Arc Welding Costs

8/8/2019 Arc Welding Costs

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Costing of Joining Methods -

Arc Welding Costs

ver. 1

ME 6222: Manufacturing Processes and SystemsProf. J.S. Colton GIT 2009

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Cost components

Examples


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Materials

Overhead


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El r

Some electrode sticks contain flux

per unit weight gives electrode cost

Quantity of flux and/or shielding gas

cost


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Other consumables m in l f l ri i if n in

overhead

ra s files blades chisels.


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rec me o we ng

time to produce a length of weld

labor rate

multiplication gives labor cost per length Set-up time, etc.

Personal time


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Usually a percentage of direct labor rate -


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o a e ec ro e s epos e as we

lost as splatter, vaporization

stub ends left

Stick-electrode welding - 65% Self-shielded, flux-cored welding - 82%

- Submerged arc welding - 100%


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Welding time Personal time

Set-up time

Electrode chan in time

Slag chipping time (for subsequent passes)

oor weld ualit increases time

Time to beat weld to remove residualstresses


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10 - 45% 65% is extreme of human achievement

Personal breaks

Set-up Change position

Chan e electrodes

De-slagging

R m vin r i l r


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-

25 - 60%

wire used

,

some processes require no de-slagging


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Over 90% if m ll - im - l in im


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Cost of electrode/length of weld= WE E

Cost of flux/length of weld

=

Cost of gas/length of weld

=


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M = WE E + WF F + V

=

CE = cost of electrode ($/wt)

= w ux

CF = cost of flux ($/wt)

= vo ume o gas CG = cost of gas ($/vol)


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CL = (t) (CR) / (OF)

t = time / length of weld

= cos o a or + over ea me

OF = operating factor (efficiency)


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,

t = 1/S

= spee o we

CL = (CR) / S (OF)

note...

11++

= nS

nSSS

t ...21

+++=


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.

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Labor cost $/ ft of weld


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E im f n m lgas = 25-45 ft3/hr, solid flux = wt of deposited metal, 1973 prices

Process Type of Electrode

ElectrodeCost ($/lb)

DepositionEfficiency

Cost ofDeposited

(%) Metal

$/lb $/ft

Shielded E7024 0.191 65 0.29 0.045

Self-shielded,flux-cored

E70T-G 0.315 82 0.38 0.059

Submer ed EL12 0.199 + flux 100 0.34 0.053

arcGas metal-arc E70S-3 0.243 + flux 92 0.31 0.048


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All about 5/ft.


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Trade-off Exam le 1/4 fillet weld, 3/32 E7024 electrode,

85 ft/hr, operating factor 30%, labor +overhead $7/hr

CL = (CR)/S(OF)

. .

Can you increase efficiency somehow? 40% -> $0.206/ft


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Factor E8018 Electrode and

Manual Welding9000C-1 Wire and

Semi-automatice ng

Labor and overhead rate (CL) $20/hr $20/hrDeposition rate (D) 3.11 lb/hr 5 lb/hr

O eratin factor OF 0.3 0.45

Cost of labor and overhead todeposit weld

$21.43/lb of weld $8.88/lb of weld

Electrode cost (CE) $0.667/lb $1.019/lbepos on e c ency . .

Cost of deposited metal $0.98/lb $1.31/lb

Shielding gas flow rate (VG) none 40 ft3/hr

Cost of shielding gas (CG) $0.72/lb dep. metal

Cost of welding $22.41/lb dep. metal $10.91/lb dep. metal

Labor cost seriously offsets cheap stick cost


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Costs of Various Processes(relative for guidance)

rocess rc spee

(ft/hr)

perat ng

Factor

a or an

Overhead ($/hr)

e ost

($/ft)Shielded metal-arc

85 0.3 7 0.274

Shielded metal-arc

85 0.4 7 0.206

Gas metal-arc 80 0.5 7 0.175sem -automat c

Self-shieldedflux-cored, semi-auto

100 0.5 7 0.140

Submerged arcsemi-auto

110 0.5 7 0.127


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Weld Comparison for Mild Steel

b ca

d

f e


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Weld Com arison Exam le 1/4 diameter, manual metal-arc electrode

,

Deposition rate 6.25 lb/arc-hr (b)

Weld required 0.6 lb of weld metal/ft (c)

Welding speed 2 in/min (5.75 arc-minutes/ft) (d)

O eratin factor 20% e

Time is 28.75 minutes/ft, labor cost at


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Calculations show what can happen, ifou have the correct e ui ment.

Other costs

, , .


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Costs of arc welding can be calculated

process selection


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Documents

Arc Welding Costs