music wire springs

[coparpanzer]

I just wound a .146 dia. music wire to make a spring 1.60 ID x 7 inches long spring to operate inside a hydraulic cylinder but it isn't very strong. Any suggestions as to making is stronger. I have a small 1/8 inch spring that seems stronger. Does it need any heat treatment?

 

[israelkk]

What are the force and cycle requirements from the spring?
How many coils in the spring? These are just a fraction of the missing information that is needed for a successful design of springs.

Try to calulate the spring properties before blindly wind an arbitrary wire. Any college mechanical design book such as from Shigley, Norton, Faires, etc., gives the basic formulations for mechanical spring design. This can be a starting point but much more knowledge and experience is needed.

Your post clearly points to the fact that you do not have the minimum basic knowledge for mechanical spring design. If you do not know why a shorter spring (less coils) is stronger than longer spring then you should study the matter first or seek professional. If you do not know if a Music wire can be heat treated or not the situation is even worst.

I am sorry for being blunt but it is the time that before posting a question a minimum effort must be done by reading, googling, etc., otherwise, even the language and wording of the posing and question is wrong.

 

[coparpanzer]

Thanks for responding and for the references, but just to give you a little backgroung info. I am an electrician by trade with trade school education.I have no engeneering education at all. I am making a hydraulic press for my shop using a one way cylinder. The spring is for the return action of the piston. I have an old south bend lathe and mill which I use to fabricate things when needed. I did read through my machinery handbook and went through the chapter on spring design and yes there are many formulas to the subject. I was hoping to get away with a simple project with out to much research buy to no avail. The book said to bake the spring @500 degrees for 30 min to relieve stress , which led me to think would this make it stronger. the spring has 3/4 inch between coils and the cycle duty is next to 10 times per year the piston dia is 1.5"

 

[israelkk]

If you had given this background information in advance it was better. However, before designing a spring you need to decide what is the force and deflection that is needed to return the cylinder and this is yet missing in your post. I suggest you visit spring manfufacturing workshops they usually have left over springs from manufacturing jobs and you probably can find a spring that may fit your need. You can also visit auto repair shops and see what kind of springs are used in cars and may be one of the springs can fit so you can buy the spring as a replacement part from the shop.

 

[IRstuff]

If anything "relieving stress" will make the spring MORE springy, not less.

You need to start by detailing the requirements for your "hydraulic" press, i.e., how many pounds of force, etc. My first impression would be that you need a substantially beefier spring, like a garage door spring, or a return coil for a light car.

iano wire is intended to vibrate, hence, their material selection and design results in a relatively low spring constant, which cannot be readily altered after the fact.

TTFN

FAQ731-376

 

[Bribyk]

One method is to design your spring so that it can be fully compressed without breaking (all coils bottoming out on each other) then do this before using it. It will be more fatigue resistant, kind of like torquing a bolt. See ASM handbook preview:

http://books.google.ca/books?id=uv0...paTaDw&sa=X&oi=book_result&resnum=6&ct=result

 

[israelkk]

Bribyk

This has nothing like torquing a bolt. When you torque a bolt you stress it within the elastic limit of the bolt. The gain is a more rigid assembly.

What you refer to is a preset process (set remove or scaragging, etc. as it sometimes called). This process intentionally yields the spring wire deeply into the plastic zone. After the load removal the spring will become shorter but will have residual internal compressive stresses that are beneficial for higher loads. However, you need to specially design the springs as such. It will not help if the spring was not intentially designed for it.

This is a very advanced subject in the field of spring design and it is beyond the scope of this forum.

In fact, I am currently involve in a torsion spring design where a preset process is essential to achieve the desired torque from the spring in a very confined space.

 

[Bribyk]

It is similar to torquing a bolt (and I said "kind of"), some bolts are torqued to yield to accomplish the same thing. Assembly rigidity is generally secondary to reducing fatigue loads on a bolt, except maybe for sealing applications.

 

[Bribyk]

Also, it's a quick and dirty possible solution to a backyard project. I did assume that this was a compression spring so it may not apply at all.

 

[israelkk]

Bribyk

Torquing a bolt will increase fatigue life only if the mated surfaces are much more rigid (usually ~10X) than the bolt rigidity. The process doesn't make the bolt stronger, the superior rigidity of the assembly is what improves the life fatigue by reducing the additional stresses on the bolt due to cyclic load/pressure that tends to separate the mated surfaces.

On the other hand the preset process actually makes the spring stronger and allow the spring to resist higher stresses.

The spring in this post is indeed a compression spring and it can be presetted by loading it at the production process beyond (far beyond) the yield point. Torsion springs can be presetted too if they are later on working only to one direction (the same loading direction).

 

[coparpanzer]

Thanks guys for all your help. My ID for the cylinder is 2" and OD for the piston is 1.5" I found some music wire on ebay the largest size being .146" for $5 dollars bought it. I wound it on my lathe with 3/4" between coils for maximum piston travel 6". The return pressure (judging on how much I have to push on it to get it to return) is at least 40 pounds. I have some vibration damper springs that are 1/4" thick wire and they are very strong, too strong for what I want. Also they are a little to big OD and ID is a little to small too. Hence my try with ebay. I did contact a spring manufacture and they wanted $20 each with a min. of 200. So that was out the window. So here I am again looking to make my own cheapspring (reletivly speaking) .146 music wire takes about 20lbs to compress as wound. Any sugestions?

 

[IRstuff]

I'm sorry, but in all those word, I still didn't see what your design requirement is. What return force do you actually need? What deflection ranges are acceptable?

The fact that you could wind your spring at all ought to tell you that the material is probably unsuitable for the job you require.

Have you looked at McMaster&Carr:

http://www.mcmaster.com/#mechanical-springs/=th9s4

and see if there's something appropriate, already off-the-shelf.

TTFN

FAQ731-376

 

[coparpanzer]

I need a spring that has an ID of 1.625 and an OD of 1.9375 that can push a piston 6" and a compressed state of 1.5" so my travel of the piston will be 4.5" what would be the thikness of the wire diameter need to be and the distance between coils and would I be able to wind it myself on a lathe?

 

[IRstuff]

What FORCE, spring constant, etc?
Which is correct, "push a piston 6" or "travel of 4.5?"

Either way, the answer is probably "unobtainium." Any spring that can compress to 1/4 or 1/5 of its uncompressed extension is not going to be a terribly strong spring.

TTFN

FAQ731-376

 

[coparpanzer]

with the piston completly inside the cylinder the spring will extend to 6". With the piston completly pushed out the spring will be compressed all the way, which depending on the wire size, would determine its length. A .146 dia wire compresses to about 1.5". The force to return the piston back inside the cylinder requires around 50 pounds of force to overcome the seal pressure and move it back in the cylinder(putting your arm on the piston and pushing it in manually is hard but with about 50 or so pounds of muscle force it goes back in. I hope this is enough crude information to be translated into scientific information to make the spring.

 

[israelkk]

So, the spring has to be able to push 50 lb all the way up to the length of 6". The meaning is that at the 6" extended position the spring has to be already in an initial loaded force of 50 lb. The result is that when it is compressed to 1.5" it will give a much larger force.

A quick check suggest that such a spring at OD=1.9375 is quite impractical even with more expensive spring wire and even with a preset process.

 

[IRstuff]

I think the combination of distension and force is not realizable. Most springs are only effective over about a 10% distension range, not 80%.

TTFN

FAQ731-376

 

[israelkk]

IRstuff

I have to disagree. If the force requirements for this spring was let say 40 lb instead of the 50 lb it was possible to design a spring at those dimensions using other spring materials such as 17-7PH CH900 in combination with a deep preset. However, such spring can not be found on the shelf and it will cost much more than the $20 per spring.