Week 9 - Attachment Feature Creation - Challenge 2
DRAFT ANALYSIS
Draft analysis is a method used in design to check whether the component created in CAD is manufacturable based on the draft condition applied. The main reason behind the draft analysis is the part manufactured should be easily removed from the mold. It also gives an idea of the draft angle from the tooling direction. Here we are giving a tooling direction in order to eject the component easily from the tool. The ideal draft angle given in automotive industries for plastic components is 3 degrees.
Some of the components where draft analysis is done are hood, fenders, roof, side doors, etc.
The draft analysis is an important tool as it helps the user to analyze the draft on various surfaces, the draft analysis in CATIA uses the color codes for the identification of the draft. Each color has its own meaning for the minimum draft negative draft and under draft.
The draft analysis toolbar provides two modes for analysis of the draft, first is the quick analysis which basically has three colors for analyzing GREEN, RED, AND BLUE on the other hand other option is the full analysis mode which enables a few more details into the draft and is used in the complex components like the instrument panel, etc. In the above challenge, we have used the quick analysis mode for analyzing the draft here. Now, bring the compass and align it with the tooling axis and click the lock button in the dialog box.
CREATING THE SCREW BOSS
Screw Boss features are commonly found in injection molding designs. They are used to aid in the assembly of molded parts by providing a channel for a screw. Their primary use is to strengthen holes or slots in the surface present in the part model.
Design rules consider while creating a screw boss
- Thickness
- Draft
- optional radii
- Boss gussets
- Type of ejection
The construction process of creating the screw boss is explained below:
For thickness, the design rule is as follows,
Thickness,w=0.6*T
=0.6*2.5
=1.5 mm
Therefore, the thickness of the boss can be 1.5 mm per side.
In this case, we have considered the size of the screw boss as M06.
Once the sketch is completed, then it is padded using the 'Pad' command. The height to diameter ratio can be 3:1
Next, the draft is given to the boss. As per the design rule, the draft given for screw boss is 0.5 deg.
Then, the ribs are created by following the rib design rules.
Hence, the ribs are created for the screw boss.
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.
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.
Once the doghouse is created. The screw boss is placed above the doghouse using the 'Translate' command.
COIN HOLDER IN DIFFERENT VIEWS
