All Rights Reserved Performance Associates Coachworks & Customs 2014 Made With Serif WebPlus.X6
Rarely will your workups be actual. Always look at it as simply a possible way.
Rarely is casting thickness the size required. It always seems to be thicker. (After all, they sell castings by the lb.) One structure that I was costing, had castings designed to be 38 mm thick. The joint was 1500 mm long, a 45 double bevel and a 6 mm root. Switching to English measures for simplicity; gives us 79.71 cubic inches or 22.17 lbs of weld. That is a lot of weld metal. Welcome to the world of over 300 ton capacity haul trucks.
The first castings come in and they are machined according to the print. The welder sets up the structure and guess what? You are called to the shop floor and find that castings are sold by the pound and are rarely the minimum thickness. One of the castings is 7mm thick 1.85 inches. Just a little extra strength built in.
This joint is 1.6” at the face.
Using about 8.4 lb per hour, it will take 22.17/10.2 = hours of arc time.Say 45 cu ft of shield gas per hour = 159.53 cu ft at .35 cu ft = 55.83. 28.36 lb of wire at 2 bucks a lb=56.72. 3.54 hr * 74.00. SVC=261.96. Add it all together = about $375. 82 bucks difference on one weld. 35% not bad. Four welds to a structure = $328 per structure
You were only 35% off on the cost and floor to floor time and it wasn’t even your fault…
The first thing you do is to show the work up to your boss. Join teams with engineering and purchasing to add a machining pass to both parts holding the thickness at 38 mm. Everybody is happy, especially the guy doing the welding and the bean counters. $328 per structure and 600 units a year=$196000 savings by adding one simple mill pass. Not bad. Gold star for you. All this is a bit of a simplification but this is how it happens. …….
By the way, you should have caught this in the collaborative stage of design. Opps! Some companies still use “Over The Wall’” design. Shame on them.http://www.workstudy.in/ as an example. http://www.weldreality.com/metric_weld_conversions.htm…..
.57*1.38+.25*1.38+.218=1.35 in2 *1500/25.4=79.7 in3/.29lb=23.12lb there about.
So we are using .052 ER70-S6 hard wire at 375 ipm wfs, 45 cfph 75/25 gas, 400 amp, 28 volt. Lets set the efficiency at 98%. The maximum width of a weld pass is limited to .56 inch by the applicable code so we are looking at 25+ passes.
23.12/8.4=2.75 hours to make this weld.
2.75 * $75.00 SVC= $206.00 labor
23.12 * 1.02=23.56 lb wire @ $2.00 lb = $46.17
Gas = $56.00 206.00+46.17+56.00=308.17 per weld.
4 welds per unit = 1232.68. There will be crane time and setup also.