Can you explain in detail the significance played by the feature "Forge Pressure Delay" in resistance welding? How does this feature works in a machine where I use an analogue pressure switch for weld pressure control? Can you also mention some reference material(books, articles, knowledge based websites etc.,) from which I can gain substantial insight into this wonderful process of resistance welding. Can you also mention similar websites like this which have academic clubs and forums on resistance welding. Thank You.

-- BALAJI RAGHUNATHAN (hanu_balaji@yahoo.com), June 07, 2001

Answers

Forge pressure is used during the weld nugget cooling cycle to refine the grain structure of the weld. Forge delay is the the weld control timer setting to initiate this forge cycle during the cooling cycle. The analog pressure switch is used to control weld forces during the expansion and contraction of the metals during the weld nugget formation. The RWMA “Resistance Welding Manual” is an excellent reference. You could also attended welding seminars, and exchange ideas with experts as well as fellow users, who may have had similar problems solved. Check out the RWMA web-site, as well as stay posted to weld forums such as this at various manufacturer’s web sites.

-- Bob Balla (bobballa@tjsnow.com), June 25, 2001.

The forge function is normally used in projection welding. Sometimes too much force causes the area of contact to increase and the contact pressure to drop. The current density will therefore be less and the heating, being equal to the square of the current, will reduce considerably. Forge function gives the advantage of using low current to rapidly heat and the full forge force to generate the required weld nugget. The current may require to be continued to allow the nugget to grow. This permits machines with less welding current (hence lower primary demand) to weld.

-- A.S.Kalbag (mechengg@vsnl.com), November 10, 2001.