Week 8 - Challenge 4 - Coin Holder Design

Title- Coin Holder Design

Aim- To create the coin holder component using the given class A surface.

Objectives –

• To create class B and C surface from given class A surface
• To make solid closed body model using class C surface
• To perform draft analysis for class A surface and solid body w.r.t tooling axis and side core axis.
• To publish class A,B,C surfaces, Tooling axis.

• Introduction-
• This report demonstrate the design of coin holder with industry principle like determine and implementation of tooling axis, draft analysis, draft angle, creation of class B and C surfaces and maintain thickness of part at 2.5 mm. The plastic component is designed with surface and part design technique in CATIA.

• Methodology-

Fig.1 Methodology for designing of door arm rest

Step- 1 Input Class A surface-

• A surface is made by designer and surface design is given to modeler to work on it.
• It is aesthetic surface and the outer most surface of any automotive component.
• Class A surface is refers to those surfaces which are visible and abide to the physical meaning in a product. This classification is primarily used in any automotive and increasingly in consumer goods industry.
• Below fig. 2 & 3 shows input received from designer.

Fig. 2. Given Input coin holder

Fig. 3 Coin holder in Isometric view

Step- 2 Design check (Pre-check) of input given door arm rest.

• After receiving class A surface/ door arm rest shown in fig.3, check the connectivity of surfaces.
• First important thing is to check continuity of given class A surface i.e to ensure that class A surface is properly joined or there is no discontinuity in the model. This can be checked by using two options, Join or Boundary feature in CATIA. 3 shows connectivity of class A surfaces.

Fig. 4 Joined and Boundaries of surfaces shows connectivity

Step-3 Determine the tooling axis

• Tooling axis- It is a direction in which mould/ core and cavity opens.
• Analyze model visually to see which direction is most suitable for tooling axis and draft analysis is done along tooling axis.
• Identify the surfaces which can creates problem while manufacturing with all 3 axes.

Following procedure is used to create tooling axis-

• A bottom surface of class A surface is extracted shown in Fig. 5
• Create a point on the surface at center using point command, shown in Fig. 6
• Generated a line along Y-direction using point- direction command shown in Fig. 7. And this line is tooling axis.

Fig.5 Bottom surface is extracted

Fig.6 Untrim the extracted surface

Fig. 7 Point is created on surface

Fig. 8 Line is created on surface

Step-4 Creation of class B Surface-

For creation of class surface here we made a geometrical sets w.r.t each surface orientation for easy understanding and working-

1. Base surface-

• Extract the base surfaces from class A surface.

• Untrim the extracted surfaces and then extrapolate the untrimmed surface such that they intersect each other.

• Trim the surfaces and an offset them at 2.5 mm shown in pick color.

2. Side Surface

• Extract the side surfaces form class A surface

• Untrim the extracted surfaces and then extrapolate the untrimmed surface such that they intersect each other

• Trim the extrapolated surfaces and offset at 2.5 mm.

3. Pad Surface

• Extract the inner pad surfaces form class A surface.

• Untrim the extracted surfaces and then extrapolate the untrimmed surface such that they intersect each other.

• Trim the pad surfaces and an offset them at 2.5 mm

4. Top surfaces-

• Extract the top all surfaces from class A surface.

• Join the all extracted surfaces.

• Extrapolate the extracted surface from top and bottom edge

• Offset extrapolated surface at 2.5 mm

5. Outer flange

• Extract the multiple outer flange surfaces from class A surface.

• Extrapolate the upper edge extracted surface.

• Similarly extract the remaining surfaces of the outer flange and untrim them.

• Join the untrimmed surfaces together.

• Trim both outer flange surfaces and offset at 2.5 mm

6. Final Trims-

• Trim base surface and side surface

• Trim last trimmed surface and pad surface together.

• Apply edge fillet to the trimmed surface.

• Trim last edge fillet surface and top surface together.

• Trim final outer flange surface and last trimmed surface.

• Extract the flat upper surface from class A surface.

• Untrim the extracted surfaces and then extrapolate the untrimmed surface.

• Offset extrapolated surface at 2.5 mm and trim extra portion of last trimmed surface.

Step- 5 Creation of Class C surface

• Extract the boundary of class A surface using multiple extract feature and make the curve smooth.

• Use the sweep feature of with reference surface to make surface using guide curve as a smooth curve and reference surface as class A surface.

• Trim the class B surface and swept surface together

• Join the sweep trim surface and class A surface together.

• Pocket on class A surface
• Extract the boundary of class A surface using multiple extract feature and make the curve smooth.

• Extract the surfaces which are near to pocket boundary of class A surface using multiple extract feature.

• Use the sweep feature of with reference surface to make surface using guide curve as a smooth curve and reference surface as last extracted class A surface.

• Trim last swept surface from joined surface.

• Class C surface doesn’t contain any open surface or boundary.

Step- 6 Publication

• This feature is used to make easy access of published component (Surface or Sketch).
• Here class A,B,C surface and tooling axis is published.
• Path- Tools > Publication > Select entity (Surface/ Sketch/Body)

Step-7 Creation of solid body

• Solid body is created using class C surface.

Step- 8 Draft Analysis

• Draft- it is an angular tapering given in the direction of mold movement at design stage to every plastic components that has to be manufactured. The draft allows the part to release easily from the mold without creating friction between the surface of component and core- cavity plates. In most application require minimum draft angle of around 0.5 to 1°, however 3° draft angle is widely accepted for cost saving purpose.

• Draft Analysis- it is a tool in CATIA which analyze and identifies zones which are deviates from specified angle value along specified draft direction using color codes.
• To perform draft analysis on class A surface go to- Insert > Analysis > Feature Draft Analysis. Then perform draft analysis on tooling axis.
• Make sure that before switching to draft analysis part should be in customer view parameter with material option of mesh.
• Next step is to align the tooling axis with class A surface by clicking on compass icon and drag it to tooling axis.
• After clicking on surface we get tab and it shows different color scales with different draft angle range. The minimum draft angle is 3°. From fig. 12we can see that red color shows 0° of draft angle, green color is above 0° and blue color is below 0°. So try to keep draft angle positive.
• Draft Analysis on Class A surface

• Draft Analysis on Solid body

• Remark

There are lot of surfaces in the red color that shows zero draft angle. Thus, these surfaces should be provided with some draft angle in order to reduce defects during manufacturing.

• Conclusion-
• The tooling axis and side core axis are identified and created for class A surface.
• The class B and C surface are created from given class A surface in CATIA V5.
• The solid closed body model is made using class C surface.
• Draft analysis is performed for class A surface and solid body w.r.t tooling axis and side core axis.
• To publish class A,B,C surfaces, Tooling axis and side core axis.

• Screenshots of the class A surface model along tooling axis with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

• Screenshots of the solid model along tooling axis with the proper color code of the draft angle in various orientations (Isometric, Front, Side, and Top View)

• Screen shots of tree structute, geometrical str. of tooling axis, side core axis, class B,C surfaces and draft analysis.

• Screenshots of the solid model in various orientations (Isometric, Front, Side, and Top View)

• Screenshots of the Class C Surface in various orientations (Isometric, Front, Side, and Top View)