Challenge

Week 9 Challenge

VVijaya Krishnan M.R18 Apr 2022

AIM: To create the core and cavity blocks with proper dimensions for the CPU fan case model also to create 2 sliders for the 2 undercuts present in the model

STAGES: create parts in the following order

core and cavity surfaces
core block
cavity block
slider 1
slider 2

PROCEDURE :

ASSEMBLY: In top-down assembly design, one or more features of a part are defined by something in an assembly, such as a layout sketch or the geometry of another part. The design intent comes from the top, which is the assembly, and moves down to the parts.

first, we will import the CPU fan case model and create the necessary core and cavity

then we will create another component and name it as core_steel and then create the core block using the below methods

then we will create another component and name it as cavity steel and then create cavity block using the below method

draft: (since we cannot change the draft angles for the given component without consulting with the designing team and can only ask them to make required changes but for this example, we are going to add drafts to this model ). A draft angle of 1½ to 2 degrees is required for most parts. This rule of thumb applies to parts with mold depths of up to 2 inches. At this size, a draft as low as 1½ degrees will allow for an easy, non-damaging release from the mold when the expected shrinkage of the thermoplastic material occurs.
scaling factor: When you create a mold you must account for the scaling factor. The scaling factor is the amount the material in the mold shrinks or expands as it solidifies. The scaling factor depends on the type of material used and the shape of the mold and is expressed as a percentage of the linear size (not volume) of the design part.
The software scales the cavity by the specified scaling factor, using this formula:

Cavity size = part size * (1 + scaling factor/100)
parting line and parting surface: It is a line that splits the mold into two parts – the core and the cavity. The concept of a parting surface is similar. A parting surface is a surface that separates the mold block into two parts – the core and the cavity. the blue line represents a parting line
core: Core is an extended or male portion of the mold that creates the internal plastic part surface. Cores are used to get the internal cavity in the castings. Cores are placed into the mold after the removal of the casting. These are made up of sand are used in permanent molds also. The cores are surrounded by molten metal and therefore subjected to severe thermal and mechanical conditions
cavity: The cavity is the female part that forms the external shape of the molding.
split lines: lines are created in order to break the curves so that we can easily use ruled surfaces to extrude the edges where we want to
boss extrude: Extrude tool is used to extend a sketched profile in one or two directions as either a thin feature or a solid feature.
surface cut: we can cut a solid model by removing material with a surface or plane.
direct editing: Direct Editing tab includes many tools that allow you to make changes to parts without modifying the existing sketches and features
shutoff surface: A shut-off surface closes up a through-hole by creating a surface patch along a parting line or edges that form a continuous loop. You can create shut-off surfaces before or after you create parting lines in a model.
combine: The common function allows you to add or subtract two bodies together, and keep the area that is common to them. To use this feature, we will select the common button, and then under Bodies to Combine, select the two bodies.
mates: Mates create geometric relationships between assembly components. As you add mates, you define the allowable directions of linear or rotational motion of the components. here we use mates so that we can bring the origin point over the sprue path

important notes:

reliefs should be given so that the core and cavity do not intersect with each other
also, some of the shutoff surfaces have to be made separately and then copies were made and then added to both core and cavity so that we can create proper blocks
sliders slider is used to turn the vertical movement of the mold opening or closing into horizontal motion. Slide mechanisms are typically composed of a few basic components including a forming surface, slider body, guide pin, wedge, press block, and wear plate
note that slider_02 has to be created into 2 parts and then combined together into a single body

images

cavity surface