Material for high speed Soleniod???
Material for high speed Soleniod???
(OP)
We have been developing a high speed solenoid valve. We have tested 430F and Carpenters 430FR. The FR performs better than 430F. ( ie greater force ). The problem is it doesn't come close to the material or competition is using. We have had our competitors material tested and it comes back as 440C ( Which we tested ) or 17-7 which we are unable to locate at this point. Can anybody suggest a material that is corosion resistant, produces high levels of force and can be machined using a screw machine?





RE: Material for high speed Soleniod???
I don't know, is Crucible or Carpenter making 440 bar?
There are a number of source for 17-7 in both bar and tube.
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RE: Material for high speed Soleniod???
RE: Material for high speed Soleniod???
The 17-7 and the 440C are mantensitic steels and will have larger residual magnetic flux which should be as little as possible when you are designing a valve.
From the post I could not understand if the problem is with the solenoid force or the speed.
RE: Material for high speed Soleniod???
RE: Material for high speed Soleniod???
Carpenter makes a couple of "tweener" soft magnetic stainless materials that have decent resistivity, decent corrosion resistance, and have higher saturation flux densities than 430 FR. They are called Chrome Core 8 (CC8) and Chrome Core 12 (CC12.) They are 8% chromium and 12% chromium respectively, compared to about 17% for 430FR. The 8% has a higher saturation flux density than the 12% (more iron, less chrome) but the tradeoff is less corrosion resistance. Both are available in free machining bar grades (CC8-FM, for example.)
Once you get past those, the absolute best material would be a Silicon Core Iron. Silicon Core Iron B-FM (Carpenter) is available in bar form, but has zero natural corrosion resistance. It would be the best option if you are willing to plate it after all machining and annealing.
Remember, you have to anneal all of these ferritic materials to achieve optimum magnetic properties. Otherwise, you will have tremendous piece to piece variations due to variations in bar annealing from the manufacturer, and from machining on your end.
-Tony Staples
www.tscombustion.com
RE: Material for high speed Soleniod???
A couple of details I missed:
1) 430FR should not make any appreciably more or less force than 430F. the 'R' is for resistivity. If your two samples, or groups of samples produced different results, it would be for other reasons. (most likely annealing)
2) 440C and/or 17-7 will never outperform 430 for force, if all are properly annealed. They are martensitic, and have approximately the same chrome level. 440C would be useful if your application needed high remnance. However, high speed solenoids generally don't. You need a material with lower chrome, and higher iron content, to make more force with the same cross sectional area, air gap, etc . . ..
-Tony Staples
www.tscombustion.com
RE: Material for high speed Soleniod???
RE: Material for high speed Soleniod???
RE: Material for high speed Soleniod???
All magnetic alloys come from the mill in an ambiguous state of anneal, in terms of magnetic properties. It's optimized for machining rather than for magnetic properties. When you machine it, you induce further cold working of the material. Hence, it needs to have an annealing operation performed, for optimal magnetic properties, after ALL machining/grinding/etc . . ., are completed.
As for annealing, any reasonable heat treatment shop should be able to do vacuum annealing. Carpenter recommends vacuum, or dry hydrogen atmosphere, annealing at 1550/1830°F for two hours, then cool at 100°F/hr, down to 800°F. Below 800°F, it doesn't matter what cooling rate is used.
As for iron content, it's not always so cut and dry. However, for soft magnetic alloys, more iron percentage generally equals higher saturation flux density. As for specifics, magnetic material properties is a subject that a book could be written on (and I'm sure several exist), and is beyond the scope of Eng-Tips. My earlier posts detail recommendations for materials that are commonly used in high speed solenoid products.
-Tony Staples
www.tscombustion.com
RE: Material for high speed Soleniod???
From your last post "What is the relationship between force generated and iron content? Is it directly proportional" I understand that you have no experience and knowledge in high speed valves design. Who is designing the valve? Does he has any experience or you are just trying to re-engineer / copy a competitor valve.
I assume you operate the valve (On-off) at a variable Duty cycles and high frequency to control the pressure in a volume/piston.
There is no simple answer to your question because the magnetic behavior is non-inear and the magnetic flux has a saturation point.
Ususlly a computer program that solves the electric coil current rise time coupled with the magnetic flux generation rise time, flax value, resulting magnetic force and the plunger movement under the generated magnetic force, acceleration, springs, fluid pressure. etc.
FEA program can help design the static condition but to analyse the valve dynamics a computer program is needed.
You have to be aware that the on and off opening time variations for the valve and the delay from command to full opening of the valve can greatly affect the performance. This is crucial for such a high speed valve.
One more issue is that the mechanical opening and closing time of the valve depends on the fluid pressure in the valve. Therefore in high duty cycle command the valve will be slower.
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RE: Material for high speed Soleniod???
http://www.uginestainless.com/
Carpenter's latest baby is Chrome Core 13FM. It has high silicon content like 430FR so it has good resistivity which definitely helps in high speed valves. It has less chrome than 430(F)(R) so you get higher saturation flux density. They seem to be pushing this grade because they actually keep some in stock unlike most grades where they tell you to take a number and wait 4 months.
If you really want a lot of force you can't beat 50% cobalt/iron alloys. These will hit 2.4 Tesla but they are hard to machine and expensive.
RE: Material for high speed Soleniod???
The saturation is OK, and the resistivity is high.
It wouldn't be my choice, but it is done.
The 12 and 13% Cr alloys are only sort of corrosion resistant. The work well, but be careful.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Material for high speed Soleniod???
On a more serious note. We have a working prototype that has some 500M operations on it. We are just looking to improve on some of its characteristics. The majority of our expertise is in circuit design and programming. So we looked to this forum for some advice.
Would a simulation program allow for an armature mass as low
as 0.30 grams? Do these simulations allow for liquids various viscosities? Who would we talk to about such a program?
The valve we are working on is used in industrial inkjet and many non-valve related issues determine the success of the design. The valve operates with its sealing surface open to the air. It must perform well with liquids as diverse as water and MEK. It must run liquids containing both salt based dies and titanium pigment.
You can get some idea of what we are using it for at www.ijp.ca
On the material side, I will try some of the suppliers and materials that have been suggested.
Thanks
A
RE: Material for high speed Soleniod???
RE: Material for high speed Soleniod???
1) Transient time domain magnetic solution – This considers nonlinear saturation and back-emf effects. In addition, motion induced eddy currents in moving the plunger and diffusion time of fields are considered. Fast acting solenoids (< 1 msec closing) are probably affected by both. These effects tend to slow the operation of the solenoid.
2) Static magnetic solution – This considers only nonlinear saturation and back-emf effects. A series of static magnetic solutions can be exported to a look-up table (flux linkage and force vs. current and position). This table creates a way to couple the electrical and mechanical systems using a magnetic model. The model is imported into a system simulator and solved vs. time. Mechanical elements are added such as mass, spring force, and hydraulic damping. However, induced effects such as eddy currents and diffusion of magnetic fields are neglected.
Some software companies offer both 2D axisymmetric and 3D solvers which are well suited for solenoids.