If you could educate some mechanical designers about electrical controls….

[agarb]

…what are some key areas that you would discuss?

I have a distant friend who owns a mechanical design shop with roughly 10 designers working for him. Yesterday, I received the following email…

We have had some discussion here about providing training to our mechanical designers in regards to machine controls. Most of the controls/electrical engineering we do not get involved in but realize the more we know the better mechanical designers we will be. We also are frequently involved in these types of discussions during design reviews and some of our designers get a little glazed over. We have seen this need from a management perspective and have also had requests from our designers.

You came to mind as someone knowledgeable of controls/electrical and also aware of the mechanical interface (whole machine dynamics). Therefore, I thought I would see if you would have any interest in helping us out on this training?

My initial idea would be to do a 2 hour learning lunch with this presentation and would like to cover a wide range of terminologies/technologies (wide but not real deep). Enough to broaden the vocabulary and be able to relate it to machine function. There are some specific areas I know of (communication protocols, FRL's, valves, PLC's, programming logic uses/limitations, etc.) but would also be interested in things you have come across in the past where you thought mechanical designers should be more aware.

Obviously, the hardest part of something like this is coming up with relevant content to supplement the suggestions he made. So I’m starting a list based on the personal experiences that I can remember. For some reason, my memory is very lacking in this area.

1. Sensor technology and selection. (NPN vs PNP vs reed switches, shielded vs unshielded proxes)
2. Safety – light curtain mounting distances, safety interlock switch selection (no proxes!)
3. Control Reliability

Feel free to share your experiences and suggestions!

 

[Peter Nachtwey]

I have given similar presentations/classes but not so much about electronics but how to design mechanical systems that are controllable.

My opinion of most mechanical engineers is pretty low. It seems they evolve or kludge systems together. Very few actually design systems. It takes a long time to teach them what they should know as mechanical engineers let a lone about sensors.

It is also important to impress upon them that not everything can be fixed in software.

As you know we sell hydraulic motion controllers. We get way too many calls from customers that we shouldn't get because the mechanical design is flawed and the poor control guy is stuck fixing it often at the last minute.

 

[James Mcquade]

We had this very problem when I worked for an oem.
the mechanical designer would do his thing and order the pneumatics and assumed the machine worked this way.

I would do my thing and program the machine that way.

it was a mess.

we finally did the following with great success!!
1. when we got a job, each of us would look at the machine specs.
2. we would then have a meeting and discuss the specs and our thoughts on how the machine worked and work out the details where we differed.
3. we then would do our initial design concept work.
4. we would then meet again to discuss the machine operation again and discuss sensors, clamps, pneumatic valve types. we also discussed why things had to operate the way they did.

it was tough for the first several projects, but the mechanical designer caught on fast.

now its easy, follow steps 1-4 mentioned above for all projects.

it may seem like you are adding a lot of labor, but we cut or labor costs in half.

regards,
james

 

[Tom Jenkins]

1) If the mechanical design is flawed you can't fix it with programming.

2) If they can describe exactly how the machine is supposed to function and the limits of operation you can develop a control strategy to make it happen. If they can't, you can't.

3) Ohm's Law and the variations.

4) The function and operating principle of converting physical phenomenon into electrical signals for the most common sensors used in your industry - pressure, proximity switches, flow measurement, etc.

5) The function and operating principle of converting electrical signals into physical phenomenon for the most common control elements used in your industry - VFDs, valve operators, etc.

6) The basic operating principle of electric motors and the meaning of each item of the nameplate data.

7) The fundamentals of motor control.

8) How to read electrical schematics (ladder diagrams and one line diagrams in particular.)

I teach classes like this for UW Madison for wastewater operators - not much different than your problems.