Draft in moulding 2

[sudhakarn]

Hi,
Got a question here.Going by the definition of the Draft,it is useful for easy removal of the part in the moulding.If we need a straight face in the final part,how do i go with it?Need clarity pls.

 

[racookpe1978]

In original sand molding, the draft angle was needed to remove the forming object from the sand mold. Today's mold forms and some modern forming options offer some ways to minimize the draft angle, but not many. Some of these options are more expensive than sand-formed-by-unskilled-workers-in-low-tech-conditions.

Without more detail of the materials, the tolerances, and the mold itself - we cannot say more. Be aware that your mold company (the casting company) does want to make it simpler for themselves! Not for yourself, or the machining that has to be done to cut the wall perfectly flat later.

 

[sudhakarn]

Hi racookpe,
Thanks for your reply.So i understand that the machining is done after the draft in order to make it a flat surface.Am i right in my understanding?

 

[John2025]

What kind of molding are you talking about? The processes and requirements vary dramatically. In most cases you can get what you want, but the costs can skyrocket.

 

[ornerynorsk]

As John2025 mentioned, we need to know the material and process before we can give useful suggestions. A drawing or sketch of the part would be equally helpful.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[BrianE22]

If the part is injection molded plastic you can use "side pulls". I think they maybe are also used on die cast metal parts. Lot's of money though!

 

[sudhakarn]

Hi folks,
Thanks for your replies.But here i want to understand the process of why the draft is given and if the part needs a flat face (apart from tapered face),then what will be the solution.

 

[3DDave]

sudhakarn - look at any book on the casting process. Google "casting draft" or "molding draft"

Presently your question requires millions of answers to maybe figure out what problem you think you have.

 

[ornerynorsk]

We cannot even begin to offer you an suggestion unless we know the material and the process. You must understand that sand casting grey iron is a far different process than injection molding glass filled nylon, and thus, requires a different method to accomplish a certain design feature. While there are many extremely knowledgeable technical people on this form, few of us are clairvoyant.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[sudhakarn]

Hi Folks,
Thanks a lot for your replies.I am a new bie for manufacturing.I just want to understand the fact that whether we provide a draft for parts with the straight faces instead of a tapered face.Please excuse me if i am not clear in explaining my requirement. Thanks.

 

[MikeHalloran]

On a typical squarish part, it is possible to have zero draft on up to two faces, by adding draft to the complementary faces.

It is also possible to mold faces that are not perpendicular to the mold's parting line.

Read a book or two.

Better, design a part and bring a print to an experienced molder.
(S)he will redline it to death, and you will learn more than we can teach you here.


Mike Halloran
Pembroke Pines, FL, USA

 

[racookpe1978]

No.
If you define a flat face (vertical face), you have defined NO DRAFT.
If you define a face with "draft" that face is IS SLOPED.

Now, as pointed out above, two faces can be parallel to each other and vertical, and - with great care in molding and mold removal - two other faces can be molded with draft.
Or you can define a face with draft (slope) and then machine the face afterwards vertical.

Or you can select a different molding technique than cheap sand casting.

 

[sudhakarn]

Hi Racoop,
Thanks a lot for your insights again.Your replies are more positive and encouraging than many other replies here.

 

[arunmrao]

"Your replies are more positive and encouraging than many other replies here."

@sudhakarn,

Your statement above is unfair and unacceptable . The members have spent their time and contributed based on your ill prepared and poorly drafted question.

It lacked details and specifics, yet these outstanding and helpful members tried their best to offer suggestions.

In fact,I restrained myself from participating as your question was a lazy one.

My advice to you is come back after framing your questions well and avoid deriding other members who tried to be helpful.

@ All other members who participated in this discussion THANKS.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[sudhakarn]

Hi Arumrao,
Thanks for your insights.Apologies in case i have hurt any one.I just wanted to mention that the users can be polite and gentle in their replies.Because had i been an expert,i would not have posted the question in that level of ignorance.

Hope you understand.Again apologies from my side.Not everyone is an expert in everything.

 

[MikeHalloran]

Polite and gentle is provided elsewhere.

Your original question was grossly incomplete, because in it, you did not reveal:
- what material you are trying to mold.
- how big the part is.
- how deep the part is.
- how complex the geometry is.
- how tight the tolerances need be, for each and every feature of the molded product.
- how many parts you need now, and over the design lifetime.
- how many parts you need in a day.
- how much capital you can raise.

The answers to that original question will vary considerably, depending on your answers to the items mentioned hereinabove, and many more.

Mike Halloran
Pembroke Pines, FL, USA

 

[SceneryDriver]

A little late to the party, but this may be of some help:

https://www.youtube.com/watch?v=RMjtmsr3CqA

SceneryDriver

 

[sudhakarn]

Hi Scenery driver,
Thanks a lot.Better late than never.

 

[enginesrus]

If you need a flat face then very simple that has to be at the top or the bottom of the part as seen sitting in the cope or drag.