03 Dec Lean, Leaner, Leanest, Willerby Holiday Homes in on its Quest to be a World Class Business
Established just after the Second World War, Willerby, with a turnover in excess of £100m and employing 650 employees at its site in Hull, UK is the market leader in the construction of Holiday Homes. Using skilled craftsmen and traditional build methods and materials, the workforce, working in departmental Silos, have been driven by a culture of ‘the more the better’. When Willerby needed to invest in a replacement scheduling system, it knew that only the most competent of scheduling solutions would suffice. Willerby found that solution in Preactor APS, provided by Preactor Solution Provider, RMS.
The work which goes into each of the Holiday Homes which leave one of Willerby’s three assembly lines every 30 minutes is vast. Working with large batch sizes, a 6 week production lead time, and 150,000 machined parts of huge variance each week, Willerby consequently faces major business challenges.
Unsurprisingly, bottleneck processes were hard to identify, rework and missing parts were common and the 11th hour subcontracting of some components was a frequent occurrence. Moreover, the 3-shift system in the machining centre left no room to gain any spare capacity so new machinery was bought and installed wherever there was space.
Different areas also provided specific challenges which combined to give the company major problems, as Craig Dunn, Lean Operations Manager, explains. “The problem was that the business was very disjointed with various areas all managing their own output and capacity requirements independently. Working in isolation, there was no regard for previous and subsequent processes within each department and material was bought in by keying dates into the MRP system from the old assembly line schedule generated by MS Access.
Each week a new schedule was created allowing for the slippage from the previous week and each department would re-plan their own area accordingly. Areas achieving planned targets would simply carry on, regardless of the fact that they should readjust their schedule, and the cycle of overproduction would be perpetuated with material and subassemblies consuming every bit of available space in the building. Missing items and damaged stock due to huge inventory levels caused constant rework and fire fighting situations, leaving management little time to problem solve and perform root cause analysis.”
As Willerby Homes produced Holiday Homes of varying cycle times across three assembly lines, each with a different number of working bays, MS Access could not produce accurate schedules. As products moved through these bays, models with a different cycle time would follow them. If a faster product went on the line behind a slower product it would have to move at the speed of the product in front until the last of these left the assembly line. It was only at that point that the faster product could move at its own cycle time. On the other hand, if a fast product was moving down the assembly line followed by a slow product, a natural gap would manifest and grow as products worked their way through each bay.
This was the main cause of the schedule inaccuracy, as the access program did not account for this anomaly.
Although very profitable, there was a realisation that this batch and queue method combined with a disorganised and inflexible style of working would not equip the company for future success. As Willerby intended to stay at the top in its field with a desire to set standards in the industry by becoming a World Class Manufacturer, the company realised it needed to instigate changes. A Lean Manufacturing approach was targeted as the way forward but first it had to understand and gain control of its processes. This was a long hard road that was to take some five years to complete but would allow Willerby to move into the visual shop floor environment.
With this in mind, the company, which at this point had no central planning function, visited the CIM show at the NEC. In their search for scheduling software they asked various MRP and ERP vendors for recommendations. The common response was to check out Preactor which the majority were already using with their own product. After talking to Preactor Solution Provider RMS and being impressed by the software they took this information back to Colin Jeffrey, Willerby’s Production Director. From there the decision was made in early 2000 to select Preactor 400 APS as the way forward.
Production Director Colin Jeffrey explains the reasons why. “Quite simply, I believed it to be the best software on the market offering the right solution and flexibility. This was based on many case studies and other literature, including articles found in The Manufacturer, which convinced me that there was no better product out there that would better satisfy our needs. We were unable to start a Lean implementation program without first understanding and gaining control of our processes and Preactor offered the solution”.
Implementation and benefits
The first step of the implementation focussed on increasing the accuracy of the assembly line schedule and began late 2000 after RMS had installed and set up Preactor and delivered the necessary training. Dunn explains. “Preactor wasn’t capable of reflecting the changeover anomaly that we were experiencing on the assembly lines through its standard functionality, so RMS was called back and briefed with the problem. They then went away and carried out various paper simulations in an attempt to understand the logic and mathematics of what was happening. Once this had been established, RMS proceeded customise Preactor in an appropriate way.”
With the work now done on the assembly lines, schedule accuracy had risen from 80% to 95% and working closely with Willerby’s staff, RMS also linked this Preactor model with the MRP system taking away the need for keying in data each week. This stabilised the supply chain.
Once the assembly lines were sorted, Willerby then focussed on the supply areas, beginning with the machine shop. This carried massive inventory and had no real workflow. Working with the machine shop manager, the process of building a Preactor system started to give an understanding of this work centre. This process was difficult as shop floor knowledge had always driven the process and there was little documented data to build a system with.
Ian Shufflebotham, General Manager describes how this was overcome. “In the absence of clear data we had to collect as much information from the shop floor personnel as possible including routing information and operation times. This gave us the foundation to simulate the shop floor activity through Preactor which quickly allowed us to see where our bottleneck and problematic areas of concern were.” Dunn explains the benefits this brought. “Using this new knowledge and creating ‘what if’ scenarios in Preactor it allowed us to create flow by rerouting products and moving machinery. The WIP was reduced to sensible levels and efficiency was maximised. Subcontracting, once a common occurrence, ceased and the 3-tier shift pattern in this area was reduced to 2. Lead times were slashed and the MRP system was brought in line reducing the amount of bought in stock carried in storage.”
With better schedule accuracy and control of the machining processes, things became much clearer. In the absence of inventory on the shop floor, visibility was created and the number of missing and damaged items dropped to a handful. Bottleneck processes were easily identified by Preactor and contingencies were discussed months in advance.
But the assembly lines were still held up waiting for supply from one particular subassembly area, the Jig Shop. This section hand made the sidewalls and bulkheads for the main construction of each Holiday Home. This area was constantly starving the assembly process and the operatives would work extensive overtime in an attempt to satisfy demand. There was no scheduling or balanced workflow in this area and operatives were left to sort through and create their own work plan with each resource not fully aware of their working colleague’s activities.
A Preactor scheduling system was implemented to put order in this part of the business. Schedules were created in advance for each resource which was given ‘work-to’ lists, and a calmer, more fluid environment began to take hold.
Further work and Challenges
Five years after its installation, Preactor has brought about some incredible changes.
Dunn again, “Production Leads are now down from 6 weeks to 5 days and WIP has been reduced by a massive 80%. Subcontracting has ceased and we are now capable of producing the same volumes on a two-shift system in the machine centre. Various ‘what-if’ scenarios have helped us re-plan our layout and provide better workflow, increasing efficiency and gaining capacity. Overtime, once abundant, is now minimal and Managers now find the time to manage. Lending itself to fit into any environment through its easy configuration and visual depiction of workflow through Gantt charts, Preactor has provided us with the means to start applying Lean philosophies to the business.
Although still providing scheduled work to some areas, Preactor is now being re-configured to produce capacity planning for the management team in some supply areas.”
Interfaced with Willerby’s MPS system, Preactor is still scheduling the main assembly lines and drives the MRP process and the balance is now being found between Lean Kanban control and finite scheduling.
Mike Novels of Preactor International concludes. “This is an excellent example of how scheduling tools, customised to meet the unique challenges of each business, can work together with traditional lean control techniques to provide the solution that companies need to become World Class in their sector.”