Week 8 - Challenge 6 - Core & Cavity Design

AIM

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

STEPS

CLASS A SURFACE

We have been given the Class-A surface and the first thing to do is to make sure that the given surface has no gap in between them. We can check it visually and also with help of Join or boundary commands.

The given surface has only one boundary . So, there are no other gaps found.

TOOLING AXIS

The direction in which the mold or core and cavity opens is the tooling axis.

TOOLING AXIS USING BISECTING METHOD

Tooling axis for the part is created by using the bisectiong method .In order to check whether the part is toolable in the direction,the class A surface is analysed and the walls which are doubtful of clearing the 3 degree draft angle to the dummy tooling axis is identified.

In this class A surface there is only three walls intersection line is created on these three walls by using the sketch tool

point is created on the extraced face of the bottom wall

An axis system is created on the point for sketching

a sketch is created to obtain the intersecton

the lines are drawn in the intersection of walls

a bisecting line is created for the two lines

for the third single wall intersection is created using new sketch

line is drawn in the intersection of wall

the minimum draft angle is 3 degree a line is drawn at 3 degree on the point to the line on the wall . it is increased to 6 degree to et more clearence.

the bisecting line is created for the line on the wall and line at 6 degree to it.

the tooling axis is created by bisecting the two lines ( bisecting line on first sketch and second sketch)

TOOLING AXIS is created

sketch solving status of two sketch

DRAFT ANGLE

When developing parts for plastic injection molding, applying a draft (or a taper) to the faces of the part is critical to improving the moldability of your part. Without it, parts run the risk of poor cosmetic finishes and may bend, break, or warp due to molding stresses caused by plastic cooling. Equally important, an absence of draft may prevent parts from ejecting from the mold, damaging not only the parts but possibly the mold itself—a costly and time-consuming detour.

DRAFT ANALYSIS OF CLASS A SURFACE

Change the view to material mode for draft anlysis

draft analysis is done using featured draft analysis tool

Use the compass fucnction to aling the compass to the tooling direction and lock the direction using lock function in the draft analysis tool bar

the surface is showing green colour so that the surface clears the minimum draft angle of 3 degree

By using the analyses under the running pointwe can check draft angle on the individual faces. It shows how much draft on specific points when we move the cursor point.

Green colour - above 3 degree positive draft

Red colour -between 3 and 0

blue colour- below 0 degree

CLASS B SURFACE

B surface gives thickness to the component. all the engineering features are made in the B surface

CLASS C SURFACE

SOLID SURFACE

PART BODY

Close Surface feature used to make a solid body from the surface.

DRAFT ANALYSIS OF COMPONENT

draft analysis is done using featured draft analysis tool

Use the compass fucnction to aling the compass to the tooling direction and lock the direction using lock function in the draft analysis tool bar

the surface is showing green colour clears the minimum draft angle of 3 degree

By using the analyses under the running pointwe can check draft angle on the individual faces. It shows how much draft on specific points when we move the cursor point.

Green colour - above 3 degree positive draft

Red colour -between 3 and 0

Blue colour- below 0 degree

TREE STRUCTURE

CORE AND CAVITY DESIGN

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.

PARTING SURFACE

Generally,injection mold has two major components : the movable halve and the fixed halve , during the injecction molding process, these two halves are pressed tightly from a sealed hollow to avoid the melt flow leakage and maintain certain holding pressure, the pressed surface are called parting surface , usually parting surface are the biggest projection outline of the part.

Design the injection mold simple as possible .Avoid or reduce side parting as much as possible to reduce complexity of the mold making.

Ensure apperance reqirement of molded parts,finish or mismatch usually occurs on parting surface , so the parting surface should not be designed on high quality requiremnent surfaces.

Ensure adequate venting.If possible parting surface should be place at the end of the mold flow.This is going to be advantage of fillng and venting.

The class A surface boundary is created and extrapolated

the JOIN of class C and class A surface is trimmed with class Bsurface accordingly to obtain THE COMPONENT AREA WITH PARTING SURFACE

THE PARTING SURFACE IS FORMED

PARTING LINE

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. Usually, the parting line is down the middle of the part, but this varies due to part geometry.

the parting line is the line where the two mold halves meet, and the parting surface is the mold surface that forms the boundary between the two mold halves

Intersection between the parting surface and part is formed to obtain parting line

PARTING LINE

CORE AND CAVITY DESIGN

CORE DESIGN

A sketch is created accordingly to make outer surface for core and cavity core and cavity

sketch extruded to create surface

the extruded surface and the parting surface with component area is trimmed accordingly to form cavity

bottomsurface isclosed by using boundary and fill command

SOLID SURFACE FOR CORE is formed

CAVITY

Same sketch extruded to create surface for cavity

the extruded surface and the parting surface with component area is trimmed accordingly to form cavity

bottom surface isclosed by using boundary and fill command

CAVITY is formed

Intersectionof assembled core and cavity

CORE AND CAVITY BODY

the Close Surface feature to make a solid body from the surface.

CORE AND CAVITY blocks in various orientations

CONCLUSION

• Created the switch bezel Plastic component through the given Class-A surface.
• the tooling axis for the given Class-A Surface is created which meeting the requirements of the draft angle
• Draft analysis is done on the CLASS A surface
• Draft analysis is done on the model.
• Using the Close Surface feature solid body is created from the surface
• core and cavity blocks are created
• Publications: Tooling Axis Class A, B, and C surface,solid body,Component, parting line, parting surface etc