Overhead handling: A heightened emphasis on ergonomics
Electronics have permeated all aspects of mechanical materials handling equipment, and overhead handling systems are no exception. Much like lift trucks, the basic function of overhead handling equipment is to lift things, move them and put them down. Yet in both cases, newer versions of the equipment are enhanced with intelligent electronics, detailed performance reporting capabilities and ergonomic features that combine to provide value far beyond the simple movement of goods.
“Today’s cranes are much smarter than their older cousins,” says Doug Maclam, vice president of sales and marketing for Konecranes. “They are easier and safer to use, more self-diagnostic and they can communicate with the outside world.” With integrated sensors, a crane can alert an operator to an overload, semi-automatically transport goods or identify needed maintenance to prevent more costly failures.
Overhead handling systems are also flexible enough to reconfigure a workstation anywhere beneath the system’s footprint. They can even be designed for easy relocation anywhere within a facility, a sharp contrast to the fixed installations of the past. “Lean manufacturing requires equipment that can be easily installed, taken down and moved around depending on how processes evolve,” says Rob Beightol, product marketing manager for Gorbel. “Customers want solutions for today, but they’re also looking down the road. I don’t think anybody has the feeling that anything is permanent anymore.”
Taking ergonomics to a new level
A renewed focus on safety and ergonomics has more customers trying to steer away from any and all manual lifting, says Beightol. Even when working with relatively small items, overhead handling systems are increasingly deployed to assist with repetitive tasks.
Following a transition from manual lifting to manually directed overhead handling systems, more customers are now using powered overhead systems to further improve operator safety, comfort and productivity, according to Stacie Wingfield, director of marketing for Columbus McKinnon. Custom lifters and pick point fixtures also add safety and speed to the process of securing a load, she says. “By pre-engineering these features, an operator no longer needs to search for a sling or other rigging to pick up a load,” Wingfield says. The operator can make the attachment from the controls, ensuring the rigging is the right size and rating for the load while keeping hands clear from pinch points.
Maclam says the biggest evolution has occurred in the controls, which frequently include variable speed drives (also called variable frequency drives, or VFDs). Instead of single- or two-speed drives that are either on or off, VFDs minimize starts and stops, extending the life of the equipment. Wireless controls allow an operator to stay clear, while anti-sway features reduce load swing, minimizing the possibility for injury or damage to product and the equipment. VFDs can also be paired with pressure-sensitive operator controls that translate worker effort into increased speed and precision.
With onboard intelligence, a crane can track its progress along an established route, automatically decelerating and positioning as it approaches its destination. “The crane knows where it is and where the load is in 3D space,” says Maclam, who suggests such systems can cut cycle time in half. “These semi-automated approaches are becoming popular as crane technology from highly automated systems becomes a cost-effective standard option for any crane.”
Semi-automated systems make productivity more predictable, offering easy and consistent performance both for experienced operators and first-timers, Beightol says. “In the past, there was just an up and down button without any of the equipment’s capabilities spelled out,” he says. “You had to guess how to use it. Now a touch-screen display can communicate clearly to the operator.”
With embedded electronics, overhead handling systems can monitor their own condition, precisely measuring run time while reporting the status of brakes, drives, temperatures and any incidence of overloading. This gives the operator immediate feedback and the equipment owner more visibility into performance and total cost of ownership.
Detailed data can also highlight opportunities for process improvement in addition to more effective maintenance schedules. “If there are too many motor starts you might need to look at the application,” says Konecranes’ Maclam. “You can use the data to target a specific time of day or a part of the process that’s out of sync.”
Starts and stops, run time and load information can all feed into an asset management system for timely scheduling of preventive service, says Wingfield. Managers can review this data or set up the system to send alerts if, for instance, the operator overloads the crane.
In the past, planned maintenance was based on counters, hour meters or motor revolutions. “It was fairly crude and led to a number of hard equipment failures,” says Bernd Forwick, senior product manager of cranes, for Terex Material Handling North America. “Now a service technician can say with greater certainty that major service will be required in five years, for example, based on actual load cycles and load spectrum. This leaves plenty of time to plan accordingly.”
It will always be easier and more efficient to make adjustments and repairs while the equipment is still functioning, rather than to wait for a complete breakdown, says Forwick. “New technology allows a customer’s maintenance approach to change from catastrophic to preventative,” he says. “Variable speed drives can increase operator efficiency. Overload devices improve safety and reduce damage. These are all individual steps in lean manufacturing, and all contribute to reduced ownership costs throughout the productive life of the equipment.”
Lean, clean lifting machines
Moving in step with lean initiatives, overhead handling equipment is increasingly customized to perfectly suit the application. The process of optimizing a worker’s comfort and productivity in a workstation benefits from a more collaborative approach between customers and suppliers of cranes, hoists, conveyors, robotics, packaging equipment and more.
These relationships combine to provide solutions beyond what any one supplier can typically offer, says Wingfield, but they require a customer to be open to a consultative approach.
“Purchasing professionals don’t always evaluate materials handling solutions based on floor space savings, uptime improvements, ergonomics and training provided, so it takes a corporate orientation committed to the total cost of ownership to truly see its value,” adds Wingfield.
As opposed to simply substituting overhead handlers for carts, forklifts or manual lifting, greater efficiencies can be found by assessing overall product flow through each process. A 300-pound piece of furniture might be packaged in corrugate intended to protect the product in transit, but not designed to support the load while it is suspended in the air. A customized combination of conveyor, lift attachments, and packaging equipment can enable a single operator to pack, tape, label and palletize the product, potentially replacing two or more workstations with one.
A thorough analysis will also ensure the overhead handling equipment is not over-engineered for the application. “Gone are the days when an engineer can flip through a catalog and pick up some chains, slings or hoists,” says Matt Forsline, senior applications engineer and product manager for Schmalz. “In the past, a manufacturer might use expensive bulky manipulators, much of which was unnecessary. We are all learning a lot about how ergonomics and lean manufacturing go hand in hand.”
Forsline offers the example of a customer who needed to move 40-pound boxes from a conveyor to a pallet up to 104 inches high. They initially had a jib crane mounted to the wall with a 20-foot radius. A powered jib was found to be too expensive and would not move as fast as the operator needed to. At the outer reach, it was very easy to manipulate the load and the crane. The problem arose when the operator tried to move loads close to the pivot point. “It required a lot more force given the mass of the crane that’s out beyond the operator’s push point,” says Forsline. The customer worked with Forsline to create equal operator input pressures under the crane’s footprint and instead selected an overhead bridge crane with simpler X/Y movement.
Depending on the constraints of the overhead system’s footprint, articulating jib cranes can add an additional layer of capability. By reaching around corners or into another workstation, a freestanding or ceiling-mounted articulating crane can sometimes do the work of two cranes with one operator, according to Beightol. “They’ve become more popular as work platforms become more complicated,” says Beightol, who notes that many articulated cranes are being designed for smaller capacities of 1,000 pounds or less.
For customers who purchased their overhead handling equipment within the past 15 years, the benefits of electronics and ergonomics might have to wait until their existing equipment is ready for replacement.
“If a general purpose crane is maintained regularly, there’s no reason why it can’t run for 25 or 30 years total,” says Forwick. “Some owners may decide to modernize safety-related equipment (limit switches, overload sensors, variable speed control), but most owners will probably not replace them with new cranes just to go electronic.” That said, a facility or network of facilities with a large number of cranes might benefit from centralized maintenance data for all of that equipment, in which case an update could prove cost-effective.
Companies mentioned in this article
Columbus McKinnon, cmworks.com
Terex Material Handling, demag-us.com