CNC ECourse Day 4 CAM Computer Aided Manufacturing

CNC ECourse Day 4 CAM Computer Aided Manufacturing

Video Info:

Here on the 4th day we talk about CAM. CAM stands for Computer Aided Manufacturing. During the CAM step of the CNC Process we use software to define how our CNC Machine should move. There are a number of CAM Software packages on the market. They range from the inexpensive to expensive. Much of the cost depends on the number of Axis's that the CAM Software has. With the CAM Software we define things like stock, location, tooling, feed and speeds and the post processor we will use. The post processor is very specific to our CNC Machine. It outputs g-code. We use the G-Code program in our control software next. Tomorrow's Lesson is CNC Control.

Video Tutorial:

Well you've made it, you’ve made it to day four. Today were going to go over CAM or computer aided manufacturing. My name is Ivan Irons and I run a website called CNC information.com Lets get started.

Well here are the five steps to the CNC process. You can see where CAM is located; the third step out of the five. Take a look at our flowchart again to give you an idea for where we are at the process. We are right in the middle of it.

So lets get into what cam stand for? CAM stands for computer aided manufacture and really what it is is translating our CAD design that we did into machine code or machine language. Really we need to know what CNC machine were going to use, what type of club material we are going to use, and what we are going to build. Translating that design into something that our CNC machine can understand is what we are after with CAM. Our CNC machine doesn't really know what we want from it. It doesn't know where the parts located and it doesn't know what tool that we should be using or even how fast to move. We need to define that in the cam step.

Here I have a graphic of the various things that we need to do during CAM. Now not all of these are done every single time but this is an overview. We need to define the material we need, we need to find a stock size, select coordinates and what they're doing with their feeds and speeds. We also need to simulate machining and then we need to post process.

Here’s a look and this is from RhinoCam. We can look at a couple of love those steps that I just showed. Here we are defining on the left the stock. This could be easily a cylinder as well, but you need to tell the CNC machine what it's holding what is the overall shape of the stock. Then on the right you need to locate the part inside of that stock. You need to tell it where to start. You’ll see the Z alignment at the top and the X-Y in the northwest corner. We need to let the machine know where to start as it doesn't have eyes and we need to describe in a very specific way how we want the machine to move.

We also need to define what tool we are going to use and you'll see that on the left and there's all sorts of tooling. Across the top are the different types of tooling that you could select in here, but they'll also have different links and diameters and how big is the holder. We needed to define all of that so the machine doesn't crash the tool into the stock.

On the right you'll see a photograph where we are defining the speed. One of those is the spindle speed or how fast you will go for a milling machine. We are also defining how fast and what area we should plunge into. These are all things that the CNC machine needless to know and we needed to find before we go out into the shop and part of that is a safety factor.

Next, I really like to simulate the machining and you can generally do this in cam if you have a higher-end program. However, most of them have some sort of animation and will do a walk-through that toolpath so you can see how your machine is going to move.

The photo on the left is milling out that center hole in that stock and you will see it goes down in a spiral fashion. This is the toolpath. Then the next step on the right is drilling four holes. This is actually a part I used on my CNC Wood router that I built. You will see the order of the drilling of the holes as well.

The finale of CAM is you post process or you define all the different parameters. You tell the machine or you describe everything that you possibly can and then you need to post process out a file and that file will be a G-Code file. There are different postprocessors as you'll see here on because there are different CNC machines and each one is somewhat unique in how it likes to move.

These postprocessors make it very flexible so you can spit out G-Code for all these different types of machines. You see a number of CNC controllers as well, but you'll see on the right that one is a plasma cutter postprocessor and the ones on the left are milling machine postprocessors. We have a file left over and that file is filled with G-Code, which is the language of CNC. It is what a CNC machine runs on. G-Code is the outcome of the post processing and outcome of the cam process and is what we are left over with were done.

G-Code is not dynamic and let me explain that. It is very static and once you post processing you have a G-Code file that file can only do one thing it's a specific set of instructions. If you go back and change your CAD design and make it bigger that G-Code will no longer build the same part you want it to.

It's not flexible. If you change CAM parameters like feeds and speeds you will need to post process again and create a new G-Code file so the G-Code is very static.

We will take a quick look at an example of a G-Code file. On the left-hand side those are the numbers and some postprocessors spit them out and others don’t. I like to see the numbers just to keep track them. This is a very small snippet of G-Code and as you read thru it you get used to G-Code over time. This G-Code is telling the machine to do very specific things. The first movement is online N01 is telling it to move in the positive Z direction. On down a few more lines it turns on the spindle and the milling machine. It turns it on in a forward direction at a thousand RPMs. G-Code is telling the machine very specific things. The N05 line is moving the machine in the X-Y direction to that location and then it moves up and then it goes in at a certain federate. Each of these lines of code are telling your CNC machine to move in a very particular way.

Since were doing CAM today I thought I'd talk a little bit about the different cam software packages on the market. Similar to CAD there's 2-D, 2.5D and 3-D. You can also get into a fourth axis and fifth axis depending on your CNC machine. Usually, these axes are an add-on to cam software programs. With cam there's free ones out there and you can spend to about infinity if you want.

One thing that I found is the dollar amount you spend really depends on the number of axes that you get with the cam software. The less axes if its 2-D, will most likely be on the inexpensive side of things and if you want five axis, get ready to give out your wallet. I have a quick listing of some various cam software packages: RhinoCam, MasterCAM, Sheetcam, and ArtCam. Those are all pretty familiar ones you'll see on the market.

That's it for CAM. Tomorrow we will go over CNC machine controls. That G-Code that we post processed is going to be taken out and we will use a control software. Then after that, the final step of machining. In the meantime if you have any questions at all you can go to CNC information.com and get some more information or you also see the address to my blog, which has all of the current things going on in CNC. Thanks.