A major refurbishment, costing over £8m was planned at their Dorket Head factory, introducing automated equipment and processes. Three factory design suppliers tendered proposals. On paper, all would work, and all had merits, but it was impossible to evaluate in advance, just by inspection, whether they really could achieve the targets and which plan was best.
Ibstock plc is the UK’s largest brick manufacturers, and employs over 2,000 people across 36 manufacturing sites.
The brick business is fiercely competitive and very cyclical – so there was a need to plan for maximum throughput in times of high demand (and prices) and greatest resilience to downturns and price erosion. This required the best compromise between throughput flexibility and minimization of fixed costs and wastage in the production process. :
Three factory design suppliers tendered proposals. On paper, all would work, and all had merits, but it was impossible to evaluate in advance, just by inspection, whether they really could achieve the targets and which plan was best.
Kilns need to be fed continuously (otherwise unacceptable temperature variations occur). Process yield must be maximised to achieve best-in-class performance. Specifically the following issues needed to be addressed:
- How to assess and minimise the impact of equipment breakdown, in order to increase reliable throughput and reduce the need for completed product buffer stocks.
- How to design the optimum shift patterns for the various processes given the interactions between process stages and the need for production flexibility.
- Assessment of the impact of other factors e.g. set-up times for brick type changes, kiln re-heat times and kiln firing profiles.
The dynamic model constructed by Paragon accurately simulated the flow of bricks through the production process revealing potential bottlenecks. The initial simulation indicated that all three proposals substantially missed the performance targets. This was because the suppliers had each used a static percentage de-rating which they applied to various process stages in their spreadsheet predictions to take account of equipment breakdowns, taking no account of dynamic interdependencies. Paragon’s modelling showed that the same downtime assumptions analysed as discrete dynamic events (as would happen in real life) would result in a flawed, underperforming design, requiring major remedial changes. Real downtime data was used from another Ibstock factory.
Ibstock then selected their preferred supplier and their initial design for further modelling analysis and improvement. Ibstock’s production team and Paragon’s ideas were modelled, evaluated, compared, revised and re-simulated.
The model revealed that the reliability of the extruding and cutting processes were key and that extra ‘kiln cars’, buffers and ‘drying car’ storage lanes were essential if the dryer and the kiln were to be used at maximum efficiency and losses minimised. Identifying this at an early stage was vital because storage space for the cars had to be provided in the factory layout – changes could not easily be made later.
Finally, the model also proved that staggered shift patterns would greatly increase workforce productivity.
The model was used to extract design improvements from the supplier in order to meet the performance targets. Dramatic changes were made to the original design and a considerable financial saving was realised.
The Dorket Head refurbishment has now been implemented and has been running for some time, delivering exactly the promised performance with great consistency due to the ‘robustness tests’ simulated under various conditions in the model.
Ibstock Production Director Keith Morton described it as: “One of the few right-first-time implementations I’ve ever seen”. What’s more, the factory can respond more flexibly to market conditions and maximise profitability as demand fluctuates.
Dorket Head became the most efficient factory in the Ibstock group and one of the most efficient in the world.