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Product category: Manufacturing Machinery and Plant Equipment
News Release from: Durr | Subject: Computer-aided paint plant design
Edited by the Engineeringtalk Editorial Team on 21 July 2000

Transforming the way paint plants are
designed

Advanced computerised modelling techniques, with 3-D graphics and powerful mathematical analysis, are transforming the way in which modern automotive paint plants are designed.

Advanced computerised modelling techniques, with 3-D graphics and powerful mathematical analysis, are transforming the way in which modern automotive paint plants are designed And, says leading paintshop systems specialist Durr UK Limited, the result is that production can be optimised and potential problems identified and solved before installation and commissioning take place

"When we started using simulation four or five years ago, it was primarily a sales tool," says Durr sales director Paul Anderson.

"Now, thanks to improvements in software and hardware, it is the backbone of many conveyor and paint finishing systems.

It provides an indispensable analysis tool that proves a system has been designed to best effect." One of simulation's many benefits is that engineers from Durr and its customers can pose "What if" questions, using the software to experiment with variables including targeted levels of throughput, production schedules, product mix, buy-off rates, shift patterns, process times and resource levels.

"We can also test the control logic of the plant before it is actually installed on site," says Paul.

"We can also introduce breakdowns into the system so that we can examine their effects, which in a complex modern paint plant can have a potentially costly knock-on effect throughout the process.

And we can feed in data on the mean time between failure and the mean time to repair." The software shows true scale and speed, with dimensions accurate to within a fraction of a millimetre across a paint plant that may be hundreds of metres long and perhaps 30 metres high.

Cranes, skids and other moving equipment accelerate and move along at exactly the rate they do in real life - the software also offers the flexibility to view that movement from different angles, and to speed up the simulation so that a year or even three years' production can be viewed in a matter of hours.

"The system allows us to measure performance, and to provide an objective comparison between different schemes," Paul adds.

"We can analyse factors such as process throughput, batch size and integrity, sequence disruption and the time that bodies spend in the system.

In short, simulation allows us to make informed decisions backed up by hard evidence, instead of relying on guesswork." By the time a simulation study is complete, Durr engineers aim to have identified all potential process-related problems and to have tried and tested the layout of the plant, establishing its control logic and operating rules and ensuring that it can operate at peak performance levels.

"Simulation is so effective at spotting problems and solving them that it really boosts confidence," says Paul.

"And it has other valuable spin-off effects for the people involved in the process - for example, it can harness the creativity of your teams by acting as a focus for discussion.

"The problem-solving exercises bring together people from all disciplines - production, plant design, logistics and systems.

By demonstrating dynamic issues in clear visual terms, it encourages people to participate and to find workable solutions." Simulation has come to be seen as an essential tool by Durr's Automation and Conveyor Techniques division, which has recently demonstrated its effectiveness during a contract to install a new engine paint facility at Perkins Engines Company's Peterborough site.

"The facility consisted of a number of interlinked overhead conveyor loops designed to carry the engines through the main process elements," explains Martin Vollmer, the division's general manager.

"These include a two stage pre-treatment process, a dry off oven, two paint spraybooths, a flash off zone, a cure oven, engine dress zone and radiator fit area.

In addition, the system had to be flexible enough to handle four basic engine block and multiple variants of engine 'dress', ranging from those which need a single coat of paint or lacquer to others - making up 23 per cent of the total - which are marine versions requiring two coats of paint applied in two passes through the paint booth.

"At a very early stage of the project, the simulation model gave the customer confidence that the design specification of 37 engines an hour was achievable," Martin adds.

"We were also able to identify the need to use slow moving process conveyors rather than static workstations." Using simulation techniques, engineers were also able to test throughputs for batches of different engine types.

"This enabled the engine dress areas to be optimised to give the best spread of components, thus preventing bottlenecks," adds Martin.

"The customer was able to test 'what ifs' such as shift patterns, reduced manning and breakdowns - so vulnerable areas could be spotted, and design or equipment changes could be specified before a cost commitment was made.

Also, Perkins were able to test current working practices and modify them to meet production requirements." Even more complex factors came into play at Rover's Oxford plant, where Durr used simulation to examine the effects the paintshop it was designing and building would have on the logistics of the new Rover 75.

Says Durr simulation specialist Mike Allen, "We went back to basics to look at the potential sequence disruption, from body-in-white to final trim.

This was complex, because we had to take into account left and right hand drive, four basic engine types, four trim levels and 17 different colours.

"The objective was to set up a sequence of overlapping batches so that we could test Rover's ideal scheme for producing the car - which for example meant that if a batch of cars with the same trim level came past, the relevant set of components would be readily available.

This minimises lineside storage and also improves quality because studies have shown that people work more efficiently if they can maintain a consistent work pattern "At first sight the demands for batching colour in the paint shop and a differing sequence for final assembly were insurmountable.

A significant investment was therefore planned to expand the painted body store prior to final assembly, costing around ?5m, to enable re-sequencing after painting.

The challenge for the simulation was to validate if this investment was necessary.

Through the use of the model operating protocols - developed to maintain colour batch size objectives for the paint shop - we achieved a 99.5% feature batch integrity in the final assembly, enabled dynamic order reallocation and the ?5m investment to extend the painted body store was therefore not required.

The Rover project also provided a good example of how simulation brought the supplier's and the customer's teams together to solve problems.

"One discovery was that a minor stoppage in seam seal would result in bodies becoming stationary in critical processes" Mike adds.

"The immediate but costly answer was that we needed more conveyor.

However, a Rover engineer was able to come up with a cheap and convenient solution - moving a transfer point - which we could test and validate on the simulation model.

"This demonstrates one of the great advantages of simulation - that customers can work with Durr to learn their new paint plant's behaviour, and then plan for success.".

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