Injection molding with new high temp resin


#1

So the owner of the company I work for is VERY interested in the high temp resin. We have some on order, just not received yet. Anyone have any experience with this yet? (I know it just came out, probably too early).

We do not use small, table top injection molding machines, however we have a dozen or so large machines such as the one below.

I guess my question is, will creating a mold with the high temp resin work for this caliber of a machine? I asked the guy who runs our machines, unfortunately his English is not very good. I showed him the specs (HDT of 289 C @ 0.45MPa) and he kinda nodded as if it was going to work.

Thoughts? Suggestions? Warnings?

  • Kevin

#2

Hello,

I would like tried it, but I do not own injection molding machine :frowning:

Solution by Stratasys:

It’s amazing!

I want it :slight_smile:

Tomas


#3

Well we have some of the resin on order and my 3D guy working with our Injection molding guy on the process. I will certainly keep this thread up-to-date with our progress.


#4

This is Objet’s Krypton Green material (now part of Stratasys). It’s usable, but both of the molding houses that have tried to develop a rapid injection molding solution using this given it up. Both of these were service bureaus.

Based on what I know of their experiences, doing it as a service is not worth the effort… that said, using it as an internal technique Wii likely be useful.

This translates directly to Formlabs high temp material.


#5

Of course, it goes without saying, but our intentions are to make small batches of prototypes…not mass produce 10’s of thousands of items with a 3D printed mold.


#6

Of course… all I’m saying is that the utility of a very short run tool, is more useful as an internal development program, vs buying it from a 3rd party. Once you add the profit from the third party… it’s a wash.

Actually, now that I look at the pic above closer… it’s from one of the vendors I mentioned. They worked closely with Stratasys.


#7

I own a prototyping business and have a lot of injection mold design experience, a machining center, and also a Form 2. So, I am very interested in this technology. But, I wonder if it is practical. You clearly need a metal master mold frame to house the 3d printed cavity inserts. That is not a big concern really, but ejection is. Every part has special ejection requirements and that requires holes through the cavity support plate, custom eject pins, and a custom pin plate. These are not major concerns when building a mold, but when trying to prototype something at low cost, it starts to get expensive and make less practical sense.

Anyway, I suspect there will be times when this might be beneficial, perhaps for medium sized runs in the hundreds. Time will tell. I am very interested. Now I just need the perfect project to give it a try.

Very exciting to see the focus on new resins.


#8

pmcgarr… You have reinforced what I have seen so far. My biggest question is how to proper (or reliably) design the mold for proper air evacuation… you are absolutely correct in that you need a metal master frame to hold the printed cavity. Not a problem, but what I want to know is if the printing alone (accuracy) take care of vents.

You may need to treat this type of tool like a MIM or die-cast… with a runout feature to allow air to evacuate, since I’m not sure that you can print a properly accurate gas evacuation path.


#9

I suppose it depends on what you’re molding. I have a lot of experience with polypropylene, polystyrene, cyclic olefin copolymer, and polycarbonate, and all of these materials typically get primary vents .0004/0006in deep. You could push those up to .0010in. which is 25 microns with just a little risk of flash, but at 25 micron resolution it would be hit or miss if you would get vent or not. As for venting I am more concerned with the temperature of the gasses. They super-heat so they are much hotter than the melt temp of the material being injected into the cavity… I wonder how much these gasses play into the life of the SLA tool.

Then you have the whole cooling thing. I design molds for the life sciences industry so they can be pretty complicated. I am always thinking about better ways to cool the mold, utilizing beryllium copper and other high thermal conductivity materials for decreased cycle time. Now, I understand that cycle time is not a major player in this scenario, but I am guessing the thermal conductivity of the high temp resin is not very good. To be fair I haven’t looked at the data sheet. But, if the resin is ok with water running through it I suppose you could do conformal cooling to make up for it the lack of thermal conductivity.

The more I think about this the more I realize there is a lot to consider. I am very interested to explore all of this, but need a project to justify it. That is the hard part.

How many of “us” are there in these forums? It’d be good to ask for a sub forum or something where a bunch of us could brainstorm, maybe work together on some experiments, sharing physical resources and skills to get some of these questions answered, and maybe develop some guidelines for us to be successful. This way we don’t all have to go through the same pains individually.

Thoughts? Now I need to go watch our countries absolutely ridiculous and embarrassing election unfold. What a mess.


#10

I thank you all so far for responding. Being a Web Developer/Graphic designer who was told “By the way, you are now in charge of our 3D printer”…most of what has been said so far is over my head. Walking by our injection molding machines to get my lunch out of the fridge is the extent of my knowledge of mold making, etc.

I will be distilling all of this info for our 3D designer, Mold guy, Inj molding expert and the owner of my company.


#11

@kevinduhe Feel free to reach out with questions if you get stuck.


#12

Right, but the flipside is lower initial melt temps are possible here, because the initial stream stays fluid longer in the insulating resin. Water jacketing also sounds like a good idea, and way easier to print into the core/cavity than machining in, or stacking up as layers.


#13

If it is interesting for you to see how my completely 3d printed 2-cavity injection molds without aluminium frame performed I have put together the results under the link below.

Even small air vents printed very good in the 50 micron resolution.


#14

I’m curious about what you are using for an injection unit. It’d be good to see pictures of the actual cavities and molded parts. I guess some of that will come with part two?

Great to see this being done with minimal complexity. Are you just prying apart the mold halves and then prying the part from the cavity?


#15

Kevin,

We just received our first sample of the high temp resin, printed our first mold and ran a few sample parts in Polypropylene set at about 390F (total part mass is 5grams). The new high temp mold material worked out perfectly and the parts came out decent once the mold heated up after a few cycles. I used the 50micron setting. Currently we have a small shot volume manual press from LNS technologies. The project is confidential so I cannot post pictures but so far I am impressed with the new Form Labs material in this application. We have some work to do on the mold design side but material seems pretty solid. Post cure it is a bit brittle so I would recommend a metal box if you intend to mold a reasonable quantity of parts.


#16

I am using a manual benchtop injection molding unit - IASCO 66M - with a handlever. This a machine similar to LNS or Galomb.

I just pry apart the mold and take out the parts - as easy as that because I wanted to have reduced complexity. For me this more like a proof of concept as a couple of people told me in the beginning that it will be impossible to 3D print molds on an prosumer grade SLA printer :slight_smile:

You can see pictures and actual parts under this link which contains part 2 - https://plasticlabs.wordpress.com/2016/09/13/how-to-bring-a-3d-printed-2-cavity-injection-mold-to-life-part-2/


#17

It’s great that printing SLA molds for injection molding works, but for short runs isn’t it easier to make a silicone mold and vacuum cast 10-100-500 parts? This is what we do at my company and we are able to cast very complex parts. Yes, it takes a lot of manual labor, but the results are perfect.

We are even thinking about making a simple but effective and cheap (compared to the existing machines) vacuum casting machine. Any thoughts in this direction?


#18

When we were developing a desktop plastic injection machine, we were not able to get mechanical parts to come out without distortion using silicone molds.

For instance, we couldn’t get a functional gear to come out. Very close, but just slightly too distorted to be usable. For ornamental parts it worked great.

What type of parts are you casting into silicone?


#19

The material properties of thermoset urethanes and the like are just to limited for a large number of functional uses. They are particularly vunerable to heat… not to mention the limitiations on the materials mechanical properties.

There is definitely a place for this technology, and a use for it’s parts Particularly if engineering resins can be utilized (PC ABS possibly nylon). For anyone that has the capabilities in house, I would argue that they would never make another cast part again. Whether or not this is commercialabizable, is another question.


#20

I might be interested. I’d be interested in see what you’re using now.