When Do Adhesives Make Sense?

There are some hollow metal door (steel door) manufacturers that glue their door panels together, as opposed to welding. It has always amazed me that a steel door that is glued together will withstand the hard use and abuse of, say, a high school, withstanding the temperature extremes, the direct water and humidity... and remain in service for years without coming apart. Impressive engineering.

My rear mirror just fell off the other day. Time for superduperglue, I guess....

Hi all

I've used Loctite for years to put components into holes bearings, pins, tubes etc. Especially bearings, the tolerance is a lot more sloppy than for a press fit, just keep boring it out until the bearing slides in easily, then a couple of drops of Loctite. The nice thing is, just heat up the housing and out it pops to use in another project.

I've also used urethane adhesive to glue colourbond steel, i.e. to glue the paint surfaces together.

When turning a flat disk, glue the disk onto a machined mandrel face with Supaglue, machine the outside, heat the mandrel to destroy the bond.

Tony

Nanotech Man to the rescue!...someday, maybe. No doubt LynDoor Industries™ will have a solution soon.

We use adhesives extensively on desktop dark enclosures which have to be light tight to less than 10 photons/sec. Any hole for a fastener is another potential light leak.

Lotus have been bonding the chassis on their sports cars for many years, I also watched a 'How it's made' programme recently which showed a American truck maker bonding most of the cab together.

Doorman's "door gluing" vs. Nigh's "chassis bonding" comments highlights a distinction worthy of having been included by the OP.

I grew-up hearing stories about how Hugh Lord built his 'empire' upon having perfected the bonding of rubber(s) to metal(s).

Having supplied several auto manufacturers with motor mounts etc for some years already, in WW-II, Lord became the exclusive supplier of engine mounts to virtually all aircraft manufacturers.

I have seen pull-tests ("time-after-time") prove bonds to be superior in strength to the cohesive strength of the rubber material itself.

Of course ... achievement of such bonding requires extraordinary attention to innumerable details , above and beyond a simple "surface-prep"...!

Nonetheless, many applications are certainly ideal candidates for use of adhesives. Many others are more appropriately approached via bonding.

[ And , just as no individual could ever possibly know "everything", SOME individuals will never understand or admit that there is a difference between these two distinctly different mechanisms.]

This is a good observation and point ndt-tom.

I simply said glued, without considering the actual condition of the door construction. I went to a manufacturer's website and found their terminology:

Cores are laminated to face sheets with contact adhesive. Also refered to as continuous bonding of core to steel face sheets.

Vertical edges are full height mechanical interlock with epoxy adhesive.

Again, these doors are very durable, and will take a beating.

"Acknowledged" ...

In the same context as the fact that (I would BET) NO participant in this forum would argue that there is a difference between soldering, brazing and welding of metals...

...and, analogous to the fact that some people (even some dictionaries) do not make a distinction between "soaps" and "detergents", but the *manufacturers* do ...

... clearly, there IS a difference between 'glues', 'adhesives', and 'bonded-joints' ("no horse or other animal ever went into the production of Elmer's Glue"... couldn't help myself). And, it would be MY hope that in the context of a professional forum, participants would strive to keep each other "in-check" (semantically-speaking)...

..."Where appropriate", of course ... not simply arguing semantics for the sake of arguing, but rather, whenever necessary to keep browsing-individuals from being mislead.

"Heaven forbid" that one day in the distant future, people who "Quote-From" threads on CR4 get (routinely) poo-poo'd for referencing such an "unreliable / deceptive / substandard" site ... ...

Imagine an elevator where the floor was held in place by adhesive alone. I don't think people would have enough confidence in an adhesive bond even if the bond was proven equal to or better than a mechanical bond. There are some areas where adhesive bonding is readily accepted, but where failure would result in death, a mechanical bond is necessary.

Try this as an example: A ledge canterlevered from a tall building put together only with structural adhesives and an identical ledge, but with dummy rivet heads or bolts applied. Which one do you think a person would risk standing on?

Adhesives are great fasteners, but they will never be used where the public "perception" of eminent or potential failure would result in their death.

"There are some areas where adhesive bonding is readily accepted, but where failure would result in death..."

Like holding a car together at 140 miles per hour?

The Convair B-58 supersonic bomber was a remarkable plane made with metal skins bonded to honeycomb cores. It stayed in service for only a short time. Rumor has it that the Air Force discovered they had no way to inspect the integrity of the bonds, and they just got afraid to fly it.