Week 9 - Attachment Feature Creation - Challenge 2

DESIGN OF SCREW BOSE AND DOG HOUSE ON THE COIN HOLDER AND DRAFT ANALYSIS.

Aim:

To design the attachment features Screw house and the Dog house on the Coin holder considering the design rules and to perform the draft Analysis.

Screw Bose:

• Screw Bose is an attachment feature used in many parts design as a point for the attachment and assembly.
• The Most common variety consists of cylindrical projection with holes. It is used whenever we need the mounting point, a location point. The Bose may receive a screw, plain shaft either as slide or press fit.
• The side walls are designed by using the normal rib rules so that they can improve the rigidity and to avoid the sink.

Design Rules of Screw Bose:

• Consider the Screw Bose nominal diameter is M6 which is about 5.2 mm inside diameter
• The Thickness of the Screw Bose is 0.6*thickness of the component. (0.6*2.5 = 1.5mm). Here it will circular body, hence the 1.5mm is added twice to the inside diameter to get the outside diameter as (5.2 + 3 = 8.2 mm).
• The Draft should be provided as 0.5 degrees of draft per side to facilitate the part ejection from the mold. If it is more than 1 degree of draft per side, it can lead to excessive thickness reduction and filling problems.
• The Fillet Radius of Rib should be 0.25mm maximum. If it is increasing, there will be a violation of the 40% thickness requirement.
• The height to the diameter Ratio is 3:1.

Dog house:

• The dog house is the engineering feature to be placed on the class B surface of the component.
• In some cases, we have to increase the height of the Screw Bose to get mounting with the mating component. This will lead to the formation of heavy material on the base component to form a Sink.
• To avoid the sink on the base component, we need to decrease the height of Screw Bose by placing it on the dog house and having a thinner section near to component to avoid the sink marks.
• It also helps to provide support for the perpendicular installed Screw Bose.

Design Rules of Dog House:

• Use the ratio steel width to height is 3:1.
• The Minimum Draft Direction is 1.5 degrees given to outside.
• 0.5 degrees is given to the inside of the doghouse.

• T indicates the Component wall thickness.
• B indicates the Height of the thinner section which is close to the component and it should be between 3 to 6 mm.
• C indicates the doghouse thickness near to component. it should be 40% of T.

Creation of Screw Bose and the Dog House

Screw Bose:

• Extract the class-A surface and draw a sketch on the surface.

• Pad the sketch.

• Apply the draft on the outer edges and it to the part body.

• Draw a sketch for the support rib on the same extract surface.

• Pad it the drawn sketch and enable the thick option.

• Apply the draft on the outer surface of supporting ribs.

• Apply the union trim to add with the rounded object and add to the whole component.

Dog house:

• Draw a sketch on the extracted surface.

• Sweep the sketch with draft direction as tooling axis and draft value as 1.5 degrees and height will be 20mm from the B- surface.

• Offset the extracted surface and trim it to get the below-shown surface.

• Thicken the surface outward to 2mm thick.

• Applying the Draft to the inner edges.

• Apply the fillets on the edges.

• Offset the extracted surface and dog house inner one and extrapolate it and trim it.

• Spilt the surface to get the thinner section close to the component.

• Place the screw bose on the doghouse using the translation option.

views:

Isometric:

Front View:

Side View:

Top View:

Draft Analysis:

• Change the view customization mode to material mode.
• Go to the Insert menu and click on the analysis and then feature draft analysis.
• Set the minimum draft value as 0.48 degrees.
• Align the compass with the tooling axis to define the new current draft direction and click on the component.
• Then the analysis under running point placed at the surfaces of Screw bose and Dog house, it shows the 0.5 degrees and it appears in green color as mentioned in the color scale.
• This shows that the Attachment Features are cleared with draft analysis, and it is easily removable from the mold without any damage.

Inside surface of the Doghouse clearing the Draft Analysis using side core axis

Tree diagram:

Conclusion:

The designing of the attachment features of the plastic component is screw bose and doghouse is done and by following the design rule and performed the draft analysis.