Fast hoists

Potain, Manitowoc’s tower crane brand, has been building crane components at La Clayette in the East of France for more than 80 years. As the business has grown, the plant has grown with it. The problem is, La Clayette doesn’t lend itself to being developed into a modern lean manufacturing line.

Bruno Durand is director of operations at La Clayette and Charlieu; previously he was director of quality for Manitowoc Crane EMEA, a role that allowed him to hone his skills in lean manufacturing. He explains, “The factory at La Clayette grew over 80 years, on a hillside: the plant is not on one level, on one line, but with multiple small entities, with parts having to travel between them.”

At Charlieu, Manitowoc has focused on self erector assembly, building Igo and Igo T cranes.

The plan is to move hoist production from La Clayette to Charlieu, creating a new lean line. At the same time, existing lines will be reordered, and the plant will take on other responsibilities.

Durand says, “There will be four pillars at Charlieu. The Crane Care service and renovation; the large weldments for mobiles; the Igo T and large self erectors; finally, hoist production.

“Hoist production is the largest project. We are moving the entire hoist line from La Clayette to Charlieu. It will produce all hoists for towers and all terrains. The line will be reindustrialised for lean manufacture.

“To make a top of the range hoist line, you need a plant with an optimized process layout. You need straight lines and a single flow. At La Clayette, there were hundreds of metres of wasted travel between different process steps.”

In lean manufacturing, the thinking you do outside the line is a vital part of the success of any programme. Philippe Cohet, Manitowoc Cranes executive vice president for Europe, the Middle East, and Asia, explains: “Lean isn’t something we’ve created, but we’ve embraced it as a philosophy for operations management. We build many products, in small runs. The approach of lean requires extremely sophisticated planning. That’s a lot easier if you are producing one product, tens of thousands of times. We have to adopt a ‘slot in’ process.

“It’s hard for the factory workers to move from working on one crane to working on another. We have to reduce the possibility of error. With lean we give the guys a very limited set of tasks and parts.

“We’ve seen an increase in overall performance. We can better manage costs on stock and inventory. Productivity is higher, and quality is higher. There is less stress for employees.

“But, there is much more work needed outside of the line. Problems are moved to the design side.”

Durand says that while lean aims to make the day-to-day work of operators clearer, their experience is still a vital part of the planning process: “The key to a well performing workflow, to lean manufacturing, is the involvement of operators. They are able to tell where the flow is wrong and to develop workstation ergonomics.

“We worked with ECAM, [The Ecole Catholique d’Arts et Métiers], a renowned French engineering school, and a centre for the study of lean manufacturing. A group of 32 master’s students came to Charlieu for three days, and worked alongside our operators. They did a lean analysis, and developed an improvement programme. Some of this is now being implemented.”

As well as optimising production lines within the plant, Manitowoc needed to optimise the plant’s position within its wider workflow. It needed to decide what the plant would produce, how it would supply other plants, which of its previous jobs could go to other plants, and which could be better performed by outside suppliers.

Key to this process was deciding what the plant’s core competencies would be. Durand says, “We used to cut a lot of steel. Now, our partners deliver cut steel, and will soon be delivering it cut and bent. But, some activity will remain, especially for renovation. There used to be a lot of oxy-cutting machinery here, now it is being moved out. Now, there is just one cutting machine left for spare parts.

“There will be an improved line for mobile crane outriggers, supplying the four and five axles cranes built at the Manitowoc factory at Wilhelmshaven in Germany. We are also making turntables for the same cranes. Both products require the same machining equipment.

“For hoists, we start with cut and bent steel from outside suppliers. We roll plate for barrels. We machine components. We tack and weld parts. Our new machining centre will machine all of our drums, all our hoist chassis. We assemble and test the finished components.

“Cutting and standard bending are not core competencies. Rolling, however, does remain a core competence: we’re working with high thicknesses, and very precise rolling. Our experience in machining at Charlieu was the reason for investing in hoist and hoist chassis machining here.”

As the hoist line moves in from La Clayette, the Igo line of self erectors is moving out, to a plant in Niella Torino, Italy. Durand says, “All of the Igo range will move to Niella. We have been building the smaller models there for some time. Now, we have moved the Igo 32 and Igo 36 and the Igo 42 and 50 will move after the summer. The Igo T cranes, the big units, will stay here.

“The Igo T is larger and more complex: it includes a hydraulically telescoping mast, which allows pieces to be added to the bottom of the mast. We’re building a new hall for flat part storage. The space freed up by this will be used for Igo T 130 tooling.”

The plant will be organised, very roughly, on a U-shape, with two main lines running through parallel within that shape. Looking down on the plant from above, one would see the main yard at the top of that U. Parts enter the plant at the first tip of the U, joining the lines for self-erectors or for hoists. They are machined, tacked, welded, shotblasted, all as appropriate,painted, assembled, and checked by quality control, before going back out into the yard at the other end of the U.

In the space between those two U-shaped main lines are the lines for mobile crane components, which shares machining equipment with the hoist line, and a separate single unit line for supplying parts for Manitowoc’s Crane Care service and renovation service.

Durand says, “A storage area is currently being used for renovation machining, for assembly and disassembly of components. The single unit line will use lots of small, very flexible stations. It will be completed over the end of 2010.

“There will be a separate line for single unit manufacture, for replacement jib parts, for example. For single unit production, lean will be implemented at the workstation level, not globally. We’re moving the single unit line, and the welding school, into one area to reduce disruption to the serial production line flow.”

Making the move will take most of 2010. Parts of the reorganisation started even earlier. Durand says, “We started introducing the large weldments for mobile cranes in 2008. That is producing turntables and outriggers for four and five axle cranes. We began the transfer of renovation of mechanical components from La Clayette in February 2010.”

Cranes Today visited the plant at the end of July 2010, as the plant was gearing up for a big push during the August shutdown. One of the big parts of that push was due to be preparation of space for the new machining tool. Transfer project director Bertrand Lehoux says, “The new hoist line machining centre is 30m long and two storeys tall. It will need to be sunk into the floor of plant. We need to be ready to start excavating and then reinforcing the foundations. It will take about a month of work.”

It has been a race to get everything ready for jobs like this, without disrupting production. Durand says, “The current Crane mast section lines have been moved out to make way, either moving internally here, or to Niella. The space was made ready in the first week of August, ready for ground works to begin. Electric, pneumatic, and hydraulic lines will be put in later in the year.”

“It should be a seamless move from La Clayette to Charlieu. There will be a phased transport process, with small sections moved incrementally: so, for example, we move one of 20 welding stations at a time. The big new machining centre will be ready before the old one closes.”

The end result will be a more efficient plant, allowing parts to flow through the facility as needed. For example, the new hoist line will share space on the painting line with the self erector parts. Durand says, “We’re adding hoists to the painting line. They will share the line with other components, but will have to follow a different flow: the hoists are not shot blasted, instead they run parallel to the main line before rejoining it.”

To accomplish this, a series of junctions, like those on a railway, have been set up. The hoist parts leave the welding line, joining the other components on the painting line as they approach the shotblasting area. Here, the hoist parts go off on another line, before rejoining the other components for painting and finishing.

The new painting line adds flexibility as well as efficiency. Durand says, “The painting line offers fast turnaround, with paint colours able to be switched in few minutes.”

On the self erector lines, Manitowoc is already putting lean techniques in place. Once, workstations would be a mass of different parts, with bins around the plant holding anything else that operators might need. Now, the only parts at hand, or on site at all, will be those that the operators need for that shift.

Durand says, “The jib components will arrive from the supplier, delivered in racks as they will be used, directly to the line. We need to develop our partner relationships, to change the way we work with out partners. Our primary partners, for cut and bent steel, need to deliver racks with any one of hundreds of parts, as needed for each shift.

“Manitowoc launched its Focus quality programme in 2009. It aims to ensure best standard process. It focuses on supplier development, relationship and process testing, and flow. We’re currently talking to suppliers and agreeing costs. It will take time to reach our performance goals. So, it will take some time to get the working line up to full output.”

It is the close planning of the tools and supplies at hand for each job that place such high demands on Manitowoc’s supply chain management. Cohet says, “The key development for us now is standardisation, using fewer individual parts, and more of each. That makes it easier for us to manage our supplier relationships.

“The biggest challenge is to convert the supplier to lean, to get them to accept a pull signal, rather than pushing parts to assembly. So, we help suppliers organize themselves to deliver parts as needed rather than 20 units at a time. We have companies that specialise in acting as a buffer, holding parts and delivering them as needed.

“If you look at the cost of holding parts, paying a few percent more on having parts delivered to order, it’s what adds to the value of the business for shareholders.”

The end result of this reorganization won’t just be a bump for shareholders returns. It should also make Manitowoc better placed to deliver cranes and components to its customers. Durand says, “We expect a productivity increase and an improvement in quality. There’ll be less reworking needed, a very significant increase in quality.

“It gives us the capacity to balance our internal load: we can balance production between launches; we can ramp up or size down production in relation to demand.

“We’re drastically reducing the length of the process line, by avoiding travel between stations. There have been some very significant decreases in work in progress, in standing, in waiting. It will lead to a reduction in lead times. That gives us a lot of flexibility. It will mean we can deliver product with days, rather than weeks of notice.”