Don't wait for ramp-up: simulate production now

Don’t fall into the trap that many manufacturing firms do when it comes to considering simulation software. It’s not something you should buy-in and give to a student to ‘play’ with. Used properly by your engineers, perhaps even integrated with your CAD systems, manufacturing process simulation software can really help companies wipe out unnecessary costs from the bottom line. How? First, most plants, whatever they make, share a common set of problems: optimising plant capacity; keeping inventory and work-in-progress (WIP) to a minimum; removing production bottlenecks; co-ordinating logistics with your distributors; and scheduling works orders through the plant. These can all be solved, or at the very least, aided by simulation software. Second, companies usually don’t have any way of getting early visibility of production costs and process times. And it’s not easy for these firms to capture, store and re-use proven, best practice manufacturing processes. With simulation software, you can do all the necessary up front ‘testing’ and ‘what if’ scenario analyses before you actually manufacture or assemble the product. The real problems start to occur if companies wait until production ramp-up time before testing new ideas or process layouts. Take vehicle manufacturing giant Daimler-Chrysler. It started a ‘digital factory’ project in mid-2000 and estimates that, by 2005, it will have implemented the complete digital verification of production synchronised with total digital verification of the vehicle. It’s easy to see why this company is taking simulation software seriously. It estimates that in its ‘traditional’ (manual) production planning system, the cost of missing or wrongly positioning weld points can be more than eur50,000 when operators have to get into the assembly stations to make changes. Another vehicle maker, Ford Motor Company has been using simulation software for its engine cylinder head machining line at Dagenham. Last year, the line was experiencing capacity concerns and the manufacturing team wanted to investigate the impact of changes to the production line on the full engine assembly line downstream. With Ford’s strong emphasis on Six Sigma (using data and statistical analysis techniques to continuously improve manufacturing processes), the team decided to use simulation software package Witness (from Lanner), which has links to Minitab, a statistical software package that provides Six Sigma teams with additional analysis capability. An Excel interface to Witness known as FIRST (Fast Interactive Replacement Simulation Tool) was used. This is a Ford proprietary tool and was specially customised for quickly modelling machining lines. As Ford’s global engine operations simulation technical specialist John Ladbrook explains: “FIRST is a spreadsheet front-end used to manually capture input data. Based on this data, the Witness evaluation side of the software goes away and automatically builds a model without engineers having to be fully trained in programming skills. We can build different models every hour once the input data has been entered. And we can make changes to the model in minutes.” Having populated FIRST with the data from the cylinder head production line (production cycle times, breakdown details, tool change information, etc) the Six Sigma team then started to determine what the key changes should be to the line. Two major opportunities were identified that led to a 10% increase in production capacity once implemented. Ladbrook: “We experimented with the model until it became clear that we could improve the method of machine changeover on the line. We have at least two different types of cylinder head to make which we have to use different tools for. As parts move down the line, tools are changed over accordingly.” The changes the Six Sigma team recommended took about six months to implement, but the 10% capacity improvement was recognised immediately after this. “The whole process of transferring cylinder heads to the main engine assembly line downstream has improved greatly,” says Ladbrook. “The flow of parts is faster, more consistent and there’s generally less disruption. We even have more time for maintenance activities on the line now.” He sums up the benefits of simulation. “A set of tools that can encompass all the variables in a manufacturing process and which can help identify where problems are going to occur through what-if analyses, before you actually commit to installation costs.” Simulate scheduling too It’s not just the car industry that’s doing it though. Port Talbot-based steel maker Corus is using it, on the one hand to optimise the scheduling of sequential manufacturing processes and operations in terms of times, quantities and energy usage, and on the other, for optimising logistics. The firm’s had PMC’s Orchestrate scheduling software since September 2001 to simulate and re-develop its iron slab manufacturing processes. Neil Richardson, who works in the manufacturing systems group, says: “Scheduling has a big impact on our operations so we’re investigating the impact of our schedules on manufacturing performance. The software is enabling my team to visualise the possibilities and iteratively improve scheduling to optimise production rates and the interfaces between processes. “The value is being able to optimise the existing processes… Re-scheduling in steel making can have a very big effect. ROI, however, is difficult to measure. We’re currently learning,” he says. “Asking questions like how much power is consumed? what throughputs, what asset costs and so on, by looking back with the plant engineers over an eight month period. It’s about using plant assets to the maximum.” And he says that with modern simulators you don’t particularly need to understand the underlying maths. It’s enough to know process times and history. But there are barriers. Dr Raimond Menges, MD of simulation software specialist Delmia (Germany), sums up the fears many firms have of simulation. “Tools used in the digital factory and their partially automated software loops mercilessly reveal mistakes that have been made by planning. It’s this transparency that should be seen as an opportunity for firms, not as a danger.” And his advice for SMEs? “No supplier should attempt to implement the digital factory in a hurry. Suppliers will not need all the complexities an OEM needs. They should not, in an act of anticipatory obedience to OEMs, try to implement it all straight away. Instead, they should start the digital factory in one germ cell and let it evolve and expand from there.”