r/moldmaking

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!

Howdy! I've never made a mold before but I'd like to take on a (potentially overambitious) project of making my own mold for casting garden stones to line the edge of my flower plot with.

I would likely 3d model the object that I want to make the casting of, then use some type of quick drying concrete in the mold itself. My question is-- what type of mold should I use for casting concrete? Silicone? I'm not looking to spend a ton of money on something I may only do once but I'm also a believer in doing things right the first time rather than super cheaply.

Thank you for any and all advice on the matter :D

Complete beginner here, reading and watching lots of videos so I think I have the general idea of the process, but often times videos skip what release agents they’re using (maybe they’re not using anything?). I will be starting with small projects for this, I am doing monster clay sculpt - hyrdocal mold - silicone final. Should any release agent should go in my hydrocal negative with ecoflex 00-45 and 00-50? Or will it just pull out?

Hi everyone, I was wondering if you could help me find the right material to stop my helmet mold falling out of it's fibreglass jacket mold?

I applied Vaseline to the walls of the entire jacket and added registration key cubes to the silicone but while I was slush casting by hand (I have made a roto casting machine but I decided to try by hand first with this issue) and the vertical walls fell inwards messing up my cast.

Hello, I'm wanting to get into vulva and breast casting. Could somebody kindly tell me if silicone or alginate would be more appropriate for this? Pros and cons of either? Thanks a lot ☺️

As the title says, I'm going to need to fill and sand the surface of 3D printed PLA to hide the seams of multiple parts glued together. Then make a mold of the thing with Sorta Clear from smooth on.

I was wondering if anyone knew of a good filler which would work with platinum silicone. I was looking at plastiflex from APP which is a plastic filler.

Thanks

I’m new to mould making and i’m looking at what to purchase. I keep seeing mould star 15 as the sort of standard recommendation but it’s 300$+ to get it where I am (for over 900g). I see BJB as a good alternative but don’t know what is the comparable option to MS15.

Any help or tips would be appreciated🙏

Hello. I am looking for an industrial engineer to give unbiased advice regarding choice of material for an injection moulded chewable pet toy. The product needs to be flexible with strong puncture resistance.

I am torn between the following choices: silicone, natural rubber and TPE
Ideally I wanted NR but cost per unit is putting me off (coming off the tool as £2 and over) and was told if I choose the wrong shore hardness the tool couldn't be used on a different rubber with a higher shore hardness due to the way NR cures. Plus not many people who like working with it in the UK.
Silicone was the next choice but its puncture resistance seems lower and so far with my prototypes don't look like they stand the test of time very well - still in testing though. Plus less people who working with it in the UK compared to plastic.
TPE keeps coming up as perhaps a good medium but I have not had much exposure to it plus liked the idea of being non plastic reliant due to ingestion risk and environmental factors.

I have in progress silicone and latex rubber prototypes to test out but I am unable to find if you can create TPE prototypes at home (liquid pourable TPE) - I found one liquid TPE replica (PT Flex Liquid Rubbers) but it was sold out.

Anyway I have read online that I could perhaps use two materials, one tougher part to reduce puncturing and softer part moulded over the top however I have concerns this would rapidly increase costs.

I am a small start up business so can't just throw money at the tool and hope for the best as I really only have one shot. Looking for the option with affordable - medium price tooling and low cost per unit off the tool ideally. The part is small which helps <100g.

Looking for someone who has experience working with these materials and can give advice on longevity and puncture resistance for each material. Is there anyone that can give some advice on materials and their physical application / point me towards a suitable consultation services or freelancer?
I would be looking for a 60 minute chat. NDA signing will be required due to the part being complex so adviser would need to know the full product and its application.

I have spoke to various tooling companies to get rough quotes so know the making the tool itself is possible but each company is recommending their own material as the most suitable but from preliminary testing I am cautious of rushing into the tooling and having a finished product which doesn't last long enough due to nature of item.

I am knew to manufacturing so I hope this is okay question to ask, any tips would be amazing. Based in the UK. Thank you

I am currently experimenting with silicone moulds, and I am thinking on creating my own. The challenge I want to address is the best way to get rid of layer lines. I have 2 option:

1: Print the mold, cast the object with gypsum(or other material). Sand the gypsum until I am happy with it, create the mold from the gypsum object.

The reason for this option is that I consider easier sanding gypsum than PLA.

2: Print the object, make it smooth, and create the silicone mold from it.

Option 2 have less steps, however I am worry that sanding and filling the PLA would take longer than expected. Since once I got the silicone mold I will not need this piece anymore. Is ther a dirty and quick way to smooth PLA?

Any suggestion would be appreciated

https://preview.redd.it/1pr5j93pozzg1.png?width=978&format=png&auto=webp&s=61834f39b502af73ac22b63b1546ae66b76b0ede

https://preview.redd.it/e8t7iu3rozzg1.png?width=967&format=png&auto=webp&s=803f4db2287818576df67981b0dfbdae6f3f0ae4

https://preview.redd.it/pkruiq2tozzg1.png?width=1272&format=png&auto=webp&s=956e7e0f4f63eced5ddfffc7a45a82c56d0876f9

Explain like im 5 yo please, maybe 4 piece mold?

Hi all. Thanks for any help.

I’m looking to fabricate a “high roof” for a van.

Basically same shape as a small boat. Should I do ABS or fiberglass with aluminum frame? I’d love any other ideas. Upside down boat is tempting, but I’d rather learn how to fabricate such a thing.