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Welded tools vs. One piece steel tool 785

Full Member Posts: 125
Welded tools vs. One piece steel tool
« on: October 18, 2018, 09:18:55 PM »
Can welded tools be as strong as one piece metal tool?

I was using my Gardena spader, and noticed the spade blade had been welded into the handle unstead of being one piece metal like my wilkinson spades.

I was wondering if welded tools like this can take as much stress as one piece and will last long as just one piece metal tools.

I always used to feel the welded part may snap if given some stress.


Head Turd Polisher Administrator Just Bananas Posts: 61,296 Optimum instrumentum est inter aures
Re: Welded tools vs. One piece steel tool
« Reply #1 on: October 18, 2018, 11:01:18 PM »
I can't say for sure- I'd be inclined to say that a welded bit wouldn't be as strong as a moulded bit, but there's a very good chance that both are well beyond strong enough for the intended purpose.

On the one hand, in shipping we have an estimated weld strength of roughly 1 ton of strength for every inch of welded material, although that is nothing more than experience talking, and it of course depends on the weld and the materials that are welded.

On the other hand, in a molding/casting process there are often faults that form inside the metal for a variety of reasons, and those faults are only detectable by running a current through it and measuring the resistance.  Or it can be detected when it fails catastrophically.   :facepalm:

I used to work for a guy who did Non Destructive Testing (NDT) for the Canadian military and everyone he worked with carried SwissTools because one of them had run a Leatherman plier head through the tests one day and they found more faults in them than in the SwissTool.  They may not have been significant faults, but they didn't want to take the chance.

Def

Leave the dents as they are- let your belongings show their scars as proudly as you do yours.
No Life Club Posts: 1,271
Re: Welded tools vs. One piece steel tool
« Reply #2 on: October 19, 2018, 10:54:42 PM »
Can welded tools be as strong as one piece metal tool?

I say it depends? How is the one piece metal tool made, and how is the weld made, and with what level of matching fill materials? Usual suspects for a one piece tool might be made to shape from a plate or sheet with say stamping, poured into a casting, machined or cut from stock, forged into shape or a combination. The end product will have different characteristics.

Welds on the other hand might be done with less than optimal preparation, done badly, or with sub optimal filler materials. Done correctly though the welded seam might very well consist of better material than the base metal and be stronger. A good weld will likely not fail in the weld itself, but cause a failure in the base material near the weld. The welding process itself heats up the base material too to a significant degree, and the resulting "heat treatment" in the base metal might cause issues with for instance hardening/ brittleness and alloy composition. With the weld being potentially thicker and different it also introduces some sharpish physical transformations of characteristics which might introduce failure areas.

In my head at least a well done one piece forged or stamped part is likely stronger than one of equal shape that has been welded together. A weld would be unlikely to improve on that if the basic shape can be made good enough with just that. The latter is a key question.

A part that has been designed for assembly with welds can be stronger overall, for instance by allowing a better shape and geometry that couldn't be made economically with just stamping or forging alone.

Thus to me I think the question is whether the welded parts and weld challenges have been worked in from the design and then implemented well. In that case a welded part can be as strong or stronger than a one piece part that might not be able to achieve the same shape. (Or which would weight a lot more doing so, and thus be less usable). In case a tool has not been made for a weld, but has broken and someone welded it, then chances are not strong enough to begin with and likely even weaker after.

The more universal answer is that the question should really be whether the product is good enough for the intended tasks regardless of manufacturing methods? Most things can be achieved in many ways, and each of those ways can also be made to fail.

(A spade from a reputable factory should be just fine with welds. I would be amazed if the welds failed due to human powered abuse).

« Last Edit: October 19, 2018, 11:02:45 PM by Vidar »

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
No Life Club Posts: 1,271
Re: Welded tools vs. One piece steel tool
« Reply #3 on: October 20, 2018, 08:56:24 AM »
It might be worth adding that the above consideration is for steel. Welds in aluminium or plastic is typically weaker than the base material - sometimes significantly weaker. (Designing around that limitation is still possible of course).

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
Full Member Posts: 125
Re: Welded tools vs. One piece steel tool
« Reply #4 on: October 20, 2018, 11:51:59 AM »
Yes, it is for steel.

It was for steel spades, most are one piece metal from blades to the shaft, but recently I saw some new models from German company called "Gardena" making their spades welding blades into shaft. They are all some sort of stainless steel, I would imagine.

This is Gardena Digging spade blade  welded into handle shaft.

https://www.amazon.co.uk/Advanced-Gardena-Terraline-Digging-Spade/dp/B00UQ8MM20
« Last Edit: October 20, 2018, 01:42:24 PM by mtoolman »
No Life Club Posts: 1,271
Re: Welded tools vs. One piece steel tool
« Reply #5 on: October 20, 2018, 08:44:29 PM »
The only spades I've managed to kill off are made of aluminium. They tend to open a rip across somewhat below the handle connection. I haven't even put a dent in the steel ones.

Gardena is a proper gardening brand - fairly sure there are some of their stuff around here.

"If only simple wasn't so hard" - me
(Partial disclosure: I design tools for a living).
Full Member Posts: 148 An old wrench tugger
Re: Welded tools vs. One piece steel tool
« Reply #6 on: November 10, 2018, 10:48:26 PM »
Looking at the link, that is a stainless spade and appears to have been TIG welded. The main problem with welded tools is someone's repair weld. They weld without proper preparation and the weld holds forever, but the metal breaks around the weld due to heat stress. TIG welding does not over heat the metal the way MIG or ARC welding will, this will allow the tool to last a long time. Most steel tools that are welded are properly heat treated to prevent the weld from weakening the steel around the weld. If you think about a Hoe, most have a sheet metal blade that is just spot welded onto a piece of round rod.  :tu:  :whistle:

just a tired old Multi-fool
Full Member Posts: 125
Re: Welded tools vs. One piece steel tool
« Reply #7 on: November 13, 2018, 10:36:35 PM »
 :tu: :salute:

Great info on welded tools papadan. Thank you.
Yes, my Gardena spade is still working great.  I have had it now almost 7-8 years using it often for gardening.

I like it because it has longer handle, so I don't have to bend my back too much when digging.

The blade coating is coming off though.

Looking at the link, that is a stainless spade and appears to have been TIG welded. The main problem with welded tools is someone's repair weld. They weld without proper preparation and the weld holds forever, but the metal breaks around the weld due to heat stress. TIG welding does not over heat the metal the way MIG or ARC welding will, this will allow the tool to last a long time. Most steel tools that are welded are properly heat treated to prevent the weld from weakening the steel around the weld. If you think about a Hoe, most have a sheet metal blade that is just spot welded onto a piece of round rod.  :tu:  :whistle:
« Last Edit: November 13, 2018, 10:37:42 PM by mtoolman »
No Life Club Posts: 3,902
Re: Welded tools vs. One piece steel tool
« Reply #8 on: December 26, 2018, 09:09:23 PM »
The tos-and-fros have more or less been said.

Welds are nothing to be afraid of, and (as stated - correctly implemented and designed from the start) can often be better than the same thing made with ill conceived stamping or casting processes (one piece shovels might tear more often, due to mysterious changes in thickness of the material as they try to make the same stock do different things....)

One could argue that a company that is paying the costs for decent welding is more invested in a quality product and doesn't want failures/returns/warranty issues, so will probably be making a worthwhile product for those reasons.

(It also happens to be that Gardena is decent stuff, I have some myself)


 

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