When Hawker Pacific Aerospace took over the landing gear division of British Airways in 1998 it needed to set up a new metals finishing facility. In June 1999 the company moved to purpose-built 13,000m2 premises near Heathrow Airport in the UK and enlisted the help of materials handling specialist Crane Care and chemical systems engineer Plasticraft to develop the electroplating and treatments facility which required.
Plasticraft’s task was to design, manufacture and install a ‘flow line’ processing facility and effluent treatment plant, where procedures including phosphating, sulphuric etching and nickel and hard chromium plating could be performed. A major part of the project was an overhead crane system to transfer components during the treatment process.
Hawker Pacific’s facility manager Roy Lavender says: “A key requirement in the design stage was to come up with a layout which would provide a variety of efficient and flexible process routes, while segregating incompatible processes.” The variety in size of components to be repaired in the plant varied immensely and required 1m deep, hand-operated process tanks and 5m-deep process tanks for the larger components.
To accommodate these tanks, a sump was built into the floor, big enough to house storage tanks as well. This means that the plant operates on two levels. The upper level runs around the four walls of the building around an open pit. Open mesh walkways, installed for operator access, look down into the pit. Below this process area are the tanks and other services, surrounding the pit. From the pit, the process area above can be observed.
Hoists and underslung cranes were needed to move components between processing lines with minimum complication and cost, explains Crane Care managing director Derek Barnbrook. The initial plan was to replicate BA’s old workshops, using roof-suspended turntables to divert loads over the required tanks, but this would have worked out costly, considering the large amount of support steelwork that would have been required in the new building, Barnbrook says The revised design is based on installing a matrix of support steelwork in the roof structure of the new building supported by free-standing compound girders. These girders also had to be strong enough to secure the floor at the top of the 5m-deep process tanks pit.
Runway beams are positioned over the centre lines of the process tanks, linked at the end and middle by three underslung cranes which are manually operated from switch points at electrical interlocks.
Radio control systems from the specialist German manufacturer HBC were put in after it was realised that they would have to be cantilevered away from the centre of the tank with a pendant arm, 10m above floor level. The use of the remote controls means that operators do not have to lean over the process tanks to retrieve the pendants.
Plasticraft then had to design and install an economical method of process heating to the plant. Sales director Brian Harvey explains: “The system installed at Hawker Pacific uses thermal fluid and has two heat generators fired by gas. Both of these are in use during the initial heat up of solutions and once up to required temperature, remain in standby mode operation, so that the solutions are kept to specification.” An effluent treatment system also had to be installed in the plant, for which a water recycling and purification system was brought in. Ion exchange columns were supplied for the treatment of re-circulated water and standby systems put in so that water is constantly available while one unit is under regeneration. The resulting ion sludge is then stored and taken away by an approved contractor while remaining fluid is passed through an evaporator and a condenser to reduce the mass. It is then returned to the re-circulation loop, stored and removed from the site by waste disposal contractors.
