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Exmac and MacDonald Humfrey create assembly line for new high performance engine at Ricardo

MacDonald Humfrey Automation (MHA) and sister company Exmac Automation have joined forces to help automotive engineering specialist Ricardo create a state-of-the-art 600 square metre assembly facility to build a new high performance engine.

The new facility at Ricardo’s Technical Centre in Shoreham, West Sussex provides a near clean room production environment and has the capacity to produce 4000 engines annually across two daily shifts. Its core is a ten-station vertical conveyor mini-line supported by incoming materials inspection and line-side delivery of components. Each station is equipped with a sophisticated MacDonald Humfrey ‘Human Machine Interface’ (HMI) providing guidance to each operator on the precise sequence of operations required at each stage of assembly. The tools and assembly equipment used at each station are instrumented, and provide data directly into a central warranty database for each engine built, providing complete finished product traceability.

Each line station is interlocked via its HMI to ensure that all operations and checks have been successfully completed and recorded before the line can be indexed and the engine moved forward to the next station. In addition to the main production line, the facility includes a cylinder head sub-assembly line, dress area and an end-of-line hot test cell that enables the performance of every engine produced to be fully tested and validated.

The brand new facility was specified, designed, constructed and commissioned in just 18 months.

This is the first time Ricardo has manufactured an engine, so Exmac Automation’s previous experience of ‘No Fault Forward’ (NFF) assembly on a similar engine build project for Harley Davidson’s V-Rod engine was invaluable.

The V-Rod line was a fully automated EMS-driven loop system but, as there was less space in the new Shoreham facility, Exmac worked with Ricardo to determine the number of stations required and understand the various processes they would need for engine assembly, how engine blocks would be loaded and unloaded from the line, the type of DC-tooling, and the level of control required, etc.

Says Ricardo’s Dave Thompson: "From the start, Exmac understood our brief, asked the right questions and were able to provide relevant technical input and their own suggestions, to help us achieve our objectives for the line. Because the space available in the assembly facility couldn’t accommodate a continuous loop system, designing the conveying system proved particularly challenging, as did the 50-minute Total Average Cycle Time (TACT), which was relatively slow due to the low production volume – eight engines per shift – and the demands of the comprehensive ‘no-faults-forward’ culture. All of which also meant that a fully automated system wasn’t justified."

The design of the Exmac handling system allows Ricardo to load engine blocks onto the line and rotate them at any of the ten assembly stations. The system is also indexed manually to allow greater control over the assembly process, provide the flexibility to accommodate long cycle times and enable Ricardo to achieve batch production of single engines or different engines as required.

To meet the specification within the space available Exmac designed a compact 10-station back-to-back manual line that takes up very little floor space in the new building.

Engine blocks are fixed to lightweight trolleys using a vertically mounted slew ring and quick release plate, which mates with a bracket located on the engine bell housing.

Whilst the engine block is locked in place, it can also be rotated through 360 degrees to allow complete access for operators. An engine starts its build sequence at station 1 and when all assembly functions at that station are completed the control system allows a stop to retract, enabling the operator to push the trolley to a holding position until station 2 is clear. The system then allows the trolley to be pushed to station 2 where the same stop and lock procedure holds it in place for that station’s assembly functions to be carried out …….and so on to station 10.

Trolleys run in a steel track to facilitate manual handling by operators; and a latched turn-post at each end of the line (providing a swing-gate effect) allows trolleys be re-directed to the opposite side of the line after assembly operations at station 5 are completed. When a trolley reaches station 10 the engine block has been transformed into a fully assembled, complete engine.

If there is a problem at any station the trolley continues to the end of the line where it is removed to a holding position for the engine to be reworked as required. Trolley and engine are then returned to station 1 (via the turntable if necessary) and moved to the appropriate station to allow the engine to continue its build programme.

Exmac-designed mechanical locking systems accurately locate and secure trolleys in position at each station, whilst also ensuring that they cannot be released until the MacDonald Humfrey HMI system confirms that operators have completed all required tasks at each station, and assembly can continue on a no-faults-forward basis.

Commenting for Ricardo, Dave Thompson says a great deal of thought has gone into the way the line operates. This has resulted in a number of innovations, including a novel low-cost method of rotating the engine using a battery-operated electric drill, fitted with a special socket that is attached to the gearbox, enabling the engine to be positioned wherever it is needed.

He adds that Ricardo also insisted on an aesthetic approach to the design of the line, ensuring that it complements the new engine-build facility and presents an attractive and technically advanced visitor environment for Ricardo’s internationally renowned customers.

Commenting on the HMI system, MacDonald Humfrey Automation project manager says Ricardo envisaged a bespoke tracking system that would provide its production engineers with a list of operations that they could vary and configure themselves. For example, not only did they want to be able to set task-by-task instructions showing assembly operators how to build the engine, they also wanted to include time allocated to each task, DC tooling operations, air tests, and gasket glue plotting. In addition, The HMI also needed to integrate all the operations and provide confirmation – with a time and date stamp – that all tasks had been completed. Effectively this meant that every single operation – including every bolt to be tightened – needed its own programme!

Such complex HMI systems are not generally available and need to be developed as bespoke schemes. Fortunately, during initial meetings with Ricardo, MHA was able to demonstrate its considerable experience, quoting similar systems developed for Aston Martin, BMW and JaguarLandRover.

The bespoke HMI system developed for the Ricardo engine line takes operators step-by-step through the process of building an engine, providing detailed on-screen information and visual aids at each of the ten stations, and even including instructions for every bolt to be tightened and its particular torque and angle. The relevant screen for this operation shows a photograph of the engine, highlights each bolt, and displays a ‘green light’ to confirm that it has been tightened correctly before the next bolt is highlighted. The DC-tooling measures torque and angle to provide full traceability as the engine moves down the line into each station, and the stringent quality control ensures that the system complies with the NFF policy. Scanners also record the 2D barcodes of every component at every station as the engine is assembled, so that any operation can be reviewed if required.

A Siemens PLC drives the mechanical operation of the line such as the stops, the push buttons and the interlocks for the tools. It is backed up by a server-based PC system that drives the build instructions and logs all the information. The build number of each engine is scanned at the start of the line, ensuring that all subsequent operations are logged to that particular engine as it moves through the build process. Data is fed to an MHA MachPick pick-to-light system to ensure efficient error-proof component picking. The system is user-configurable to allow sequential or simultaneous picking, with real-time event reporting and control. It also provides zone indication alerts and profile checks, as well as stock monitoring for replenishment.

The system uses algorithms to examine the different tolerances of matched components such as crankshafts, pistons, shells and clamps and, in this case, automatically identifies shims to match the tolerances of the different parts. The pick-to-light system selects and highlights the correct shim and as the operator selects it from the hopper, a light beam is broken to confirm that the operator has selected the correct shim. The valve lash of each engine is also recorded and the data fed into the HMI system.

In order to optimise the 2-hour engine build sequence, Ricardo also uses the HMI system to monitor the line’s indexing against real-time operator performance. An on-screen display indicates whether the operation at each station is ahead of, or behind, schedule in relation to the system’s TACT.

Whilst this is a manual system and trolleys are pushed to each of the ten stations, they are locked and released by key switches at each station; enabling Ricardo production engineers to verify the status of every aspect of the build. The company can also reconfigure every aspect of the line – from DC-tooling, manual operations, air testing and so on – to introduce engines from other manufacturers.

Before the line at Shoreham was assembled, a FAT line was pre-built at MHA’s Luton plant, where it was approved by Ricardo with few changes. Next, in order to allow Ricardo engineers to test the line thoroughly, two stations were built in the Shoreham facility for prototype engine assembly.

Summing up, Paul Crosbie says: "The result is typical of what MHA and Exmac are good at. Mechanically the Exmac handling system is extremely robust but quite simple, but when combined with the highly complex yet utterly functional MHA control system, the completed line has more than exceeded Ricardo’s overall performance expectations."

Marcus Hunter, Exmac Automation
Gregory’s Bank, Worcester WR3 8AB
Phone: 01905 721500, Fax: 01905 721539
Email: MH@exmac.co.uk, Web: www.exmacautomation.co.uk

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