Maintenance Strategy

How air casters integrate CNC machining and business operations

Lean methodologies are supported by flexibility in plant floor layouts

By John Massenburg December 11, 2020
Courtesy: AeroGo

CNC machines present a conundrum for many manufacturing operations, but a solution is available.

Automated and highly accurate, computer numerical control (CNC) tools are used by manufacturers who produce complex parts at high volume. Getting these and similar machines into the manufacturing facility, however, can be a major challenge. Once installed, CNC machines are frequently positioned amidst production lines that offer minimal clearance around them, rendering them seemingly immoveable monuments around which production lines must contort themselves, regardless of any negative impacts on efficiency.

Consider one typical machine shop using multiple CNC machine operations to make one part. Often, CNC machines don’t end up next to each other, which turns the manufacturing environment into a logistics puzzle. First, the product has to go to the first machine tool. The parts then go to the other side of the facility, and this process continues because the various machine tools are scattered throughout the facility. What’s worse, at each stop each machine requires its own operator. This results in an encumbered production flow with increases that ally increases time, movements and manual labor for the overall production process.

However, more of today’s manufacturers are using air casters to re-configure their CNC machines into a single cell using a single operator.

Mobility of air casters

Air casters fit within the footprint of a machine, minimizing the maneuverable space around it. Courtesy: AeroGo

Air casters fit within the footprint of a machine, minimizing the maneuverable space around it. Courtesy: AeroGo

Originally developed in the 1950s, air casters float extremely heavy loads by using compressed air to inflate donut-shaped tubes. Once the tubes are inflated, compressed air leaks beneath them to create a film of air that is no thicker than a business card.

Similar to how a plastic puck travels atop an air hockey table, machinery can be glided over the facility floor by operators using a fraction of the force that would otherwise be required. On most floor surfaces, operators need to exert only 5-25 pounds of force to move loads of up to 5,000 pounds when air casters are employed, compared to 300 pounds of force required to move a load of the same weight when using wheeled casters. As a result, air casters can also more easily move CNC machines that weigh tens of thousands of pounds.

Furthermore, because air caters fit within the envelope of a CNC machine, they require far less operating space in which to maneuver, can move omni-directionally, and can rotate in place. Air casters won’t damage flooring, including epoxy-coated floors, since the casters float the machines with almost no friction.

Air casters thus make it possible to navigate even awkward CNC machines more nimbly throughout space-constrained manufacturing facilities, enabling operators to traverse maze-like corridors between production machines with more ease.

Operators can also more seamlessly slide large machine tools off the production line, float them through narrow corridors and around tight corners, and more accurately position them in a new location.

Once the CNC machine reaches its destination, the air casters are deflated, and the machine gently settles into its new position. They can then be re-inflated when an operator is ready for it to be moved again. All that’s required is access to standard shop air.

Difficulties moving CNC machines

By contrast, traditional systems of moving heavy equipment are not typically known for their agility, as described below.

  • Forklifts: Often the typical go-to solution, forklifts require relatively expansive space that most shops lack. Even if a facility has forklift access to move parts or products in and out, they likely lack sufficient clearance for forklifts to get into the production line itself and move the entire machine. Additionally, if the CNC machine is particularly large (i.e. tens of thousands of pounds), forklifts become infeasible because these weight totals fall outside the range of most forklifts’ normal capacities.
  • Overhead Cranes: Unless the facility already has an overhead crane installed, this can be an expensive solution that may be overkill for one’s needs. Furthermore, even those facilities that do use cranes usually have only enough capacity for the parts being produced, not for the entire machine tool.
  • Wheels: Skates and wheeled casters offer a third potential solution. As with air casters, they can fit within the envelope of the machine being moved. However, they require an enormous amount of force, will almost certainly damage delicate floors, and aren’t fully omni-directional at a push.
  • Riggers: Of course, the facility can always hire a rigger to perform the machinery move, but this route can also be expensive and will cause sufficient disruption to limit any re-configuration involving CNC machines to rare occasions. Additionally, riggers themselves must still work within existing logistical constraints, such as a lack of open space.

As a result of the limitations of these material-handling systems, CNC machines tend to be treated as immoveable monuments. Once they’re placed, they’re left untouched. If they must be moved, the job would become a major undertaking that necessitates stopping the production line entirely.

Manufacturers gain the ability to arrange their CNC machines around the flow they want instead of arranging the flow around the machines. Courtesy: AeroGo

Manufacturers gain the ability to arrange their CNC machines around the flow they want instead of arranging the flow around the machines. Courtesy: AeroGo

Worse, if the manufacturer relies on any kind of “lean” methodology, it can easily run into problems. Lean manufacturing is a production philosophy that emphasizes efficiency: operating at maximal quality output with minimal waste. It’s about tailoring every aspect of the manufacturing process—workflow, plant layout, distribution and usage of people—to ensure the most effective production possible while still delivering a high-quality end product. However, re-engineering, resequencing and repositioning production lines are nontrivial challenges because most traditional material handling systems—including forklifts, cranes and even wheeled casters—force inefficiency into the floor layout. These systems require more space, more labor, and more time to operate, while creating more risk. Air casters require less of each of these resources.

Air caster efficiencies

Air casters provide the ability to move machines that simply weren’t considered moveable before. As a result, air casters can become a routine part of the production process without seriously disrupting production flow. Then, once moving a CNC machine becomes a trivial exercise, manufacturers can achieve production efficiencies that can strengthen both overall production speed and total business operations. Since the immobility of monuments inherently hampers efforts to generate production efficiency, turning monuments into minor loads can transform the manufacturer’s ability to implement lean processes, as described below:

Manufacturing engineers can determine the most efficient flow for a product and move the tools around this flow rather than attempt to contort the flow, inefficiently, around the CNC machines.

Thus, air casters reduce wasted space (shops don’t need to allow extra space for material-handling systems that require more maneuverability), wasted motion, and transportation (which increases costs and adds risk), as well as other inefficiencies.

Operators place air casters under a CNC machine to move it to a sequential position in the work flow. Courtesy: AeroGo

Operators place air casters under a CNC machine to move it to a sequential position in the work flow. Courtesy: AeroGo

Using this technology, shops can potentially increase throughput, improve capacity, and achieve other lean production goals.

Air casters provide an easier method to reconfigure these machine tools together to produce more efficient production cells by lowering the cost of moving that tool into its position. With such cells, parts no longer need to crisscross the facility floor as they move between disparate CNC machines.

Space between machines is minimal to prevent inventory from building up, as well as to reduce motion and conveyance. A key difference between traditional and lean plant layout is that in a lean environment, there is very little room for waste and when there is waste, it becomes visible.

When the manufacturer completes the current order, the machinery can be easily reconfigured back to where it was before, or into a new, more efficient layout based on the next part to be produced.

While forklifts, cranes, and riggers are always options to consider, they fail to answer the central challenges of dealing with CNC machines specifically. They are also cost prohibitive for moving these machines with any kind of frequency. Furthermore, the constraints of each, such as the space required for forklifts, or the need to ensure the machines fit within the crane’s capacity and reach envelope, still limit how much, how frequently, and how easily these tools can perform these moves.

Plant floor design is key to an efficient production environment. Courtesy: AeroGo

Plant floor design is key to an efficient production environment. Courtesy: AeroGo

End-to-end, air casters have proven that the process of moving a typical CNC machine can often be completed in significantly less time than cranes or forklifts can accomplish, even when the job is performed in a constrained environment. Air casters enable shops to organize their CNC machines in a manner that makes for a more efficient production operation.

Moving CNC machines into an efficient layout can increase throughput and efficiency to contribute to lean manufacturing. Positioning CNC machines closer together and building a solid, functioning workflow lessens the cost of inventory, the cost of material transportation, and the cost of physical real estate on the shop floor. Air casters fit within the machine footprint, allowing them to fit into tighter spaces and, from that standpoint, gain the ability to increase efficiency by creating the cell structure. Manufacturers gain the ability to arrange their CNC machines around the flow that they want instead of arranging the flow around the machines.


John Massenburg
Author Bio: John Massenburg, MSME, is president and chief executive officer of AeroGo, Inc., Seattle, Washington, USA. AeroGo manufactures heavy load equipment utilizing hovercraft technology for moving heavy, awkward or delicate loads. For more information, please visit https://www.aerogo.com.