Re: [femm] Re: PM design - Simulation results far from Prototype results....

[Sven Olsen <a1greatdane@xxxxxxxxx>]

Dear Tony,

I take it we are talking about a circular airgap structure for a loudspeaker voice coil. You indicate 1.2 Tesla in this gap, but the steel pieces can very well be saturated - check with the cursor in femm for point properties and see what the reading are or lay a line contour through the steel. If you read more than 2 Tesla, there's a good chance your 1018 steel is saturated.

Best regards

tonyrouget <tonyrouget@xxxxxxxxx> wrote:

> Dear All,
> Thanks for your help and share of knowledge...
>
> 1)I am pretty sure about the Neo35H since I have the spec sheet and 
> it's a reliable supplier, 
>
> however I wasn't expecting the Steel to be one of my problem..Maybe I 
> have too much saturation in my design..
>
> Is 1.2T saturated for 1018 steel ?? I thought it was a bit higher for 
> the 1018..
>
> Thanks for your help.
>
> Regards
> Tony
>
>
>
>
>
>
>
>
> --- In femm@xxxxxxxxxxxxxxx, Sven Olsen <a1greatdane@xxxx> wrote:
> > Dear Tony,
> > the results I have with using femm indicates that some thing else 
> is wrong in your real world implementation. My real world results is 
> normaly at max 5% out from the simulations. Are you sure about your 
> quality of steel? It only takes a small lead contenst to render the 
> magnetic quality of the steel virtually useless. How
> about the 
> quality of the neo? You say 35N, but are you sure? There's many 
> qualities comming out of 'ping-pong land'. Is the neo fully and 
> optimally magnetized? It takes a very serius magnetizer to fully 
> charge the circuit.
> > Best regards
> > A1greatdane
> > 
> > tonyrouget <tonyrouget@xxxx> wrote:
> > Dear All,
> > 
> > First of all, thanks David for your great software!!
> > 
> > I have a quick question:
> > 
> > Did anybody already experienced any problems to relate Femm 
> > simulation results with the real world??
> > 
> > And if Yes, what could be the cause of the simulation error.???
> > 
> > In other words, I have designed a loudspeaker motor assembly with 
> > Neodymium 35 and I was expecting 1.2 to 1.4T in the airgap.
> > Confident of my design and simulation results I built a prototype 
> and 
> > could only get 0.8T Maximum in my Airgap with the Gaussmeter..
> >
> > I am using 1018 Steel and Neo 35H. I've been inputing the tech 
> specs 
> > of my magnet and editing a new model in my library..
> > 
> > If you had already experienced simulation problems, please give me 
> > your input..
> > 
> > Regards
> > Tony
> > 
> > 
> > 
> > 
> > 
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