r/InjectionMolding

Looking into buying my first machine, used. Which brand would you recommend?

A machine that will last is obviously important, but so is ease of use.

Any recommendations would be greatly appreciated.

Someone suggested these guys to me for low-cost molds at low-mid volume. Does anyone have any knowledge of them? They only take bank transfer for payment as well which seems like a scam.

Hi all,

I'm not an injection molder but have worked a fair bit on plastic component development over the last few years. We've always opened steel tools even for low-volume parts and even prototypes. It strikes me as very wasteful if the tool isn't being used to produce hundreds of thousands or millions of parts, and so I wanted to hear the community's thoughts about typical prototyping workflows.

I'm aware tools can be made in aluminium or even high-temp plastic, but for some reason our molding partner has always been reluctant to do this. Any thoughts as to why?

Something that may complicate it slightly is that we're looking to make overmolded or 2K molded parts which combine soft TPU with a rigid polymer component, and we're targeting a strong chemical bond (the parts will be used to seal a pressurised vessel, so the bond must be airtight even at pressure).

Any advice on how best to prototype this kind of part in a cost-effective way is much appreciated!

Hey guys,

Hope you're all doing well.

Just curious what sort of resin price increases you've seen so far? Particularly in the PA6/66 range. What % increase letters have you seen so far from your suppliers?

Thanks,

How are you guys safely accessing the tops of machines for maintenance/ repair? We have a lot of machines that are very close together so MEWPs are not an option. Thanks

The program has been running for months fine until now, with all temperatures stable during the production cycle. We are now getting a Temp too high on Zone 3 of 4 ( 4 being the hopper, 1-nozzle). The barrel heater in zone 3 does not even show as being on during the production cycle, but the zone 3 heats up 2-3deg on every plasticising stroke, and just keeps on heating up.

The temperature is stable when in stand-by which makes me think the sensor is ok. Material is PEEK, temps are from 350-390deg C up through each zone.

Plasticising back pressure is on 6bar, now when reduced to 0, then the material stops heating up. Is this a mechanical problem? or program parameter that has changed?

I’m curious how other people here feel about collapsible cores in injection molds.

We usually see them used for parts with internal undercuts where a normal core can’t release the part cleanly. In some cases they save space and avoid more complex side actions, but they also seem to bring more concerns about wear, maintenance, and long-term stability.

For people who use collapsible cores often:

• What kind of parts are you mainly using them for?
• Do you think they are worth it compared with sliders or other solutions?
• What problems show up most in production: wear, sticking, flash, cleaning, or something else?
• Any design tips that make them run more reliably?

Would be interested to hear real production experience, especially on cap molds, closures, or other high-volume tools.

Im a supervisor at a plastics company on the east coast, ive done some Paulson courses after I got the promotion but ive not been given any other ways to further my processing knowledge. is there any good books that can help with this?

Hi folks. Im new to the sub and looking for advice if any can be given.

Im a young industrial designer and for the last year Ive been designing, prototyping, and producing a small silicone product for our med device start up. One thing that is always annoying is the flash. My best method right now is to go along the edges of the part with a knife, but it can be time consuming and often it can leave unwanted marks, cuts, and etc, causing for an imperfect part.

My molds are 3d printed in FDM (though SLA is also on the table with inhibition precautions). For the last few months I have been trying to create a "gutter" or an "overflow well" (or valley) along the part perimeter to stop using the knife. Unfortunately the only benefit I have added to the mold design is being able to grab the flash easier. I know the nature of FDM printing also creates inconsistency to the mating faces and in turn the flashing itself. This is where I think SLA would work much better (though imperfectly) considering its resolution.

My leading concern is how to design this gutter or valley. Ive been looking and testing myself by offsetting my cylindrical gutter at .1-.2mm away from the cavity but nothing has really stuck yet. I have wondered if I should be putting it closer, or further; maybe even adding an intentional gap right next to the cavity. Im even considering a triangular geometry with one point converging at the cavity perimeter. None of these strategies are trivial in CAD so for the sake of time Im looking for advice.

Im not really even sure what questions to ask here so Im just going to post and hope to have a discussion with someone much more familiar with the process or maybe direct me to a more appropriate sub. Thanks so much for your time and I hope this isnt too difficult of a problem to discuss on reddit.

PS. My understanding of mold terminology is limited so please bear with me.

Hello,

I work in an R&D lab doing injection and blow molding. I've been tasked with finding a small desktop or portable injection molder that we can use for small part applications (i was not given any specifics on this, i assume "small" in this context would be a shot size of under 5-10g). Cycle time was unspecified, but i want to steer away from manual presses due mostly to lack of pressure control. We do injection process profiling, but i dont know what kind of control to realistically expect considering most units I'm seeing utilize a plunger vs screw.

We have in-house cnc and sla moldmaking capability, and i believe this will be used as a cheaper mold alternative to trial small parts rather than ordering molds for the larger presses. ("Why dont you just print the parts in the first place??", you may be wondering. Thats a GREAT question. I just work here.)

Cost and precision will be the primary factors here (of course they'll want the best quality control for the lowest price). We have working air in place already so pneumatic vs hydraulic aren't big factors. Space and noise aren't important either since this will go in an active shop environment, though im personally leaning towards a vertical unit for a few reasons. Materials will be fairly standard, likely PP and HDPE, but a unit with higher heat capabilities will keep options open for a variety of projects.

Are there models that anyone recommends, from experience working with them in a similar application, or machines/companies to avoid? Hopefully i didn't miss any details, but since i really wasn't given any criteria on what they're after i am keeping an open mind. I appreciate any feedback.

I have an Arburg 305 producing spoons (38 spoons per cycle). The box under the machine gets filled very quickly (in around 30 minutes), so I have to be there every 30 minutes. I want to be able to let the machine work alone for at least a few hours.

My idea was to get an inclined conveyor belt. I talked to someone and he said and he said it's costy and it requires maintenance, so for me (im a beginner), it's better if i lift the machine up.

I like the idea, but my concern is, does that work? Does that damage the machine? Can you give me any advice?

I have a small manufacturing plant for manufacturing recycled plastic ( PP) granules, mainly from the scrap from the dealers all around make it grind , wash and then mix up with colors and all . Etc

We do use the white pp waste to produce granules -

But I do have a problem making a special color from a client ,

The shade is just similar to the ink of the ball blue pen .

I tried various pigments which I used before for the coloring .

But none of them work , ordered 2-3 different *high quality * pigments too but none do the job .

can any of you guys help me with some contacts or links or anything which can help me through this .