Mold Design Goes with the Flow

13 Mar, 2004 By: Adrian Scholes

Solid Edge offers a practical solution for mold designers that combines data import, cleanup, and shape modeling with mold design automation, documentation, and integration with analysis and manufacturing. Here are some ideas to explore as you implement Solid Edge for mold design.

Data Import and Validation
Getting a product design into your mold design system with minimum hassle is critical. Using Solid Edge's import wizards, you can import, validate, and analyze thousands of surfaces. The Import Options dialog box lets you specify how Solid Edge uses imported data. For example, you can have Solid Edge heal any inconsistencies in the surfaces or solids contained in the imported file. Solid Edge cleans the faces to resolve underlying problems such as self-intersection, multiple intersections, and edges equal to or smaller than the minimum stitching tolerance. Once it cleans the faces, Solid Edge identifies and removes sheets that are invalid due to bad trimming curves as well as sheets that result in slivers. Healing also repairs solids by resolving issues such as self-intersections, tolerant edges, and topology problems. These wizards ensure your product design data is intact and accurate before you begin your mold design.

Part Preparation
Once data is imported, the part often requires further design work. This might involve a relatively simple preparation of the model for manufacture, such as defining a parting line, or more detailed modeling to ensure the part will mold successfully. Solid Edge's Rapid Blue approach to surface definition lets you focus on getting a clean, correct shape while maintaining C2 continuity. For any detail work, you can access features such as web networks, mounting bosses, and lip/groove that are typically used for constructing molded plastic parts. You can easily add draft to faces, blend edges, and "thicken" areas of the part to ensure successful manufacture. Watch for a future installment of On the Edge dedicated to using Solid Edge for plastic part modeling.

To ensure that surfaces are smooth and able to produce quality molds, Solid Edge provides a variety of curvature display, shading, and zebra-striping analysis techniques. Using Draft Face Analysis, for example, you can graphically inspect a model for manufacturability in terms of mold ejection. After you set the required draft angle, Solid Edge displays faces of the model in an appropriate color so you can identify positive, neutral, and negative face angles and faces that are less than the specified angle.

Figure 1. The yellow faces on the ejection (negative) side of the part indicate that the draft is in the wrong direction (positive) and won't eject from the mold.

Once you have a valid part, scale it to allow for shrinkage and use the Parting Edge command to automatically generate the parting line. The Parting Surface feature adds a surface that radiates from this line, and you can use a simple Boolean command to create the core and cavity. From this you can begin to build the mold, using either Solid Edge's assembly creation capabilities or the new, automated Mold Tooling application.

Changes and Collaboration
As with any design process, changes are likely to occur once the mold design is in progress. Insight Connect can help streamline this change process. Last month's column detailed how Insight Connect facilitates OEM/supplier communications by automating process workflows such as design reviews and enabling native view and design markup.

Mold Tooling Automation
Much of mold tooling design is highly repetitive. You can save time using the automated, step-by-step workflow in Solid Edge's new Mold Tooling application. This application leads you through a logical process, beginning with applying an accurate (uniform or nonuniform) shrinkage factor to the molded part. It then determines parting surfaces and automatically sizes and creates core and cavity blocks based on the part size. For multicavity molds, you create a pattern of the blocks. Mold Tooling lets you quickly reorient the individual blocks and automatically center them in the mold base for a balanced runner system. Mold bases that support common international standards, such as DME, Futaba, Hasco, LKM, and Misumi, are included with the application. Pick the appropriate standard and Solid Edge creates the mold base using the cavity and core pattern to determine the catalog size for the plates.

Figure 2. Solid Edge Mold Tooling automated the creation of core and cavity, mold base, and supporting components to successfully mold this utility knife.

Once you create the mold base, add the remaining components such as bolts, ejector pins, return pins, leader pins, and support pillars. The system makes all necessary updates to the mold base and plates. When you place a bolt, for example, Solid Edge creates the correct tapped holes, clearance holes, and counterbores in each of the affected plates and automatically shapes the ejector pin ends to match the contour of the parting surface. To finish, use a simple 2D sketch to define the path for the runner system, and Solid Edge Mold Tooling adds the runners to the 3D model. Select the gates you wish to use, and the system automatically adds them to the end of each runner system in the mold.

Document the Mold
Accurate and complete shop drawings are still an essential deliverable for most mold designs, along with any other communication methods that aid the design-through-manufacturing process. Thanks to similarities inherent in new mold designs, Solid Edge Quicksheet templates can help speed up and standardize drawings. You can set up a template for how you wish your drawings to be completed-ISO and BOM on sheet 1, sections on sheet 2, details on sheets 3 and 4, and so forth-and just drag new mold designs into the template. Solid Edge regenerates views, balloons, bills of material, and other details to match the new design. Its capabilities for exploded views, shaded views, hole tables, parts lists, and bills of material are indispensable for mold tooling drawings.

Manufacture and Assembly
At this point, you've used Solid Edge to develop a part and mold design that will result in the part the customer expects. Now you can use other downstream tools for flow analysis to make sure that the plastic material will fill the mold correctly. The final step in the process is to manufacture the mold and assemble it for use in the injection molding machine. Using CAM solutions from the Solid Edge Voyager program, you can provide seamless data for tool creation. And you can use Solid Edge to create clear assembly documentation using exploded views, rendered images, and animations.

End-to-End Solution
Sophisticated features, developed specifically to ease the design of complex shapes prevalent in consumer products, already make Solid Edge a powerful tool for mold designers. With the introduction of Solid Edge Mold Tooling, the system provides an end-to-end solution for the consumer products industry. Add to that its unique collaborative environment, and you can improve customer communications and service-minimizing changes and reducing delivery time without high-priced implementations.

See you On the Edge next month.

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