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

1. Title of the Project:

Design of Ribs and Screw bosses for drill handle Plastic component through the given Class-A surface data, using Catia V5.

2. Objective:

To create the Ribs and Screw bosses features for the given drill handle part,by considering standard design rules for it.following that draft analysis is performed for the respective part.

3. Methodology:

• Class A Surface Refinement:

It is the initial stage, such that the class A surface input data is verified for its surface Continuity & Tangency, and ensures that there is no dis-continuity in between two surfaces in the model.

Note: By analysing the class A surface, It is noticed that the surface has many dis-continuity and Tangency issues when it is offsetted to 3 mm. So it is recommended that Class A surface designer has to refine the surfaces or need to redesign the surfaces.

• Creation of Tooling axis:

Initially analysing the model visually to check which direction would be most optimum for tooling axis, such that it would result in gaining better product with optimum cost, by selecting the X and Y axis planes an intersection is generated. Using the bisecting lines the intermediated tooling clearing along their direction is generated. Using this tool clearing direction lines, the actual tooling axis is created for the Drill handle model.

• Creation of Class B & C surfaces:

Class B surfaces are the surfaces which consists of engineering design features for the class A component.it may consists of ribs,screw bosses, latches, fits, stiffener etc. initially the class A surfaces are extracted and individually and offsetted to distance of 3mm.using surface features exact replica of class A surface is generated, which is later considered as Class B surface.

Class C Surfaces are the surfaces which connects class A and B surfaces together to form a single model. This surface is generated using sweep option by giving the desired draft angle for the model and it is blended with class A and class B to form a complete design of the component.

• Generation solid model using these surfaces:

Once the complete designining of surfaces is done,by swapping into part workbench, using the close surface option, the surface model is converted into solid model.further operations are performed to refine it. and also secondary features are generated on the B side of the component.

• Design of Ribs with Design standards:

Ribs are the engineering feature which are spotted in plastic component at B side surface,this features helps in increase the strength and stiffness of the part without increasing the over all wall thickness.these features also acts as locators during the assembly of the parts,the above image indicates the actual design standards of the rib design.

• Design of Screw Bosses with Design standards:

Screw bosses are the engineering feature which are spotted in plastic component at B side surface,These are cylindrical projections with holes designed in it, to assemle the screws,threads,inserts or other fastening elements inside. this features helps in increase the strength and stiffness of the part without increasing the over all wall thickness.these features also acts as locators during the assembly of the parts,the above image indicates the actual design standards of the rib design.

• Performing draft analysis:

Draft analysis is performed on a component in order to identify whether there is any negative and positive angle is involved in the component.This draft angle allows the part to eject easily from the mold. The draft angle reduces the friction between mold and part.it also tends to avoid the damage occurring to the mold and part during its ejection process. frequently used draft angle is 3 deg and minimum draft angle is 0.5 deg.

By applying the material to solid model, draft analysis is done by aligning the compass to the tooling axis and minimum and maximum draft angle is entered to get the desired result on the model. After interpreting, if there are any negative draft angle is identified, then the tooling axis or the model needs to be isolated for further design correction.

4. Modelled Components:

Iso view Front view Side view

Top view

5. Conclusion:

As per the Aim and Objective defined,the design of Ribs and Screw bosses for the drill handle plastic component has been generated, through given class A surface.the drafting analysis is also performed on the part and their respective engineering features in order to verify whether the part is feasible for manufacturing using injection molding process.The above draft analysis results ensures that minimum draft angle is invloved in the model and it can easily manufactured.