Cellular Manufacturing Evolves

September 1, 2018

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We don’t hear the term cellular manufacturing as much as we did just a few years back. Then, production machinery such as a press brake and laser-cutting machine or welding station, grouped together, perhaps with a robot providing part- or material-handling duties, produced a component or completed a range of production steps in one location. Following, technology enabled lights-out production within these cells.

Today, advanced communication capabilities, paired with advanced machine capabilities and software that can tie individual machines and processes to company-wide needs, have propelled cellular manufacturing into the virtual realm. Cellular these days not only means physical proximity, but virtual proximity that redirects, sets up and delivers material and parts exactly when and where they are needed.

To explore the issue, MetalForming spoke with Tobias Reuther, director of the Trumpf Smart Factory Chicago, in Hoffman Estates, IL. The factory showcases fully networked production, highlighting how people, machines, automation and software interact to produce sheetmetal parts and assemblies. It demonstrates how manufacturing in general, and sheetmetal forming and fabrication in particular, have made, and will continue to make, tremendous strides in adopting and implementing new technologies to transform mature manufacturing processes.

Reuther describes the various ways that fabricators can, and do, arrange equipment in the new cellular world, beginning with relatively simple layouts.

“Fabricators may want to connect two laser-cutting machines with one storage tower for supply of raw material or parts,” Reuther says. “Suppose a fabricator employs six laser-cutting machines. Two lasers can mate with a single storage tower to yield three individually managed cells.”

In this scenario, an issue with a single machine does not affect the two other cells, so two out of three continue to run. Redundancy results from this setup, but it comes at a price.

“Floorspace is sacrificed,” Reuther says. “Secondly, to shift orders from one of these cells to another, the storage tower must contain the right material for the shifted production. Alternatively, connecting all six laser-cutting machines to a large storage system allows more freedom in production. Fabricators can push down an order to any other machine because they all have access to the same inventory.”

It all depends on the production strategy, explains Reuther. Many fabricators choose the cellular approach while some opt for a monolithic cell structure instead of each cell acting as a logistics center.

“A large storage center can connect 10 or 15 individual machines, with transport of material from multiple processes covered under one system,” he says. “This means no need for forklifts and the associated time and money costs of transport.”

There is no right or wrong with various layouts, it just depends on fabricators’ needs. Of course, cost is a factor, as well as space. Where some fabricators may be able to accommodate a cell layout within a new building, others must deal with space and process constraints in existing structures.

Specific Cells for Specific Needs

“We ask fabricators what they are looking for when they consider automation,” says Reuther. “Do they want a small-cell approach, or a flexible logistics center that can be fed with orders where they manage just one inventory compared to three?”

Some fabricators may manufacture three main product lines, with each of them providing enough work for one or two dedicated laser-cutting machines. In this case, according to Reuther, it makes sense to operate them as independent cells.

“Clearly distinctive production lines can benefit from this approach,” he says, “but it is not very flexible. With an A-B-C production line, what if production drops suddenly on A but increases on C? A fabricator can’t shift to the other cell without giving up efficiency and flow, and must change the inventory and ensure location of the right material in the right cell. A large storage system with six connected machines enables a fabricator to shift and prioritize work easily. Dedicated product lines benefit from smaller cells, but if jobs change frequently over time, multiple machines connected to a central storage center enable the needed flexibility.”

Such smaller cells, as cellular manufacturing may have been described a decade or more ago, were, back then and in many cases today, essentially production islands. Bridging those islands these days are advanced communication software and manufacturing execution systems (MESs) that allow cells to work in concert, bringing flexibility where previously it did not exist.

“Even multiple individual cells served by a couple of storage towers can connect to an MES,” Reuther says, “bringing a greater level of freedom and flexibility, thus making cellular manufacturing more powerful than ever.”

Optimized Layouts Serve Individual Sectors Well

Today, cellular-manufacturing layouts often reflect the industries served by fabricators.

“For example, agricultural manufacturers tend to produce distinct products that change little from year to year, using similar parts from similar materials in similar thicknesses,” Reuther explains. “These manufacturers know that these products will be manufactured for the next 10 to 15 years, so they focus on larger systems due to volume and the expectation of constant work.

“Appliance fabricators, on the other hand, deal with a much higher variety of parts,” he continues. “They place importance on quickly producing many part types. They tend to opt for several small cells that allow flexibility based on demand. Software connects these cells to help optimize productivity. And, with most material being thin-gauge stainless steel, it doesn’t matter if it is stored in three or four towers, or just one. Due to lack of material variety, inventory poses only a minor challenge.”

These examples illustrate how cellular layouts arise from various fabricator needs. Where agricultural suppliers may deal with known part types and volumes over an extended period but require a variety of materials in various thicknesses, appliance suppliers could face part variety but little material differentiation. Cell solutions exist for both. Some combination of these application attributes reveal other cellular possibilities, where the large system tackles high-volume, varied-material jobs while small cells run smaller-lot jobs.

Transparency Keys Cell Advancements

“Transparency is the key to production efficiency, especially in cellular environments,” explains Reuther. “Knowing how a machine performed on the last shift, knowing the idle times and errors…how do you find out?”

Smart factories, using the advanced communication capabilities in newer equipment, combined with software that tracks, analyzes and helps manage all aspects of operations, bring cellular manufacturing to a whole new level via transparency of processes, machine utilization and workflow. Machines or software can notify operators or management of issues, leading to almost instant response and resolution.

“That transparency dramatically reduces downtime and increases efficiency,” Reuther says. “Connectivity of machines that enable communication with a general software system is an absolute necessity for ideal shop-floor productivity. Otherwise, machines and processes would require constant monitoring by humans. Machines can ask for help or keep the system updated on job progress, ensuring that the next job will be ready to go.”

And, should troubles arise that can’t be solved inhouse, new technology such as remote monitoring by machine manufacturers, or augmental-reality glasses that let machine-builder technicians see what the fabricator sees, quicken troubleshooting and repair by leaps and bounds. The options cost less than flying a technician out to take a look. MF

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See also: TRUMPF Inc.