Injection molding small parts with a 3d printer

[Wingklip]

My double motor extruder is up for it.
I wonder if I am able to make a little box type mold of clay or something and use that to make accurate injection molds with 220*C ABS or even PBT?



I don't think anyone has tried this before but perhaps this is one of the cheapest ways to get into injection molding without special tooling, after all, the mold can be really easily 3d printed and then used to make a clay or silicone mold around it for excellent insulative properties. With high enough bed heating and a quick extrusion rate, I think we might just be able to have a small injection molder good enough for making thick keycaps using 3d printing filament.

My reasoning here is that it would make for great mass production rates

[sinusoid]

I don't think anyone has tried this before

Quite a few people, actually.

https://www.youtube.com/results?search_query=benchtop+injection+molding

It's a thing in the rapid prototyping industry/market. People usually make metal molds for it, but there are special polyurethanes that can be used for producing mold inlays.

Look around, there are some diy benchtop injection molding machine projects on the internets.

[Wingklip]

I don't think anyone has tried this before

Quite a few people, actually.

https://www.youtube.com/results?search_query=benchtop+injection+molding

It's a thing in the rapid prototyping industry/market. People usually make metal molds for it, but there are special polyurethanes that can be used for producing mold inlays.

Look around, there are some diy benchtop injection molding machine projects on the internets.

You got me wrong comrade, I meant to use the extruder of the 3d printer as the injector head for small plastic bits

[sinusoid]

Sceptical due to forces/pressures.

Benchtop presses can make 2-8 tons of pressure, commercial machines go into tens and hundreds.

Keeping that in mind, do try it, and post results. It might exceed expectations.

Few tips. Don't overheat the plastic to make it flow better, it will decompose. You'll get toxic fumes, bubbles, and worse mechanical properties. Carbon from pyrolysis can damage the nozzle and heater area, especially with PLA. Stuff from ABS decomposition is more tar like and won't stick, while PLA goes straight into hard carbon residue you'll have to remove mechanically, likely damaging the nozzle beyond repair.
Plan the vents in the mold to get the air out, and extrude till they all overflow, or at least fill up halfway.
Pre-heat the mold, too, so the plastic doesn't cool too fast.

Good luck!

[Wingklip]

Sceptical due to forces/pressures.

Benchtop presses can make 2-8 tons of pressure, commercial machines go into tens and hundreds.

Keeping that in mind, do try it, and post results. It might exceed expectations.

Few tips. Don't overheat the plastic to make it flow better, it will decompose. You'll get toxic fumes, bubbles, and worse mechanical properties. Carbon from pyrolysis can damage the nozzle and heater area, especially with PLA. Stuff from ABS decomposition is more tar like and won't stick, while PLA goes straight into hard carbon residue you'll have to remove mechanically, likely damaging the nozzle beyond repair.
Plan the vents in the mold to get the air out, and extrude till they all overflow, or at least fill up halfway.
Pre-heat the mold, too, so the plastic doesn't cool too fast.

Good luck!

Naise

I just found out that the problem with my extruder was due to the carbonisation of the pla inside the extruder head lol. Been dunking it in meth for the past 3 days, about to stick a needle through it lol

[sinusoid]

Loosen the extruder filament press clamp, or whatever it's called, heat up the extruder on no filament, push in some filament and pull it out rapidly just when you feel it soften. Should come out with an audible pop. Trim the molten end. Repeat several times. Should dislodge a lot of the carbon, you should see it on the end of the filament.

Order a new nozzle Steel or teflon inlay in the heater? You might want to change these too soon.

I hate PLA.

[Wingklip]

I thought it was good

[sinusoid]

I thought it was good

Well, that was just my opinion
PLA prints much better than ABS because of little shrinkage and good reaction to cooling.

I don't like it for several reasons i don't get with ABS:
- low melting temperature
- bad decomposition
- brittleness
- impossible to process mechanically, can't grind it (burns, melts), hard to cut with a knife
- can't be reprocesses into juice without uncommon dangerous solvents
- decomposes over time, esp. in UV exposure.
- material switching is troublesome (wash bed & recalib for low temps)

I still use it when I want solvent and chemical resistance, want to spam people with fast cheap prints, or I'm using someone's printer that has it installed.

ABS is problematic in different ways, for example it likes warmth, needs heated bed and enclosure. If your machine has steppers in the printing volume, they tend to heat up all the way into their max allowed temps (83degC), because there's no way to get the heat out. Fumes are toxic.

[Wingklip]

Has anyone got an injection mold prebuilt? I'm trying to find some craftsman quality hi temp clay on ebay

[kolec94]

your issue is the time it takes for a 3d printer heater to melt plastic is to long.
injection molding heaters are 200+w and heat filament quickly so can flow or be forced into the mold

[Wingklip]

I'm going to try to make a mold out of silicone from the tube. I heard silicone has insane insulator properties, so I'll see if that works for it. Relatively simple, after all.

But seriously does no one have an injection mold and a 3d printer at the same time in their house?

[kolec94]

I'm going to try to make a mold out of silicone from the tube. I heard silicone has insane insulator properties, so I'll see if that works for it. Relatively simple, after all.

But seriously does no one have an injection mold and a 3d printer at the same time in their house?

no reason 3d printer is for prototyping and injection mold is for production
injection molding has a huge cost of entry

[Wingklip]

I'm going to try to make a mold out of silicone from the tube. I heard silicone has insane insulator properties, so I'll see if that works for it. Relatively simple, after all.

But seriously does no one have an injection mold and a 3d printer at the same time in their house?

no reason 3d printer is for prototyping and injection mold is for production
injection molding has a huge cost of entry

Precisely why I am attempting this

[kolec94]

I'm going to try to make a mold out of silicone from the tube. I heard silicone has insane insulator properties, so I'll see if that works for it. Relatively simple, after all.

But seriously does no one have an injection mold and a 3d printer at the same time in their house?

no reason 3d printer is for prototyping and injection mold is for production
injection molding has a huge cost of entry

Precisely why I am attempting this

checkout lns technologies and how are you making for molds?
and this http://makezine.com/projects/make-41-tinkering-toys/diy-injection-molding/ but this can be improved and cost less

[Wingklip]

Made a 2 piece mold with sculpey
Looks horrid XD but it is accurate to the third of a millimeter.

Need to sand it down but yeah. I might need to press the keycaps instead of inject them because, well, damn plastic is viscous af