Week 9 - Attachment Feature Creation - Challenge 1

AIM:

To create the rib formation for the Centre console coin holder considering the design rules by using Catia V5.

OBJECTIVE:

• Create a tooling axis following the OEM standard
• Making the Rib According to design rules
• Part Thickness : 0.75 mm and Draft angle : 0.5 Deg
• Performing the draft analysis to the component

INTRODUCTION:

Ribs are a feature in plastic injection molded parts. They are thin extensions that run perpendicular from a wall or plane. They are commonly used to provide additional support and strength to a part.

Thickness and location are essential to rib design. Here are some helpful design guidelines:

• They should be designed with a thickness that is ½ the wall thickness to avoid a thick section at the wall base
• To minimize sink marks, design ribs that are approximately 60% of the joining wall thickness for minimum risk
• Best practices include spacing at a distance of at least twice the wall thickness
• Glossy materials require a thinner rib (40% of wall thickness)

An advantage of using ribs is that they increase the strength of the part without increasing wall thickness. Walls that are too thick can sink, warp or result in other defects. Their integration into a part results in less material usage; therefore a more cost effective solution.

Working with an experienced injection molding manufacturer can not only lessen your risk with production issues but also save costs and time in the long run.

Design Rules for Rub Creation:

METHODOLGY:

• Creating the Tooling Axis

The tooling direction is used to find the direction in which the part is removed from the core and cavity. The draft angle should be positive to the tooling axis to manufacture the component easily. The step by step procedure of creating the tooling axis is given below.

Step: 1

Creating the point on surfaces respectively also extract the surface of the component.

Step: 2

Now creating the intersection to the Z-Y and Z-X direction of the surface as shown below.

Step: 3

It is symmetry and normal surface, hence we can directly by zero distance value based to normal to the surface.

Finally we get our main tooling axis for the door arm rest component.

• Creating the Rib on the Coin holder:

Step: 1

Creating the sketch by extracting the class A surface, by each surfaces separately, point and axis system created simultaneously on the surface. Using positioned sketch making as shown below.

Step: 2

The sketch extruded to surface and it is thickened for 1mm thickness as shown below.

Step: 3

The thickened rib is drafted for 0.5 deg and it is assembled to main body and it is filleted for radius 0.25 of smooth edges as shown below.

Step: 4

Analysing the Rib root thickness for the coin holder rib by creating intersection for the model as shown below.

Measuring the distance between the two ribs and fillet radius, all this values are solved by the following design rules.

• Performing Draft Analysis:

The Draft Analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on colour ranges identifying zones on the analysed component where the deviation from the draft direction at any point, corresponds to specified values. This rule of thumb applies to parts with mold depths of up to 2 inches. At this size, draft as low as 1½ degrees will allow for an easy, non-damaging release from the mold when the expected shrinkage of the thermoplastic material occurs.

It’s also important to remember that draft angles are just one component of an effectively designed injection molded piece. Design for manufacture is one of the easiest ways to improve the quality and efficiency of your injection molding process, and it never hurts to stay up to speed on all injection molding best practices.

1. Draft Analysis for Rib formation:

Step: 1

First we have to set the compass on the main tooling axis to get the direction of core and part moves along as shown below.

Step: 2

Once compass is locked in the axis, directly click on the surface it will appear quality of draft surface whether, it is pass or failed. Here the draft angle is given as 0.5 degree. Hence we achieved green colour on top surface. Hence it accepts the draft angle for the surface, so we build good quality component.

Step: 3

Now we check colour variant scale to ensure the maximum and minimum area draft angle is achieved by displaying by green, red and blue colour respectively. If the surface appears red in colour while analysing it is not accepted.

Step: 4

We can check the angle of draft given to surface by using draft tool analysis just point the over the surface where we have check angle of given draft to the component as shown below.

Screenshot views of coin holder with draft analysis:

Front View:

Top View:

Isometric View:

Publication:

Conclusion:

Creation of the Rib on coin holder has been successful done by guidance of design rule. It has been converted from surface into solid body. The tooling axis has been created according the OEM standard. Drafting Analysis has been performed and results has been updated in step by step methodology. Hence we created perfect final Rib on the component.