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

AIM

TO Create Rib and Screw boss for the door handle considering design rules

Objective:

The main aim of this challenge is to create B-side features of the 'Door Trim', with the help of CATIA V5.

Procedure for the projects

• Creating the tooling axis
• Draft analysis of Class A surface
• Creating Class B surface
• Creating Class C surface
• Surface and solid body
• Draft analysis of Solid body
• Engineering features Rib and Screw boss
• Draft analysis of Solid body with engineering features

MATERIAL SELECTIION OF ATTATCHMENT FEATURES OF (RIB&SCREW BOSS)

POLYPROPYLENE

• polypropylene, a synthetic resin built up by the polymerization of propylene.
• One of the important family of polyolefin resins, polypropylene is molded or extruded into many plastic products in which toughness, flexibility, light weight, and heat resistance are required.

MECHANICAL PROPERTIES

RIBS

• Rib is a B-Side Engineering feature which provides a means to economical Stiffness and Strength in Plastic Molded parts without increase in overall wall thickness.
• Rib also facilitates locating and arresting components of an assembly.
• It provides alignment in Mating Parts.
• It acts as Stop and Guides for Mechanisms.

WHY RIB

• They provide strength,rigidity to the part and support to other features like boss.
• Ribs are provided instead in areas to avoid thick walls to avoid plastic defects like sink marks,warps and voids.

Design considersation of the Rib

• BASE WIDTH OF A RIB IS :0.3-0.7T.
• RIB HIGHT :LESS THAN 5T.
• SPACING BETWEEEN THE RIB IS:MORE THAN 4T
• RADIUS ATB BASE OF THE RIB IS:T/8(OR)0.258MM/MAX.
• DRAFT OF THE RIB IS:0.5DEG -2DEG.
• RIB ROOT THICKNESS SHOULD BE LESS THAN 0.4T.

SKETCH OF MAKING RIB

ATTACHMENT FEATURES OF DOOR HANDLE COMPONENT (RIB)

SCREW BOSSES-

• Bosses are common structures on plastic parts in home appliances and interior and exterior of auto-mobiles, mainly for positioning and fastening.
• The base of bosses often cause sink marks on the back surface of a part, this is because of the large wall thickness.
• The solution is to core out some material at the base.

WHY SCREW BOSS

• They are used to aid in the assembly of molded parts by providing a channel for a screw.
• Designing plastic screw bosses is fairly straightforward but there are a few considerations to ensure a strong connection between parts and mitigate cosmetic defects.

SKETCH OF MAKING SCREW BOSS

ATTACHMENT FEATURES OF DOOR HANDLE COMPONENT (SCREW BOSS)

RIB ROOT THICKNESS

• The thickness of the rib should be approximately 50 to 60% of the general wall thickness of the part.
• Exceeding this value may lead to sink marks on the surface opposite the ribs.

CLASS A SURFACE

• Class-A (or 'Strak') is a term used in specifically in automotive design.
• It describes the final production surface data for the aesthetic parts of the car.
• The term 'Class A' is often misunderstood, but it's generally seen as the 'Holy Grail' of surface modeling.
• Class A surface is used to show to the customer visulization,and it is a aesthetic syurface.

CLASS B SURFACE

• The Class B finish is a quality finish with only minimal imperfections.
• A Class B finish is the most common finish for exterior surfaces.
• It is normally specified on surfaces such as external covers, panels, and parts that are fairly prominent.
• It is a offset surface of A,Which the surface were can not able to see Over the customer.

CLASS C SURFACE

• The Class C finish allows more imperfections than Class A or B.
• Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled, or surfaces which the Customer feels do not need to meet a high cosmetic finish.

DRAFT ANALYSIS

• The draft analysis technique is used to analyze whether our part model created in CAD is manufacturable based on the draft condition applied.
• Here the part should get easily removed from the panel dies .

DRAFT ANALYSIS OF DOOR HANDLE CLASS A

DRAFT ANALYSIS OF DOOE HANDLE FINAL COMPONENT

DRAFT ANALYSIS OF DOOR HANDLE WITH ATTACHMENT FEATURES

CONCLUSION:-

• Class A surface of Door Handle is successfully converted into solid body And all the B side Rib and Screw Boss also created on Class B surface with the correct terminology.
• its passes the draft analysis also means we can conclude that its is manufacturable or Formable.