Automated machine design project

Hi all, I just register to this forum as I am eager to learn more about the automation world

I have been working on a personal project for the last couple of months and am planning to start my company early next year. I have an enormous amount of work to do until then and getting competent with control systems is one of them.

I am currently designing a machine that will manufacture the product for my company. The machine is relatively simple, and will need the following actuators:

-4 servo-motors
-6 pneumatic cylinders
-4 multi-position cylinders (so it has to be electrical cylinders ??)
-2 long reach/low load cylinder, probably telescopic cylinders

I haven't made a list of the required sensors at the moment, but there will pretty much only be proxys.

I am from a mechanical engineering background so the design of the machine itself is not a problem. I am also comfortable with Ladder programming, and also know how to use VBA, C, C++, VB.net, Matlab.

The problem that I have is the connection between hardware and software.
For me automation happens like this: Ladder code put cylinder to "on" -> *some kind of magic* -> cylinder extend .

I understand that you load your program in a PLC, but then do you connect all your actuators/sensors to the PLC ? That doesn't make sense to me

I also have no idea how to decide which control supplier to go with, from what I understand AB is the most popular out there, but if I want to minimise my initial costs, should I go with a smaller supplier ? If I buy an AB PLC, do I need AB actuators/sensors ??

I read this book http://www.booktopia.com.au/industrial-automation-frank-lamb/prod9780071816458.html but it was a bit too basic. If you have any good book to propose that would help me please do so.

Experts, thanks in advance for your help, it is much appreciated.

Have a talk to Tech Source - 08 9472 1999 - they are the Omron distributors in WA. The new Omron PLC is designed for machine control and uses Ethercat.

2 questions arise, what product do you make, are there different types?
how do you want to make them i.e. the process, the quantity. etc.
Design is a good thing, and dont make your first machinesoftware yourself, but have some type of backup or example.

shooter said:

2 questions arise, what product do you make, are there different types?
how do you want to make them i.e. the process, the quantity. etc.
Design is a good thing, and dont make your first machinesoftware yourself, but have some type of backup or example.

Click to expand...

Hi shooter, thanks for your interest.

I hope you'll understand that I don't feel confortable talking about my product for the moment. I am not inventing anything, but would be the first in Australia to automate the manufacturing process. Similar automated project as however been done in countries like Canada & Korean.

What I can say is that it involve machining and assembling. The machining part is the easiest part as it will be done by various standard CNCs. What I am trying to automate is the assembly part, which consist in press-fitting the various machined item. The item is always the same, but the different dimensions change from customer to customer, there is literally an infinite number of combinations, no 2 customers have the same dimensions. And the quantities vary between 20 and a couple of hundreds.

But like I said the mechanical part is under control, the design is pretty much done. I (roughly) know which actuators and sensors I need, the problem for me is the connection between the actuators/sensors & my PLC. If you take a pneumatic cylinder for example, do you connect it straight to the PLC ? how is the pressure fed into the cylinder ?? I feel like I miss a link between the hardware and the software.

When will come the time to put the machine into place, I will get the services of an electrical tech/eng to connect everything together, but I still want to know how it works as I want to buy everything that I need for my project.

The best thing you could do is get in touch with a good, competent industrial electrician. If you find the right one they will know how to connect everything. If they are a decent enough sort of person I'm sure they would be able to give you a crash course in what they are doing too. Electricians and electrical engineers study for years to understand what you are asking this forum to help you with.

I understand you wanting to control costs by supplying (and possibly connecting) everything yourself but in my experience this will probably end up costing you more than if you sought out competent help from the start. If you get something wrong by not understanding the difference between part XXXXXXA and XXXXXXB that could cost you a lot of money. You will probably also find that whoever you engage will have good supplier contacts (read: discounts) and be able to supply components to you for the same price as you would be able to buy them or better.

If you are from a mechanical engineering background then that's all well and good. Do the mechanical design but leave the electrical to someone that knows what they are doing. My old boss was always fond of saying life is too short to learn more than 1 trade properly.

Hi Mots,

I work in a company that also builds new machines.
But we have people doing the mechanical design, and then I do the automation, so I can try to give you a hand on your problem.

It won't be easy tought, if you don't have an electrical background, to make everything yourself, and that includes choosing and buying the hardware you need.

First I think you need to choose the PLC you're going to use.
My advice is to see which makers you have available close to you, so that they can help you to choose the appropriate hardware.

Answering your particular question about cylinders, between the PLC and the cylinder you need an electro actuaded pneumatic valve, that will receive your plc output command and move the cylinder.

I can see that you will be doing some press-fitting, will you need to control/check the force you're doing?

I totally agree with you both,

I understand that doing the electrical side of the project myself would be really difficult.

I never had the intention of connecting the system myself, but I would have though that selecting the right cylinders for example, would be more of a mech eng job ? I know that I need 6 cylinders with a stroke of 3 in that has a maximum base of 2x2 in and could lift up to 50kg (FoS included), is there anything on the electrical side that I need to know ?

I guess I could just put temporary cylinders in my design..

To answer your question about press-fitting, the required force will vary depending on the dimensions of the product, so yes I will need to control it. The difficulty (I think) with one of the press is that it will have need 3 possible position: off, on, and somewhere in between just before press-fitting.

Mots,

For choosing the PLC to use, a good summary & comparison of PLCs sold in North America can be found at http://plccompare.com.

Mots,

the question you should be asking is what plc's are in the area?
what vendor has a good inventory.
who provides good support?


then ask your customer what do they want?
learn how maintenance likes to see the programming done.

i know you are new and not trying to slam you, but here is the bottom line.

document your work in detail.
keep the manuals simple and understandable.
don't go buy a brand new product just hitting the market, buy something that is proven to work.
the plc code must be easily understood by maintenance - they are the backbone of the machine. NEVER forget that !

hope this helps,
james

Mots said:

I totally agree with you both,

I understand that doing the electrical side of the project myself would be really difficult.

I never had the intention of connecting the system myself, but I would have though that selecting the right cylinders for example, would be more of a mech eng job ? I know that I need 6 cylinders with a stroke of 3 in that has a maximum base of 2x2 in and could lift up to 50kg (FoS included), is there anything on the electrical side that I need to know ?

I guess I could just put temporary cylinders in my design..

To answer your question about press-fitting, the required force will vary depending on the dimensions of the product, so yes I will need to control it. The difficulty (I think) with one of the press is that it will have need 3 possible position: off, on, and somewhere in between just before press-fitting.

Click to expand...

To choose a pneumatic cylinder you don't have to consider anything electrical, just when you choose the valve (24Vdc or whatever)

It won't be easy to do press-fitting with simple pneumatic cylinders, specially if you want accurate middle positions.
There are already made press kits, with force and position control on the market

Velociraptor said:

Mots,

For choosing the PLC to use, a good summary & comparison of PLCs sold in North America can be found at http://plccompare.com.

Click to expand...

What's your connection to this website?

FWIW, selecting a PLC is part art, part science and simply looking at feature set doesn't tell the whole story.

air cylinders are done with electric valves.
push control can be done with pressure switch, or a sensor and a solenoid.
To get a sequence and control over it , you can use a PLC.
Standard ones use 24 Volt for everything.
Most PLC have 24 volt input and output.
with the outputs you control the cilinders etc.
the 6 cilinders are each having two solenoids to push or pull them.
The multipositions can be done with double cilinders, or with switches controlling the position. (that is depending on the accuracy needed.)
and yes electric cilinders are working the same as servo motors.
The long reach can be either air or electric.
Servo motors are expensive as is their control so if any way possible, please use simple ones.

Thank you gentlemen for all your input.

It makes more sense to be now. So if I understand correctly, I can already choose the air cylinders, and then when will come the time to do the control implementation, the electrical tech the appropriate valves.

jmsmoreira, I would prefer buying the press off the shelf, I have a hard time finding manufacturer of horizontal press that I could use on my automated line. Could you think of any ?

Mots said:

Thank you gentlemen for all your input.

It makes more sense to be now. So if I understand correctly, I can already choose the air cylinders, and then when will come the time to do the control implementation, the electrical tech the appropriate valves.

jmsmoreira, I would prefer buying the press off the shelf, I have a hard time finding manufacturer of horizontal press that I could use on my automated line. Could you think of any ?

Click to expand...

Check these ones, to which suits you better:

Schmidt
TOX
Promess

Mots,

in all fairness, hold on a second.

i understand that the mechanical design is no problem,
but here's a big mistake i see from designers. they assume the electrical people can do anything the machine designer wants.

while we can do a lot, this process is not a s simple as you design and throw it to the electrical guy to make it work.
i worked for am OEM for almost 20 years in the mechanical and electrical design.

here is my suggestion:

1. do a concept of your design and sketch it.
2. think the process through reading the specs.
3. visualize the machine operation going from step a to z.
4. where do you need sensors (part detection photos, prox
switches, and so on). how will you confirm air cylinders
art at their correct location?
5. does the part need to be held in place at all times?
6. if you loose power while the machine is in operation, what
will the pneumatics do? do you need single solonoids,
double solenoids, open or blocked center valves?


not trying to slam you in any way, just trying to inform you that the electrical guy(s) need an input on the machine design. consider this a marriage of a sort. you give and take.


it took a while for the oem i worked for to realize this after several projects that we lost a lot on. when we started working together, we made up for it.

regards,
james