Week 8 - Challenge 5 - Core & Cavity Design

Objective :

• To design core and cavity for switch bezel with 3 mm thickness
• Performing draft analysis to verify the creation of the Tooling axis and C Class surface

Introduction:

Parting Line:

A parting line, in industrial casting of molds, is the border line in which draft angles change direction. That is, it is the dividing line that splits the core and cavity halves of a molded part. It is sometimes a starting point for the mold parting surface. In engineering drawing, parting line is often abbreviated as PL. ASME's Y14.8 standard specifies a symbol for parting line. Engineering applications (seals, tight running molded parts) that require precision for shape control, call for removal of flashes. Many molders will repair or even replace the mold tooling so that the flash is reduced to an acceptable tolerance or eliminated altogether. Secondary operations to remove parting line flash include hand trimming, vibratory tumbling, media blasting and cryogenic deflashing.

Parting surface:

The parting surface of a mould are those surfaces of both mould plates adjacent to the impressions which butt together to form a seal and prevent the loss of plastic material from the impression. The parting surfaces of a mould are those portion of both mould plates, adjacent to the impressions,which butt together to form a seal and prevent the loss of plastic material from the impression.

Core & Cavity:

The core & cavity are the shaped sections in either half of the mould tool which give the plastic product its final shape. The hot molten material is injected into the core & cavity and then sets hard into shape. The design of the core & cavity is essential in the correct formation of the product.

Methodology:

Procedure for parting surface:

• Extract the Class A surface boundary lines with boundary option
• Extrapolate the Class A surface by 15mm
• Trim the extrapolated surface with Class C & B surfaces respectively

Procedure for design core:

• Open the new sketch in XY plane
• Create a rectangle and constraints it
• Extrude the sketch on both sides
• Trim the parting surface with the above surface of the rectangle
• Fill the open surface with the Fill option
• Join the filled surface with the trimmed surface

Procedure for design cavity:

• Trim the extrude surface with b surface
• Fill the open surface with the Fill option
• Join the filled surface with the trimmed surface
• Now open the Part body
• Create two bodies separately and create closed surfaces
• Intersect with the perpendicular plane and unhide the tooling axis
• Translate the bodies in required directions

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Procedure for draft analysis:

• Go to the Insert menu and select the Analysis option
• Select Feature Draft Analysis
• Select the Material option and select the surface
• Drag the compass and place on tooling axis
• Make sure that the top surface is in green colour as draft angle should not exceed 3deg
• Click on Okay after confirm the model