Any mold maker around?

[kanankeban]

You can make new inserts for much less than new molds. It's a though anyway.

Tell me more about this inserts?

Regards...
Hector

[snaggletto]

Hey,
I worked in a mold shop for a few years. An insert is the part that you spend hours machining, the area of the mold that forms the plastic. Basically you rough out large pockets in the mold A and B plates. Usually with a step and a way to bolt the insert in from behind. Then you make the 'mold' on other pieces of material (the inserts). The benefits are; if you scrap it, you only scrap an insert, not the whole mold plate. If the customer needs a big change, you just remake the insert. I've even seen where several different sized parts where made with the same mold base, but with different inserts.

The insert has to be a very close/flush fit to the mold plate. Any slop or uneveness can cause flashing and other problems. As one of the other posters said, if you can find an older mold base, you can machine out the old mold pattern and make pockets for your new inserts. Good luck.

[723]

From an owner and operator of a mold making shop. We slowly moved away from the injection molding business to a job shop because, like stated earlier, everything is moving overseas. To be a mold maker, you need to become a machinist, CNC programmer, designer, EDM operator, CAD/CAM designer, and a few others to be able to compete with this kind of market. I personally know a few people who can do the above tasks, but are not qualified to be a mold maker. It takes more then a few years of experience to start cutting your first mold.
To answer some of your questions: First of all there is no such thing as an injection mold with loose tolerances. Your part might be, but not the mold. You also need different molding machines for diff. Parts. You cannot mold a bucket with a 150-ton machine unless it is a very small bucket, so before making any purchases, do a little research. The easiest part of molding/mold making is buying molding machines. At local auctions they go for dirt-cheap prices. There is much much more involved to this then you can imagine. To get started enroll in a school. Start working in a shop so you can get your feet wet. After a few years, decide if this is what you want to do, and then go from there.

[vacpress]

hector

there is lots and lots of information available from the web. goto molding machine company sites, and look at the white papers. you will learn about all sorts of mold making terminology, and how complex even a simple mold for a garbage can could be.

imagine how the the walls of a typical plastic wastebasket are.. maybe.. .075 .1? anyways. that means your tolerances do have to be pretty low?

regardless - there is tons of info if you look for it. asking people for basic "how do i start a mold shop" is just asking for generalized advice that wont help much.

the gingery book might be a good 15$ buy for you. not that the machine is usefull, but it describes manual machining of an aluminum mold.

check out www.protomold.com to see what the competition is. its very tough. this company spent many millions on automation and 5 axis cnc centers. they only need a few people to run 15 machines or something...

plastic manufacturer websites will provide lots of info also, possibly. also, consider all the other support material you need for a machine, like a plastic pellet hopper, exhaust fan and system, and likely plumbing, and 440v or more electricity? all of these costs can add alot to a $15,000 used molder.. i would imagine.

as far as a fair estimate for how much it would cost to buy equipment to make some first molds for a decent used commercial machine.. lets guess:

used\referb 5 axis CNC Center - auction price - $20-40k ? maybe? i dunno.
Lots of tooling and stuff like that.. specific stuff for the first job - $5k?
surface grinder? a cheap import? - $2500
polishing and finishing equipment - $1200?
big blocks of steel or aluminum... for a guesstamite: checkout www.metalexpress.net

making molds with moving inserts, proper cooling cycles, proper cooling chanels, and other issues is generally not a task for someone who has to ask in a public forum what basic issues with the plastic mold making industry.

i would imagine you could build a reasonable business plan around aquiring used equipment carefully on auction market, and then using cheap labor to make inexpensive comodity items like trash bins.. then get a loan to buy the equipment? maybe. loooking at books on finding startups will possibly really depress you when you realize you are going to be a businessman, not an engineer or whatever...

with luck, "if you build it, they will come"
get a working cnc center and molding machine.. i bet someone will help you learn to run it for a reasonable rate.
hell. fly me out. i will figure it out.. and show you. im sure there is a faster, intuitive, well researched and executed and inexpensive path to your goals.. the research could take time. its a classic engineering maxim: "you can have 2 of the 3: speed, quality, low cost"

hope this helps.

[vacpress]

ok. more on that cost thing.. i realized..

you need 3d/cad software with a mold wizard, a year of experience, and a NC toolpath generation progra, or a damn good NC programmer.

buy a real fast computer with a good 3d card! $4500 and also, you probbly need a bunch more stuff than i mentioned. 5k of tooling should do it.. maybe a 10-15k used 4axis cnc lathe, and another computer.
and some desks, lamps, shelves. a few reference books. well. alot of reference books. a small LAN, internet access, health insurance for the workors.. oh wait. thats mexico. duh. uhm. fish tank, a secretary... hmm what am i forgetting.

you need 200k probably

[Jim Estes]

I am a Moldmaker and have had my own moldmaking shop for 7 years now. I have done everything from large vacuum cleaner parts to very tiny computer parts. I have done hardened steel multi-cavity production molds, and single cavity prototype molds. Moldmaking is a very precise process, but once you learn the way it is done, it gets to be routine. I use a surface grinder for a lot of the work, along with Sink EDM and Wire EDM. Most of the milling and drilling I do on a Machining Center.
As for the "cheap parts" like the buckets and cups, just because the parts are simple, it doesn't really mean that the mold can be built cheap or that it will be easier to build. There will always be a certain amount of "precision" required to put a mold together and not have a lot of flash to trim, or uneven wall thicknesses, or weak point in the part. Also, if you plan on building molds, get used to spending hours and hours with a stone polishing, plastic will show every single scratch in a piece of steel or aluminum, and even cheap parts won't sell if they look scratched or "used". In most cases though you can "texture" the cavity to hide a good bit of the machining marks, you can use a bead blasting cabinet to texture. If you just want a few cheap parts to mold, maybe check with some mold shops around, most shops are always looking for more work, and these days the ones who are still in business are usually trying to find ways to build them cheaper and faster.
This is my first post here, I have been around CNC for 12 years and this place is awesome. Im very glad I found you guys.

[Stevie]

hi Jim

we have a Maverick Mold & Tool right in a town 1/2 hour from me (Ontario Canada)
Are they part of your operation?

Welcome to the forums; these are a great bunch of guys here; helped me out a ton
I have been at the trade for 35 yrs; and yes molds do take lots of time (I used to do Lex; and polish is everything)

[Jim Estes]

No, my "operation" consists of me and my machines, and occasionally my better half doing the taxes. I purposely kept my shop small to reduce overhead, because I know that the molding industry in KY is flooded with moldmakers, and ther just hasn't been enough business for me to grow my shop. I am branching out into other areas of machining to help take up the slack from the loss of moldmaking business.

I have always been very interested in hobby cnc and home brew cnc. Before I got my machining center I was researching a lot of different retrofits for my manual mill. There is so much information out there that it gets confusing just keeping straight what you could do. I even came up with a design for a High-speed CNC mill dedicated to making 3D electrodes. I haven't put my ideas to work as of yet, but I keep it in the back of my mind.
I am currently looking to retrofit my Sink EDM machine to be CNC controlled. The way I work, I try to keep both my Sink EDM and Machining Center running, and then I go and do work on my surface grinder. I get a lot of work done when I don't have to baby sit a machine.
Jim

[Stevie]

Like me; i just run my little shop and i do everything

I am slowly getting bigger and making more complex parts; like these babies

CNC turned then CNC drilled
German 7.92mm MG17 for the 1/24th scale ME109G
my site

[wizard]

The tooling requirement can vary widely as can the required quality of the molds. This based on experience in the die casting industry years ago. It wouldn't be impossible to get started with just a Bridgeport type mill if you really had too. You won't be doing extremely fancy molds going that route but most molds shops, need or have a manual milling machine anyways. I've seen some exceedingly crude molds in my day.

However that is a short time solution. Eventually you will need a CNC mill, grinders and all the rest of the stuff that is required to build a mold.

The thing is going the whole shot isn't wise in my opinion, better to concentrate on one end of the business first. If you want to mold parts seriously consider having your first few molds built by an established mold shop.

As to used Van Dorns or actually used injection molding machines in general they can be beaten to hell. Buying used plastic injection molding machines is something that requires great care least you get stuck with something that won't do the job. Hydraulic machines are especially bad when it comes to wear that can't be seen.

Originally Posted by kanankeban Hi. I'm setting up the business...looking for used equipment mainly...an the objective is to produce cheap plastic household items..nothing new around just plain plastic cups, spoons, napkin holders, maybe the bigest thing cold be a water bucket. Have some questions for you? 1. What tolerances should I look forward to obtain in teh molds 2. What kind of cnc machine center whould you look for? or what will be the machines needed to start machining this kind of mold. What type of machines besides the machining center do you need for finishing (polishing) the molds, etc. 3. As you mention earlier, you inject your self. What size and brad of injection molding machinesd you use. Any recomendation on a brand or used molding machine seller?

Personally I'd stay away from hydraulic machines these days unless you really require very large machines. As far as used machines go the Cincinnatti / Fanuc ATC series was a very reliable machine.

Regards... Hector

[mblount]

If you could learn the business and show your work I would go to 4 or 5 of the big guys and ask them if they turn down small runs would they refer the business to you. Keep in mind a smart shop owner will want to log in the work so you don't steal a potential customer that might have a bigger order later. You will also have to prove to the big boys that you have the talent. Some times the big boys get busy and need to sub out some work. This philosophy would also work on small mill work that the big boys don't want to do.

[trialanderror]

Good thread. Glad it was bumped. What are good machines to invest in now a days? Electric, hybrid, or hydraulic?