Recently I was asked to put an internal generic training class together on spotwelding. (Safety, what to look for, general practices) What I would like to know is "How do you calculate out a spotweld schedule for various materials and various thicknesses"? The welders we currently use are Tailor Windfields, single phase, 100 and 150 KVA. Also, is there a question and answer book available for the types of things I may be looking for for this type of training? Sure could use some help on this inherited task! Bill

-- William S. Andrews (wand14470@aol.com), April 07, 2001

Answers

Response to How to calculate out a weld schedule

Many different forms for estimating weld currents, forces, and time:Try this: Setting up by the seat of your pants:

Weld Tip Size = .1+ Total Material Thickness. Example: Two pieces .032” = .064” Weld Tip = .1 + .064 or .164” diameter.

Weld Force Place the weld control in “No Weld” Bring electrode down If “No Indent” - increase pressure. “Slight indent” - reduce 10%

Weld Current Set course transformer tap setting as low as possible. Set “% Heat” at 70%. If metal does not stick together increase tap setting and repeat above. If metal is expelled at the start of weld current, decrease tap or “% Heat” as available. Continue until a weld nugget can be pulled. The nugget should be slightly less than the contacting tip diameter. Note: Changes to % heat and tap will adjust current up or down..

Weld Time = 100 X Total Material Thickness. Example: Two pieces .032” = .064” Weld Cycles = 100 X .064 or 7 Cycles

Different Metals Base Mild Steel:

Stainless Steel Do not use less than 5 cycles if possible. 2 to 3 times pressure. 10 – 15% less current.

HSLA Approx. 1.5 times longer. Longer weld times necessary to eliminate brittleness. 1.5 times pressure. 10 – 15% less current.

High Carbon Longer weld times necessary to eliminate brittleness. 2 to 3 times pressure. 10 – 15% less current.

Aluminum 40% less weld time. Pressure about equal to less. 2 to 3 times more current.

Copper To .035 Molybdenum tip. 50% more pressure. 6 x 7 times current. For a very good seminar you may wish to contact our website: http://www.tjsnow.com/seminar.htm

-- Bob Balla (bobballa@tjsnow.com), April 13, 2001.

Response to How to calculate out a weld schedule

RWMA publishes the "bible" on resistance spot welding. You can find RWMA on the web or if you send me your address....I will forward you a copy of our training manual which includes weld schedules, etc.

-- tom mitchell (atekweld@aol.com), April 24, 2001.

Response to How to calculate out a weld schedule

Since you are currently using Taylor-Winfield resistance welding equipment your company is eligible to receive an on-site basic resistance welding seminar that includes weld schedule development. Feel free to e-mail me for further information -- Rj Bob Hosa, rhosa@taylor-winfield.com

-- RJ Bob Hosa (rhosa@taylor-winfield.com), June 27, 2001.

I have always used the schedules specified by the weld lab of the customer I am holding classes for. The problem is, the customer owns this knowledge and I can't give it away to others. The RWMA will sell you their information, but some machine suppliers will recommend settings also. The offer you got from Taylor Winfield sounds like the way to go. I don't know why it is so difficult to get people to share this information, they must think like Sir Francis Bacon did when he stated "Knowledge is power". Or maybe they think "Knowledge is money"... Looks like you got an offer from ATek too, they sell controllers, so they actually want you to know about weld schedules.

-- David Bacon (dbacon@updatetechnology.com), April 20, 2002.