3D further on

[Manteuffel]

Is then 3D model necessary for the production of injection molding?

What software is mainly used for its design?
It Has To Be Compatible with CNC machines Which I guess are Preparing Form?
Can anybody guess what is the cost of form for lets say WW2 Destroyer?
Just tooling without data preparation.

Thanks for reply

[Guest]

It is possible to create molds for injection molding from 2D drawings - that is how it was done for decades before 3D CAD came along. However, today I suspect most new design is done with 3D CAD because it can be used to drive CNC milling machines to prepare the molds.

Numerous CAD programs are used for mold design. Anything that has CNC code output could be used. If you are planning to work with a specific machine shop you should ask what they use.

I have only a little experience with injection molding, but the last time we created a two piece custom plastic injection molded case the cost of the molds was around $100,000US to $125,000US. It was a bit fancy, with a rubber grip molded around the plastic, so a mold for a simple single piece hull might be much less, perhaps a fourth the cost.

Perhaps someone with more experience can give more precise numbers.

Phil

[Cadman]

2D CAD will get you close, but it just means more work for the machinist who is tasked with cutting the tools. What is really needed are good 3D solid models of all the parts. But it is more than just creating the outside of the parts. Someone has to hollow or shell out the parts figure out where to split them and add locator pins and tabs as needed. Careful planning on where the ejector pins are located, where to add risers and where the sprues attach to the actual parts. The latter is a balancing act between efficient filling of the mold and easy removal by the modeler.

[Manteuffel]

Do big manufacturers use programs like Creo Elements/Pro, does anybody has experience with similar one?
From information mentioned does it mean that when using this software, you dont need real model,
this electronic 3D software should allow even prepare mold and import data into NC machine preparing plastic injection mold. Is that current manufacturer SOP or are they still preparin fyzical model etc...
If not, what software are big using?

[DrPR]

A physical model of the design is unnecessary when working in 3D CAD. The virtual model is used to create all of the NC machine code to drive the machines that make the mold.

Usually the first run test pieces are used to check the molds and refine the design if necessary.

Many CAD programs have modules or add-ons that are used to create the mold patterns. These compute the mold relief and injection channels needed for injection molding.

You need to look at the web sites for the different CAD programs and see if they have mold making support. User forums are a good source of information.

Phil