Mould structure Basic features in the injection molded or high pressure die cast part: draft, corner rounding, parting surface and undercut.

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1 Parting 2 Technical University of Gabrovo Valentina Todorova- Lazarova Tampere University of Technology Tuula Höök Theoretical background CAD tools in the exercise parting_2_1.sldprt Mould structure Basic features in the injection molded or high pressure die cast part: draft, corner rounding, parting surface and undercut. Mould manufacturability Steps to follow Take the SolidWorks part (start_parting_2_1.sldprt) or one of the neutral format models. Scale the part and prepare a parting line and a parting surface. Make a tooling split. 1. Scale the part. The scale factor depends on the plastic or metal alloy in use. Decide which material to use and find a suitable value. 2. Prepare the parting line with the tool provided with the software. If the part is designed with proper draft in right places, the software usually chooses the parting line position automatically. Parting line is positioned to the level of changing draft angle directions. Draft angle analysis is part of the SolidWorks parting line tool. The first step in using this tool is to select the pulling direction and to make the draft analysis. Draft analysis shows the draft angle directions with colors. There should be one uniform color in the core side and one uniform color in the cavity side. The parting line follows the part outer surface in the edge of the changing color. Parting line tool creates normally two surface bodies: One surface into the folder named Cavity Bodies and another to the folder named Core Bodies. See that the box Use for Core/Cavity Split is ticked. Features Plane Fill Trim Knit Mold Other Draft Analysis Scale Parting Line Tooling Split Reference Plane When ever there are problems in using these tools, open Solid- Works help and try to find the solution there. 3. Prepare the parting surface manually using plain surface tools, not the SolidWorks parting surface tool. Hide the parting line and use the part edges as references for the surfaces. If there are even small slot between the manually created parting surface and the part core and/or cavity surfaces, the tooling split operation will fail. The same situation occurs if the core and/or cavity surface and the parting surface overlap. Extend the surface at least mm outside the part. The parting surface should take the form shown in the image on the next page. This round form is ideal from the machining point of view. Pay attention to the shape in front of the slot. The shape should follow the part outline curvature. Parting 2_1-1

2 4. If it is necessary to prepare many separate surfaces, you need to knit them together with the Knit tool. Figure 1: Left: The shape of the parting surface. It is important that the parting surface follows the outline shape of the part. Right: Use sketches and part edges in creating the front shape. 5. Insert mould folders with the Insert Mould Folders tool. It is located under the Insert -> Molds menu. Parting line tool created a folder named Cavity Bodies and another folder named Core Bodies. Insert Mould Folders tool creates yet another folder named Parting Bodies. Drag the knitted parting surface inside this folder. 6. Prepare the tooling split. Start by sketching the mould or die workpiece outlines to the parting surface. The software should find all necessary surfaces from the folders Core Bodies, Cavity Bodies and Parting Bodies. If not, locate the surfaces manually. Tooling split creates three separate solid bodies: One is the original part, one is the cavity side of the mould (or die) and one the core side of the mould (or die). It is not necessary to take the workpiece dimensions from any real core or cavity plates. You are able to model the pieces further. Learning Objectives Advanced tools for creating the parting of the mould or die Machining point of view CAD tools to learn Features: Planar, Filled, Trim, Knit Mould: Draft analysis, Scale, Parting Line, Tooling Split Other: Reference Plane Evaluation criteria Accepted Finished tooling split with the listed tools Excellent Finished tooling split with the listed tools Material is chosen. The scale factor is chosen according to the material data. The front shape is tangential to the part outlining shape Parting 2_1-2

3 CAD tools quick guide Insert Molds Scale Insert Molds Parting Line This tool scales the part with a given factor. You are able to give one single factor or separate factors in x, y and z directions. This tool places the mould parting line to the corner where draft angles change direction. This corner should be sharp, not rounded like other corners in a casting. Parting line is the starting point for the mould parting surface. Parting surface divides the mould into core and cavity halves. If there is no corner where part draft angles change direction, you may show and/or define the corner yourself, but it is quite likely that in this case the part is not moldable or castable. In a real life mould design situation, you need to ask the customer to modify the part construction. Parting 2_1-3

4 Insert Molds Tooling Split Insert Reference Geometry Plane Insert s Fill This tool creates mould or die core and cavity halves as separate solid bodies. The tool uses the surfaces placed into the Core, Cavity and Parting Bodies folders. Reference plane is like one of the basic planes (top, right or front). You can define where and which direction to place it. Use the reference plane for sketching if no feature face is available. This tool forms a surface inside a sketch or selected solid or surface edges. Combination of sketches and edges will also do. You may select the border condition either to contact or tangent. Parting 2_1-4

5 Insert s Planar Insert s Trim Insert s Knit This tool forms a simple planar surface inside a closed chain of edges or a sketch. Combination of edges and sketches is also possible. This tool trims a surface with another surface. The tool requires two surfaces, a surface and a plane or a surface and a sketch. A combination of a surface and a solid will not do. Solid is cut with Cut with surface -tool. This tool knits two or more separate surface bodies together and forms one knitted surface body. If the surfaces form a closed sphere, you can form a solid from these surfaces directly with the knitting tool. Parting 2_1-5