
Welding breakthrough could transform manufacturing - gooseus
https://phys.org/news/2019-03-welding-breakthrough.html
======
sjcsjc
"The process relies on the incredibly short pulses from the laser. These
pulses last only a few picoseconds — a picosecond to a second is like a second
compared to 30,000 years."

Nice bit of exposition.

~~~
lozaning
You might enjoy this video of Grace Hopper explaining how to visualize a
nanosecond
[http://www.youtube.com/watch?v=JEpsKnWZrJ8](http://www.youtube.com/watch?v=JEpsKnWZrJ8)

~~~
cmroanirgo
Wonderful. For the time it takes an electron to travel in 1 microsec (in
vacuum, yada, yada):

> 984 feet ... We oughta hang one over every programmers desk, or over their
> neck (:audience chuckles:), so they know what they're throwing away when
> they're throwing away microseconds.

~~~
theandrewbailey
That would be incredibly useful today for web development.

------
Tor3
Very interesting. Welding glass and metal together instead of using an
adhesive. This could be big, depending on how long-term testing comes out. The
trick seems to be to use picosecond laser pulses to avoid running into thermal
issues with the very different materials.

------
panic
This seems to be the original press release from the university website:
[https://www.hw.ac.uk/about/news/2019/welding-breakthrough-
co...](https://www.hw.ac.uk/about/news/2019/welding-breakthrough-could-
transform.htm)

------
ganzuul
Have we forgotten lightbulbs, CRTs, and a myriad of other vacuum tubes used to
be a thing? They used the alloy 'kovar' for much greater temperature variation
tolerance than this new tech was tested for.

~~~
syntaxing
Kovar is still widely used. Besides the low thermal expansion coefficient, the
thermal expansion is extremely close to quartz which makes it ideal for optic
purposes.

------
aristophenes
I wonder how long until no one can repair phones anymore, because they are
welded shut.

~~~
d-sc
We have glues that for practical purposes would be just as hard to repair.

Repairability is generally a choice of the designer/manufacturer.

Cars have lots of welding on them and are still plenty repairable.

------
cimmanom
This won’t eventually lead to the glass cracking as temperature changes cause
the metal to expand and contract?

~~~
senorprogrammer
No, the terms picosecond and micron are pretty integral to the process.
Imagine using a propane torch to heat up the side of a single brick in an
apartment building wall for a few seconds. The temperature change in that
brick, considerable compared to all the others, will have effectively no
impact on the building itself.

~~~
yetihehe
Yeah, but it's about long term stresses leading to cracking. I wonder how big
elements you can weld with this. Centimeter scale windows for chips will
probably have no problems. While screens in mobile phones - I suppose they
will crack within weeks/months.

~~~
AstralStorm
It is very much possible that such essentially atomic level weld will be more
resilient than the glass itself.

The interesting bit is if anyone can make new and exciting multilayer material
composites using this kind of welding.

------
tromp
This could make titanium rimless glasses even more minimal, no longer needing
to drill through the glass.

------
syntaxing
I'm kind of confused...Isn't laser welding a pretty well studied technique?
Laser welding is pretty common for high tech industrial products. Is the
breakthrough the mix of materials? Even then I've seen different plastics
laser welded together. Also, pico laser has been the industry standard for
lasers for a while now. The main race is getting a robust fempto laser.

------
benj111
So could we see the return of square windows to aircraft? This would allow
that right?

[https://en.m.wikipedia.org/wiki/De_Havilland_Comet](https://en.m.wikipedia.org/wiki/De_Havilland_Comet)

~~~
serf
The square windows didn't do the Comet in, it was poor engineering and
testing, leading to improper fuselage reinforcement.

It's covered in that wikipedia article that you linked under 'Window shape
misconception'.

~~~
benj111
Ok I'm trying to parse that, and marry that with my own understanding.

The linked article seems to suggest that window corners weren't _the_ cause of
the crashes. My understanding is that corners can lead to propagation of
cracks etc, thus why modern aircraft window have a large window radius. And
large radius windows require less reinforcement, and thus weight.

They aren't contradictory are they?

Edit: Missing word.

~~~
_archon_
The hard rectangular angles lead to fatigue failure from stress concentration.
If more testing had been done and this had been known during the design phase,
it would have been possible to reinforce the rest of the airframe around the
windows such that the airframe would be able to withstand the forces while
retaining rectangular windows. No cracks, no crashes. However, the tradeoff
for such strength would have been complexity, weight, and manufacturing
difficulty; thus, modern airplanes have curved window ports to allow for
windows while being light and simple. Aerospace and sports cars are the places
in industry where lightness pays compounding dividends over raw strength. For
a plane, if you can shave a pound off the design, you do it, since that's a
pound you're not going to have to burn fuel to keep aloft for the entire
lifetime of the aircraft. Or, for equivalent fuel, you could go faster
instead.

I suppose there's another question I never asked myself: What is the merit of
a rectangular window? Why would we want rectangles on our airplanes? They're
on our houses because they're simple to frame and create openers for, neither
of which are important for planes.

~~~
LoSboccacc
> What is the merit of a rectangular window?

less blind spots! cockpits in fact tend to maximize the window surface area
and you'll find square/trapezoid on most of them. (counterpoint: SpaceShip One
went for rounded windows because they maximized for strength).

