CWB Test

My company wants me to take a CWB fluxcore flat weld test next week and I was wondering if any welders have any tips and/or tricks that may prove usefull!
The test comprises of this:
3/4 plate, single 30* bevel with 3/8 backing bar, in the flat positon with 1/16 CO2 shielded flux-core wire. Not too sure of the gap but I think it is about 3/8 wide.
I have been told to run about 27 volts and around 220 to 250 amps.
Anyone with any info or tips/tricks would be very helpfull. I haven't tested for many a year and I would like to pass on the first attempt.
Thanks in advance
Gary

The gap at the root is VERY important. You had better check your copy of the code. I have an old copy and it is 16 mm gap for flux core. That means 5/8th inch not 3/8!!! The gap is less for SMAW. The initial mistake people make is thinking that the first weld bead in the corner has to be large. Code calls for 8mm fillet maximum. Don't lay down a monster bead! You will have to do at least one stop, start.on that first bead. Practice your stop start on scrap until you can do it blindfolded... well sorta anyway. The stop start is often the point of failure. Do not get crazy trying to pour in your following beads in massive layers. Ensure each bead is relatively flat . There is no requirement for the number of passes so a few extra is better than a massive bead with lack of fusion at the edges. Your cap must not be excessive. You should be shooting for 1/16 above the plate. Too much and it can be rejected. Don't try to make a massive wide cap. Much better to do it in two or three passes. It is easy to wander on your cap so lay a chunk of scrap alongside the edge to give you a guide n the smoke and bright light. Other people highlight the edge of the prep with soapstone. Be freindly to the inspector. He/she is your friend and has no interest in failing you. Ask for pointers. Often they will give you insight into how people are failing the tet.
Good luck Randy
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Thanks for the info randy, The test plates have already been made up by the company welding inspector's supervision so the gap is already setup. I think the CWB tester will want 1 stop,start on the first pass on the square corner of the joint.
I was wondering though, how the first 3 or so passes are placed. ie: is the second pass is next to the first or is it on the beveled plate with the 3rd pass inbetween the other two? I know that the first couple of passes on the backing bar are very critical, with the remaining passes laid beside each other to fill the joint.
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Hello
The second pass is placed against the beveled plate and the third goes between them.
The company weld procedure should be available to you so you can place all passes in the order required, there is may even be a recommendation as too the number of passes required.
It is also a good idea to trim your wire at a 45 deg angle for the stop and start, instead of just breaking it off by hand or using the end left from the stop. This will assist you in your goal of a getting a good start.
If you like I can send you graphic of the weld joint and passes.
John
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The objective of this test is to measure your ability to weld both fillet welds and groove welds. The first pass with the stop start is the fillet part of your test. The remainder is a groove weld test. The sequence of the first few passes is important. They do not dictate how you lay them down so everyone has their won style. You are starting with a 16 mm gap in the bottom. Your 8mm maximum filllet will leave you with a flat spot on the bottom 8 to 10 mm wide. Now John says two passes but I like to do one flat 10 mm wide pass concentrating on melting the toe of the bevel plate and the corner of the fillet. If the flat spot is over 10 mm wide then two passes are wise since you risk lack of fusion at the edges. I hope the company made up some scrap joints so that you can dial in machine. John's suggestion to angle clip the wire is a very important point. I pull the wire and clip it so that the feed rollers are up to speed before the wire charges out of the contact tip. John is on the East Coast and I am on the West. It's important to travel left to right when you are on the West Coast and right to left when on the East Coast... Or is it the other way round? :')) Randy
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Now look at what you have done,,,,,coffee everywhere.
This type of question has popped up from time too time in this group, maybe it is something that can be added to the FAQ web site.
I am still working on the jig design for attaching base plates to columns which lead to: -A Drilling Fixture for Base Plates, "not happy with this one yet" -Clip Installation Jig, "untested" -Tool for evenly spacing ballasters on hand rail, taking into consideration the max 4" C/C spacing by some codes. Takes less than one minute to determine the required spacing.
At this rate I may have to bundle them all together too form a booklet that can be distributed in pdf format. So if anyone would like to contribute to this project please do, you will recieve all rights and credits to the information you send. The completed project will be posted as a beginners guide to fitting/fabrication on the weldingfaq for all too download.
I have the graphics for the SMAW/FCAW test showing the positions they are to be in for welding along with joint configuration, as well as the picture showing the weld pass order somewhere around here. I will post them to the http://www.weldingfaq.com/ as soon as I sort them out and Zip the files.
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One thing to avoid when you test with flux core, is when you tie in the backing plate to the test plate, don't travel so far toward the test plate that the wire stubs (? for lack of a better term) on the test plate, pops, and you have a bad spot on the root. A little hand bobble can do it, or the welding lead to the gun jerking.
JTMcC.
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As this sounds like a welders qualification, you just have to follow your company procedure for doing this type of weld. You shouldn't have to figure out any voltages or amps for yourself.
Thinking for yourself is a bad thing ;-)

The most important aspect of wire welding is to not have TOO Much "stick-out" no more than 1/2" for the root. You have to make it possible for yourself to get the contact tip to be inside the joint so that you can get the penetration into the base metal that you need . Fish-mouthing the shielding cup works or you can smash it so that it is oval shaped and narrow enough to fit down inside the joint . Are the test plates cold when you start ? This condition adds to lack of penetration . It can be remedied by tacking up your plates when you are ready to weld them ,witch means don't tack them up then take a brake to get relaxed before you start to weld . When you tack them together run three heavy welds on each side of the backup plate to warm up your test plate . Find out how big of welds you can use , most likely they will be thinking of the minimum size make sure you know the max . Some people say that if you have a long stick-out you just have to increase the voltage a little . To say this correctly it would be if you want to increase your welding speed without overheating the part then you can use a longer stick-out with a voltage increase . Stay on the leading edge of your puddle to get the most penetration . This way you are adding the heat to the base metal that is ready to melt . If you stay too far back in the puddle then you are heating up metal that has just been applied which is now on "top" of the base metal . Don't think of amperage as you do with stick welding . The more wire speed the more amperage , but you will NOT end up with more heat at the arc . Your wire speed should be slow enough so you can weld fast (travel speed) without the wire stubbing and fast enough so when you weld fast you don't get undercut or a skiping weld . You have to start with enough VOLTAGE to melt the metal then adjust the wire speed to match the voltage . Travel speed regulates the size of the puddle . If you HAVE to weave to get a wide puddle then your voltage is to low . If you can NOT get the puddle to move along at will then the voltage is too high . This is the nuts and bolts of ALL wire welding . I look forward to any comments .

A couple more things . Start your weld at the beginning of the back up bar and weld to the end of the back up bar so as to start to heat things up a bit and to make it easier to completely fill up the plates , this might be necessary to pass .

During a weld test increasing the preheat temperature can lead to a failure if the inspector wants to be fussy.
The extra heat can help you pass, but there may be other things that need to be looked at first such as technique and essential variables. With the 1/16" wire CO2 combination there is good penetration when the wire speed and volts are set according to the weld procedure. However it can be much smokier than a Argon/Co2 mixed gas so visibility will be reduced this is where ideas like a soap stone line for the cover pas comes into play.
This is one time that using a pushing technique is not recommended instead use a a slight pulling technique or even perpendicular travel. a) Pushing reduces penetration b) Perpendicular max penetration c) Pulling can provide a slight increase if done correctly
Some may want to argue that pushing gives max penetration but I have a nice cross section of a weld that was guaranteed to have complete penetration and it missed horribly. weld metal never even made it to the base of the bevel on either side.
For 300W and 350W up to 20mm the minimum preheat temp is only 10 deg C so taking it up a few hundred degrees before starting the root pass may be considered cheating to some inspectors, only because there is little chance that you would use this much preheat on a routine basis and the test is suppose to reflect actual welding conditions as much as possible.
There are circumstances that require an increase of the min preheat but a weld coupon does not fall into that category normaly. a) Highly restrained welds b) certain combinations of steel thickness or composition contains carbon,manganese, chromium and nickel at or near the maximum values by the steel spec c) For high strength weld metal d) For joints where transfer of tensile stress occurs in the through-thickness direction of the material.
Also as mentioned below run your welds from backing bar too backing bar, not forgetting that one stop and start is required on the root pass. This falls under workmanship, for a normal weldment the ends would be removed and cleaned up. providing you with full thickness material across the entire plate.
John
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I always use perpendicular to a slight drag with flux core. My foreman regularly uses a slight push. I have tried his way and I screw up every time.
Randy
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