5. Joint design and material thickness. Some electrodes create an arc that penetrates deeply, performing well on thick sections with narrow grooves or no bevel. Poor fit-up calls for electrodes that can bridge wide gaps.6. Efficiency. Meeting all other conditions, engineers select the electrode that gives highest deposition rate. For heavy-section joints, use powder-metal-addition fillers.Designating electrodes for carbon and low-alloy steels, following the prefix E'', to signify a SMAW electrode, come two or three digits to indicate minimum tensile strength in 1,000 PSI units; a digit indicating usable current and electrode-coating type; and, in some cases, a hyphen followed by a letter and number suffix to denote weld metal composition. Example: E7010-A1 is a SMAW electrode (E), of 70,000-psi tensile strength (70), for use in all welding positions (1), having a high-cellulose-sodium coating tin use with DCEP (0). -A1 indicates a particular composition listed in the A5 specification. A-1 suffix, as in 7018-1, indicates high impact toughness at a temperature lower than specified for a standard E7018 electrode.

Pump it up"Centrifugal autoceramicheaters pumps have become more robust, with much tighter tolerances and stress analyses of components to increase efficiency and machine time to failure," according to Bruce Smith, North American sales manager for Fristam Pumps Inc., Middleton, Wis. Shaft deflection that results in moving parts hitting stationary components in the pump is a major contributor to pump failure, and manufacturers are addressing that concern.Liquid ring pumps are coming into play in the industry as an alternative to standard centrifugal pumps, adds Smith. Although these scavenger pumps have been around for a quarter of a century, pharmaceutical manufacturers have embraced the technology and forced redesigns that have expanded their applications. Liquid ring pumps are particularly adept at handling fluids with entrained air, an issue with cream, which tends to foam during transit. Liquid ring pumps do a superior job in fully evacuating a tank, a material-savings advantage that appeals to ice cream manufacturers and liquid egg processors, according to Smith. Pump improvements have been accelerated with the application of computational fluid dynamics (CFD) software, points out Russell Jones, business development manager-pumps for Alfa Laval in Pleasant Prairie, Wis. "From an R&D point of view, CFD is a big advance in optimizing design and increasing pump efficiency," he says. The technology has been instrumental in boosting pump efficiencies from the 40 percent range to 60 to 70 percent in recent years.

©2003 www.autoheaters.net All rights reserved.