing not to make anyone redundant. `The moment you cut jobs the ideas won’t work.’

Three-cylinder advantages

The three-cylinder compact is the latest addition to the Ecotec family of engines whose underlying philosophy is an emphasis on low weight, easy serviceability, low emissions, and in particular outstanding fuel economy. Opel claims the new engine will be among the most fuel-efficient in the world.

It believes it has overcome the traditional objections to a three-cylinder engine – lack of balance and noise – so it now has advantages over a four-cylinder engine of the same size. A three-piston configuration reduces frictional losses and makes a compact and light design easier to achieve. For thermodynamic reasons, GM says, spark ignition engines perform best when the capacity of each cylinder is between 300 and 500cc. A four-cylinder one-litre engine falls significantly below this limit.