Driving store control

Land Rover is part of the UK-based Premier Automotive Group (PAG), owned by the Ford Motor Company, whose other thoroughbred brands are Aston Martin, Jaguar and Volvo. The four-wheel drive vehicle manufacturer employs 11,000 people in the UK at two key sites in the Midlands: principally the manufacturing centre in Solihull, Birmingham, and the Gaydon research and development centre, also in Warwickshire, with a further 1,500 employed at offices around the world.

Bought by Ford from BMW in 2000 for £1.8Bn, Land Rover builds and sells, through its franchised dealer network, around 165,000 4×4 vehicles a year in more than 142 countries to hold a significant stake in the highly competitive sports utility vehicle (SUV) market.

At the centre of the Solihull manufacturing facility there is Paint Shop 21. Here, every vehicle body for all Land Rover models is painted and prepared for assembly according to individual customer order specification – for both domestic and international sale. At the centre of the operation is the Store Control System (SCS) from Central Systems & Automation, performing the critical linking operation between Land Rover’s manufacturing MIS and all mechanical handling equipment (MHE).

Paint Shop 21 was built between 1995 and 1997. A leading-edge automotive facility, it covers more than 9,300sq m, is three stories high, 1,200ft long and has 14-plus miles of conveyor track. Paint Shop 21 can accommodate 1,400 cars and process 75 vehicles per hour in approximately 600 different colours.

It processes each Land Rover car body right through the paint process – from phosphating, electro-coating, sealing and undercoating to colouring, waxing and quality control. The facility comprises of three Automated Storage and Retrieval Systems (ASRS), each using a Programmable Logic Controller (PLC) based Store Control System. PLC-based systems are ideal for automating factory floor processes, being both robust and easy to configure.

Painted Body Store 1 (PBS1) has six cranes and holds the painted bodies before they move to the assembly line; Painted Body Store 2 (PBS2) also has six cranes and is used as a buffer store for painted Freelander bodies; and thirdly, the Skid Store (SKS) which has three cranes. PBS1 holds 405 car bodies, PBS2 holds 284 and the SKS holds 244 Body-Skids and 61 Conveys.

The SKS contains three aisles of empty Skids and Conveys on five levels which run on the conveyor system and carry the body through the painting process. There are four different types of skid: one each for the Defender, Range Rover, Discovery and Freelander. PBS1 is for the Defender, Range Rover and Discovery with PBS2 for the Freelander: each has six storage aisles that are three and two storeys high respectively, holding the appropriate vehicle bodies on skids. The PBS1 and PBS2 cranes enable the bodies to be sequenced into the product build plan and also act as a buffer store between the different assembly processes. All three ASRS need to be able to work independently or in tandem, in full auto-mode and in assisted auto-manual mode.

Paint Shop 21 can operate 24 hours a day, 365 days a year.

Monitoring systems

Central Systems & Automation’s Storage Control System (SCS) software modules provide the critical link to the MIS-based order system as well as the Plant Environmental Management (PEMS) system that monitors all crane and conveyor systems across a facility-wide Ethernet network. All movements are managed by the SCS: connectivity around Paint Shop 21 – including the cranes – is provided by Modbus and Modbus Plus industrial networks.

The SCS runs on AEG-Modicon PLC units, including enhanced CM1000 Basic modules with serial ports for interfacing with Premid Radio Frequency Tag Readers. The tag-readers read heat-resistant tags on all the skids as they move along the conveyors and through the three ASRS areas; they identify the precise location and identity of each skid and whether or not it is empty or carrying a body.

Precision is extremely important. Conveyor system skid alignment is accurate to within plus or minus 3mm. Each of the stores has a Panel Mate human machine interface (HMI) for general control, accessing status information and for maintenance trouble-shooting.

Space management is important on the Solihull site as it is enclosed by a park, residential area and Birmingham International Airport: extensive use of automation and computerisation ensures a highly efficient site footprint. With production at 75 chassis per hour, it also means a very quick output by the standards of any car manufacturer in Land Rover’s class.

The SCS gives Land Rover total control of customer orders, meaning that the volume of the different cars can be altered with ease. Each car can be built to an individual customer’s specification thanks to the flexible combination of manufacturing management systems. Paint Shop 21 was designed to run a PLC-based body processing system: full PLC compatibility with the SCS has made its introduction straightforward.

The key performance criterion for the system is percentage-based uptime – the minimum service level begins at 99.8%. Each software module and PLC sub-system module has its own uptime log that is connected to PEMS via the Stores Control System. Any faults are immediately logged by PEMS which will then prompt one of the maintenance teams to investigate. Efficiency reports are then generated on a regular basis by PEMS.

The bottom line for Land Rover is system reliability. Solihull runs a continuous operation to feed the main vehicle assembly line. Paint Shop 21 is the hub of the entire production process, because all vehicle chassis have to be processed there before they are assembled.

Stock contingencies are pre-programmed and each ASRS system can work independently as well as collectively, automatically and manually. This mean that the engineering team can cope with any necessary repairs and keep the assembly line fed. The Stores Control System is also equipped with full remote access for Central Systems & Automation’s support engineers who are on call at all times. This means full diagnostics checks can be made over data connection as well as complete systems management.

Paint Shop 21 is a very robust facility: with high uptime and already high production levels, the power and flexibility of SCS means the facility can easily match Land Rover’s planned growth targets.