Week 8 - Challenge 6 - Core & Cavity Design

Aim

Create the Core and cavity blocks for the switch bezel designed in the earlier challenge.

INTRODUCTION:

The parting line indicates the direction of the line of draw for the mold, or the point where you can separate the two halves of the mold to release the part without damage

A parting surface is a surface that separates the mold block into two parts – the core and the cavity.

Report

A detailed report should be done explaining the draft analysis and the tooling axis creation.

An explanation should be given on the way of creating the tooling axis, particularly the Bisecting method.

Draft Analysis:- Draft is a taper applied to the faces of the part that prevent them from being parallel to the motion of the mold opening. This keeps the part from being damaged due to the scraping as the part is ejected out of the mold, to do that the analysis is done and known as Draft Analysis

Tooling axis: The direction in which the mold or core and cavity opens is called as the tooling axis.

Tooling axis creation

As in 3D we can see there is a top surface where we can make the tooling axis perpendicular to the surface but the only issue comes in the pocket area so in order to do that we have to use the Bisecting Method and the procedure is mentioned below

Bisecting Method

• The base surface of the class – A was extracted and a point at the centre is created and an axis system was inserted to the point with the current feature is disabled.
• Then, using project intersection along yz plane is created and the two inclined lines were drawn inside the positioned sketch.
• Then bisecting lines with the two inclined lines were drawn.
• Now the same procedure is done along the xz plane but on one side we don’t have inclined lines so the centre point is used to extrude a line along the z-direction and gave a anle of 3 degrees initially as the minimum draft angle which is later on changed as per the draft analysis result
• With these two lines from sketches 1 and 2, the bisecting line is crated and published as Tooling Axis(tooling direction).

The tooling Axis determines the direction of Class C boundary swept with draft direction.

To check the correctness of Tooling axis, viewing it from tooling direction normal all the parts that are drafted should be visible so it gives an rough idea to determine product manufacturing in Injection molding.

Draft Analysis for Solid Plastic Part

First the class – A surface is checked before creating the Class –B&C surface and finally the solid body must be analysed. Both can be done by following the below procedures.

By changing the view mode to custom view parameters – Material mode then the feature draft analysis is enabled.

Then the compass was activated and placed with the tooling axis by dragging the red pointer and then locked it.

Then, by selecting the quick analysis mode, the nominal value will be 3 degrees and checked for the component's draft angle.

The green colour area shows that it satisfies the 3-degree draft angle. If not satisfied then by using the Running point tool the area is measured and then altered to get a successful draft for the created tooling direction.

The produced body is not clearing the draft analysis(the blue face) so the Tooling axis is again changed by changing the angle given to the line from 3 degree to 6 degree and again the above procedure is done before rectifying the error occured(The class A is extrapolated by 0.05mm to cover the gap and trimmed of and join by the class C surface and then trim is changed by replacing the class A+Class C surace and then it was given thickness)

It is showing that at 3 degree draft angle all faces are clearing the analysis and good to go for production

Draft Analysis of Class A Surface

Core and Cavity Design

Steps to design the core side

• Extract the boundary of class A and extrapolat the boundary of the class A by 15mm
• Use the Class A+Class C surface and trimmed with the extrapolated class A surface and then trimmed it with the class B surface
• Sketch a rectangle covering the inside of the trimmed surface and extrude along the tooling Axis and then trimmed it off and filled the top surface and used the closed body command to make it solid.

Steps to design the Cavity side

• Use the Sketch (rectangle) covering the inside of the trimmed surface and extrude along the tooling Axis and then trimmed it off (Bottom side) and filled the top surface and used the closed body command to make it solid.

Parrting Line and Parting Surface

Intesect the Parting surface, core side and cavity side along ZX plane and to get a parting surface line with component are highlighted by blue dash line

Intersect the B surface with the switch bezel to get the parting line and Parting line should always be on the B side

Parting Surface

Split the Parting line with the parting surface with component area to get the parting surface

Screenshots of the core and cavity blocks in various orientations (Isometric, Front, Side, and Top View)

This is how the core and cavity looks and move along in order to get the component

Isometric View

Front View

Side View

Top View

Please find the attached part file for your review