Springs 1

[craghav]

Hey guys, how do we define springs? in gauges? or just based on diameter? are there any guidelines in adopting springs in design? any standards available for springs in United states or In India??

 

[MintJulep]

By physical and performance requirements. No. No. Yes. No and probably not.

 

[TheTick]

No simple answer to that. There is a LOT to know about springs.

Century has a good catalog of springs. So does Lee.

some links:
[URL unfurl="true"]http://www.centuryspring.com/[/url]
[URL unfurl="true"]http://www.leespring.com/[/url]
[URL unfurl="true"]http://smihq.org/[/url]

 

[KENAT]

Lee springs also used to include some application data in their catalog as well as some idea how to specify a custom spring.

In terms of specifying wire size, generally convention these days is give the actual dimension but practically you want to have this dimension match a standard gauge.

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[craghav]

I think most of the springs used in Automotive applications (not suspensions) are mass produced, right?

 

[btrueblood]

Most of ANYTHING used in automotive applications is mass-produced.

 

[KENAT]

If rather than 'mass produced' you mean 'off the shelf' then I don't actually know for automotive.

However, from experience I do have then because of the volumes involved there may not be a big price difference between custom springs and straight out of the catalog.

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[drawoh]

craghav,

Springs are things that are intended to be flexible, and able to exert force on stuff. Not all springs are coil springs.

Is this an engineering question or one of those philosophy[ ]101 questions, like "which way is up?"?

--
JHG

 

[dgallup]

With drawings. On the drawing you will have things like wire size, material specifications, heat treatments, length, ID or OD, loads at specific lengths, end conditions, special treatments such as shot peening, etc., etc. They not very standardized although there are many off the shelf springs available.

Check out the Spring Manufacturing Institute.

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[JohnRBaker]

On the drawing you will have things like wire size, material specifications, heat treatments, length, ID or OD, loads at specific lengths, end conditions, special treatments such as shot peening, etc., etc.

The only time that sort of information would be needed on a Drawing would be a) you're going to manufacture the spring yourself, or b) the Drawing was part of a request for a quote to purchase a custom-made spring. If you're simply calling out a standard spring as part of a product Drawing (i.e. Assembly), then just the vender catalog number with perhaps some basic 'size' info should be adequate.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[dgallup]

He wants to know how to define a spring, that is how you define a spring. I define lots of springs, none of them come from catalogs and we don't make any of them.

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[NickE]

There's also Associated spring:

http://www.asbg.com/

nick


Nick

 

[KENAT]

Thinking about it, there is (was?) a British Standard for specifying/designing springs - at least torsion springs - but it's been about 14 years since I looked at it.

Posting guidelines faq731-376

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[ivymike]

I define lots of springs, none of them come from catalogs and we don't make any of them.

exactly my thoughts - there is a lot of system work which goes into the spring design, and its usually best for an engine (and probably car) OEM to fully define the required functional characteristics of the spring and let the supplier figure out the details of manufacturing it. You wouldn't normally be able to go select an appropriate valve spring for a new engine design from a catalog, and I assume the same goes for a suspension spring.

If you're shopping from a catalog, then yes a part number is probably adequate in the short term - but you don't have any control of whether that part number refers to different geometry/characteristics over the long term.

 

[chicopee]

Any Mechanical Engineering handbook will have a design section on all sorts of springs.

 

[kjoiner]

Hello,

When I am picking a spring from a catalog, I have the performance constraints in mind and narrow the selection down from there. The physical parameters of a spring are going to narrow down your choices. Once I have one selected, I usually list the specs available such as OD, free Length, wire gauge, pre-tension (for extension springs), K (rate) and type of material (usually music wire or SSTL). I have to create a spec control drawing and this information is useful in case I have to find another source. Compression springs can also have other specs such as ground ends. For an extension spring, I may also have to define the style of end loops and their orientation relative to each other.

If I am working on a new design and nothing comes up in the catalog, I work with a spring manufacturer. I can narrow down the physical specs as I did above, but a spring company will have more expertise and experiance than I do and they usually have software to check fatigue life etc. Once we have arrived at a design, I will takes those specs and list them out like I do for a catalog part and create a spec control drawing.

Kyle

 

[MikeHalloran]

A long time ago, I wrote a BASIC program for designing springs, and used it quite a lot. It was not nice and polished, but it produced credible results quickly, and allowed me to manually iterate and optimize my spring designs.

Eventually I discovered that when I designed a spring conservatively, and used readily available materials, I always ended up with something very close to what was already available as a stock spring.

So I suggest that, if someone hasn't already painted you into a corner, i.e. with unusual environmental requirements or too little space available, it's best to design from a stock spring catalog. It's nice to know how to roll your own, but the spring manufacturers do a damn good job of covering the problem space with good-enough solutions.





Mike Halloran
Pembroke Pines, FL, USA

 

[kjoiner]

I agree with Mike. Take a look at supplier like Lee Spring. They have thousands of springs available. They also have a parametric search tool to help narrow down your choices.

Kyle