Looking for some better cavity/core tutorials

I'm not jk or mm, but I might be able to tell you what you need to know about the SW mold tools.

If you are doing anything more complex than a trivial box, SW mold tools are likely to choke. In fact, if the PL has any section where it is concave at all, the mold tools are almost guaranteed to not get you where you need to go. By "concave", I mean if the projected outline of the PL onto the parting plane is like a "C" instead of like an "O", then forget it. The weakest links of the SW mold tools in my experience have been the Parting Line, Shut Offs and Parting Surface functions.

In fact, the Tooling Split function is going to give you multi bodies instead of separate parts in an assembly. Feed that to your CAM program.

I won't bother plugging the mold software I like, cuz your old school fella isn't gonna like it, but in general, here's an outline for how the mold splitting stuff works:

1) Draft analysis. Figure out what faces are on which side of the PL, and if any faces straddle it or form undercuts (undercut would be a single blue face (core direction)in a sea of red faces (cavity direction)).

2) Split any straddles and put them to the correct side, fix undercuts

3) Collect faces of any side pulls. This is actually something that the SW tools are really good at - in SW05 there is a new "Core" function (extremely unfortunate name) which allows you to just make a sketch and extract a core.

4) Build the parting faces. This is typically the hard part. For simple PLs, it can be done using a Radiate or Ruled surface from the PL, but in more complex PLs, it's not a single step, you might have to use planar, or extruded surfaces, lofted surfaces, etc.

5) Close any windows or shut offs. A hole through the part needs to have a surface placed where the steel from one side of the mold will touch the steel from the other side of the mold

6) Passing shut offs are a manual modeling exercize regardless of what software you use (as far as I know).

7) Knit the parting surface together with all of the faces on one side of the mold together with the shutoffs and passing shutoffs. This basically creates the functional end of one side of the mold insert.

8) Extrude up to the surface you just knit together. This should be done in an assembly. Don't make a multibody part. This is just an opinion, but there are a lot of reasons behind the opinion.

9) Extrude the other side up to the same surface, and subtract the original plastic part from it with an incontext cavity feature.

10) If you followed that much, you can figure out how to do any side pulls, cores, actions, lifters, etc.

Anyway, that's the method (plus or minus) used by Splitworks or Faceworks or even Imold, I think. You can also do it manually. To do that it's easiest if you use a face selection filter and window select while looking straight down at the PL.

Anyway, good luck.

matt

Sporkman wrote in news: snipped-for-privacy@bigfootDOT.com:

I'd kind of quit responding to these threads. However, since you mention me by name, I'll speak up. I just read what Matt had to say and agree with his approach. I can't say that I always do it that way myself, though.

As far as what he says about the mold tools, I'd have to agree. The multi-body approach doesn't make any sense to me either. Maybe somebody can explain to me some day how one gets from having all of those nice separate solid bodies in one part file to having a sub-assembly of separate solids to drop into my mold base.

That being said I have found ways to use some of the functionality in the mold tools as a way of collecting surfaces for creating cores,cavities,side pulls,etc. I'm also not a big fan of the way SW generates a parting surface, and I will almost always do that manually.

I often don't use any sort of surfaces sort of approach to the split at all. I just extrude blocks and do what I call preparing them for the cavity function. (this is a way of dealing with the parting line and all of the openings that Matt was referring to.) Then I use the cavity feature and my core or cavity feature drops out.

There is no good cookbook that I have seen for brewing all of this up. I know that what I have just spent 10 minutes typing does not scratch the surface or maybe even make much sense to you. That is one of the reasons that nobody has written a tutorial- everyone does it a little differently and each job is unique.

I don't mean to sound like a mold design snob, but it's hard for me to imagine how somebody who doesn't do it every day is going to get proficient at splitting cores and cavities on an irregular basis. One way to approach it would be to hire somebody to split some of your parts with SW and then have them go over it with you step by step. I'd offer to do it for you, but it's my brother who lives in Charlotte-not me. I'm in California, and rarely get back there. Matt's a lot closer.

Good luck.

jk

Thanks for your replies, both Matt and John. I understand enough to see that it's as clear as mud and that's just the way it be. No fault to you. I appreciate what you wrote, though, and I'll see how much of it I can make sense out of.

Best regards, 'Sporky'

jk wrote:

Don't be discouraged. To me, learning how to do mold design was the toughest work I've ever done in SW. I had to work with some people who knew what they were doing in order to get the hang of it. It may not come to you overnight. Knowing how to do the modeling is one thing, then there is knowing all the details of how the mold works, where to put the cooling, what type of cooling, different types of mechanisms, and all of the engineering details that make it almost as much machine design as anything. I can't do the second part, and my hat's off to those who can.

Anyway, good luck.

matt

Sporkman wrote in news: snipped-for-privacy@bigfootDOT.com:

jk,

I will try to explain one way. It is not very "straight forward" but:

1. In the Solid Body folder, right click one of the bodies and select "Insert into new part". A new part will be created with this body only making up the entire part.
2. Repeat for all bodies.
3. Insert ALL of the newly created parts into a new assembly dropping each one of them onto the origin.
4. You now have a sub-assembly of the molding inserts that you can use to drop into a moldbase. Changes WILL propagate to these new parts that were made from the bodies.

Hope this helps.

Even easier than that is to use the Split (Insert, Features, Split) command which takes the bodies, saves them all to individual parts, and assembles them back into an assembly.

My point is that an assembly is what SW should create as a product of their mold tools by default because most CAM systems can deal with individual parts better than multibody parts. Beyond that, to create drawings from a multibody part requires doing a dance with configurations. Plus, just from a data organization standpoint, with the multibody approach you're putting all of your tooling and plastic part design data into a single file.

"Seth Renigar" wrote in news:gNlnd.6378$ snipped-for-privacy@twister.southeast.rr.com:

True! I agree with everything you say... That's one of the reasons why I don't use these tools. I just use SW with no add-ons. I have developed my own methods and techniques that would take a small novel to describe, but is very robust. It might not be the most efficient way, but like you say, from a data organization standpoint it makes sense (at least to me anyway).

Thanks to Seth and Matt for clearing up that business with the muti-bodies. I use a base part type of technique myself, and I thought it might be something like that. Like Seth, I have a way that works for me that is difficult to explain. What's important is that it works and handles revisions well. Also, because I have a method that works, I never spent too much time with the new tools-might have figured out that multi-body to assy thing for myself if I had, I guess.

I used to use MoldWorks and SplitWorks, but now I also only use the SW core. Everything that you need is in there, except the library of mold bases and components. I had a very long slow period and spent my time then working on my personal library. That's probably the biggest stumbling block to somebody getting started.

jk

Thanks to all three of you for attempting to educate me. I've found a way that works for what I need right now, and I'll go back over all of these other ideas later. Using the info you all supplied may help someone else as well.

Best regards, Mark 'Sporky' Staplet>

Hello and thanks to everyone that contributed to this thread. It has been quite helpful AND I am still waiting for a concise, thorough book or tutorial to help me with this topic of mold building. I do some very simple molds for plastic, but mostly design and manufacture patterns for metal castings.

Thanks again, Jerry Forcier

Sporkman wrote:

Matt-

I've reluctantly given up on split parts and gone back to the base part method because while they seem the ideal solution to a number of toolmaking problems, the problems they create can be show stoppers.

I've spent hours trying to pin down how my problems occur in simplified assemblies (i.e. emailable) with no luck, and just gave up on the whole business a few months ago. The problems seem to center around parts with a complicated base part feature and multiple configurations. If the part containing the base part contains a split feature and is opened without the base part being open as well, all the features below the base part feature fail with a message something like "no body to act on".

That's only one problem. Additionally, split part features take a really long time to regenerate and seem like one of those swx features that can get set to always rebuild.

Also, there's something buggy when the feature that creates the split (the sketch or surface body) changes, then the split bodies references get lost. My sense is that this one may be improving with the newer sp's.

It's really a shame, because the concept is so promising and in theory a big time saver, not so much for the initial tool splitting, but for the more everyday stuff like sub inserts and corepins.

-Jason S.