Help & FAQs    Search BCF    Members    Groups    Events Calendar
Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Whats with the great dirty welds?

 Reply to topic
Bike Chat Forums Index -> General Bike Chat
View previous topic : View next topic  
Author Message

swiftb
World Chat Champion



Joined: 20 Oct 2008
Karma :
PostPosted: 16:43 - 23 Jan 2011    Post subject: Whats with the great dirty welds? Reply with quote
One thing that always seems to stand out on a bike is the beautiful external machine welds all over the bloody frame and swingarm.
I assume when constructing the frame/swingarm etc its easier to join smaller sections together etc - no doubt contriibutes to the whole strength of it too?? But ive noticed some seem bizzarely placed. Like on my old zxr.
The swingarm was welded in sections like you would expect, cross member and two parralel arms. But the arms were also welded just a few inches from the end - just past where the axle attaches. I always found this a bit odd and ive seen other bikes with what seem like odd places to join. Im guessing there not actually 'joined' and the arm is cast in one piece and the welds are there too add additional strength???
Any engineers (or anybody really) care to explain this as id be interested to know the reasoning Thumbs Up
 Back to top
View user's profile Send private message You must be logged in to rate posts

Hetzer
Super Spammer



Joined: 19 Feb 2007
Karma :
PostPosted: 16:51 - 23 Jan 2011    Post subject: Reply with quote
Possibly the main unit is a generic shape and size that fits many types but needs to be longer/shorter etc for specific models so they weld those bits on. Cheaper way of doing it than having multiple molds.
____________________
"There's the horizon! Ride hard, ride fast and cut down all who stand in your way!"
 Back to top
View user's profile Send private message You must be logged in to rate posts
Blau Zedong This post is not being displayed because the poster is banned. Unhide this post / all posts.

swiftb
World Chat Champion



Joined: 20 Oct 2008
Karma :
PostPosted: 17:07 - 23 Jan 2011    Post subject: Reply with quote
BLUEX5 wrote:
The actual "arm" part of the swinger is extruded section and the chain adjuster / axle mounts are cast pieces. It's not like they can araldite two seperaate components made by totally different processes together.


Makes sense, yes I appreciate theyre not going to araldite or superglue them to each other. . What I wondered was did piece one and piece 2 below here start out as two seperate parts or was it one part and the welds where to add some kind of additional strength.
I wondered why it wasnt just cast as one solid piece but it makes sense thats its easier/cheaper to manufacture them in two seperate parts and join them together. (didnt realise the actual arm was probably just cut to length from a much longer section)

https://i441.photobucket.com/albums/qq135/photobucca/CIMG32222.jpg
Thumbs Up
 Back to top
View user's profile Send private message You must be logged in to rate posts
Blau Zedong This post is not being displayed because the poster is banned. Unhide this post / all posts.

swiftb
World Chat Champion



Joined: 20 Oct 2008
Karma :
PostPosted: 17:18 - 23 Jan 2011    Post subject: Reply with quote
Cool. Yeh my K7 has the whole front section cast as one (I think) then the two arms incorporate the chain adjusters/axle locater. 3 parts in total seemingly stronger than 5.
 Back to top
View user's profile Send private message You must be logged in to rate posts

The Tot
World Chat Champion



Joined: 11 Jun 2004
Karma :
PostPosted: 17:34 - 23 Jan 2011    Post subject: Reply with quote
The presence of welds actually makes the material weaker. You would have issues such as porosity, embrittlement and inclusions in the welds. The welds themselves would be weaker than any parent material as a result of this.

The reason why they have the weld at such point is that it allows the swingarm to be as stiff as possible. Remember that the swingarm has to cope with the tension of the chain pulling against it as well as the dynamic forces of the road acting through the wheel and suspension.

Picture this. Imagine having a long plank of wood that's anchored down at one end. Let's hypothesise. On one plank, you've got a groove directly in the middle of the span. On the other, it's a few inches from the end. Now if you were to jump on the freely supported end, which plank would you reckon would survive the forces? Same thing with a swingarm.

Extrusion is a relatively cheap process compared to casting, which is why they used make wingarms like that. But castings you can incorporate intricate details into the design. It's the best compromise.

I suppose the other argument would be that welds on extruded/cast sections such as the frame and swingarm are placed where they are so that the chassis can flex in the way that it's supposed to be to give feedback. Take a look at the welds on your headstock and frame for example. No point having a totally rigid chassis. I remember the factory yamaha team in 06 with their chatter issues. They actually took hacksaws to the frame to tune their frame feedback!

I'm sorry if i've gone on a bit. Maybe I can ask the metallurgists at work their opinion. Being in the materials group , I tend to get contradicting answers for the coneheads. Most of my work mates have got letters after their names and whatnot so I'd like to respect and value their opinions when it comes to these things.
____________________
The Tot 2019 Z1000SX - 2007 R1
Never argue with autism
 Back to top
View user's profile Send private message Send e-mail Visit poster's website You must be logged in to rate posts

swiftb
World Chat Champion



Joined: 20 Oct 2008
Karma :
PostPosted: 17:50 - 23 Jan 2011    Post subject: Reply with quote
Nice info Tot. Thumbs Up Its interesting to see how things move on also. Swingarms for example, the swinger on my ten year old ninja could be mistaken for something knocked up in home workshop whereas a lot of the new stuff is bordering on a work of art (as well as the older exotic stuff , single arms etc).
 Back to top
View user's profile Send private message You must be logged in to rate posts

Ichy
World Chat Champion



Joined: 15 Jul 2005
Karma :
PostPosted: 18:41 - 23 Jan 2011    Post subject: Reply with quote
The Tot wrote:
The presence of welds actually makes the material weaker. You would have issues such as porosity, embrittlement and inclusions in the welds. The welds themselves would be weaker than any parent material as a result of this.


Very misleading. If welded correctly the overall characteristics will not alter from that of the base material. Your assuming that there is an inherent fault in the weld.

The Tot wrote:
The reason why they have the weld at such point is that it allows the swingarm to be as stiff as possible.


There may be a misunderstanding in your intended message but its simply a means of attaching an extruded part to a cast part. Doesn't change the torsional characteristics of the entire part. look at the left and right side of a swing arm then consider the torque stresses applied by the drive or under braking. Both differ significantly not only in direction but also in magnitude. Swing arm looks similar both side though? Stiffness isn't always good.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :
PostPosted: 20:12 - 23 Jan 2011    Post subject: Reply with quote
swiftb38 wrote:
Nice info Tot.


No it's not, it's misleading, uninformed and contradictory. Some people should think very carefully before dishing out info on stuff they obviously know little about.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

swiftb
World Chat Champion



Joined: 20 Oct 2008
Karma :
PostPosted: 20:18 - 23 Jan 2011    Post subject: Reply with quote
Shite info Tot Middle Finger









Laughing
 Back to top
View user's profile Send private message You must be logged in to rate posts

Teflon-Mike
tl;dr



Joined: 01 Jun 2010
Karma :
PostPosted: 22:05 - 23 Jan 2011    Post subject: Reply with quote
Being fair...
The Tot wrote:
The presence of welds actually makes the material weaker. You would have issues such as porosity, embrittlement and inclusions in the welds. The welds themselves would be weaker than any parent material as a result of this.

Spot on.
For integrity, (and cost) you should design for 'least-welds'.
In 'Theory' welding joins two identical metal components, homogeniousely, as 'one'... ie, heating the metal up to molten on both sides then pouring in a bit more identical metal, accross the join you get a single continiouse bit of metal, with the chyrstal structure of the 'set' metal continuing accross the joint....
But that's in 'theory', an ideal and perfect arena.
The real world is far from it. And the nature of welding means that you virtually NEVER get a 'perfect' weld, free of imperfections.
Then the 'discontinuity' of a weld, and the ripples and ridges of the puddling we 'see' as the evidence of the art, are, structurally 'stress-raisers' areas where the change in section causes a concentration of stress, making the joint weaker than a smooth straight section.
Consequently, when designing around a welded joint, you have to compensate and increase structure strength around the joint to avoid or dissipate localised stresses, while the finished weld should be 'dressed' to reduce the stress raisers and the weld rippling.
A 'perfect' weld would not be visible, it would be polished out.
(Again, imperfect world; and in prctice, its a compromise between forming a strong 'functional' weld, and the time, cost and effort to achieve 'perfection'. Though I do know a couple of artisans of the arc, who strive for nothing less... but they are strange creatures with a fetish for 'real-steel' Ford Model A bodies and the like!)
When it comes to aluminium welding, the situation is complicated further from the 'theoretical' by the fact that we are working with an aluminium alloy, rather than a pure metal. (Situation is actually the same for steel, which is a pseudo alloy of iron/carbon and, depending on grade, variouse other metals.)
Aluminium alloy compesitions vary greatly, and the composition of casting grade alluminium is very different to that of extrusion grade, which is different again to that of sheet.
Consequently, welding a cast finial onto an extruded section, braced with sheet, results in a component where it would be impossible for the 'welds' to be even close to perfect and have a continiouse chrystaline structure and comosition accross the joint. In fact, technically, the joint will more often, have properties more akin to a pure 'braze' than a pure 'weld', as the two metals being blended are not the same, so can be like gluing copper to plastic!
https://i441.photobucket.com/albums/qq135/photobucca/CIMG32222.jpg
The Tot wrote:
The reason why they have the weld at such point is that it allows the swingarm to be as stiff as possible. Remember that the swingarm has to cope with the tension of the chain pulling against it as well as the dynamic forces of the road acting through the wheel and suspension.

Not spot on... (& this bit is probably best answer to OP)
Reason there is a weld at THAT point is to join a cast 'Vernier' chain adjustor to an extruded sing-arm beam.... and THAT is about as much as we can say, without a HELL of a lot more info from the designer!
Remember, the structural strength and weight of the component is only a small part of the design remit, and on a production road-bike, the importance of those criteria will be minimised to merely 'sufficient' strength, and 'reasonable' weight before they even begin.
Cost will be at the very top of the list of priorities. 'Marketability' will be only a few notches lower.
Structurally, as well as ecconomically, a straight extruded beam, with simple 'slot' for the wheel-spindle, with internal spacer against crushing the box, and an end-plate for location/adjustment, would be the most elegant and least-cost solution. But it would look 'ugly' and unsophisticated.
Consequently, the designer has PROBABLY sacrificed some 'strength', and certainly added some cost, by including a joint and more sophisticated cast finial to the extruded section, to incorporate the vernier adjuster-block, which has a greater 'percieved' value; ie adds more to the saleable price of the bike than it does to the manufacturing cost, becouse of its asthetics and functionality.
The Tot wrote:
Picture this. Imagine having a long plank of wood that's anchored down at one end. Let's hypothesise. On one plank, you've got a groove directly in the middle of the span. On the other, it's a few inches from the end. Now if you were to jump on the freely supported end, which plank would you reckon would survive the forces? Same thing with a swingarm.

Five years in the lab, being made to support and bend 'beams' and prove 'engineers beam theory' and I am utterly perplexed by what you are trying to illustrate here, TBH!
Think what you MEAN is, if you have a 'cut' in a beam, the change of section, ie where the material is 'missing' reduces the strength of the ENTIRE beam to that of one as thin as the bit where the cut is.
Worse, the change in section creates a 'stress-raiser' or concentration of stress, such that the 'effective' section is even less than the 'thin-bit'...So thats where the beam will break when loaded!
THEN, the greater the distance between the applied load and the weak-point, greater the leverage the load has over the weak-point, so the lower load it will break under.....
I think.....
Which MEANS, that having the welded joint (Weak-spot) close to the axle support, its not as bad as having a welded finial at the pivot end..... possibly?
The Tot wrote:
Extrusion is a relatively cheap process compared to casting, which is why they used make wingarms like that. But castings you can incorporate intricate details into the design. It's the best compromise.

That's all very relative, but close enough.
Extrusion is actually not that cheap a process. Main advantage of extrusion is that you can reletively cheaply and easily form a veriety of reletively complex stock 'forms' which can simplify fabrication.
As such fabrication from stock extrusion can be a lot cheaper than fabricating from sheet or pressing.
But depends on production volume as well as many other considerations, like whether there IS a 'stock'; extrusion in the form you want.
Casting, a 'one-shot' process, can actually be the CHEAPEST way to make an artifact, but it comes down to artifact complexity, and production volumes. (Think 10p kiddies cars!)
You are right, in that it comes down to the 'best-compromise', but as said, that compromise, for a road-bike, will be one with commercial considerations prioratised far higher than structural ones.
The Tot wrote:
I suppose the other argument would be that welds on extruded/cast sections such as the frame and swingarm are placed where they are so that the chassis can flex in the way that it's supposed to be to give feedback. Take a look at the welds on your headstock and frame for example. No point having a totally rigid chassis. I remember the factory yamaha team in 06 with their chatter issues. They actually took hacksaws to the frame to tune their frame feedback!

Err.... yeah.... the 'Dynamics' of chassis design had got to the point they realised that some 'complience' was necessery, and ultimate rigidity could actually be unhelpful, back in the 1950's.
(Actually possibly earlier. Rigidity of cars & motorcycle chassis increased exponentially imedietly after WWII when aeronautical practices were transferred into vehicle manufacture. Precedent of the feed-back structural 'complience' provided having been noted in pilots preference for wooden super-structure Hurricane fighters over the more sophisticated, aluminium monochoc spitfire, during the Battle of Britain!)
As far as road-bikes are concerned, though?!?! It will NOT be a very big consideration in the designers remit.An awful lot of inherent 'feed-back' will be provided by the fact that 'ultimate' rigidity will have been sacrificed for production costs before they even begin, and they will have been working down to 'adequete' stiffness from the very start.
The Tot wrote:
I'm sorry if i've gone on a bit.

Carry on... normally I'm the one getting slated for long posts and technical accuracy!
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :
PostPosted: 22:19 - 23 Jan 2011    Post subject: Reply with quote
The presence of weld *can* make the material weaker but it doesn't follow that it will, and it's NOT for the reasons listed because what was described were flaws in welding not features of it.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

Ichy
World Chat Champion



Joined: 15 Jul 2005
Karma :
PostPosted: 22:39 - 23 Jan 2011    Post subject: Reply with quote
Just to add to Petes post.

The only significant factor in the strength reduction of aluminium alloys by welding is down to the heat employed. The ones listed would generally be considered good reasons to scrap.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Teflon-Mike
tl;dr



Joined: 01 Jun 2010
Karma :
PostPosted: 22:57 - 23 Jan 2011    Post subject: Reply with quote
Pete. wrote:
The presence of weld *can* make the material weaker but it doesn't follow that it will, and it's NOT for the reasons listed because what was described were flaws in welding not features of it.

Entirely down to view-point.
As a welder, 'flaws' are detremental to the integrety of the weld, undesirable, and to be avoided, and if present to the degree they impare the integrity of the joint, are 'faults'
As an engineer, a flaw is an inherent property to be anticipated and accounted for within the design solution.
Flaws are NOT necesserily 'faults'.
Its entirely an argument of symantics and interpretation.
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :
PostPosted: 23:16 - 23 Jan 2011    Post subject: Reply with quote
Flaws are flaws, not features. You don't design around them except for defining allowable tolerances, you discover them during inspection then grind them out and do it again.

I'm not arguing semantics - most of what The Tot wrote is simply inaccurate. I won't to try to argue the technicalities being a welding novice but post it up on a decent welding forum like ukwelder and see what the response is.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts
warped one This post is not being displayed because the poster is banned. Unhide this post / all posts.

neatbik
World Chat Champion



Joined: 27 Jun 2007
Karma :
PostPosted: 07:19 - 24 Jan 2011    Post subject: Reply with quote
Im with Pete and marki on this one.
Thumbs Up
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts
Old Thread Alert!

The last post was made 14 years, 344 days ago. Instead of replying here, would creating a new thread be more useful?
  Display posts from previous:   
This page may contain affiliate links, which means we may earn a small commission if a visitor clicks through and makes a purchase. By clicking on an affiliate link, you accept that third-party cookies will be set.

Post new topic   Reply to topic    Bike Chat Forums Index -> General Bike Chat All times are GMT
Page 1 of 1

 
 You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 
Debug Mode: ON - Server: birks (www) - Page Generation Time: 0.14 Sec - Server Load: 0.55 - MySQL Queries: 14 - Page Size: 116.13 Kb