c h a p t e r t w e n t y- t wo welding representation

C H A P T E R T W E N T Y- T WO

WELDINGWELDINGREPRESENTATIONREPRESENTATION

2Technical Drawing with Engineering Graphics, 14/eGiesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman

© 2012, 2009, 2003, Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.

OBJECTIVESOBJECTIVES

1. Describe the various welding processes.

2. Draw the common welding symbols.

3. Dimension a welding drawing using standard ANSI welding notation.

4. Identify and draw a fillet weld, groove weld, back weld, spot weld,

seam weld, projection weld, and flash weld.

5. Describe the use of welding symbols in CAD drawings.



WeldingWeldingWelding is widely used in fabricating machine parts or other structures that formerly would have been formed by casting or forging. Structural steel frames for buildings, ships, andother structures are often welded.

Welding symbols on a mechanical drawing provide precise instructions for the welder. The weld type and the location of each weld must be clearly defined using standardized symbols. CAD libraries of welding symbols can simplify the drawing process. Weldingtemplates can speed the process of drawing by hand.



Welding ProcessesWelding Processes• Arc welding (SMAW, Shielded Metal Arc Welding, GMAW Gas Metal Arc Welding, plus others…)

• Resistance welding (RSW, Resistance Spot Welding, and others…)• Gas welding (OFW, Oxy Fuel Welding)

GMAW

RSW

An automobile frame is welded on a robotic automobile assembly line. (Courtesy of Vladimir Pcholkin/Stone/Getty images.)

OFW



UNDERSTANDING A WELDING UNDERSTANDING A WELDING SYMBOLSYMBOL

A welding symbol added to the drawing has many different features that specifyeach detail of the weld. The items that can be specified are:

• Type of weld• Process• Depth of bevel, size, or strength for some weld types• Groove weld size• Finishing designator• Contour• Groove angle• Root opening• Length of weld• Number and pitch (center to center spacing) of welds• Whether the weld is to be field welded (done on site)• All-around indicator• Which side of the material is to be welded



WELDED JOINTSWELDED JOINTS

Butt joint

Corner joint

T-joint

Lap joint

Edge joint

A number of different types of welds are applicable to each type of joint, depending on the thickness of metal, the strength of joint required, and other considerations.



Basic Welds and SymbolsBasic Welds and Symbols



WELDING SYMBOLSWELDING SYMBOLSThe basic element of the symbol is the “bent” arrow The arrow points to the joint where the weld is to be made Attached to the reference line, or shank, of the arrow is the weld symbol for the desired weld.

The weld symbol is placed below the reference line if the weld is to be on the arrow side of the joint, or above the reference line if the weld is to be on the other side of the joint. If the weld is to be on both the arrow side and the other side of the joint, weld symbols are placed on both sides of the reference line.



Supplementary SymbolsSupplementary Symbols

End the weld at the starting point, or ALL THE WAY AROUND

End the weld at the starting point, or ALL THE WAY AROUND

Weld at the final construction site (Not in the “shop”)Weld at the final construction site (Not in the “shop”)

Fully penetrateFully penetrate

Consumable insert is melted into the final weldmentConsumable insert is melted into the final weldment

A back strap or backing plate is placed onto the back of the joint

A back strap or backing plate is placed onto the back of the joint

Final contour should be flush (possibly by grinding or machining)

Final contour should be flush (possibly by grinding or machining)

Final contour should be Convex (possibly by grinding or machining)

Final contour should be Convex (possibly by grinding or machining)

Final contour should be concave (possibly by grinding or machining)Final contour should be concave (possibly by grinding or machining)



The Welding Symbol TailThe Welding Symbol TailReference to a specification, process, or other supplementary information is indicated by any desired symbol in the tail of the arrow. Otherwise, a general note may be placed in the tail. If no reference is indicated in the symbol, the tail may be omitted.

UNLESS OTHERWISE INDICATED, MAKE ALL WELDS PERSPECIFICATION NO.XXX

Resistance Spot Weld and an Electron Beam Weld are called out in the Tail of the Welding Symbols.



FILLET WELDSFILLET WELDS

Dimensioning of Fillet Welds

The size of the weld is the length of one leg, For fillet welds on both sides of a joint, the dimensions should be indicated on both sides of the reference line, whether the dimensions are identical or different.

.5 Leg lengths



Fillet Weld Length and PitchFillet Weld Length and Pitch

TWO inch length of weld, with a FIVE inch pitch (center-to-center). The .25 represents the weld leg length.

THREE inch length of weld, with a TEN inch pitch (center-to-center). The .25 represents the weld leg length.



Surface Contour and Fillet WeldsSurface Contour and Fillet Welds

Fillet weld with a Flush FinishFillet weld with a Flush Finish

Fillet weld with a Flush Finish by Grinding

Fillet weld with a Flush Finish by Grinding

Fillet weld with a Flush Finish by Chipping

Fillet weld with a Flush Finish by Chipping

Fillet weld with a Flush Finish by Machining

Fillet weld with a Flush Finish by Machining

Fillet weld with a Convex Finish by Machining

Fillet weld with a Convex Finish by Machining

KEY: C= chipping G = grinding M = machining R = rolling H = hammering



GROOVE WELDSGROOVE WELDSSymbols and their Result



BACK OR BACKING WELDSBACK OR BACKING WELDSA back or backing symbol opposite the groove weld symbol indicates bead-type welds used as back or backing welds on single-groove welds.

Back or Backing Weld Symbols



SURFACE WELDSSURFACE WELDSThe surface weld symbol indicates a surface to be built up with single- or multiple-pass bead type welds. Because this symbol does not indicate a welded joint, there is noarrow-side or other-side significance, so the symbol is always drawn below the reference line. Indicate the minimum height of the weld deposit at the left of the weld symbol, except where no specific height is required. When a specific area of a surface is to be built up, give the dimensions of the area on the drawing.

Surfacing (or Hardfacing)A Plow Blade



PLUG AND SLOT WELDSPLUG AND SLOT WELDS

The same symbol is used for plug welds and slot welds.

If it is in the arrow-side member, place theweld symbol below the reference line

If it is in the other-side member, place the weld symbol above the line

A plug weld is understood to fill the depth of the hole unlessits depth is indicated inside the weld symbol

A plug weld is understood to fill the depth of the hole unlessits depth is indicated inside the weld symbol



SPOT WELDSSPOT WELDSThe size of a spot weld is its diameter. If you need to indicate the minimum acceptable shear strength in pounds per spot, instead of the size of the weld, place this value at the left of the weld symbol. The pitch would be placed to the right of the weld symbol if needed .

.



SEAM WELDSSEAM WELDSThe seam weld symbol, with the welding process indicated in the tail, The size of the seam weld is its width. Show this value at the left of the weld symbol, on either side of the reference line. If you need to indicate the minimum acceptable shear strength in pounds per linear inch, instead of the size of the weld, place this value at the left of the weld symbol, and show the length of a seam weld at the right of the weld symbol



PROJECTION WELDSPROJECTION WELDS

In projection welding, one member is embossed in preparation for the weld.

Projection welds are dimensioned by either size or strength. The size is the diameter of the weld.



FLASH AND UPSET WELDSFLASH AND UPSET WELDS

Note that the process reference for flash welding (FW) or upset welding (UW) must be placed in the tail of the symbol.

Note that the process reference for flash welding (FW) or upset welding (UW) must be placed in the tail of the symbol.

Flash and upset weld symbols have no arrow-side or other-side significance, butthe supplementary symbols do.



WELD SYMBOLS FROM CADWELD SYMBOLS FROM CADMost CAD systems provide a way to quickly generate weld symbols to place in your drawing.

SolidWorks Weld Symbol Dialog Box

c h a p t e r t w e n t y- t wo welding representation

Documents

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welding drawing

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use of welding symbols

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resistance spot welding

resistance welding rsw