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Aerospace flies east.

ERG has recently installed a massive processing line at Hyundai in Korea. Here the company tells Finishing how it managed to complete such a complex task

ERG ENVIRONMENTAL RESOURCE Group's Process Plant Division is widely recognised as a leading supplier of metal finishing equipment to the aerospace industry with many large installations in the UK, but the largest project to date is installed in Korea.

Hyundai, who are better known in the UK for its cars, have a large aerospace division at Sosan, about three hours drive south west from Seoul. This facility has been set up principally to manufacture wings for the new Boeing 717 Aircraft and required all the metal finishing facilities on site. ERG were contracted to design five plants from 2m to 17.65m (6ft to 58ft) wide covering a range of processes including anodising, chemical milling, dye penetrant NDT solvent masking and electro-plating.

The project was won against stiff international competition from the USA, Germany and France and resulted in a contract for ERG to supply all of the design work plus technical items such as the control systems which have fully intelligent transporter sequencing. The manufacturing was carried out by local contractors working under ERG's guidance and the whole project was commissioned by ERG engineers.

ERG had manufactured several plants in the 8m range but a move up to double that size represented new challenges but also brought about new opportunities, with a slightly larger plant 18.75m (61ft) nearing completion in the UK.

The sheer size of the project comes home with the fact that the 'L' shape pit to accommodate the equipment is itself 80 metres (262ft) by 70 metres (280ft) and from the bottom of the pit to the top of the transporter is over 12 metres (41ft) plus the cross transfer trolley on the largest line, moves over 21 metres (69ft). The lines cover a wide range of processes. These are: Chromic anodise, sulphuric anodise, penetrant NDT; aqueous degrease, chromic anodise, chromating, phosphoric anodise; hard anodise, metal bond etching, black oxide coating; cadmium plating, chromating; solvent maskant coating and chemical milling.

ERG had installed aqueous degreasing tanks on previous projects but again the size of the largest line meant that one tank required six pumps, each connected to 6" pipework in order to provide the volume and distribution of flow to the Eductor Systems.

A major innovation on the process lines was the inclusion of dye penetrant NOT within the transporter operated plant. The long components are lowered through the top of the penetrant booth by the transporter and automatic lids close to prevent penetrant escaping and reduce lighting levels within the booth. An automatic carriage then travels along the work, within the booth, spraying penetrant and returns along, after a contact time, spraying water to rinse off excess penetrant, coverage may be inspected at this point if required. The workbar is transferred to a drying oven and then to a developer booth by the transporter The lids close and again a carriage travels along the work, this time spraying developer powder. After a sufficient developer time the operator enters the developer booth to carry out the inspection under ultra violet light using motorised platforms either side of the work piece which have a hoisting capability to allow inspection of all surfaces of the work. Having cleaning, penetrant, deve loper and inspection all carried out on one line with one set of jigging greatly improves the efficiency and ease of handling of the very large parts.

Environmental considerations were regarded as an important part of the project and a Closed Loop Dl Water System was provided, combined with a mixture of spray and immersion rinse stages on line to give the most efficient rinsing. To further enhance the rinsing action, several of the spray rinse stages were able to spray hot water or even cycle cold, hot, cold. In order to reduce heavy metals usage, a chrome recovery system is installed on the rinses after the chromic anodise tanks which cascades the rinse water to concentrate it and returns the concentrates for topping up purposes.

A further environmental consideration was in the area of energy reducing where the use of automatic lids on all tanks with fume exhaust allowed the amount of air extracted, when the lids are closed, to be reduced to about 10 per cent of the normal open tank volume. Automatic dampers increase the air flow when the lids are open but this is typically for very short periods when raising and lowering the work. Overall this system typically reduces extraction volume by 60 to 70% leading to major energy savings in three ways:

a) Process Tanks lose less heat.

b) Building heating costs are reduced as less cold air is drawn in.

c) Motors on exhaust fans are smaller thus reducing electricity consumption.

All of the above also translate into significant running cost savings and a more pleasant working environment. The extra costs of installing the lids are offset in part or even in whole by the reduced costs of exhaust trunking, fume scrubbers and fans, so can be a win/win situation.

As with many aerospace finishing facilities a wide range of processes are required on the same plant, all with precise control of processing times and yet still retaining maximum plant efficiency To this end ERG installed truly random transporter controllers which fully maps the routes of the work bars through the plant in order to ensure that all work is processed as close to the minimum permissible time as possible and never longer than the maximum. It also ensures that work never clashes in the same stage and optimises the output by maximising the throughput on whichever stage is most heavily loaded. The system allows work to leap frog over other work, allowing work with short processes to proceed, rather than wait for work with long processes. There is a system for setting priorities so that critical processes are more closely controlled than non critical, and this is also used for recovery from any unscheduled stoppages, in that high priority processes will be attended to first. The system includes SCADA features such as display of process parameters, alarms, transporter positions, as well as more advanced options such as work histories, production reports, historical alarms and maintenance schedules.

The transporters on the largest process line each have a 5 ton safe working load and are able to be programmed for tilting or slow movements on hoisting. Tilting is used to assist with draining the long components and slow movements are used to prevent damage to large, thin sheet components which may tend to plane in solution or bruise due to surface impact. As a further precaution, the air agitation is automatically turned off when lowering to further reduce any risk of damage.

With Line 1 being such a large plant, it takes a significant amount of time to load a single workbar. To assist with this, a second load stage is incorporated to the side of the first and work is transferred sideways by a cross transfer trolley and picked up by a third transporter for placing into the load stand. Although the process tanks are in a pit, loading and unloading takes place at floor level and the transporters are able to operate at two different heights. Due to the depth of the tanks, the workbars in the load/unload stages are too high above floor level to be reached and each load/unload stage includes screw jacks to allow the workbar to be lowered to any accessible height under manual control, automatically returning their normal height when loading or unloading is complete.

The whole project has been a very successful one for ERG in allowing further development of technologies and increasing skills in project design management, indeed the project has been given an award by parent company AEA Technology as recognition of this.
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Publication:Finishing
Date:Oct 1, 2000
Words:1321
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