Forum Replies Created
If you need more pressure using the current levered design, @andyn made a clever change in his version where he could change the piston diameter without changing the tube. Of course, you trade injection volume for pressure but for small molds with narrow passages it may be an option.
It should just be the area of the piston face pushing on the plastic. In your case
I get 5.3e-4 sq meters and about 39.6 bar. I think to get to 45 bar, the PP guys eat more chocolate.
Sounds like a great project. Is there a link to a more detailed description?
I’m curious what is the predominant plastic type that will be processed and what will they be making?
Thanks for posting.
Well, if you are building a machine to the specifications on that page, it states that it has a leverage of 3. So if you are 70 Kg (about 700 N) and hang of the end of the bar, you will apply 2100 N of force on the piston. If you divide that by the area of the piston in sq. meters, you will get the pressure in Pascals.
If you take more accurate measurements of the machine you are building, you will get more precise estimates for your machine.
If you need more pressure, the rack and gear designs are an alternative.
They should be near the heaters they control but the sensor tips should be on the thing you are trying to control the temperature of, in this case the tube and maybe the nozzle. Take a look at my description in the Dec 14 post in this thread https://davehakkens.nl/community/forums/topic/injection-molding-what-am-i-doing-wrong/#post-151288 . If you follow that approach, I would dremel a shallow dimple for the thermocouple tip to press press against. The laser should work but may not be precise enough at this temperature. A BBQ probe sensor could work as well.
It is hard to tell from the photo, but it looks like the thermocouples are attached to the heater bands. The tube may be cooler. Do you have a way to measure the tube temperature independently to check?
There are several threads on this issue like this https://davehakkens.nl/community/forums/topic/v4-fume-extraction-4/ . Looks like the V4 efforts finally started to address safety in some of the designs and documentation https://preciousplastic.com/solutions/machines/overview.html .
If you have 3 machines going at once, I would make three fume hoods extracted by a common fan and ducting. Whether you filter the exit probably depends on your local situation
I guess, technically it isn’t single use plastic anymore. Now if we could set up a nuts-for-bags exchange program, the forest would get cleaned.
I don’t have an answer for you. If you search the forum, there have been several attempts at working with PET. The only successes I remember are the finely shredded PET used in direct 3D printers. The general observation appears to be that PET is both moisture and temperature profile sensitive and may be too difficult for simple DIY recycling.
You didn’t say what discipline you are studying, If possible, I would consult with a polymer chemist to get a recommended process cycle and control tolerances.
Do you know it is HDPE? The link you provided said polyester.
If it is only HDPE, that should work well.
Plastic yes. Used toilet seat….not so much.
Also if you see these guys coming……Take down your “zimmer frei” sign…just a suggestion.
That is a great summary, thank you
The spec table for the V4 sheet press shows 1.5 KW not 15 KW do you know which is correct?
I think the basic question is how much energy is consumed to heat up the machine and then make each sheet.
You may want to check the build documentation for the exact heater power ratings. I would guess the numbers specified are the total for the heaters. I have not seen a number for the actual energy used per sheet. You are heating up a lot of material other than the plastic so energy consumption will be significant, especially during the initial heat up. If you are talking about the large V4 sheet press, you may want to ask the question in the V4 portion of the forum or on the Discord channel to see if any of the PP people respond. Good luck
The page shows 2.8 KW for the basic and 1.5 KW for the pro, though it probably depends on your build and use.
You may want to put your question into the precious plastic portion of the forum (rather than the phonebloks)
Also, there is some information on the precious plastic site https://preciousplastic.com/solutions/machines/basic.html
Solar concentrators are always interesting and there are many designs. It would be nice if they posted some engineering and performance data for the lytefire system.
Interesting reading https://www.coleparmer.com/tech-article/uv-properties-of-plastics . There are other articles like it. For roof tiles, I would consider both UV and temperature sensitivity. A dark tile can get pretty hot.
There have been a few threads on skateboards. The injection machine does not have enough capacity for a skateboard. This thread may help https://davehakkens.nl/community/forums/topic/extrusion-machine-products-v4/ .
If I was doing it, I would test out the board design with a simple press mold to make sure you are happy with the result, given the mechanical properties of the plastic.
You didn’t say what type and size tile you are planning. When you did the volume calculation for your tile design, how did that compare with the PP injection machine capability? It is quite limited for larger objects. There have been posts about making roof tiles or pavers from a plastic and sand mixture. They appear to use a larger, auger based machine to melt and mix. Then a press is used to form the tiles.
In the podcast that @frogfall posted on 2/2/20 ( https://davehakkens.nl/community/forums/topic/plastics-related-stories-in-the-media/page/2/ ) there is a brief mention of the villagers burning plastic as cooking fuel instead of wood. Providing them with a liquid petroleum fuel instead, has to be well worth the effort.
I would be skeptical. I think the hot glue gun works because the piston (glue rod) diameter is small and moderate force creates decent pressure. Also I think the hot glue material has lower viscosity when liquid than something like HDPE. There was a post about a handheld extruder that was motor driven.
Using the oven heating makes it hard to know when all is melted and ready to inject. Also the fumes need to be considered.
If you try this approach, post your results, it will be new data for the forum.
I realize resources are different around the world but I was able to build a desktop injector for about $100 in parts ( https://davehakkens.nl/community/forums/topic/portable-desktop-injection-machine/ ). Depending on what you have available locally you may be able to reduce it further ($30?) to just the two controllers and heaters.
Actually, on my desktop unit, I just use a pair of shallow wedges to press either the molds or the block of wood against the nozzle, no clamp.
https://davehakkens.nl/community/forums/topic/portable-desktop-injection-machine/ (see Jan 31 post).
Happy to hear you are back in production.
Great colors in that soapdish. It is funny, when we are buying stuff like liquid laundry detergent, I am conscious of the color of the container and how I could use it.
Sorry to hear you are having problems. There are some things you can check and do before you call an electrician. Every time the system goes hot and cold, there is stress and a chance for something to fail. Are there any sounds? (sparks?) when the circuit breaker trips?
Here is what I would do, stop if you are uncomfortable with any of these.
First, I would open up the electronics enclosure and do a careful inspection of all the components and wires/connections. Is anything burned, melted, smells burnt, loose wire, etc.
I would disconnect the heater wires from the SSR modules and from the line connection. If you have a multimeter, measuring the resistance of each of the two heater circuits and also resistance to ground should tell you if the heaters and wiring are OK.
If the heaters are OK, I would work my way backwards, isolate each of the controllers and see if they power up without tripping the breaker.
It is frustrating but there are only a few components and they are relatively cheap to replace if they happen to be bad.
I just press a block of wood against the nozzle during heating and compaction to contain the plastic. Works well.
@soumyaadhikary , I think there is a lot of interest in what to do with plastics that are hard to recycle (PET, etc.) on the small scale. Do you have an overview of your design or the expected size? If you have an estimate of how much energy it will take to produce a kilo of fuel, that would be a good comparison to the total energy needed to produce fossil based fuel.
The world will be using liquid fuel for a while, might as well get rid of some plastic in the process.
Sounds like an exciting project.
I don’t know if the V3 or V4 shredder can handle tennis balls. Probably depends on what you plan to do with the chips and how small they need to be. I would optimize the design for tennis balls if that is the primary use.
I repurpose my tennis balls. I have built a ball dispenser that I put in front of the house. Dog owners and small kids are pretty good at keeping the dispenser empty. I realize the balls eventually get thrown out but at least they took the place of new chew toys or game balls. Also donated a bunch to animal shelters.
Some of the more clever uses I’ve seen, one was at an airport, the maintenance guy had a tennis ball on a stick and was using it to remove scuff marks off of the tile floor..worked very well as a brush. I also saw a mail delivery person carry a stick with a tennis ball at the end. He said that when a dog charges him it wants to bite something. The tennis ball is the best option.
So lots of repurposing options that don’t need a shredder.