Fast PLC or PAC brands?

Hi,

I will need a controller soon for a molding machine and I would like to know who makes fast PLC or PAC not too expensive. As expensive I mean like RX3i is which I think would be near 6k-8k for my needs.

Here's the application specs :

- 8 PID heat loops (so I need thermocouple inputs) which 3 would be fast loop time
- 3 analog inputs for pressure and position

By now, I think to give the Productivity 3000 from A-D a try. Spec are 600μs for 3K Boolean, 1K I/O.

Also, this machine will not to be extremely precise as thin wall molding machine must.

So which brand offer fast and affordable PLC or PAC?

Thanks!

Hello Philippe,

B&R supports high speed task classes; up to 200 microseconds (depending on the CPU-type).

http://www.br-automation.com/downlo.../BRP44400000000000000121689/X20CPx48x-ENG.pdf

There controllers are very powerfull.
It's not an 'easy' brand to work with though, it takes some effort to acclimatize to the system and the programming-environment.

What are your requirements for the update scan of the i/o ?
Any dedicated motion ?
Drives ?

NB. I cringe whenever I see "PAC".

Pick any two.
**GOOD**
**CHEAP**
**FAST**

If you are familiar with Step7, the cpu's from Vipa might be interesting. The 314ST/DPM has SPEEDBUS and also 8+8 interrupt capable inputs integrated.

http://www.vipa.de/uploads/tx_sbdownloader/SPEED7_EN_11_2009.pdf

Kalle

No real dedicated motion as the injection AND the clamping motion is control by a prop. pressure relief valve.

Injection can be control for speed (velocity in/sec) or pressure. Pressure transducer and linear transducer are monitoring the injector cylinder pression and the position.

So when opening/closing the clamping, pressure is control to avoid mold banging. Micro-switch are placed to detect if the mold is near fully close or near fully open to reduce the hyd. pressure.

For the injection, when running in pressure mode, pressure tranducer read the pressure and controller apply a 0-10v signal to the prop valve to reach the command pressure. In speed mode, the position is monitored, the controller apply the same 0-10v signal to reach the command speed.

So the scan time must be the fastest possible to react quickly to the command without going crazy due to the scan time.

I've already make the same system on another machine using a DL-205 A-D PLC. The result was not as good as I expected, even with staging my program to reduce to the maximum the scan time. Scan time was 5ms and the resolution was not very good for the injection motion.

To answer RussB, I would say cheap and fast.

For an injection mold machine...pick your favorite color. Unless you get soemthing really low end or your mold machine has servo valves then just about any PLC will be fast enough.

Just for the record.... We ran thin walled injection mold machines on TI5's. Those beasts didn't even have clocks in them.
All the big brands support PID and have thermocouple cards.

BTW why fast loops???? Is your heater a blow torch????

Position on an analog? Sounds scary... You sure you wouldn't want to go with something with a bit higher resolution???

I mean when your talking about several tons of steel knowing EXACTLY where you are at would be a good thing in my opinion?

In most molding apilcations position I have worked on use temposonic rods with a serial or encoder style feedback.

Speacking of position... What kind of valves are you using? Precise speed control of all that steel and plastic is almost as important as knowing where it is at...


Know my post sounds a bit sarcastic... just wanted to get my point across that you may want to look a little deeper... Scan time is going to be the least of your worries...

BTW why fast loops???? Is your heater a blow torch????

Click to expand...

For my injection motion. When I want the injector to reach 1.25/inch/second, I want it to reach it fast without bumping.

Speacking of position... What kind of valves are you using?

Click to expand...

KBCG-3 Vickers pressure relief valve.

On the last machine project, the 15ms scan time of the PLC was giving near 5/8inch of margin of error in the clamping motion, which was WAYY too much. For the injection, with the DL-250 PLC, I cannot reach the reaction speed of one of our other machine with a Barber-coleman Maco 8000 controller. I've tried every setting in the PID without success. I must specify the DL-205 have a minimum loop PID update rate of 0.05s.

We ran thin walled injection mold machines on TI5's

Click to expand...

What's that? Which brand?

I think you are using the wrong tool for the job. Your PLC scan times are just fine. You need a controller specific for the injection and clamp and just use the PLC to tell it when to go and watch for when it is done.

One such set of components are here:
http://www.boschrexroth-us.com/coun...tries_sm/plastics/injection_molding/index.jsp

Specifically for injection, I would look here:
http://www.boschrexroth-us.com/coun...m/plastics/a_downloads/RA_08421_05-06_DPQ.pdf

Other companies make similar products.

<disclaimer - I work for a Bosch Rexroth distributor>

My first choice would be DL260 from Automation Direct. Second is Productivity 3000. Are you going to provide customer with source code and edit capabilities? If so, I might lean towards productivity 3000 because software is free.

Keithkyll, the machine is for us and not to resale. We make our own machine, molds, machining process...

On the last machine project, the 15ms scan time of the PLC was giving near 5/8inch of margin of error in the clamping motion, which was WAYY too much. For the injection, with the DL-250 PLC, I cannot reach the reaction speed of one of our other machine with a Barber-coleman Maco 8000 controller. I've tried every setting in the PID without success.

Click to expand...

How exactly are you using the PID. I mean this to me is an excercise in setting up accell and decel profiles.

The Mold machine that used the TI5 was a huskey.

Clay,
No pid was used in this motion, I simply command the prop. flow. dir. valve to 10% when reaching the cushion position to slowed the clamping. With a scan time of 15ms, the cylinder was not slowing at the same position shot to shot. After some calculation, I founnd that the scan time was the big part of the problem.

For the TI5 I mean, what is the brand of that PLC? I only know few PLC brand.

TI= Texas Instruments....

They stopped making PLCs a long time ago...