What is inside a coffee maker?
In this video we explore what is inside a coffee maker, how it is made, and how it works. Created by Karl Wendt.
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- So is the thermal fuse one-use?
(Hey, that rhymes.)(17 votes)
- probably, yes. However the threshold for breaking it may be as close to a worst care scenario tempurature as possable (to avoid loss of the product). While buying a new coffie maker might help the company, hurting the customer certainly will not. hope this helps :)(16 votes)
- Could you provide a better explanation for the action that causes the heated water to rise in the tube? I always thought an internal check-valve would keep the heated water from returning to the reservoir, but apparently that is not the case.(9 votes)
- According to http://home.howstuffworks.com/coffee-maker3.htm,
•When you pour in cold water, it flows from the reservoir through the hole and into the orange tube.
•Then the water flows through the one-way valve, into the aluminum tube in the heating element and then partially up through the white tube. This all happens naturally because of gravity.
•When you turn on the switch, the resistive heating element starts heating the aluminum tube and eventually the water in the tube boils.
•When the water boils, the bubbles rise up in the white tube. What happens next is exactly what happens in a typical aquarium filter: The tube is small enough and the bubbles are big enough that a column of water can ride upward on top of the bubbles.
•The water flows up the white tube and is dispersed to drip evenly on the waiting coffee grounds.
This explanation sees to make sense to me. I think the one way valve would be needed to make sure all of the water is consumed. If it could go up either tube, it would be difficult to empty the reservoir of all of the water. I may hve to check out one of my old ones to see if they have a one-way valve.
I also found this on how perculators work:
The tube is smaller in diameter than bubbles, so that each snugly-fitting bubble that passes through the tube will carry a bit of water above it along its upward journey.
As these continuous jets of water reach the top of the Pump Stem, they discharge onto the Spreader Cover, which helps disperse the water over the grounds underneath in a more uniform manner, and also keeps grounds from
splashing up.(15 votes)
- What are safety screws, and what makes them so safe?(4 votes)
- I'm not sure about the screws in the video because it's a little difficult to see, but typically they are flathead screws where the head is designed in such a way that when you turn the screwdriver clockwise (to tighten the screw), it engages the screw normally, but if you turn counter-clockwise (to loosen the screw), the screwdriver will slip out of the screw's head, making it impossible to turn. This way, it tightens like a normal screw, but can't be undone without a specialty tools. (see: http://en.foerch.com/documents/thumbs/-1642553479_20111511074942_800x800_Fit_0_0.png)
What makes it "safe" in this case, is that it prevents the customer from being able to open up the bottom of their coffee maker and either burn themselves on the heating element, or spill water on exposed electrical wires.(17 votes)
- How does the water go up the tube, doesn't gravity pull it down?(3 votes)
- Water doesn't go up the tube. STEAM goes up the tubes. On the reservoir side of the heating tube the steam is blocked by a trap in the tube. The liquid water always moves TOWARDS the heater coil until it has all been converted to steam and passed out to the pot. See above.(10 votes)
- What actually happens in a coffee maker when it has the water and coffee bean grounds it it and it's on? I have never opened a coffee maker when it was on, not to mention that I don't even touch coffee, I am 11! :) Does the water drip into the grounds, and does the coffee grounds "contaminate" the water making the water brown and bitter? and how does it get into the pitcher?(5 votes)
- It happens pretty much like you said! If you go to4:00in the video, you see the part of the coffee maker where the filter goes. Inside of the filter you put the coffee grounds. The filter allows water (Actually, coffee at that point) to drip through, but keeps the grounds in the maker. There's a hole the freshly made coffee drips through that you can see, directly into the kettle below. So yes, hot water drips out onto the coffee grounds, soaks through them, dissolves much of the grounds (In the process picking up their flavor and color), and drips through filter and the hole into the kettle.(6 votes)
- Hi, may I ask if there is any resistor inside the circuits? Also, if possible can anyone show me how to draw the circuits? Thank you!(4 votes)
- does the nicronium heat the horse shaped U tube directly or the temperature controller ( having the bimettalic stip heats it ) ......... heat is basically generated by resistor in this case its the nicronium so how does heat flow from there ?(3 votes)
- how does the water comes back to the top of the coffee maker ?(1 vote)
- When water is hot, it starts to expand. When it expands, it travels up the pipe. Do you see how narrow the circumference of the pipe is? In Physics, there is this thing where the size of a pipe affects how fast water flows. With thermal expansion and the circumference of the pipe water can defy gravity. Check out the Fluids and Thermodynamics sections under Physics on this website for more information. Hope that helps out!(5 votes)
- What will go wrong if there is no water in the reservoir?(2 votes)
- Nothing. This is a normal operating state for this coffee maker. Recall step one was to fill the reservoir. As the coffee is brewed the reservoir is emptied. The coffee maker then functions only to keep the base of the pot hot.
A better question is what happens when the thermostat fails. You can just see the thermostat at https://youtu.be/XQTIKNXDAao?t=615 it is hiding under the black clip just above the right thumb. Normally this device regulates the temperature by opening and closing the electrical circuit as described in the video. However, if it gets stuck in the closed position we are in trouble as the heater will get very hot. Hot enough to cause a fire.
This is where the failsafe devices kick in. If you look at the video at time https://youtu.be/XQTIKNXDAao?t=615 you will see two round devices suspended by wires in the middle of the heater coil. These are thermal fuses. If they overheat they “pop” thereby removing electricity to the coil. Normally these are one time devices. One failure of the thermostat causing an overheating event and the coffee pot is garbage.
- Why is the power looped? And what is this process called?(2 votes)
- Hello Com212,
At10:00we see the heating element separated from the plate that heats the coffee pot. The heater is in the look to the left. Observe the white gunk on the heater plate. This is thermally conductive material that ensures good heat transfer from the heater to plate.
The heater is a simple resistive element.
Please leave a comment below if you have more questions.
- [Instructor] Okay, so this is our Black and Decker coffee maker. Wanna take a look at what it's made out of and how it works. This is the coffee holder and the carafe or whatever you'd call it. So it's made out of a glass and I believe the way this glass is made is it's heated and blown into a mold and then it's allowed to cool and there's a little, while it's still molten, there's a mechanical device that creates the shape for the spout, there. This is a band of stainless steel that wraps around the edge, here. It's molded into the indent in the glass. There is a handle here. This handle looks like it's made out of polypropylene, it's a fairly low-cost plastic. It's no texture on it or anything fancy, you can actually feel some of the mold seam there, but it's a very low-cost handle. You can see this part just pops out. It's got a snap fit there and, again, polypropylene lid and handle. That stainless steel piece there really does a good job of hold all this together. I think we can probably pry this handle apart and see what is inside of it. I might need to get a larger screw driver. I should say a smaller screw driver, so I can pop this apart and see if we can see what's on the inside of it. It's not meant to come apart and it may be solvent bonded or something like that, so we may not have a lot of luck with it, but we'll give it a go. Oh, it's not. It's just a snap fit, okay. You can see that that's how they molded the part. They're two different pieces there. We're gonna go ahead and remove this, this screw here, to show you how it all goes together. Alright. Oh wow, it pops apart there. You can see there's a little bracket on the inside that the screw goes into and holds this steel band in place. That's what the handle is help on by. Then at the top, there's just a little lip that holds the top of the handle there in place. Just a little piece that folds over the glass and snaps on. So that's how that's held. This is made out of one molded part, this is made out of another, and this is made out of another. So that's how they made the handle, there's three different molded plastic parts there and the molds came together like this. You can tell that because you can feel the mold seam on the inside of the handle, there. You can also tell it because of the handle's shaped. It would make it easy to pull the mold out this way. They probably also had, it was probably a three part mold and there was a section that also came out in this direction. Then this is just another injection molded part that snaps onto this one, as we've seen. This is the part that holds the handle on. Very important part. I think they definitely paid the extra money for a stainless piece there because it's really important that that doesn't come loose and it probably gets fairly wet, so if it was made out of regular steel or another material it might rust and could potentially come apart. We wouldn't want hot coffee on us, now would we. Alright, so that's the coffee kettle. So, inside, here's our coffee maker. We know that hot water... We've got a container here and in this container, on the inside of the coffee maker, is a space where we put our coffee filter and then we put our coffee grounds and we fill this with water and then we close the top and we turn it on and we wait. What happens is that water that we pour in drains down a little hole on the inside there, you can see it right there. Let me point to it with the screw driver. It drains down that hole and it goes down into this underside, so we'll take a look at the underside and see what happens down there. Okay, so, I've modified a screw driver. This was a low-cost screw driver. It was a 99 cent one, so I modified the end of it so I could take out these safety screws. Don't do this at home unless you have a professional with you because this is not meant to be taken apart. That's why they use these special screw heads, so you won't take it apart. But I did want to show you what is inside. There we go. Again, this is an injection molded part. This is a co-molded part, it looks like. Which means that there were two different materials molded together. Let's see if I can knock that screw out. Okay, it wants to stay, that's fine. This material here is, these feet are made out of a softer material and this is a polypropylene material. So it's a plastic, a low-cost plastic. So the mold comes together and they injection mold this material and then once this material has begun to harden, they injection mold the softer material, so it's co-molded or it's a dual molded part. You can see other parts are done like this, like sometimes you'll see toothbrushes that have soft saniprene and then the hard toothbrush and they're molded in one mold. It's a dual shot mold. In any case, so that's the bottom. This allows heat to get into, or allows air to get into the heater chamber to vent out, I think a little heat in there. So here is the heater. This is where all the magic happens. The water comes down this tube, and it goes around this horse shoe shape, and then it comes up here. What causes the water to raise back up and go all the way up this tube. It goes all the way up the tube, here and then it comes out this apparatus here and then it goes and drains out of these holes right into here. There's just a little piece of plastic that causes this part to line up right over the top of this, when you close it. The water just comes up that and drains right out and into your coffee grounds and then makes your coffee. So the heater does two things. It causes the water to go down this pipe, expand out, and to drip into your coffee maker. But it also heats up the plate, this plate right here. The way it does that is it uses a material called micron wire, which is a alloy of nickel and chrome and it heats up really easily and it's a good resister. When it heats up, the aluminum is also an excellent conductor of heat, so it conducts heat very well, into the plate and also into the water that's inside of it. There are a number of different safety mechanisms inside this coffee maker. We've got two thermal fuses here and if it gets to hot those will blow and prevent it from getting hotter. There's also a temperature sensor here that can shut the coffee maker down if it gets too hot. I believe what's inside of that is a bi-metallic strip and so it could be a strip that has something with a low thermal expansion co-efficient like Invar which is an alloy that doesn't expand very much at all in heat and then it could be alloyed with another metal like, say copper, which expands fairly well in heat. What happens is, when those two metals are next to each other, one of them, the Invar doesn't expand very much so it sort of sits still, but the other one expands and it causes the bi-metallic strip to bend like that. When it bends, if it was conducting the electricity, it moves away from the contact. Let's say this is the contact, here, it moves away from the contact when the temperature is too high. So they choose those bi-metallic pieces based on, they calibrate them based on how much temperature they think it's gonna take so they'll pick how much, the size of the metal and the amount of metal and the types of metals that they alloyed together for that strip are based on the temperature that they want the coffee maker to get to. They don't want it to get to like 500 degrees or anything close to that, so there's probably a temperature that they have chosen and then they select a bi-metallic strip that will respond to that temperature and shut the circuit off and I think that's how this temperature sensor will work. We're gonna go ahead and take apart the rest of this. So this piece right here is kinda cool. It's a little bar that holds the heater in place. This little bar has the screws on it and the screws have these curious little washers on them and the washers are made out of a fibrous material that does not conduct heat very well. That is very helpful because you don't want the screws conducting heat into the plastic, into this, because otherwise, if they conduct the heat into the plastic, then the plastic will potentially get soft and deform and maybe even melt. So we don't want that to happen, so that's why we isolate this bar that holds the heater in place. We're gonna continue to take these screws out, here. The screws are set in something called a boss, a screw boss. That is just a protruding piece of plastic, on the inside, that holds the screw in place. You can see that the heater is held in place, it's got this paste around here and that's called thermal paste and that aides in the conduction. It helps the hot temperature to be conducted from this horse shoe shaped heater to the steel plate that the coffee maker sits on. We're gonna take these screws here out. These screws hold the plug in place or the wire in place. You'll notice that the wire is looped around itself and that is so that you can't pull the wire out of the coffee maker. That's important because you don't wanna pull loose any contacts because if you have any loose wires in the coffee maker, potentially that's a cause for a fire or an electrical short. We don't want that and that loop helps to prevent that. If we go down a little further, here, I think we can take this part, here, loose. We're taking the two halves of the coffee maker apart. I don't know if you can see inside of that very well, but down in there there's a little symbol that says PP and that stands for polypropylene. So that's how we know what kind of plastic this is. Polypropylene is a low-cost plastic that's widely used in commercial products. One of the lowest cost plastics. They use it in everything from dishwasher tubs to you name it. Coffee makers to hair dryers. In any case, I'm trying to get this screw out, it's kind of in there pretty good. You can see, as I'm taking these screws out, it's separating, the two halves are separating. See if we can finish getting this apart for ya. Alright, we've got one more screw here. Okay, so you can see that this is how the two halves of the coffee maker come together. Whoa. Alright. So they come together like that and there's a bunch of screw bosses here and they actually like up with holes on this side so that you can press the two pieces together. These two halves are injection molded, the molds come together like this and like this and then the two parts come together and that's how they're able to create this shape. You can see that the water comes in this tube, here, gets heated, and rises out this tube, here. This, right here, is the ring that went around the inside, right here. This is the metal plate that the heater sat on. So there's a separate ring, here, that the metal plate sits inside of. Gives it a nice finish. Yeah. I think that's about it for our coffee maker. That's how it works and that's what it's made out of. Hope you've enjoyed it.