Week 9 - Project 1 - Door Trim Lower with Engineering Features

Aim: The main aim of this challenge is to create a solid body of 'Door Trim Lower' with the help of the closed surface method by using the 'Surface design' workbench in CATIA V5. Performing the 'Draft Analysis' on the solid part body of the Door trim.

TOOLING AXIS:

• The next step is to create the tooling axis for the part which will determine the direction in which the core and cavity of the mould will move.
• Designer must ensure that all holes and slots are covered in the main tooling and thus side core must be avoided whenever possible
• After analysing visually for the best possible tooling axis, an axis system is created on the centre of one of the surfaces of the door trim.
• The main tooling axis is created normal to the y direction.

Draft Analysis :-

• Draft angles are tapers on part faces that help them eject from the mold properly. They are calculated as a degree measurement from the vertical axis of a mold, and they help account for the fact that injection molded parts shrink as they cool.
• Without a draft angle, parts are more likely to stick to the mold and warp or break when they’re removed. Draft angles help reduce friction between the finished part and the side of the mold.
• Draft analysis is performed based on colour ranges identifying zones on the analyzed element where the deviation from the draft direction at any point, corresponds to specified values. Minimum draft angle is considered as 3 degree.

CLASS B SURFACE

• Now create a class B surface.
• In class B, first create base of class B from class A. Insert geometrical set define as class B, that is base of class B.
• Use extract command and extract a base from class A. Then use untrim tool get full body of a base. Next use extrapolate tool extended a base , then offset of 2.5 mm.

CLASS C

• Class C is nothing but its connecting part of Class A & B.
• Unhide the class A and take boundary of its and now boundary select the all corner of a class A and use sweep commends the we get a class c of boundary in Class A.
• Then trim it finally get class C.

CLOSE BODY

• Go to the part body workbench then use close boby tool and finally get close body of base bracket.

CREATING THE RIB

Ribs are thin wall protrusions that extend perpendicularly from a wall or plane. They are usually found in clusters offering support to a plane that would have otherwise been too thick, but can also be stand-alone support for a single wall. They are commonly used to provide additional support and strength to a part. Thickness and location are essential to rib design.

First, the base surface where the rib has to be created is extracted using the Extract command.

Next, the profile is extruded, to find the height,h=Wall thickness * 5

=2.5*5

= 12.5 mm

Therefore, the height is 12.5 mm.

The extruded surface is thickened,

Thickness,w=0.4*t

=0.4 2.5

=1mm

Therefore, the thickness of the rib is 1 mm.

The draft is applied to the sides of the ribs. As per the design rule, the ideal draft angle is 0.5 deg.

Then fillet is applied to the faces of the rib. As per the design rule, the fillet can be 0.25 mm.

The locators restrict all the other degrees of freedom except the translation along the direction of tooling axis Le along y-axis. For restricting that degree of freedom we will be using the heat stakes.

In heat staking, we use local heating and cooling to raise the temperature of plastic components and allow plastic reforming to be carried out.

The draft is applied to the sides of the ribs. As per the design rule, the ideal draft angle is 0.5 deg.

Then fillet is applied to the faces of the rib. As per the design rule, the fillet can be 0.25 mm.

CREATING THE DOGHOUSe

The dog house is an engineering feature used in the plastic trim design. Dog houses are used as a supporting feature. Sometimes other engineering features like snaps; locators, etc. are mounded on them to increase their strength.

The doghouse is created by following the design rules.

The nominal wall thickness guide range is from 0.75 mm to 3 mm for reinforced materials and 0.5 mm to 5 mm for unreinforced materials.

Related Courses

WALL THICKNESS (W) = 0.70 (NOMINAL THICKNESS OF PLASTIC MATERIAL)

This process is usually done by Thicken surface command.

The fillets and the draft are given as per the design rules.

An important thing while designing a doghouse is to maintain 40% less thickness than the wall thickness (T) at the area of the intersection to avoid sink marks. So, a C shape is formed at the intersection.

This can be made using the split command to remove the solid at the intersection.