Industry may never see World War II production rates again - but the lessons live on
Guy Norris/Seattle Ian Sheppard/London Graham Warwick/Fort Worth
For Boeing, it was back to the future when it began implementing lean manufacturing in 1993, as many of the real lessons were taught back in the Second World War when the Seattle, Washington, plant was churning out B-17 bombers. At the peak, 34,000 workers produced one B-17 every 1.3h - 17 a day - and the cost of each dropped from $242,000 in 1940 to $139,000 in 1944 as the benefits of lean manufacturing took hold.
The assembly flow time was strictly controlled by a big clock which acted as a giant pacemaker. Teams would complete a task en masse and, when time was up, would move on to repeat the process on the next aircraft. This idea of "takt" (or heartbeat) time is a basic tenet of today's lean manufacturing, the principles of which are based on the Toyota Production System developed in the 1950s.
"The Japanese, because of their urgent need to rebuild the country after the Second World War, borrowed Ford's conveyer system, US quality control processes and industrial engineering functions, went to our supermarkets and saw the 'kanban' [signboard] system," says Lean Manufacturing Office director John Black. The kanban concept allows stocks to be replenished only when needed and avoids the build up of wasteful inventory.
The combination led to a change not only in manufacturing techniques, but also of principles. Traditionally, these state that price is defined as cost plus profit. Using the lean equation, this changes to profit equals price minus cost. This is market driven and means that, to increase profit, a company has to lower its costs.
The market driven principles also apply within the factory because the process of moving products down the line is based on workers at the end of the line requesting the next unit. The production process is not being "pushed" as new components are loaded on to the line, but "pulled" as complete aircraft leave it. The more aircraft required, the more pull on the line.
"We are working towards a vision that operates 'just in time', where you have minimum inventory and have standard work in place. By working the takt time, and being connected upstream with suppliers, you can control production to a degree that, no matter how many aircraft are ordered, you can still build them without hiring more people," says Black. Boeing's targets for lean manufacturing include improving quality by more than 50% a year, increasing productivity by 2% a month and reducing lead time by 90%.
So what has Boeing learned so far? Black says that lean manufacturing "...needs to be both bottom up and top down. The leaders have to lead and the workers have to believe in it." Incentives tied to benefits such as a share value scheme can help. Care should be taken when introducing changes. "Don't go in to re-engineer something and take away the very people who understand the process. You can't save the patient by killing him. Keep him alive while doing the surgery," he says.
LEAN TRICK
The real trick with lean manufacturing of military aircraft today is to achieve the sort of cost and time reductions that Boeing's Second World War B-17 plant saw, but without the massive production rates. In fact, for military manufacturers, lean principles hold the key to producing aircraft affordably at today's low rates.
Lockheed Martin has been working on lean manufacturing for at least as long as Boeing, "...but we have a different idea of lean now", says Larry Pike, director of the Lean Deployment organisation at the company's Tactical Aircraft Systems division in Fort Worth, Texas.
"First, you have to figure out who you are. We're not experts at everything, so we establish what we are good at and apply lean to what we do best," Pike says. Lean manufacturing principles form one of two pillars of the production system now being deployed at the Fort Worth plant (see P32). The other is advanced manufacturing methods. Both need a "motivated, engaged workforce" as a basis to achieve the goals of "best quality, shortest span and best value", says Pike.
Aerospace has "...challenges other industry does not face" in achieving an engaged workforce, he believes. Efforts to motivate workers "...are going beyond what we have done in the past. It takes every idea from every person" to achieve the goals, he says.
Continuous improvement, the first principle of lean manufacturing, will not happen without the workforce providing ideas on ways to eliminate waste and shorten flow time. For the new production system to work, an atmosphere of trust must exist which encourages "prudent risk taking" and values employee suggestions.
"The risk-taking conservatism in the industry has filtered down to every employee. This has to be modified to create the environment for continuous improvement," Pike says. "The environment must invite ideas for change."
Assessing its success so far, Pike says that the company has made "good progress" with advanced manufacturing methods over the past three years, and is "Éjust seeing the results" of over two years' work in engaging the workforce. Lean manufacturing, however, is still at the pilot stage. These include establishing a "kanban" pull system for machined parts used in the F-16 fin, which has cut span time by 50% and inventory by 75%. The next phase will be to establish a pull system for kits used in assembly of the F-16 forward fuselage, says Pike.
EMPLOYEE FOCUS
Donald Craig, director of the UK's Lean Aircraft Initiative (see P34), believes that the focus of lean manufacturing now needs to shift to what employees actually do.
The lean approach requires areas such as information technology to be kept in context - for example, "control boards" work better than computers on the shop floor, he says. Also, to realise the advantages of the "virtual organisation", participants need to grasp the fundamentals of team-based working.
The starting point for lean manufacturing, Craig says, is identifying what is valuable, which the customer must define. This is a process Lockheed Martin has gone through on a pilot project involving an F-16 wing pylon, defining as value added "...changes to form, fit and function that the customer is willing to pay for".
The manufacturer must then operate a pull system, Craig says, making only what the customer wants and aiming to get it right first time. Pike agrees, saying: "The concept is: don't produce until needed and don't produce what isn't needed." The permanent crusade to eliminate idle time and waste requires flexibility from the workforce and an acceptance that constant change is the steady state condition, Craig says.
Aerospace must learn the best practices already in use in other industries, he says. Car companies receive prepared parts kits, plus tools, with only enough time for them to transfer to the appropriate position on the production line. This is something Lockheed Martin's Pike aims to achieve by having suppliers provide parts in kits already arranged for easy assembly.
In the end, the key to lean manufacturing is that, if it can be made to work, both the manufacturer and the customer will benefit.
Source: Flight International
