We're talking about alignment today in the factory. 

Pick and place machines can work with really tiny parts. This resistor that maybe you can't even see is a millimetre long and half as wide. That means it's extremely important to correctly align the pick location. That's the point in space where we tell the machine to pick up fresh components. 

Alignment is necessary because components, feeders and tapes all come in different sizes which together determine where the true pick location will be. It's up to the operator to find that location empirically.

Welcome to The Factory, a Core Electronics series where we explore electronics assembly and share what we learn along the way. 

Good alignment starts with a level machine. When our K1830 was delivered we were advised to seat it on bare concrete rather than the carpet in the rest of the room, and the technician brought a very expensive looking spirit level. We were advised that the tray is the most well-controlled surface to level the machine off.

The next step is to load components and perform the alignment. We'll start with the XY alignment. Let's jump on the machine. 

We're in tab four, the feeder information tab and I'm going to work with feeder 23 here that's loaded with 603 capacitors. 

We'll first set the pick XY location, and to do that we use the manual alignment. 

So I'll click the align button, and the head moves to about the right place. You can see on the screen here, we have some tape with some populated positions, there's an empty position here and this is the pick location for this tape. This is the first exposed component. 

Things aren't exposed super well at the moment so I'm just going to lower the brightness, so we can see the edges of the tape window here.

So when you're aligning these components, I don't want to select the middle of the component, I actually want to select the middle of the tape window, the middle of this pocket that holds the component, because on average that's about where the centre of the component will be. 

So using my mouse I'm just clicking and fine-tuning that location. 

What I'm looking for, I can see on the left side here I'm one minor tick over, that's in line with the edge and on the right side here I have another minor tick over as well and I'm just looking for that same symmetry vertically. 

I'm happy with that alignment so I'll click save and back, and we can see just quickly those pick XY locations updated to suit.

Other important things for alignment are pick height and place height. We like to work with a 0.2, 0.3, we call it squish factor, we like to push the component into the panel by some very small amount. so here the place height is 0.8 millimetres and the thickness is one millimetre. So that difference, that 0.2 millimetres is how much the component is going to get driven into the panel.

To do a pick test, we open the feeder test menu here and select the appropriate nozzle. For this feeder I'm using nozzle 4, so I need to select nozzle 4 from the drop down and we'll just proceed slowly. I can step the pick test to begin. 

The nozzle has moved in into position over the component, and the next click will move the nozzle down. The next step moves the nozzle upwards and we can see if we've picked up the part and indeed we have. I can see the component is being held by the nozzle.

This next step, if I click yes it will throw the component away. I'm going to click no, and perform a recognition test. 

So the component is passed over the camera and we can see that the component has been recognized on the screen here. So now I'm going to throw the component. 

We can see that the part is fairly well centred on the nozzle and you can actually see the edges of the nozzle peeking out around the component. 

If you find that components are consistently off to the side of the nozzle or rolling, that could be an alignment issue, or it may be that you need to perform a calibration. 

Here's another angle of the vision system. You can see the flashing strobe when it takes a picture. This happens every time you move the camera. 

Now we'll move on to pick height. We'll work with a larger component here so you can see a little more clearly. We currently have a pick height of zero and this corresponds to the top surface of the PCB, when it's clamped in the rails.

Now this will likely not even pick up the component, because this feeder sits a little below that level but let's step through the pick test and have a look. The nozzle moves over and now the nozzle moves down. and you can see this nozzle hasn't actually touched the component. The spring is at its full natural length, so let's move the nozzle upwards and tune the pick height.

We started with a pick height of negative two millimetres, and this was pretty close but you can see the component jumping out of the tape and meeting the nozzle. There's not actually positive contact between the two. 

Next we tried for negative four millimetres and this was a bit of an overshoot. I'm not really happy with the amount of spring travel here. For a big part like this that probably doesn't matter. For smaller parts though that might be a problem. 

So we split the difference and went for negative three millimetres and here you can see the nozzle just coming in and kissing that component so there's a positive contact before it lifts it out of the tape.

Thanks for joining me in the factory today. If you have any questions or you'd like to see something with a little more detail let us know in the Core Electronics forums. Catch you next time.