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Chuck you're thinking about some welds but not all. Many welds are actually chemical as well as just flowing the metals together. Especially bonds between diffe

Chuck you're thinking about some welds but not all. Many welds are actually chemical as well as just flowing the metals together. Especially bonds between different kinds of metals. Also there are many adhesives that require temperature treatment so where do you draw the line between "welding" and "adhesives"? Just a thought experiment. I know there is probbably a strict definition. However if you've ever used a mig or flood welder, it's really not very far off of from a hot glue gun or just dumping glue on the thing.

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jdietrich 11y ago
>However if you've ever used a mig or flood welder, it's really not very far off of from a hot glue gun or just dumping glue on the thing. As I understand it, the defining trait of welding (as compared to soldering or brazing) is that the process fundamentally alters the structure of the materials being bonded. The bonded faces are not merely adhered together with a filler material, but become a cohesive whole on a molecular level. The engineering problems posed by adhesive bonding arise largely because the properties of three materials must be taken into account - the two materials to be bonded and the adhesive itself. The adhesive could react chemically with one or both of the bonded materials, it may be stressed by differences in the coefficients of thermal expansion etc.
- grogenaut 11y ago
  @jdietrich, while this is generally true there are a bunch of special welds like silver to steel, aluminum to other metals, etc that have specially formulated multi element fillers so there's chemistry going on there, it's not just steel to steel with a slightly different steel filler. Bronze, copper, it can get interesting.
  - nkurz 11y ago
    I can't tell whether you are making a subtle technical point, or if you are don't understand the terminology the rest of us are using. Commonly defined, welding involves melting both the base metals, and the joint ends up as strong as the weaker of the two. Soldering and brazing, on the other hand, melt only the filler, and the joint strength is limited by the strength of the filler or its adhesion to one of the metals. When you say "multi element filler", it seems likely you are saying "welding" when we think you should be saying "brazing". True welding of dissimilar metals is sometimes possible, but is not very common, and usually requires some exotic processes most of us are less familiar with: laser, ultrasonic, diffusion, explosion. There's description of some of these here: http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=152 http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=k...
- grogenaut 11y ago
  also I meant that a mig wlder is like squeezing glue all over things... sure it works completely differently on the physical level but the high level action is like using a glue gun. It's wicked. And don't get me started on plasma cutters... oooh yeah.

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jdietrich 11y ago

>However if you've ever used a mig or flood welder, it's really not very far off of from a hot glue gun or just dumping glue on the thing. As I understand it, the defining trait of welding (as compared to soldering or brazing) is that the process fundamentally alters the structure of the materials being bonded. The bonded faces are not merely adhered together with a filler material, but become a cohesive whole on a molecular level. The engineering problems posed by adhesive bonding arise largely because the properties of three materials must be taken into account - the two materials to be bonded and the adhesive itself. The adhesive could react chemically with one or both of the bonded materials, it may be stressed by differences in the coefficients of thermal expansion etc.

grogenaut 11y ago
@jdietrich, while this is generally true there are a bunch of special welds like silver to steel, aluminum to other metals, etc that have specially formulated multi element fillers so there's chemistry going on there, it's not just steel to steel with a slightly different steel filler. Bronze, copper, it can get interesting.
- nkurz 11y ago
  I can't tell whether you are making a subtle technical point, or if you are don't understand the terminology the rest of us are using. Commonly defined, welding involves melting both the base metals, and the joint ends up as strong as the weaker of the two. Soldering and brazing, on the other hand, melt only the filler, and the joint strength is limited by the strength of the filler or its adhesion to one of the metals. When you say "multi element filler", it seems likely you are saying "welding" when we think you should be saying "brazing". True welding of dissimilar metals is sometimes possible, but is not very common, and usually requires some exotic processes most of us are less familiar with: laser, ultrasonic, diffusion, explosion. There's description of some of these here: http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=152 http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=k...
grogenaut 11y ago
also I meant that a mig wlder is like squeezing glue all over things... sure it works completely differently on the physical level but the high level action is like using a glue gun. It's wicked. And don't get me started on plasma cutters... oooh yeah.