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CMW Inc. 2006CMW Inc. 2006
Presents:Presents:
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Spot Welding is theprocess of joining two
pieces of metal together bypassing current through arelatively small area (spot)while applying pressure for
a given amount of time. Spot Welding is used for
resistance welding. Otherwelding methods are (Arc,Torch, MIG, & TIG).
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A Spot welding system typicallyconsists of a: cap or electrode that contacts
the metal
Holder that retains the cap orelectrode Gun arm that retains the
Holder Welding machine that thru a
hydraulic cylinder, delivers
pressure to the metal Controller that defines theweld cycle
Transformer that steps theline power up to the weldingpower level
Cooling chamber that keepsthe water at a constanttemperature that circulatesthru the entire system toremove excess heat
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There are threestandard types ofSpot Weldingsystems Base Type #1 Robotic or Cell
Type #2 Portable Type #3
Each has itsadvantage based onvolume, accessibility,operationalrepeatability
Type # 2
Type # 1
Type # 3Copyright CMW Inc. 2005
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Based primarily on volume, the user will either use Caps orElectrodes. Both Caps and Electrodes can be reconditioned orredressed to near their original shape for extended life. Electrodescan be redressed more times than Caps but ultimately more copperis thrown away. Caps, when used with a Shank, can be bothreconditioned and ultimately disposed of with less waste of copper
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Cap or Electrode noses areavailable in a variety ofshapes and are specifiedbased on the type of metalthat is to be welded, thespot desired and customerpreference.
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POINTED
DOME
FLAT
OFFSET
TRUNCATED
RADIUS
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The anatomy of aCap/Electrode is asshown on the right.The Face comes indirect contact with themetal and largelydetermines the size ofthe spot. The Taper ispreciselymanufactured to allowa water tight sealbetween mating parts.
The Shaft is varied inlength andconfiguration to alignthe Face to the metal
TAPER
FACE
SHAFT NOSE
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Electrodes andShanks can be
supplied with or without water tubes. Thepurpose of the watertube is to better focusthe cooling waterflowing on the systemat the point where theheat is beinggenerated at theweld face.
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Caps and Electrodes are available in industry standard (RWMA) tapers to provide awater tight seal between the cap, shank and holder or between the Electrode andHolder.
Typical tapers are 4, 5, 6, & 7. The taper used is based on the current and pressure required for a given weld. The
higher the current/pressure, the larger (the taper number) taper will be used.
Caps, Electrodes and Shanks are available in either Male or Female configurations
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Electrodes andShanks areavailable in anumber ofconfigurations to
allow the Face ofthe Cap/Electrodeto come in direct flatcontact with the
metal.
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Electrodes are also available in a number of special configurationsfor specific applications
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Electrodes are also available in a number of special configurationsfor specific applications
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Single Bend or DoubleBend Electrodes can be
specified by OverallLength (C), Offset (D),and Nose Length (N), toallow easy access forspot welding in a tightarea.
Various holderconfigurations can alsoadd even more flexibilityto allow you a spot weldin a tight position.
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Caps/Electrodescan be specifiedin three basic
materials basedon the material tobe welded. (seethe weld chart)
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Holders are available in a number of configurations thatinclude (in addition to Taper options):
Straight (of various lengths and diameters) Offset (of various offsets)
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200 Series (Ejector) WaterCooled Electrode Holder
100 Series (Non-Ejector)Water Cooled Electrode
Holder
300 Series Premium (Ejector)Water Cooled Electrode Holder
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Holders can
have amechanicalassist (knockout button) toremove thewornCap/Electrodefrom theHolder
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What to look for to find Spot WeldingCustomers: Uses Sheet metal in their product
Appliances Automotive and Transportation Filing Cabinets Computer and other Electronic Chassis
Manufactures shelving made of wire rods weldedtogether (typically at 90 ) as in Appliance shelving
Manufactures a container (Tank, Barrel, or Vessel) that haswelded seams (Seam Welding)
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Shown on the right areproducts which are used toSharpen or Redress Capsor Electrode
This purpose is to Use Redressing tools as
shown
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Pneumatic Power Handle Electrode Dresser
Electrode Dresser With abrasive cloth
Electrode Dresser
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While there are a number of variables that must becontrolled to obtain a good weld, the most important are(after the selection of the correct components and Welding system)
The current settings on the transformer The timing of the weld (clamping, welding, and holding) Water flow These variable can be selected by using the Weld Tables as
supplied by the Manufacture of the Welding Components orSystem or referring to the RWMA website ( www.RWMA.org )
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A good Spot is stronger and more energy efficient.
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Go to Troubleshooting Guide
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Visit us at www.cmwinc.com for more spot welding information and product line types.
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