Welding of Forklift forks

[bmlkidd]

My maintenance crew wants to take some forks off of a lift that had an engine blow up and use them on a similar sized capacity forklift. However, the mounting is different. Thus, they want to remove the existing clip type mount and weld tubing to the top to enable mounting on the other lift. My questions are:

1. What are the ramifications of welding and/or tempering the forks by welding on the top where it mounts to the vertical risers?
2. After welding, what should be done to temper the welds?

A quick search revealed this information:

1. Preheat to 600*F with a soft flame.
2. Postheat to 800-850*F with a soft flame.
3. Cool slowly.
4. NEVER weld on the face, or under any circumstance the INSIDE RADIUS of the HEEL.
5. Normally, never weld within half the diameter of the face. IE, 2" thick forks can only have a 1" weld on the sides.
6. Anything else causes soft spots and weakens the forks from their load rating.
7. Always match the lesser steel, usually mild steel, and use a low-hy electrode such as 7018 or 71T-1.

This a condensed, generalized weld procedure from many fork manufacturers.

Is this a fairly accurate procedure?

Thanks!

 

[unclesyd]

I don't have the current regulations on forklifts but under the older rules one was not allowed to weld on any part of the lifting components unless you were a factory authorized repair depot and you needed to use manufacturer's approved welding procedures. We had a fleet of over one hundred forklifts at one time so we were able to be a licensed repair station for the majority brand of forklift.
When it came to the forks we only allowed welding to attachment points using an approved procedure. We never changed the attachment design as this would require factory approval and testing. One reason for doing this was the forks were made from different materials, from 4140 on down. The forks were essentially considered an expendable item. When we did weld on the attachment points of the forks we required a proof test of the repair.
In the USA OSHA frowns on any failure of any lifting device where someone is injured. We found out the hard way.

 

[tygerdawg]

Just extrapolate the worst case scenario of Do It Yourself fork modification. It may be OK, but what if it is NOT ?

DIY mods
unanticipated metallurgy changes
catastrophic fatigure failure
equipment damage / injury / death
root cause investigation
lawsuit
jury award

The Big Flashing Neon Sign of Liability Avoidance says get new forks from the manufacturer.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[MiketheEngineer]

TOTALLY agree with the above

 

[desertfox]

Hi bmlkidd

All the above and not to mention your companies insurance as just been made invalid.

desertfox

 

[ornerynorsk]

This is a big no-no. If the worst would happen, you are royally screwed. Your company, your insurance company, the family of the injured or deceased, EVERYBODY will want a piece of whomever gave the OK to do the mod in the first place.

 

[rmw]

Don't even think of it. The reward comes no where near the risk in a case like this.

rmw

 

[IceStationZebra]

Ditto - not worth it. Even if you were determined to monitor the forks for cracks they could fail catastrophically. ISZ

 

[Metalfixer]

I wanted to add another caution to this discussion. Some forks are never checked for heel wear, from the constant dragging on metal loading docks and cement floors. Forklift mechanics have a gauge to check this wear. I've seen more fork failures from this commonly overlooked problem, than from welded hangers or clips.
I've welded plenty of forks in the past 30+ years, as an AWS certified to D1.1 all positions, all thickness. D1.1 is for structural steel, forks are probably covered under D14.3, D14.4 or D14.6, some type of machinery and equipment. I was also an AWS CWI for 9 years.
ITA (Industrial Truck Association) has 4 classes of fork hangers or clips, class 1 for 13" high carriage, class 11 for 16" ,class 111 for 20" and class 1V fo 25". The proper replacement hanger should be used,as well as proper workmanship practices and properly stored or reconditioned electrodes (E7018).
Some forks require a middle hanger added when used on a rotator. Some forks need blocks welded to them for attaching hydraulic cylinders, or leadscrews for positioners. The forks with rings or tubes should be replaced with the same material and size as when they were manufactured. Every fork that I have seen has been welded at one time or another, and most of the broken ones are from worn heels or misuse, which is also a common problem. I don't recommend everyone repair forks, it's not a simple task removing worn hangers,they don't come off easy, you have to be careful not to cut into the fork. I've replaced the tube type hangers on forks that were 4" thick,used 1/4" diameter E7018 electrodes, and positioning the fork in the flat position, makes for a long day. I've never done this , but the company that I do work for heats and straightens bent forks, and have never had a problem.

 

[IceStationZebra]

Obviously it can be done, otherwise they couldn't be manufactured. But 90% of mechanics and welders shouldn't attempt it. I've worked for several OEM forklift manufacturers and have seen some nasty field repairs/upgrades.

ISZ

 

[unclesyd]

I concur with IceStationZebra but would raise the percentage to 99%. One big problem I encountered was since they were welded in the manufacturing process it is OK to make additional welds. In the US qualification by any recognized standard, of the welder wasn't the primary emphasis, it was complying with a procedure approved and sanctioned by the manufacturer. I don't know whether this requirement is still in the current OSHA standards, it once was as a carryover from the ANSI standard. As mentioned above I've visited several facilities where there was some very ugly welds on modifications to components of the lift system on fork trucks running around.
I know it has changed but when OSHA started out they were out to prove a point and would bear down on any infraction.
A case in point was that a guest organization at our site make some unauthorized modifications, higher reach, to several high lift fork trucks which was well and good until they had a lost time injury with the resultant OSHA investigation. When it was found out that these trucks were serviced by our fork shop even though we didn't make or check these modifications we came under the investigation. The result was that all our trucks has to be called into the shop and looked over by the OSHA inspector. OSHA required that the modified trucks be brought back to OEM condition and since the lift components were of a newer design we had to build a ramp to test the stability of newer configuration. Aside from the substantial fines imposed the company had to rent standard trucks to service there warehouse.
At the time the only thing worst in OHSA's eyes was welding on a crane boom when it came to lifting devices.