Week 8 - Challenge 6 - Core & Cavity Design

AIM

Create the Core and cavity blocks for the switch bezel

THEORY

What is Draft Analysis

The draft analysis technique is used to analyze whether our part model created in CAD is manufacturable based on the draft condition applied. Here the part should get easily removed from the panel dies (in case of Sheet metal part) or Mold (in case of plastic).

The draft analysis command enables us to detect if the drafted part can be easily removed. This type of analysis is done based on the colour ranges identifying the zones on the analysed element where it makes a deviation from the normal values.

Draft

For molded or cast parts, the draft angle is the amount of taper perpendicular to the parting line. It is measurable in degrees. Because plastic shrinks and sticks on molding surfaces as it cools, for molded or cast parts, the draft angle is the amount of taper perpendicular to the parting line. It is measurable in degrees. Because plastic shrinks and sticks on molding surfaces as it cools, we draft the walls of the plastic part so that it ejects or breaks free from the molding surfaces more easily and without dragging. To reduce the risk of damage to the parts and ensure ejection, a functional injection molding part must have drafts on both the cavity and core sides.

Draft Angle Guidelines

• 0.5o0.5odegrees on all vertical faces
• 1o−2o1o-2o works very well in most situations
• 3o3o is the minimum for a shutoff
• 3o3o is required for light texture
• 5o5o or more is required for heavy texture

Tooling Axis Creation

Tooling direction is the main consideration for the plastic part and the mold parts because it defines the movement of the mold part and the possibility of the plastic part coming out from the mold part (core & cavity). Tooling direction is critical for plastic product design because it determines mold direction

Steps Involved

1. a reference point is created on the extracted surface.
2. a new axis system is used to plot the extracted surface
3. The x and y axis were used to develop the tooling axis using the Intersection curve
4. The two clearing lines were bisected to form the Tooling axis,
5. The tooling axis's graphic properties are changed to identify the Tooling axis

Design Consideration

• Class – A surface should be aesthetically smooth and good.
• Class – B surface should have all the supporting features like ribs.
• The parting line should coincide with the B surface since flashing couldn’t affect the aesthetic of Class – A.
• Class – C surface should also pass the draft analysis.

Core and Cavity

Cavity and core are used in the injection molding process, where the concave part of the mold is the cavity and the convex part is the core.
The cavity and core are used in pairs, with the cavity also referred to as the female mold and the core as the male mold.
These two mold components are the most important parts of a mold.

Parting Surface

The injection mold has two major parts: Core and Cavity. These parts are interlocking and form a sealed hollow volume at high pressure where the mold is poured in and thus preventing it to flow out. The surface which the molten plastic touches are the parting surface that separates the two halves of the molding machine.

Guidelines to follow when designing the Parting Surface

1. Design the injection mold as simple as possible to avoid or reduce side parting
2. To reduce the complexity of mold making.
3. De-molding should be easy
4. Ensure the dimensions of the molded parts are accurate
5. Ensure appearance requirement of molded parts
6. The parting surface should not be designed for high-quality surface requirements.
7. Ensure adequate venting.

Core & Cavity Parting

Final