Project 1

TABLE FAN OUTER CASING MOLD DESIGN

OBJECTIVE:

Creation of Mold for a table fan outer casing using SolidWorks.

INTRODUCTION:

The injection molding process involves heating & injecting plastic material under pressure into a closed metal mold tool. The molten plastic cools & hardens into the shape inside the mold tool, which then opens to allow the moldings to be ejected or removed for inspection, delivery, or secondary operations.

Injection molding is a manufacturing process that allows for parts to be produced in large volumes. It works by injecting molten materials into a mold. It is typically used as a mass production process to manufacture thousands of identical items. Injection molding materials include metals, glasses, elastomers, and confections, although it is most commonly used with thermoplastic and thermosetting polymers.

WORKING:

The first stage of injection molding is to create the mold itself. Most molds are made from metal, usually aluminum or steel, and precision machined to match the features of the product they are to produce.

Once the mold has been created by the mold-maker, the material for the part is fed into a heated barrel and mixed using a helical-shaped screw. Heating bands melt the material in the barrel and the molten metal or molten plastic material is then fed into the mold cavity where it cools and hardens, matching the shape of the mold. The cooling time can be reduced through the use of cooling lines that circulate water or oil from an external temperature controller. Mold tools are mounted on plate molds, which open once the material has solidified so that ejector pins can eject the part from the mold.

METHODOLOGY:

The injection molding process requires careful design, including the shape and features of the part, the materials for the part and the mold, and the properties of the molding machine. As a result, there are various considerations that need to be taken into account when injection molding.

Step 1: Draft analysis

Draft analysis Examines the faces of the model for sufficient draft, to ensure that the part ejects properly from the tooling. By using draft analysis we check if there are any missing drafts in the model and do the necessary changes.

Draft analysis was set to 0.5 degrees and checked if there are any features that require a draft.

We can notice that there is a Draft that is required for the model Therefore a Draft of 1 degree was provided.

Step 2: Scaling

Depending on the material, the part will shrink when cooled after molding. Therefore our mold needs to be a little larger than we want our final part to be. So we will scale up our part.

Assuming the material for the model as ABS (shrinkage - 0.6%), the scale value is determined as (0.6/100)+1=1.006 for the model.

Since there will be shrinkage we scale the model to 1.006% to avoid shrinkage.

Step 3: Parting lines

Now we need to separate the model into core and cavity. for this, we use the parting line command.Parting lines are made to separate into core and cavity.

Step 4: Shut off surfaces

We can observe that there are few openings in the part. we have to cover these parts before creating the mold. For this, we use the shut-off surface command. All the opening holes are covered using a shut-off surface.

Shut-off surface Creates surface patches to close up through holes in the molded part.

Step 5: Parting surfaces

The parting surface is made along the parting line to separate the core from the cavity.

Step 6: Creating core cavity surfaces

Step 7: Open core cavity in assembly

Step 8: core block was created

Stop 9: created a parting surface for the core block

Step 10: cut the core block with the surface to create a core block

Step 11: Cavity block was created

Step 12: Created a parting surface for the cavity block

Step 13: Cut the core block with the surface to create the cavity block

Step 14: Ejector pins

Ejector pins are created for the part to be pushed out from the core when the part has cooled down.

Step 15: Created relief for Ejector pins

Step 16: Sliders

Undercuts are those features in an injection-molded part that prevent its ejection from the mold

In the Table fan outer casing model there are two holes that form undercut. This prevents the removal of the part from the mold towards the direction of the tooling.

To prevent this we create Sliders. Sliders are separate blocks created which can be slid out of the mold before the part is removed thus preventing the obstruction by the undercuts.

Sliders are created using the split command by making the sketch as the profile of the undercut and the plane up to where it has to split.

Step 17: Washers and locking mechanism

Washers are created on the core block between the slider and the core block.

Along with this, we provide a locking mechanism where the slider locks after traveling a certain distance.

(explode view)

Result:

Hence, by adopting these methodologies steel molds with sliders and ejector pins have been successfully designed for the Table fan outer casing using SolidWorks.