Quantcast BACKHAND WELDING

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
Figure 15-32.—Forehand welding. Figure 15-33.—Backhand welding. welding rod back and forth in opposite semicircular paths, you balance the heat to melt the end of the rod and the side walls of the joint into a uniformly distributed molten puddle. As the flame passes the rod, it melts off a short length of the rod and adds it to the puddle. The motion of the torch distributes the molten metal evenly to both edges of the joint and to the molten puddle. This method is used in welding most of the lighter tubing and sheet metals up to 1/8 inch thick because it permits better control of a small puddle and results in a smoother weld. The forehand technique is not the best method for welding heavy metals. BACKHAND WELDING.—In this method the torch tip precedes the rod in the direction of welding, and the flame is pointed back at the molten puddle and the completed weld. The end of the rod is placed between the torch tip and the molten puddle. The welding tip should make an angle of about 45° to 60° with the plates or joint being welded (fig. 15-33). Less motion is required in than in the forehand method. the backhand method If you use a straight Figure 15-34.—Four basic welding positions. welding rod, it should be rotated so that the end will roll from side to side and melt off evenly. You may also bend the rod and, when welding, move the rod and torch back and forth at a rapid rate. If you are making a large weld, you should move the rod so as to make complete circles in the molten puddle. The torch is moved back and forth across the weld while it is advanced slowly and uniformly in the direction of the weld. You’ll find the backhand method best for welding material more than 1/8 inch thick. You can use a narrower “V” at the joint than is possible in forehand welding. An included angle of 60° is a sufficient angle of bevel to get a good joint. It doesn’t take as much welding rod or puddling for the backhand method as it does for the forehand method. By using the backhand technique on heavier material, it is possible to obtain increased welding speeds, better control of the larger puddle, and more complete fusion at the root of the weld. Further, by using a reducing flame with the backhand technique, a smaller amount of base metal is melted while welding a joint. Backhand welding is seldom used on sheet metal because the increased heat generated in this method is likely to cause overheating and burning. When welding steel with a backhand technique and a reducing flame, the absorption of carbon by a thin surface layer of metal reduces the melting point of the steel. This speeds up the welding operation. WELDING POSITIONS.—The four basic welding positions are shown in figure 15-34. Also shown are four 15-25



Aviation News
Improving performance with incremental innovation: The first enhanced 242-tonne A330 variant is granted EASA airworthiness approval
Underscoring the company’s philosophy for incremental innovation across its product...
airbus.com
EASA certifies the latest and most capable 242 tonne A330 version
• Latest example of Airbus’ incremental innovation strategy;• The most...
airbus.com
Elbit Systems America Integrates CHDTS on US Navy Test Aircraft
Elbit Systems of America's color helmet display and tracking system....
aviationtoday.com
Airbus Helicopters Signs First HCare Fleet Availability Contract in Asia
Taiwan’s National Airborne Services Corps' (NASC) fleet of 10 AS365...
aviationtoday.com
Northrop Grumman to Distribute AirRobot UAS to US Law Enforcement
An AirRobot unmanned aerial system flies at Fort Benning, Georgia....
aviationtoday.com
US Army CH47F Chinooks Receive RNP-RNAV Capabilities from Rockwell Collins
The U.S. Army has upgraded its CH-47F fleet with the...
aviationtoday.com
Airbus and Provincial Aerospace Look to Global Expansion
Simon Jacques, Head of Airbus Defence and Space, Canada; Pablo...
aviationtoday.com
Northrop Grumman Refocuses on Growing ISR Business
[Avionics Today 03-31-2015] Northrop Grumman Corporation's Electronic Systems sector is...
aviationtoday.com
New Turbine Engine Is Army's Number One Priority, Shyu Says
The Army's new Improved Turbine Engine Program (ITEP) is the...
aviationtoday.com
US Army Ups RNP-RNAV on CH-47F Chinooks
CH-47F Chinook. Photo: Boeing [Avionics Today 03-31-2015] The U.S. Army...
aviationtoday.com
Breeze-Eastern Completes Milestone Delivery of Rescue Hoist Systems
Breeze-Eastern Corporation, the aerospace industry’s only dedicated hoist and winch...
aviationtoday.com
L-3 Tapped to Supply UH-60V Cockpit
New York City-based L-3 Communications has been selected to upgrade...
aviationtoday.com
L-3 to Upgrade Cockpit Displays for US Army Blackhawks
Blackhawk UH-60V cockpit upgrade. Photo: Northrop Grumman [Avionics Today 03-31-2015]...
aviationtoday.com
Raytheon to Provide South Korean Ground Support for Global Hawk UAS
Global Hawk UAS in flight. Photo: Northrop Grumman [Avionics Today...
aviationtoday.com
First Lakota Trainers Arrive at Fort Rucker
The first shipment of UH-72A Lakota helicopters began arriving at...
aviationtoday.com
Japan Commissions Largest-Ever Helicopter Carrier
The Japanese Maritime Self-Defense Force (MSDF) commissioned the 814-foot DDH-183...
aviationtoday.com
NHIndustries Delivers NH90 TTH to Italian Army
On March 26, 2015 in Tessara, the Italian Army took...
aviationtoday.com
Airbus Group Provides Army's First New UH-72A Lakota for Initial-Entry Training
Airbus Group has delivered to the U.S. Army the first...
aviationtoday.com
AgustaWestland Signs Latest AW101 Support Contract with UK MoD
AgustaWestland has signed a contract with the UK Ministry of...
aviationtoday.com
NATO’s AWACS Aircraft to Upgrade Avionics to Meet Mandates
NATO’s Airborne Warning and Control System (AWACS) aircraft. Photo: Rockwell...
aviationtoday.com


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +