Work lift balance23 November 2020
The “work smarter not harder” mantra seems to have pervaded all areas of industry. Fortunately the opportunities for the use of workstation cranes is also becoming wider with a greater choice of structural materials, lifting capacities and installation options all helping to open up the workplace to new solutions. Simon Hastelow reports.
Mostly found in manufacturing plants handling assembly of heavy objects, a workstation crane is fixed in position but allows the operator to lift, rotate and position loads ranging from 50kg to over 2,000kg. The hoist and trolley can be either manually operated or powered but all are designed to take over the heavy lifting to improve worker safety and improve ergonomics. There are three main types of workstation crane: gantry, bridge and jib.
A gantry crane is usually a free-standing, floor-supported structure, the beam is supported by legs which run on wheels or rails in the floor. The bridge crane locates the beam on rails built into the buildings structure or mounted on vertical columns, the trolley and hoist cam move side-to-side along the beam fully operating within a rectangular area defined by the supported rails. The jib crane can be floor or wall mounted and features a cantilevered bridge supported on a vertical column. The hoist and trolley move along the bridge and can cover an arc described from the centre column. It is fair to say that up to a few years ago the main considerations for the design, installation and use of a workstation crane boiled down to what the structure of the surrounding building could accommodate. Floor-standing steel structures required substantial reinforced concrete foundations and ceiling-mounted rails required a survey of the building structure to ensure it could support the desired use.
The introduction of aluminium columns, supports and rails has reduced these requirements somewhat but with the tradeoff of offering lower lifting capacities and shorter span or jib lengths.
HSI Crane, based in Illinois, USA offer a foundationless solution that eliminates the disruption and cost of laying a reinforced concrete foundation.
“We were one of the first companies to offer foundationless jib cranes. The beauty of this is that there is no need to dig up the floor and pour a new concrete foundation. We have engineered the system using epoxy anchors which lends itself well to a lot of different applications, primarily for one-ton and under. This hits a home run for most of our dealers as there are a lot of half and one ton cranes out there,” says Bret Lussow, director of business development at HSI Crane.
“Foundations can cost two or three times the price of the crane causing frustration for the buyer. Not only is it expensive but it is also disruptive to production, messy, and very time consuming. The end user should allow one day to cut and dig and one day to pour the concrete. On top of this, they need to wait ten days before they can load the crane on the foundation and should wait 30 days before they can use the jib crane at full capacity.
“HSI has developed a full line of foundationless jib cranes with capacities up to 1 ton, 16ft (4.9m) span and 16ft height under boom. These cranes are available in light duty (5 to 10 lifts per day) or heavy duty (continuous use) configuration depending on the application.
“The installation of a foundationless jib crane takes hours, not days and the crane can be used the same day.”
An alternative approach to surmounting the issue of having a static foundationmounted crane comes from Vetter and its Mobilus slewing jib. The jib and mast are mounted on a base of concrete rings which can be moved around the factory floor using a fork-lift, towed using the built-in draw-bar or lifted on a hoist. The concrete gives it stability to operate throughout its 360° slew.
Being a modular system the base can be used to erect a standard jib, underbraced jib, lightweight aluminium jib or articulated jib arm. Additional concrete rings can be added or removed to adapt the specification to the requirements of each lift.
STEEL OR ALUMINIUM
Weighing up the choice of aluminium versus steel for the structure of a workstation crane is a decision that is narrowing rapidly. Several large crane manufacturers offer aluminium alongside steel with very similar characteristics where it matters most: the lifting capacity.
Even fairly recently aluminium was restricted to situations requiring lifts of less than 500kg but that is no longer the case, with capacities of up to 5,000kg now possible. Steel structures still have the edge for absolute longevity but with an increased overhead of slightly higher maintenance.
Steel also offers longer suspension distances and spans than aluminium, but aluminium can deliver a 50% saving in overall weight. While continuing to serve its customer base with lightweight and portable lifting requirements, Reid Lifting, based in Monmouthshire, UK, offer a solution constructed from aluminium with a capacity up to 5,000kg. The company states: “Our top quality and highly durable PortaGantry is lightweight and extremely strong. This portable system can be manually assembled, using just four bolts and can safely lift up to 5,000kg, making it the ideal system for multiple applications.” Other products in the Reid line-up remain aimed at users with lower capacity lifting in the 200kg to 600kg range, all offering the benefits of easy transportation, portability, usage in confined spaces and in areas where structural foundations are limited, such as roof-top maintenance.
“Given that we are in the midst of a global pandemic, the market for lightweight, portable gantries has been reasonably resilient,” says Simon Luke, managing director, REID Lifting. “That’s partly because our products are used in so many essential industries such as utilities maintenance, food manufacturing and infrastructure building, where there has still been an ongoing requirement for lifting and lowering solutions.”
Speaking about the company’s recently launched Porta Base, Luke adds: “Porta Base does more than other systems on the market, yet it is still lightweight and transportable enough to make it a practical and cost-effective option for a wide range of applications.”
Konecranes offers both steel and aluminium in a range of profiles, and states: “Workstation cranes have various system configurations, and steel and aluminium systems can also be combined. Modular system and multiple profile sizes provide options to match demanding lifting needs. Combine workstation cranes with electric chain hoists, pneumatic lifting devices or manual hoists.”
The choice of aluminium over steel could also come down to aesthetics. The anodised finish offered by some manufacturers gives a long-lasting fresh look for less industrial, clean environments. Aluminium also offers a lower rolling resistance, reducing the effort required to manoeuvre the hoist, thus improving dayto- day ergonomics for shop-floor workers.
This reduction in effort also offers the additional benefit of removing the requirement for a motorised drive, more simple, manually operated push/pull trolleys can be deployed in more situations offering further cost savings and reduced maintenance schedules.
Steel retains an edge in sheer strength and durability for heavy duty use or where longer suspension spans are required.
Hoist UK, based in Moreton, Wirral advises that as a general rule the choice of heavy-duty (predominantly steel) and lighter-duty cranes should be based on a number of factors: “Heavy-duty gantries should be considered for applications where the majority of the loads will be close to the gantry’s safe working load (SWL), manual or powered lifting appliances will be used, the gantry will be used regularly and often. Light-duty gantries may be considered for applications where loads will mostly be below the gantry’s safe working load, manual lifting appliances will be used and a less robust structure is suitable.” The company adds: “If your gantry is for light duty use its recommended that jacks are utilised to ensure the load is not being supported on the castors.”
FLEXIBILITY OF DESIGN
While several companies offer standalone lifting solution for workstations there are many that will build a crane for a specific installation or requirement. One such is HSI, mentioned above, which uses the NikoRail system.
The Nikorail light crane system is a modular product with five different enclosed-track rail profiles. Each rail supports up to 2t and is delivered in lengths up to 10m. It is an almost maintenance-free rail that requires very little pulling force due to the placement of the guiderail rolling on the inside surface of the track.
“We are the US manufacturer for NikoRail from Helm Hellas in Greece. We manufacture the NikoRail and closed track cranes in the US. Niko Ltd in the UK are doing a similar thing to us. We import the Helm Hellas product from Greece and manufacturer the end product here. NikoRail is its own brand and everything is embossed with the name. We buy the embossed rails and carry out the fabrication and welding here. It has been a very good partnership,” says Lussow.
“With the NikoRail line we have also launched an online tool to enable dealers to create their own quotes and drawings. This allows the dealer to get a quote and 3D CAD drawing within minutes. We are going to be expanding on this over the coming months. There are other products from Helm Hallas that we haven’t tapped into yet, such as the aluminium profiles, but it is just a matter of time before we add this to our own product lines.
“Having new product lines, like the Niko Rail products has been useful during the Covid-19 pandemic as it has opened up new sales for us that we didn’t have before. We do build a lot of cranes that no-one else wants to do. We take that challenge to create custom products.”
Thus far we have covered structures and lifting capacities and the narrowing gap between aluminium and steel for workstation cranes. However there is a subsector which is increasing in prominence, according to several manufacturers, and that is pure ergonomic solutions: workstation lifting facilities designed to reduce or remove the everyday, repetitive effort required in lifting lighter loads.
The drive for a safer working environment and an increase in productivity has prompted the use of lifting equipment for items as light as 10kg-15kg. An ‘Easy Arm’ lifting device from Gorbel was utilised in just such a situation at the Oerlikon Fairfield plant in Lafayette, Indiana, USA. The company makes Torque Hub gears and drives for OEMs worldwide.
Once assembled, each product weighed 25kg to 40kg. Workers on the assembly line manually moved each part to a worktable from nearby stacks, rotated and flipped the assembly which increased in weight after each step in the assembly procedure, then moved the finished product to a storage area. “This approach resulted in each worker assembling only six or seven units per shift, about 20 per day over three shifts. More importantly, the manual lifting produced excessive wear and tear on the worker day after day,” says facility engineering supervisor Anthony Schenk.
The company installed Easy Arms from Gorbel to improve worker ergonomics and increase productivity. A handle with end-ofarm tooling enables the assembler to easily retrieve parts, rotate and flip the assembly. “A worker now assembles 20 units per shift—a 300% increase,” says Schenk. Taking this process one step further the automation of lifting and handling processes becomes a logical step for some companies.
Columbus McKinnon, headquartered in Getzville, New York, USA recently launched the Unified Industries ProPath automated workstation crane for this very purpose. The company states: “In this challenging business environment, companies are coping with the need to balance increased worker safety and social distancing with meeting required production output. Columbus McKinnon is helping customers set up standardised operations and process flows that not only drive efficiency but ensure a consistent product. This allows for faster throughput and provides added safety features that enable social distancing on the production floor.”
The ProPath crane is aimed at the material handling industry, combining lightweight Enclosed Track Aluminum (ETA) rail with semi- or fully-automated smart material handling solutions. The result is an automated material handling solution that helps efficiently and precisely manage the flow of materials throughout a production facility.
ProPath is available in two configurations, semi-automated and fully automated. In its semi-automated configuration, also known as auto-dispatch, the ProPath enables automated movement alongside worker assistance for precise actions. This allows multiple areas to share a single crane and for a finished product to travel through a combination of work locations. The fully automated system enables repeatable processes, reduced idle time, consistent operation, and improved cycle times for increased productivity