This past fall, Saskatoon carbon fiber composites manufacturer SED Research Inc. (SRI), a Calian subsidiary, commissioned Kristian to increase their shop productivity with the design and installation of three new overhead cranes. The cranes were needed by SRI to construct their line of 10M composite carbon fiber antennas for the satellite ground systems industry.
Their custom order included two Demag column-mounted jib cranes, 1 ton each, and a 5 ton Demag top running single girder bridge crane. These overhead cranes were chosen to assist SRI in their day to day production processes of manufacturing their sophisticated, state-of-the-art satellite earth station antennas. SRI provides composite carbon fiber reflectors to Calian SED, a global solution provider of advanced communication systems for over 50 years.
Both jib cranes were selected from a standard Demag construction, ensuring a straightforward and uncomplicated installation consistent with Demag’s quality design. However, the 5 ton bridge crane offered up a few challenges for the Kristian design and production team.
Kristian’s main obstacle designing the bridge for SRI was their specification that the entire crane structure, including the runways, must be completely freestanding and could not be tied back to the building’s structure in any way. Freestanding bridge and workstation cranes are not unusual in any sense, but with a span of 45’ and a runway length of 77’, this was no small freestanding crane. The larger the crane, specifically the span, the less weight the structure is able to support properly without the possibility of the columns pulling in towards each other. In order to stop this from happening, brace support beams must be placed along the crane, crossing from column to column, to reinforce the entire system. But considering the span of this particular crane system, these brace support beams would cause a large additional amount of extra weight to stretch across the entire structure.
In such cases, the Kristian design and production team will utilize a truss bridge beam. Truss beams are comprised of bracket-type rods, straight, or cambered pieces joined together by trussing. Truss beams are significantly lighter and can be less expensive to manufacture as they require less material overall. However, constructing a truss beam properly is complex, and the additional labour hours required can also increase the overall cost of a project.
This is where our Kristian design and production team found an innovative solution to keep costs down without sacrificing SRI’s design specifications. Ernie Dajavs, Project Coordinator, proposed a plan to design and construct our own castellated beams to save time.
A castellated beam is made by cutting an I-beam down its longitude in a repeating, tooth-like pattern. Once the beam is separated into two parts, it is welded back together on an offset with the cut patterns mirroring each other; creating identical slots along the beam. The finished castellated construction allows for an increase in beam height without an increase in weight.
Kristian outsourced a local Edmonton company to have the beams professionally cut with their CNC equipment. When the freshly cut steel was returned to our Edmonton manufacturing shop, our fabrication department went to work welding the plasma-cut pieces back together in the castellated pattern.
Prior to being cut, the original beam measured 10” high, but once reconstructed the beam measured more than 15” without the standard additional weight.
“It is an estimated 30% lighter,” says Ernie Dajavs. “A truss beam would have taken us two to three days each just to manufacture, while the castellated-style only took about 6 hours each.”
Although the SRI project marked the first time Kristian has utilized this design in a crane system, it won’t be our last.
“It is an old-fashioned technique and you don’t see it used for cranes much anymore.” says Dajavs. “A beam’s strength comes from its depth (height), and by taking weight out and making it taller, it actually ends up making it stronger. It’s a neat way of doing it.”