Spring setting
Spring setting
(OP)
Hello, Engineers.
Presetting is a process by the spring manufacturer in order to increasing the ability of the wire to withstand higher stresses.
The spring will be compressed to max deflection in the final device. So, is it allowable for the manufacturer omit this process? (Will lead the set on service to a worse ability?)
This question is related to costs reduction asked by an important client.
Thank you.
Presetting is a process by the spring manufacturer in order to increasing the ability of the wire to withstand higher stresses.
The spring will be compressed to max deflection in the final device. So, is it allowable for the manufacturer omit this process? (Will lead the set on service to a worse ability?)
This question is related to costs reduction asked by an important client.
Thank you.





RE: Spring setting
Looking at it another way, a perceived need to maximize the spring stress is a symptom that the assembly designer has painted himself into a corner by not allowing sufficient volume for a more robust spring.
... and usually, all the other parts are expensive, long lead, and there are several years' worth in inventory in anticipation of huge sales volume, etc.
Mike Halloran
Pembroke Pines, FL, USA
RE: Spring setting
RE: Spring setting
Pre-setting of a helical compression spring normally occurs when the spring you have designed has all the right characteristics but cannot be compressed to level required, without the spring taking a permanent set. So a spring manufacturer will make the spring longer than the required free length so that when the spring is compressed in service it returns to the required design compressed height.
Either the end user can compress the spring in service or the spring maker can perform the final setting and usually the spring doesn't take further permanent sets after this operation and so no detriment to the spring.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Spring setting
We are the spring maker. I need to answer to my boss if we must to suggest to the client to reduce the spring mass (no feasible by stress), to omit the presetting or to lookfor other cost reduction in manufacture line. We can't to buy a new fastest coiler machine now.
MikeHalloran: It's true. The assembly designers restrict the spring space, so it's difficult to propose a robust design. So, the most spring designs are at the limit.
tbuelna: You are OK, the spring cost is very small Vs. assembly cost. But the client ask us to decrease the spring cost.
desertfox: Thank you for your answer. You confirmed me that the end user can compress the spring in service. I'll suggest to my boss to ask the entire assembled device to the client so we can to do make some tests with presetting by end user.
Best regards,
Jh0an1
Venezuela
RE: Spring setting
you're welcome
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Spring setting
If you could post your spring requirements or even drawing I can check if you can produce more load or same load in smaller space. Please include all requirements, including type of use, static, cyclic, life, environment, etc.
https://sites.google.com/site/israelkk/
RE: Spring setting
The spring requirements are:
Material: ASTM A 227 class II
Wire diameter: 2,50 mm
Inner diameter: 9,20 mm
Bore diameter: 8,40 mm
Free length: 32,50 mm
Max. deflection: 6 mm
Total coils: 6
Rate: 60,4 N/mm
Ground
Use: in oil filters of cars
Static
Thanks by your help.
Best regards,
Jh0an1
Venezuela
RE: Spring setting
RE: Spring setting
What will happen if by mistake it will be pressed to 20 mm? It may yield. How you can avoid it?
RE: Spring setting
RE: Spring setting
The only possible use of a spring within a filter is as part of a differential pressure relief valve, which I would expect to open on every cold start.
Given the filter's finite life, that's not a lot of cycles in the fatigue world, but it's not none, either.
Mike Halloran
Pembroke Pines, FL, USA
RE: Spring setting
Even as static spring it it is not valid or sound design. This is why I try to ask questions to get the proper requirements before final check. I am sure Jh0an1 will do the most effort to answer my questions. I mentioned static because he defined only one deflection case of 6 mm and not two points of work. If there are two point of load the whole picture changes and life cycle comes to the game.
RE: Spring setting
The ends are closed and ground. Please, see attached sketch.
I see your suggestion about unused deflection, and why it could be a trouble. I think this design could to work:
Material: ASTM A 227 class II
Wire diameter: 2.50 mm
Inner diameter: 9.20 mm
Bore diameter: 8.40 mm
Free length: 14.00 mm
Max. deflection: 3 mm
Total coils: 4
Force @ height of 11 mm: 362 N ± 10 % (around 53 % of tensile strength)
Closed & ground ends
What do you think? I tried to avoid presetting but we need 2.75-3.00 mm wire and more mass: it's no a good choice.
About relaxation: The client have asked us to review this issue. They want to evaluate it for eight years. I don't know how to check this parameter for a long period. I am searching information about this issue.
About if static or dynamic service: the client have explained me the operation: similar as Mike explained it. It's not strictely static. But, for springs analysis, is it approximated as static?
Best regards, and thanks,
Jh0an1