Define Welding

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Old 05-05-05, 10:50 AM
h nu
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Define Welding

I am curious what all of 'you' think, defines the term welding. (Dont go google for a dictionary response or anything). I will use this information probably, for upcomming welding lessons where I teach.

So tell me, what does a weld consist of?
 
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Old 05-05-05, 10:53 AM
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Wink

Just out of the box here. It means to melt two pieces of metal together and make them as one.


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Old 05-05-05, 11:28 AM
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To me, it is a means of joining two pieces of metal OR plastic together by melting them together by means of a filler material that will (or should be) stronger than the base materials you are joining. Best I can do.
 
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Old 05-05-05, 03:16 PM
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Welding consists of connecting a joint between two materials such that each of the materials temporarily enter the liquid state and the two liquids mix at the boundary before becoming solid again.

There may or may not be filler material added at the joint.
The two materials may enter the liquid state as a result of a solvent action (think plastic) or applied heat (think metal).
The material surrounding the joint may also have its properties altered once the material has cooled (heat-affected zone).

Some adhesive connections, while quite strong, such as brazing or epoxy glue, do not qualify as welding since the parent materials are not comingled.
 
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Old 05-05-05, 05:57 PM
h nu
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This is a good start. Lets try to amend what we have.

Why does it have to be just metal or plastic(polymer)? why not ceramic? (Ceramic, polymer and metal covers just about every material there in exsistance) what polymers can you not weld? (wood? why or why not?)

if fusion of 2 materials (specifically metal) is all it takes to make a weld, could you then take any number of metals and weld them together? (like some examples of things many people claim can't be welded) Copper to Steel, Copper to Aluminum, Copper to Copper, Aluminum to steel, Silicon to Copper, Gallium to tungsten? Do these still fit within the definition of weld? or should they be excluded?

Must the materials involved, absoultly enter 'liquid' phase to accomplish the homogeneity of fusion? Why?

What percent of components must enter the weld zone to consider it a weld. (like if a smaller %of one base metal enters the weld zone than another, for example, 10% copper mixes with 90% aluminum in the weld zone with gradients of 1-100% trailing the zones to their respective base metals)
 
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Old 05-05-05, 07:27 PM
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Once we attempt to "amend" the subset of the universe of processes that connect two objects in some manner, we are beyond opinion and must examine the rules by which amendment occurs. Without boundaries of rules, we could "weld" two pieces of water together by pouring them into the same container. Here are the rules:

a : to unite (metallic parts) by heating and allowing the metals to flow together or by hammering or compressing with or without previous heating
b : to unite (plastics) in a similar manner by heating

So, the rules are:
1. the parts must flow together: No flow, no weld.
2. must heat the parts or force them together by mechanical compression/hammering. Blacksmithing as well as inertia and friction welding of metals qualify.
No heat nor mechanical compression, no weld. I can deform two metal parts such that they interlock and cannot be separated, but that's not welding.

My earlier opinion that using a chemical solvent to liquify plastic and cause the boundaries to adhere is not welding. It's more like using glue.

Therefore, all joining processes that qualify as welding must satisfy both requirement 1 and 2 as stated above.
Amend away!
 
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Old 05-05-05, 07:46 PM
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We must also avoid circular definitions, i.e. fusion; which is

- the act or process of liquefying or rendering plastic by heat.

- a union by or as if by melting: as above, a merging of diverse, distinct, or separate elements into a unified whole

This refines our understanding because it requires a "unified whole". We can MIX oil and water but they will not become a unified whole. On the other hand, we can burn sodium in a chlorine atmosphere creating another substance, sodium chloride. Welding seems to be a bit in the middle of this. If the two dissimilar metals are melted, one is likely to float on top of the other creating a mixture of metal particles but not a unified whole. The result is a weaker or more brittle than it would be if the two metals were more compatible. Thus, mild steel welds easily to itself while other combinations don't weld together at all and other joining processes such as brazing and riveting hold the surfaces together without asking them to flow together.
 
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