New Products

Schnell IDEA Cage Machine

During the summer of 2004, Contractors Materials Company (CMC) and MMI of Kentucky (MMI) each installed a Schnell IDEA rebar resistance (fusion) welding machine at each of their locations to compliment the Schnell GTM-MIG rebar welding machine that was installed at CMC in early 2003. Whereas the GTM machine MIG welds spiral rebar cage assemblies together, the IDEA machine resistance welds individual T-2, T-3, and other individual rebar stirrups into a skeletal cage into which longitudinal and/or vertical bars are then traditionally tied. The IDEA machine requires that the individual stirrups be ASTM A706 low alloy weldable rebar. The individual stirrups are resistance welded to three individually placed W5 (1/4") holding or sacrificial wires meeting the specification of ASTM A82 low carbon rod. The IDEA machine's welding and pitch (stirrup spacing) is computer controlled. Both IDEA machines are installed within the enclosed and secured areas of CMC's and MMI's respective warehouses.

The advantages of the IDEA skeletal cages are that they provide a very rigid framework into which the vertical or longitudinal bars are to be tied. The spacing of the individual stirrups is accurately positioned and consistent in every cage every time. Because the individual stirrups have to be placed within the three established fixed welding positions, the outside dimension of the tied cage is consistently accurate insuring proper concrete cover. Besides the three "holding" wires providing dimensional accuracy, they also provide the framework for a very rigid tied cage assembly. In all but the largest cage assemblies, the IDEA tied cage assemblies require no additional "racking" bars to maintain their design dimension during field handling. This rigidity also enables the IDEA tied cage assembly to be placed easier and more safely than traditionally tied cages.

The IDEA rebar cage assemblies are new to the U.S. East Coast markets. As of January, 2005, only four of these resistance type welded cage machines exist east of the Mississippi. They are, however, very prominent in California with in-place fabricators who recognize the benefits of pre-tied shop rebar cages. Because of California's seismic building code, they are currently stocking and using the more expensive A706 low alloy rebar exclusively in the reinforcement of concrete. As of January, 2005, South Carolina has also adopted the CALTRANS seismic building code for their transportation structures.

A706 steel was developed in 1974 for the California Department of Transportation and the Atomic Energy Commission. In other than the closed engineering circles that deal with nuclear and seismic construction, little is known of A706 rebar which is necessary for consistent success in the welding of rebar. In March of 2004, the Concrete Reinforcing Steel Institute (CRSI) published their Engineering Data Report (EDR) #53 titled "Assembling Reinforcing Bars by Fusion Welding in the Fabrication Shop." This publication now endorses and recognizes the successes of shop resistance welding "by machines under a continuous controlled process" of "reinforcing bars conforming to ASTM Specification A706/A706M" to "holding wires conforming to ASTM Specification A82 or A496." The free downloading of this publication is available at www.crsi.org/PDF/edr_53.pdf.

IDEA cages can be made with #3, #4, or #5 A706 individual stirrups up to 4'-06" wide and 8'-00" tall. The skeletal cage assemblies can be made continuous of up to 40'-00" in length. Longer cage assemblies of up to 60'-00" in length can be made with multiple skeletal cages and continuous vertical or longitudinal ASTM A615 reinforcing steel. IDEA cages are not limited to circular, square column, or drilled caisson cages. Median barrier and grade beam cages are excellent IDEA cage applications as well. Call your CMC or MMI representative for more information.