There are several ways to join pieces of metal together,

Mechanical fasteners (including wedges), bolts, rivets, pop rivets, Clayton clamps, etc

Fusion (usually melting two metals together), electric arc welding, Stick, MIG, TIG, solder, etc, gas OX/AC welding, fire welding, friction welding, explosive welding. etc

Glues and adhesives, and etc.

Other methods

 

What are the advantages and disadvantages of each and when should they be used?

A lot depends on if its cosmetic or structural, and what the user has on hand for technique/skill options. I'll go out on a limb and say "I assume that the majority of people don't have explosive welding capabilities at hand"

Interesting thread....does magnetism qualify? I also have plans to use segments of springs as large as truck leaf springs to create a friction join between two pieces of metal for a project that requires a tight sliding joint.

Advantage - easy to apply, disadvantage...temporary joins.

• 35 minutes ago, Glenn said:

  explosive welding, etc

  That makes me think of the truck crash in the Matrix and the use of thermite to weld RR track. I know thermite is not an explosive so I guess it would fall under fire.

Ernest

thermite qualifies as fusion welding; Explosive welding is one of the solid phase welding processes like vacuum welding and galling.

1 hour ago, Glenn said:

What are the advantages and disadvantages of each and when should they be used?

Well Glenn, that's a tall order on very broad lines.  

Recently we had an issue of a tech welding a front reinforcement bar on a Chevy sonic with "factory type" spot welds.  Well they didn't look up the procedure for That vehicle because it seemed straight forward. The tech did everything else right that he normally should have done like removing the battery. Most other cars it would have been a proper repair.  The car was finished and fine but then came back with engine codes and was not running properly. Apparently the welder magnetized the engine and the shop had to pay to replace the head and sensors in the vehicle. We came to find the repair procedure called for mig plug welds and no spot welding. Needless to say we are paying more attention to factory procedure even on things that normally seem cut and dry. 

Vehicles use Many different metal joining procedures and sometimes multiple types on even a single panel. And just because the factory used one type in assembly dosnt mean you can use the same in the repair. Or maybe you can.  

I watched a fascinating 'how its made' video about how a certain luxury car was made. 

The body was a bunch of pressed aluminium sections that were glued together. 

The sections went into a jig, glue applied, and additional sections rivited into place for alignment. 

The whole body/chassis was then baked in an oven to cure the glue. 

Crazy that material science is that far these days... Trusting glue to hold hundreds of horse power together

I believe it was General Motors that guaranteed the metal to fail before the glue joint on a panel that was glued on. I may be wrong, but just going by memory from body shop days.

1 hour ago, jeremy k said:

A lot depends on if its cosmetic or structural, and what the user has on hand for technique/skill options. I'll go out on a limb and say "I assume that the majority of people don't have explosive welding capabilities at hand"

I use to do Cadwell grounding to steel structure way back when, hated it.  That was explosive enough for me

 

16 minutes ago, jeremy k said:

I believe it was General Motors that guaranteed the metal to fail before the glue joint on a panel that was glued on. I may be wrong, but just going by memory from body shop days.

This wasn't just a panel, it was the entire structural part of the car 

If you search YouTube for 'How Its Made Dream Cars " Aston Martin Vanquish' you should find it 

Edited January 3, 20188 yr by JustAnotherViking

They use glue to hold metal studs and other metals together in the construction industry.  

Superglue: The original cyanoacrylates (the chemical name for the glue) were discovered in 1942 in a search for materials to make clear plastic gun sights for the war, and scientists stumbled upon a formulation that stuck to everything that it came in contact with. 

They have a structural adhesive out now that I'll say I believe that statement Jeremy. It's a bear to separate the panel areas that have it. You really have to heat it up to get it to separate  

The newer aluminum Ford F-150 rivets are pretty neat. Our shop doesn't have the tool to deal with them yet tho so we have to outsource. 

As to having explosive welding to hand; I can hear them doing it from my shop---does that count?

http://www.emrtc.nmt.edu/   (not a commercial link!)

An advantage of mechanical fastenings is that they can be handsome enough on their own to be the aesthetic of a job (especially if repeated multiple times) and so extra frills aren't required. E.g Industrial riveted bridges.

Joel is correct. And he spells better than me.

Choose the technique that  creats the esthetic you are striving for.

As Blacksmiths, always be proud of your joinery and the esthetic it creats.

modern construction is counter to this because architectural details are "too expensive". Thus hidden hinges, ground welds are common. Our market is for those who want something different. 

Patching metal,, Tinkers Dam

I generally divide into two catagories.....perminent ie welded, or removeable, ie bolted. (machined joints should also be included if it's not been previously)

What method is chosen depends on, requirements, materials, ability, equipment and sometimes cost and time.

If its on an industrial/production scale, cost and time are ALWAYS considered, usually over every other factor. 

Why do we use rivets instead of bolts, or bolts instead of rivets?

They have built bridges, boats, buildings, and even old steam engine boilers (traction engines etc) using rivets. A rivet will squeeze down and fill any void in the hole, and can be tightened with a hammer. It is tough to loosen, but can be re-tightened when needed. 

A bolt is a set diameter, a small head will need a washer to additional surface area. The other end will need a washer to add additional surface area, plus a lock washer,  and nut to maintain tension on the fastener. In order to lock it in place you may need to double nut the fastener. You also see some bolts with a nut and the end of the fastener rounded over with a hammer to lock the nut on to the shaft. The bolts have the additional advantage of being able to be torqued to a certain tension spec. and to be able to be removed form the application when needed.

So why do they use rivets for certain applications, nuts for others, and not use them interchangeably?

Why do we use rivets on tongs and use bolts on pliers?

 

I would add a few more characteristics for both rivets and bolts. 

Rivets are cheaper than bolts so when it is a building or a bridge, a few million fasteners make a difference in the budget. 

Rivets are not only cheap but made of mild or low carbon steel. This makes it easier to rivet but makes it also more susceptible to lose grip.. A slight movement in the plate and the rivet is permanently deformed and lose. A bolt depending from material used is more flexible. Rivets are associated with permanent. Bolts with demountable. 

A bolt besides being more expensive, can be tighten to specifications and keeps a permanent tension. If the nut is locked after tensioning it is a permanent fastener but can be dismantled anyway and the locking washer replaced as in connecting rods or propeller nuts. 

The question of rivet on tongs and bolts on pliers is a bit sui generis. There are pliers that are made with rivets and others that have bolts. The important difference between a tong and a set of pliers is the material they are made of.  

Secateurs can have bolts to compensate for wear.A tong that starts rattling is fixed with a hammer. Try that with a plier or sicateur and you are up for a new one

4 hours ago, Glenn said:

Why do we use rivets instead of bolts, or bolts instead of rivets?

The small to medium sized commissions I do don't really require stress load calculations, (furniture, gates, sculpture etc), so for me it's mainly down to aesthetics as a rivet or a bolt will often do the job just as well as eachother.

The situations that immediately pop to mind where I use bolts: holding something together temporarily before riveting. On site fixings that have to be done cold.

Again, Joel, right on.

Even for on site installs, a half inch plate with a countersink, two vice grips, a torch(or set cold) is all that's needed to set a rivit in the field.

 

On 1/8/2018 at 9:51 PM, Marc1 said:

Secateurs can have bolts to compensate for wear.

That's "pruning shears" for us 'Murricans.

3 hours ago, anvil said:

Even for on site installs, a half inch plate with a countersink, two vice grips, a torch(or set cold) is all that's needed to set a rivit in the field.

The interesting thing about @Glenns question is that what may suit one area may not suit another. My Dad (architect) commented to me the other day that in the UK we have the perfect storm for the worst corrosion, so everthing done on site / in the field has to be pre-weatherproofed if it's to last, i.e galved or stainless, which doesn't really allow for much on site heat work.

From memory that's why I fixed the hatch on this riveted well cover with stainless bolts on site - so the weatherproofing treatment could get right into every surface whilst all the parts were separate. If treated as a whole there would spots that didn't get treated and would have rusted.

Removable fasteners and parts that are keyed together are have the big advantage of being separated if necessary. Welding, Rivets and Glue have the disadvantage of permanently affixing things together and are not intended to easily come apart in most applications.