Week 9 - Attachment Feature Creation (Ribs & Screw Boss) - Challenge 1

OBJECTIVE : To Create the ribs for the Drill Handle considering the design rules mentioned in the video.

Create the Screw boss for the Drill Handle considering the design rules mentioned in the video.

General Guidelines for Bosses:

• Draft - 0.5 degrees on the walls of boss
• Thickness - Typically 40%* of the nominal wall at the base.
• Height to Diameter Ratio - 3:1
• Radii - 0.25mm maximum radii.
  

REPORT AS FOLLOWS :-

Ribs and Screw Boss creation

Tooling Axis :

Class-A surface is first analyzed to create the tooling axis or tooling direction that molds pull apart in injection molding. Tooling direction is important for plastic product design as it decides the direction for mold separation.

Draft Analysis :

The Draft angle is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees. A functional part for injection molding has to have Drafts facing both cavity and core sides to reduce the risk of damage to the parts and ensure ejection. And also important is to overcome the vacuum forces by letting air in between the metal to the plastic for the part to release properly. Adding maintaining a decent cosmetic finish.

The draft should be a part of the design for manufacturing and the plastic product Designer should be aware of its need at the outset of the design process. This allows considerations for design requirement's to be taken into account.

Nominal values for Draft angle :

• 3 Degrees is the nominal Draft angle.
• 7 Degrees of r textured surface.
• A minimum of 0.5 Degrees can be manufactured with special tools. But it will increase the manufacturing cost.

Let us get into the model :-

Given Class-A Surface :-

Tooling axis creation :

Let us take the intersections at two directions and create a bi-secting line between them as follows to create the tooling axis.

After checking the continuity in the given class-A surface let us run Draft analysis on the given input surface as follows.

DRAFT ANALYSIS OF CLASS A SURFACE

Green colour indicates values above 3 degree positive draft

Red colour indicates values between 3 and 0

orange colour indicates values below 0 degree

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 analysis under the running point we can check draft angle on the individual faces. It shows how much draft on specific points when we move the cursor point. It is as shown below.

Creating class-B surface from A-Surface as follows :-

Let us create CLASS-C from Class-A surface boundary as follows:

Now to trim the Class-C surface with the class A and class-B and joining them as follows

Complete simplified TREE STRUCTURE as follows

RIB CREATION AFTER CONVERTING THE SURFACE INTO SOLIDBODY :-

After applying draft :-

DESIGN EVALUATION AS PER STANDARDS :-

Taking intersection :-

Hence all are as per design standards mentioned , but Since its a customised Door handle and follows different HEIGHT TO DEPTH RATIO FOR THE SPACING BETWEEN THEM LET US MODIFY THE SAME.

Rib design Tree structure as follows :-

SCREWBOSS CREATION :-

Translating to duplicate 2nd screwboss after draft

DESIGN EVALUATION AS PER STANDARDS :-

Taking intersection :-

Screwboss design Tree structure as follows :-

Complete tree structure as follows :-

DRAFT ANALYSIS for the COMPONENT as follows :-

Draft analysis is done using featured draft analysis tool

Use the compass fucnction to align 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 and 0.5 deg on RIBS and SCREWBOSSES

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

Different views for draft colors are as follows :-

CONCLUSION

• Created the DOOR HANDLE component using 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.
• Class-B and Class-C surface is created.
• Using the Close Surface feature, Solid body is created from the surface.
• RIBS and SCREWBOSSES are designed as per design considerations.
• Draft analysis is done on the Final Component.