We have the same wave and I have never seen any temperature shoot overshoot. The temperature reading increases to 520F and stays constant at that valve from a cold start. Takes about 3 hours from room temp to reach 520F.
Amol S. Kane
Process Engineer
Catalyst Manufacturing Services
941 Route 38
Owego NY 13827
Office : 607-687-7669 X349
Fax : 607-687-9733
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard D. Krug
Sent: Thursday, September 02, 2010 8:34 AM
To: [log in to unmask]
Subject: Re: [TN] Wave Temperature Overshoot
I'd suggest talking with Electrovert for recommendations on changing PID controller settings.
You've got me thinking about additional cost savings here. We use the timer functions to turn off the solder pot heaters at night and then turn then back on in the morning. We turn on the heaters at 2:00 AM M-F, even when pot may have been off all weekend. Pot always is ready for production at 7:00 AM.
I'm going to record pot temperature for a week to see what actual temperatures are. I may have a temperature overshoot but have never seen it based on our warm up timer settings. A record of actual overshoot could provide insight into PID controller setting changes.
Dick Krug, CSMTPE
SMT Process Engineer
Sparton Corporation
30167 Power Line Road
Brooksville, FL 34602-8299
p (352) 540-4012 (Internal Ext. 2012)
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Thursday, September 02, 2010 7:41 AM
To: [log in to unmask]
Subject: [TN] Wave Temperature Overshoot
The following problem is on an Electovert Vectra with SN100C alloy.
Due to a decision to allow the bath to cool over night, to save energy,
we are experiencing over temperature shoot for several hours after
reaching temperature. Once the overshoot has gone the bath then seems to
control OK.
The PID controller for the bath has the same terms in it as it had for
SnPb.
If I make an assumption that SN100C is 100% Sn in terms of its Specific
Heat then I have 0.244 J/gm/K vs. 0.180 J/gm/K for 60/40 Sn/Pb. (1.36:1)
This is a big difference in specific heat.
Intuitively I feel that the SN100C should be less likely to overshoot.
Does anyone have experience of having to have the PID terms adjusted in
their wave having changed the alloy in order to maintain temperature?
Has anyone done the arithmetic to show that allowing the alloy to go
through a phase change in cooling down is more economic than just
keeping it above the phase change point? Again my intuition says it is
better to let it cool but I've been asked justify my assumption! :-)
Regards
Rex
Rex Waygood
Technical Manager
Hansatech EMS provides value manufacturing through engineering and
quality
Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole
Dorset
BH17 0RY
+44 (0)1202 338200
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