I am in the UK I don't have a problem with getting them made anywhere though. The US appears to be much more familular with Ti. I have a problem with the design, Ti is lighter and therefore will contribute less to the Valve train total Mass, and would therefore not have to be as strong? Also Ti has properties that require less material to be used (higher modulus of elasticity)? to give the same tension, hence further reduction in mass, and a further reduction in strength to keep control of the valve at 16k + rpm (Crank Shaft). Who would be able to help with the design? I have acceleration figures etc for the cam, and mass etc for the valve assy' but this is a science all to its self? Surge? any help would be very much appreciated.
First, all of the above suppliers have the design and engineering capability to provide you with a fully functional valve spring. Be careful with your description of terms, specifically strong/strength. The titanium wire needs to have as much strength (yield strength/tensile strength) as possible, so as to allow the greatest design flexibility. The spring rate (measured in N/mm or lbs/in) may be different depending on the cam acceleration profile, surge effects, etc. FYI, Ti has a lower elastic modulus than steel, which is important because of the following equation:
resilience = &[ignore]sigma[/ignore];2max / 2E
Maximizing the material strength and minimizing the elastic modulus creates a spring with the maximum resilience (elastic energy absorption).
I think that the most important is to avoid resonance therefore you should design a variable rate (progresive rate) spring with variable pitch.
Can you give more info what are the demands from the spring such as:
1. Length at first loading point and the respective force
2. Length at the second loading point and the force.
3. Desired spring outside diemeter.
4. Working temperature
5. The type of titanium wire alloy (spec)
6. Frequency of loading etc.
Have I missed anything about a Titanium valve spring for an engine. The Titanium that I know doesn't like be rubbed on anything and especially itself. That is on of the biggest problems we had with titanium internals for stainless steel distillation columns. We also had trouble with Pall rings where they rubbed togather and caused a fretting like condition that lead to fatigue failure the same condition as the trays. Titanium doesn’t wear very good either.
Has some made Titanium springs that operate in the conditions seen on the top end of a motorcycle engine.
If you are not familiar with current titanium valve spring applications (e.g. racing vehicles), then yes, you may have missed something. You are right that titanium will gall (which is why titanium valves have coatings to minimize galling), but that hasn't been a big problem with springs.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
CoryPad,
Thanks for bringing me up to speed. The last time I checked they were still struggling with the Titanium spring problem. Still learning things even in my old age even if I can’t keep up with the information age.
Good luck to "morepower" in his quest for speed.
I onced owned a KHRM bike. I probably couln't crank it today.
I have formula's here for checking surge in springs but I would need all the info you have like space envelope that the spring can fit into and the forces and deflections the spring is liable too encounter.
-In regards to titanium rubbing. Does the issue need to be addressed when the end coil touch the active coil on compression?
-If the rubbing is an issue what coating can be used to reduce damage that would cause fatigue? Since I'm designing these springs for suspension use, I could add some rubber insert/bumper on the coil ends.
-What are the material designations/specification for titanium springs wire?
-I'm currently working on compression springs for shock absorbers and found this forum. Thanks in advance any suggestions you guys provide.
The full weight of a valve spring is not counted in the valve train mass because one end is stationary. The amount of weight saved might be very small when you compare it to the weight of the valves and retainers. Granted, it could be worth it if you are going after the last fraction of a percent for racing.
