NX Routing Mechanical Notes – Part 3

NX Mold Wizard: Impressive Commands

This 3-part article will discuss a few of the commands within NX Mold Wizard functionality that indicate the level of sophistication of the software product. Part 3 will discuss the steps that create the cavity and core inserts. In addition, it will discuss how to slice it into the two halves. It also provides a rough overview of completing the process of building parts and subassemblies of the complete mold assembly.

Defining the Workpiece in Your Mold Wizard Project

This step can be implemented with several different approaches.

The Part

As an example, we’ll work with a small injected molded part designed to rotate like a pump vane. It could even be a part in an industrial assembly machine that loads parts into position in an assembly.

You’ll see in the references that follow that the part is named “double_flipper”.

Reviewing the Mold Wizard Work Flow Process

Any user involved in designing tooling that fabricates parts and products using molding processes can benefit from selected portions of this functionality:

• Create Mold Wizard product assembly

• Apply a shrink factor

• Define core and cavity regions within a product model

• Create patch up geometry

• Create mold tooling inserts

• Use mold base libraries to choose a standard mold base

• Use standard part libraries to select and position common parts, including insert pockets, sub inserts, cooling channels, gates, and runners

• Create a bill of materials

• Begin mold assembly and component drawings

To reinforce these best practices, we’ll assume that some of the tasks we’ve already discussed in Part 1 and Part 2 of this article have already been accomplished.

Normally, you will want to validate the part design for moldability.

Check wall thickness.

Check regions and pull direction

Drafted faces – 2° reference draft

Check regions and pull direction

Drafted faces – 2° reference draft

Define Region – cavity

Define Region – core

Perform a mold flow analysis and display the results

Here’s the one we did in Part 1 of this series, “The Skinny on NX10 Mold Wizardry”:

Initiate the Mold Wizard project

This is an essential step. If you remember from Part 2 of this article, this command creates the entire mold assembly structure. This includes subassemblies and many bottom level components that can accommodate optional parts and data that you may choose to include in this Mold Wizard process.

Although this task doesn’t create the actual bodies of the parts in the mold, it does create the containers for them. The project initiation process does use template parts that contain some geometry. For instance, try making the “prod” assembly the Work Part and highlighting the “cavity”.

If we make the “cavity” file the Work Part, we can see a solid block and a sheet body. The are both named and assigned the attributes/metadata necessary to make all the links work for you within the mold assembly.

Every time you complete a step and close a Mold Wizard dialog, you should save all. This needs to become a habit because one of the things NX does when it saves is to “clean up” for itself by updating features and geometry as well as interpart links and other information such as metadata, the Undo buffer, and many other things. You’ll find this tends to preserve the integrity of your Mold Wizard sessions too.

Assigning a Mold CSYS

Consider the possible situation that in its own part file the product part that we’re building a mold for is oriented in a way that is contrary to how we will want our mold to be oriented.

Mold Wizard has a function called Mold CSYS. This function allows you to change the product part location and/or orientation within the mold assembly without affecting the model in the product part file. This is of particular importance when it comes to the parting surface or plane of the part. It is important to place the part in space where that parting line/plane is relative to the two halves of the mold.

In this “double_flipper” part file, orientation is acceptable but we have to look at the plane where the cavity and core sides will part. Look at the hole in the middle and the coloration that the Check Regions function did for us. If the orange is the cavity side and the blue is the core side, we’ll need to part the mold where the hole meets the counterbore.

The Big Picture

The entire outside of the part down to the bottom will be formed by the cavity side. We need to part the mold at that plane on the bottom of the part. Fortunately, that plane happens to be at the X-Y plane of ABS. No problem!

We can create core pins that “kiss” in the middle to form the hole, counterbore, slot, and countersink on the bottom. However, this is only as long as the possibility of a small amount of flash at that parting surface is acceptable. An acceptable amount might be .01” or so. It depends on if this part is just going to be stuck onto the end of a drive shaft or rotor. If you’re a mold designer, you hopefully know all about these kinds of considerations.

Adding Shrink to the Mold

At this time, it would be good to incorporate shrink into the definition but we’ll keep the discussion short. If we incorporated the shrinkage right now, Mold Wizard would automatically make the “shrink” file the Work Part. We would would have three options to choose from:

Mold Wizard will default to the shrink factor identified when we first selected the material in the initiation of the project (1.0045). Based on the selected option, Mold Wizard will allow us to manually enter different values for the various directional elements.

The Workpiece

The Workpiece task allows us to define the core and cavity insert as one homogenous part. Mold Wizard can use that to calculate default mold base sizes, split into the individual regions using the parting geometry, and modify with the various mold tool. Most of these procedures can be done without changing Work or Displayed part. Mold Wizard does that automatically.

Notice that when you choose the Workpiece icon, NX changes the Displayed Part to be the “layout” part file and the Work Part to be the “workpiece” part file.

The dialog uses the default Workpiece Method of “User Defined Block”.

After Selection

As soon as the Workpiece icon is selected, Mold Wizard will read the default settings and create the geometry. When User Defined Block is the default Method and Sketch is the default Definition Type, it creates a rectangle in a Sketch that is larger than the product part by predefined Expression values already stored in the Mold Wizard definition. Notice the Distance values in the Limits fields highlighted above.

The Sketch has predefined Dimensional Constraints being driven by these built-in Expressions as well as some Geometric Constraints controlling the shape.

By activating the Sketch, we can see the actual expressions that result in those values and the Geometric Constraint symbols.

4 Options for the Workpiece Method

The 3 involving the cavity or core offer options to select an existing solid or solids as the Workpiece(s). You could also select from the Workpiece Library.

When you select the Workpiece Library icon, the Reuse Library tab is opened in the Resource Bar and another dialog appears to aid in defining the Workpiece(s).

An alternate Define Workpiece option is the Definition Type of Reference Point which uses the ABS 0,0,0 position as a base point. This allows the user to input positive and negative offset values manually.

You need to be careful about clicking in the graphics area while this is in process. Mold Wizard will redefine the base point and mess things up a bit.

If this happens, you can use the Point Dialog option to reenter the base point values for ABS 0,0,0. You can also Reset the dialog. This will change all options and entered values back to the way the dialog was set when first opened.

Regardless of the options and values chosen, select OK to the Workpiece dialog and a result similar to this will appear:

NOTE: The Workpiece is translucent. If yours is not, you may need to turn on this option in your Visualization preferences.

In the Visualization Preferences dialog box, on the Visual page, select the Translucency check box.

Once that step was completed, Mold Wizard automatically returned the Work Part back to the “top” assembly file.

Parting Geometry

Now we’re ready to check regions again, which will have retained information from doing it earlier. We’re also ready for defining the regions. This is a more definitive assignment of faces to be formed by cavity or core sides of the mold. This will enable Mold Wizard to automatically identify a split between cavity and core sides of your Workpiece.

All of these functions are in the Parting Tools group on the Mold Wizard tab.

But before that, another step is necessary. Any planar regions where there aren’t faces of the product part body but where the cavity and core will need to meet face to face will need a separator face. These are called Patch surfaces and can be easily created on a part like our “double_flipper”.

Define Regions

Now we could move on to the Define Regions step and fully assign every face in the part to a region. The objective here is to make sure there are no “Undefined Faces” in the model. We can do this by alternately selecting “Cavity region” and Core region” nodes in the Region Name list and selecting faces of the model to add them to the desired region.

If desired, additional regions can be defined for side pulls, slides, lifters, etc. Remember that all faces of the model have to be formed by steel in the mold. Steel exists in one part or another, whether it’s cavity, core, slide, etc.

Next, select “Apply” to complete the definition of regions and when everything is assigned. Turn on the Create Regions and Create Parting Lines options and choose OK.

Design Parting Surfaces

The next step you might complete is to design the parting surfaces. In this step, Mold Wizard creates continuous surfaces that will cut through the Workpiece and divide it into cavity and core sides.

There are a lot of options here and, depending on the complexity of the shape on the product part, it can get intense.  As soon as the icon is selected, Mold Wizard builds a surface at the parting line of our part which has a cutout at the actual part geometry.

And then there’s a step to Define Cavity and Core. This is where Mold Wizard actually splits the Workpiece into two.

Upon choosing OK, the graphics area flashes a bit and then a preliminary result is displayed, waiting for your approval. Here’s our cavity insert, top/cavity side:

And the bottom/core side:

View Parting Result

If all is well, choose OK in the View Parting Result dialog. Sometimes, the normal vectors can get reversed. The result might show the core side as the cavity side and vice versa but this doesn’t happen often. If desired, you can reverse the normal just to check some things out.

Now that we’ve split our Workpiece into real cavity and core inserts, we’re ready for the big finish. Make the “top” assembly file the Work Part and here’s what she looks like.

We haven’t even created a single piece of geometry, Mold Wizard has done it all!

Building the Mold Geometry

To say that we’re going to build the actual mold geometry is a bit deceptive. As you have seen, much of what you do in Mold Wizard is tell it what to build and how. This step relies heavily on the Reuse Library and in particular, the Mold Wizard Engineering Data Base.

The Mold Wizard Engineering Data Base must first be downloaded from the Siemens website or our Swoosh Customer Portal. It must then be unzipped to a new folder within the NX base directory. The zip file for NX10 is “mwnx10_data.zip”. Also, we’ll need to create an environment variable:

MOLDWIZARD_DIR = <yournode>:\<yourbasedir>\moldwizard_data

Next, start NX10 and explore your Reuse Library to find stuff like this:

Mold Base Library

To get these mold assembly parts modeled and built inside our assembly structure, we will first make sure we’re working on our “top” assembly file of our mold structure. Then we’ll go back to the Main group in the Mold Wizard tab of the Ribbon Bar where we started this article and choose the Mold Base Library icon.

Once selected, it’s possible this can be a bit confusing, especially if your default dialog position is right on top of your resource Bar.

The Cue Line says nothing. It’s waiting for you to move the Mold Base Library dialog and select from the Reuse Library that it just opened for you. And if you don’t have your Member Select group open, you don’t see much of anything to actually pick.

Now you can select the various vendor folders above and peruse the vast list of mold configurations.

Speaking of configurations, do you remember when we first created the mold assembly structure by initializing a project? The mold configuration you selected will have an impact on what and how Mold Wizard will build for you.

You should also open up the Preview group of the Reuse Library to see what these molds will look like, at least in the basic definition. Upon selecting an actual mold base member, be patient. Mold Wizard is going to not only show you a picture in that Preview window but will also display a popup that has a side view diagram of the plate design.

And if we look a little closer at the Mold Base Library dialog, you’ll see a few things worth noting.

Rename Components

There’s an option for Rename Components so you can replace the default acronyms like TCP_h and EP_3 to something more meaningful to you or that complies with your standard part names.

There’s an Information Window icon that controls that diagram popup that appeared.

You can also edit any of the expressions and attributes listed in the Details group, make it smart, base it on a spreadsheet, etc.

Choose OK and watch Mold Wizard go to work! And you have to be patient here because it is referencing hundreds of definitions, expressions, attributes, configuration settings, etc.

There are options where you can get into the Register and Data Base attributes that Mold Wizard uses prolifically. That’s a whole other story there.

But you’ll see, if I go to a right side view, I was a little hasty. I probably needed to resize the A and B plates along with a few other tweeks.

Looking at the Assembly Navigator, you’ll see some new additions to the structure. There’s a whole new “base” subassembly.

And if you choose the Mold Base Library icon again, it allows you to edit those things. You’ll also notice that many of the expressions in the list have multiple choice drop-down lists to stay with standard sizes offered by those particular vendors.

With just a few new selections of values and selecting Apply, I can get a whole new design very quickly. Now my cavity and core inserts actually fit!

Summary

There’s more to it than just picking a mold base from a list. In addition, there are more considerations for how a mold should be designed. If you look at the orientation of the part, the cavity and core side positions, and location of the ejector box, things would probably work out better if that was reversed. Accommodations can be made while building it, or later based on your standards and traditional practices!

The process of building this whole mold in NX is fairly painless compared to starting from scratch. There are certainly a lot of mold shops that already have their own templates, tool libraries, mold design philosophies, etc. that might not do a lot that Mold Wizard offers. A lot of companies are only aware of the price and not the extremely robust capability it now has.

Other Considerations

There are many other common and not so common steps:

• Molded Design Validation
• Establishing a Mold CSYS
• Incorporating a shrink factor, uniform or non-uniform
• Defining closure (patch) surfaces
• Establishing mold parting faces
• Defining regions for cavity and core side surfaces and side-pulls, inserts, slides, sub-inserts, etc.
• Creating tool geometry directly from cavity geometry
• Using Standard Parts from the Mold Wizard Data Base
• Designing gate and runner systems
• Inserting the cooling channels and hardware
• Auto-creating pockets for hardware, standard parts, ejector pins, slides and lifters, etc.
• Mold parting and ejection simulation
• Merging cavities
• Creating drawings of mold parts and assemblies
• Defining BOM’s
• Adding hole tables and ejector pin tables
• Interrogating mold structure and design such as interference, calculating surface area, WAVE management, etc.
• Exporting mold data such as BOM’s, reusable parts, attributes, etc.
• Customizing Mold Wizard

If you’d like to read more about these Mold Wizard capabilities, send us some feedback and let us know! There’s a lot more to talk about.

This concludes Part 3 and the Mold Wizardry blog series.