Tech Directions - December 2008 - (Page 17)

stant regardless of voltage (arc length) changes—and that is what frustrated Mike during his stick weld test. Mike could have been the world’s best welder, but a “TIG machine that can stick weld” simply couldn’t react correctly to Mike’s manipulation of the stick electrode. Manufacturers of conventional TIG/stick welders have overcome some of these performance limitations by adding Fig. 2—Notice how the TIG volt/amp curve an arc force control function on this modern TIG welder is nearly vertito the welder. However, many cal. Amperage will remain constant even if school welding labs have the operator varies voltage (arc length). older TIG equipment without output power (watts) by increasing this function or, if they have modern amperage—and that extra amperage equipment, may not understand how (penetration) could blow a hole right to use arc force. Either way, students through thin material. are at a disadvantage when learning For this reason and others, manhow to stick weld. Further, TIGufacturers design conventional TIG speciﬁc welders tend to have more welders so that variations in voltage complicated controls, which could don’t affect amperage. As the volt/ confuse beginners. Finally, while amp curve in Fig. 2 shows, such a many welders work very well, they welder provides more of a vertical simply can’t beat the beneﬁt and CC output. It holds the current conperformance of new technology. Choosing the Right Welder Inverter technology enables manufacturers to create welding machines with “multiple personalities,” as the volt/amp curve in Fig. 3 indicates. Basically, because the welding output is controlled through microprocessors and high-speed current switching Fig. 3—The CC volt/amp curve of an inverter “changes personalities” when switched from stick to TIG modes. Also, notice how the percentages for arc force control increase amperage as voltage drops. www.techdirections.com WELDING 17 http://www.7corners.com http://www.7corners.com http://www.7corners.com http://www.studica.com/netop http://www.studica.com/netop http://www.7corners.com http://www.techdirections.com

Table of Contents Feed for the Digital Edition of Tech Directions - December 2008

Tech Directions - December 2008 Contents Advertisers Index Technically Speaking Direct from Washington The Report Technology Today Technology’s Past Mastering Computers Digital Portfolios—Powerful Marketing Tool for Communication Students Choosing the Right CC Welding Unit—Student Success Depends on It Think Green—Increasing Awareness of Garbage and Recycling Think Green—Teach Students Smart Ways to Reduce Home Energy Use Go International! Build a Simplified Shortwave Receiver Mooresville Middle School Snags Web Site of the Month Gifts for Geeks More than Fun

Tech Directions - December 2008

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