Week 12- Final project

1.

AIM :

 

 Abstract: 

The project report deals with the explanation of steps and procedure followed while developing the Door Trim Panel of a car using CATIA V5. Using the CLASS-A surface and master sections as input, we were able to create a Tooling axis, CLASS-B surface, CLASS-C surface, Flanges and form a solid body after which the attachment features such as Dog House, Push Pins, Heat stakes, etc are created. To check the manufacturability of the parts, a Draft Analysis has also been performed using the main/side tooling axis on various components such as 

 

      1) Arm Rest

      2) Upper Map

      3) Lower Map Pocket

      4) Lower Substrate

 Outputs required : 

• CLASS-A surface extraction
• Creation of different Geometrical sets for each component such as lower substrate, map pocket (upper & lower part), armrest , etc.
• Tooling Axis / Side Core Axis Creation
• Creation of Flanges
• Creation of CLASS-B Surface
• Creation of CLASS-C Surface
• Joining of CLASS-A, B & C Surface
• Performing a check for boundaries
• Forming a Solid Body from closed surface
• Attachment features creation
• Performing Draft Analysis

 

THEORY :

 

•  Car Door Panel : 

Door panels serve as an interface between the interior of the car and the inner workings of the door, and between vehicle occupants and the door. They are expected to meet a variety of design specifications regarding safety, aesthetics, and functionality. In addition, they are expected to continue the material theme of the dashboard and pillars while concealing intricate electrical and mechanical components for operating locks, windows, and other features. The door panel has evolved from a simple two-part system of latch and simple winding mechanism to a more sophisticated enclosure. Doors currently have an inner full-width panel consisting of electronic windows, central locking system, and speakers. These panels typically consist of a foamed core covered with either textiles or plastics                  

 

 fig : conventional car door panel.         

Door panels are expected to meet one of the toughest sets of requirements among interior car components. These panels should be designed to withstand and channel loads into the body of the car while being thin (<2>

Federal Motor Vehicle Safety Standard No.214 therefore sets forth directives to manufacturers in order to limit this injury. It states that the Thoracic Trauma Index (TTI) should not exceed 85 g for a four-door or 90 g for a two-door passenger car. This test is performed at impact velocity of 53 km/h, which accounts for 90% of side impacts in North America.

Conventionally, door panels consisted of polyvinyl chloride (PVC) or polyurethane foamed core with appropriate textile fabric coverings. Subsequently, there was a shift toward thin-wall moldings of ABS or PP backed by textiles in order to manufacture a contour-backed panel with recesses. This is primarily because integrated injection-molded door panel assemblies reduce the need for other energy-absorbing materials, resulting in cost reduction for manufacturers due to simplification of door construction.

Door currently have an inner full width panel consisting of electronic windows, central locking system and speakers.These panels typically consists of a foamed core covered with either textiles or plastics.

 Automotive Plastic Trim: 

The design of Automotive Interior and Exterior plastic components is called Trims. The plastic components that you see inside the car are Interior. Ex: Dashboard, Instrument Panel, Doors, seating, and pillars. Plastic components that you see outside of a car are Exterior. ex: bumper, light assembly, hoods. 

 Plastic Part: 

When designing parts for injection molding,the manufacturing process is an important consideration. Injection molding is a process in which solid thermoplastic resin pellets are melted, injected into a mold, and then cooled back to a solid state in a new form. During both the injection and cooling stages of the manufacturing process, there are several factors that may affect the quality of the final product and the repeatability of the manufacturing process.

 

CLASS-A & MASTER SECTION EXTRACTION

The first step to follow in this project is to extract the CLASS-A surface (individually for each component) of the Door Trim Panel and divide these surfaces into different Geometrical sets as follows.

• Lower Substrate
• Map Pocket Upper Part
• Map Pocket Lower Part
• Arm Rest

We first check the given styling surface for any error in the surface elements. To do this we have to first extract the styling surface and then join it with the merging distance of 0.001 mm. This will show where the surface elements are weak. These weak sections have to be improved. The joined surface is then given as an input to the A-surface geometrical set. 

We have to ensure that the Class A Surface for each part is connected as one single profile,to do that take Input file which has a single Geometric set with all the surfaces of the Class A Door trim then We have to extract and assign the respective surfaces to each component.

•  Class A surfaces :--

 

•  Class A of Arm Rest  

 

•  Class A of Upper Map pocket  

 

•  Class A of Lower Map Pocket  

 

•  Class A of Lower Substrate   

 

The next process or step is to create the tooling axis for the part which can be either made using the Biscecting method or using the Draft analysis approximation method. When checking the draft analysis all top surface has to turned green.

CONSTRUCTION OF TOOLING AXIS :

Tooling axis : 

Tooling direction is basically the direction that mold pulls apart. The mold is built in two seperate pieces, basically you have a cavity side and you have core side, The core pulls apart from the cavity and that's the Tooling direction. While creating a Tooling direction make sure that waterver that is created that is going to be used as a reference to design it may also include Ribs, Pockets, Walls Bosses etc. All are going to be drafted with respect to Tooling axis to make sure that the core can pull apart from the cavity nice and clean.

 Process : 

since the extracted class A are of complex geometry for Bisection method to get the tooling axis ,even though we create it,it won't be accurate when we apply draft analysis on that tooling direction and also takes too much time and effort.so it is better if go with the trial method of moving compass until we get the satisfied analysis result to do that go to Insert > Analysis > Feature Draft Analysis and Simply place the compass on the largest flat surface then Check the Analysis by Tilting the Compass by Orientation or Rotation about an axis to get the desired result. After choosing the particular orientation,lock the compass direction.

now we have locked the definite direction of tooling axis now we will create a straight line which itself will be tooling axis.first we create a point on the surface before creating tooling axis .

 

  

CREATING B SURFACE

Class B surfaces are the secondary surfaces that you may see sometimes or may not, but are less important. These must be smooth and "error-free" as well, but are not held to the standards that class A surfaces are. After creating the Tooling axis, B surface is to be created which is nothing but the surface parellel to the A surface. B surface contain all the fillets and the edges which the A surface containsDepending on the geometry, the extraction and offset of the fillets might generate non-uniform thickness. So it is advisable to extract only the flat surfaces and then apply fillets at the end of Class B formation.

lets start the process of creating class B by choosing the respective A surface and extract with no propagation option then untrim the extracted surface to get the basic geometry.after getting the original/basic surface the surfaces have to overlap each other in order to facilitate trimming therefore extrapolate it up to the required dimension.then we finally trim them.

now after trim operation is done offset the Trimmed geometry by the value of the thickness of the component,this Offset is our B Surface.at last We will measure the filler radius values to create fillets on the class B

 

 

 

•  Addition of flanges with reference to the master sections : 

   

 

 

 

 

 

 

 

CREATING C SURFACE

 

C surface is the part of the geometry that connects Class A with B surface.Rules to be followed for C surface creation is A minimum draft of 3 degrees should be provided to facilitate the Ejection of the Molded component.The parting line should be on the B surface. This means that the draft should sweep outwards, from the C surface

•  Arm Rest 

 

•   Arm Rest 
•   

 

•  Lower Substrate 

•  Upper Map Pocket 

•  Lower Map Pocket 

 

•  Making closed solid bodies from joined surfaces 

This task shows you how to create a solid by closing the joined surface. For this we must call up the Part Design workbench.
	Select Part Design from the Start -> Mechanical Design menu. The Part Design workbench is displayed.
	Click the Close Surface icon . This icon is available from the Split sub-toolbar:
	Note that the Join element should be active in tree. The CloseSurface Definition dialog box appears.
	Click OK to create the closed surface feature. The specification tree is updated.

  

 

 

CREATING ENGINEERING FEATIRES            (Doghouse,pushpin,heatstakes)

 

 (1) DOG HOUSE : 

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

 

Dog houses are subjected to draft analysis to prevent breakage of the component during ejection from mould cavity. Dog house and other engineering components are built on B-surface.now we will proceed with creating a dog house and mount the boss on it by following the design rules mentioned below :

 Doghouse design guidelines (used as reference) : 

 

 

 

 

 

 

   

Create a straight line sketch using the surface as support.In the Surface workbench, Extrude the line in the direction of the Tooling axis.Trim the surfaces according to the required geometry.Go to the Part workbench and add Thickness to the extruded surface.

We now have a solid rib of definite volume and density.Give Draft of 0.5-1.5 degrees on all the vertical faces of the rib.This is done for easy ejection of the Core and to avoid any damage to the molded component.Select the faces to draft, neutral element, and pulling direction.

  PUSH PIN  :  

Pushpin which helps us in Locating and Arresting components of an Assembly and it provides Alignment in Mating Parts and it also acts as a stopper or guide for various mechanisms.

DESIGN GUIDELINES FOR PUSH PIN

 

Draw the Boundary of the sketch to be revolved.Revolve the sketch about it's axis.There are some slots in the revolved geometry to facilitate as guideway for locating and arresting.Create a Rib sketch and then Pad it.Remove the Padded rib from the revolved geometry to get the desired shape of the pushclip.

or otherwise it is already provided on the given input

 

 

We provide rounded corners at edges to facilitate easy flow rate and avoid Flowlines.Min. Radius = 0.25 mm

we only have to duplicate with control D then we do the manupulation on it

 HEAT STAKE : 

•  Heat stakes :

                In manufacturing products with thermoplastic components, it is often necessary to join a thermoplastic to a part of dissimilar material, whether it be metal, a dissimilar plastic, or other material. This technical information sheet provides design guidelines, configurations, and techniques for successful thermal (heat) staking.

GENERAL DESCRIPTION:

Thermal staking is an assembly method that uses the controlled melting and reforming of a
plastic stud or boss to capture or lock another plastic or metal component of an assembly in place.
The plastic stud protrudes through a hole in the component to be locked in place. The heated thermal tip contacts the top of the stud, which melts and fills the volume of the tip cavity to produce a head, locking the component in place.

 

The progressive melting of plastic under continuous pressure forms the head.When staking, the right combination of heat and pressure for the application is critical.

ADVANTAGES:

• Simplification of machinery
• Reduced cost of machinery
• Multiple fastening points
• Allows higher density of welds compared to hot air cold form or ultrasonic welding

Design rules and construction procedure :

There are no standards for Dia,it depends on the manufacturer.The dimension is altered in such way that sink marks are avoided.There is no standard for thickness as well, but keep it lesser than the part thickness.Minimum 0.75mm at the Tip of the Rib.Molten material won't reach any further. give Height of Heatstake < Height>

 

 

 Design of Gusset to support heat stakes : 

 GUSSETS :  

Gussets are rib-like features that add support to structures such as bosses,ribs,and walls. As with ribs, limit gusset thickness to one-half to two-thirds the thickness of the walls to which they are attached if sink is a concern. Because of their shape and the EDM process for burning gussets into the mold, gussets are prone to ejection problems. Specify proper draft and draw polishing to help with mold release.

Create a straight line sketch using the surface as support.In the Surface workbench, Extrude the line in the direction of the Tooling axis.Go to the Part workbench and add Thickness to the extruded surface.

We now have a solid rib of definite volume and density.Give Draft of 0.5-1.5 degrees on all the vertical faces of the rib.This is done for easy ejection of the Core and to avoid any damage to the molded component.We provide rounded corners at edges to facilitate easy flow rate and avoid Flowlines.

 

 TRANSLATION AND  OF PLASTIC FEATURES 

After creating a single feature, we can translate it multiple times to the desired location.First Copy the respective feature's part body into the main part file Copy > Paste Special > As specified in Part Document this removes the Parent-Children relationship and we can edit the translated part according to our needs.

 

We have to add all the translated features to the Main body of the Substrate.The Union Trim operation fit the best option for our needs.Define the Main part body as the Working Object  Select Feature Body > Union Trim > Select Faces to remove/keep 

 

 

Holes on flanges for fixation :

The door trim Assembly has to be rigidly fixed as one unit.The 4 components will be permanently arrested to the Lowered substrate by using the Heastakes.The Heatstakes will pass through the flanges of the components, therefore some clearance of 0.1mm has to be provided.

 

 

 

FINAL DRAFT ANALYSIS

In the injection molding process, plastic products are difficult to demold due to friction force between the cavity and products, thus, finished products might be deformed or damaged. Therefore, designers should add a draft angle to the geometric surface of products, which is parallel to the unloading direction, in order to help the products eject smoothly from the cavity. This study uses CAD software as the main architecture to develop the function of automatic draft angle recognition and construction. The study is divided into three stages. First, the geometric features of products are identified in the CAD model by induced algorithm, then the quilts to be added in the draft design are determined and classified. Finally, draft angles are created in different ways according to different surfaces

The draft analysis button within CATIA V5 will help you quickly gather the draft angle on multiple surfaces without the need for tedious manual measurements.we go to Insert > Analysis > Feature Draft Analysis.it will automatically enables a popup window to ensure you have the Material view mode ON.

once the material mode is selected Define the Draft direction using the "Compass" option then drag the Axis system representation close to the model and align it along the tooling axis to avoid the accidental movement of compass we will lock the Draft direction using lock compass option in the menu when we right click on the compass,set the Colour scale as shown below 

 

Place the Analysis Tool (Arrow Icon) anywhere on the model and review the colours on the feature.If any feature is showing Blue/Red then choose the same option again (It will switch to Analysis under Running point) and place it on the respective feature to review the deviation of the sweep angle from the Tooling Axis.

    

 

 

 

 

 

 

 

 

 

BOTTOM-UP ASSEMBLY

The components are created in separate part files and are then inserted into the assembly file. They are assembled at their working position by applying assembly constraints to them. To create an assembly using this approach, it is recommended to insert the first component and fix its position after properly orienting it in the 3D space. The other components can be inserted and positioned with reference to the first component. 

 

 

Note :

Before submission of the challenge/project i have ensured that i have followed and submitted all the reuired things as listed down below :

Creation of CAD model considering following inputs as like in OEM and tier1 companies

a) Class A surface

b) Nominal thickness : Refer master sections

c) Attachment strategy : 

Find a attachment strategy for the door panel complete work.

Use Push pin with Dog house for Lower substrate – Door panel attachment

Use heat stakes for part to part attachment

Output required:

• Created thickened part using master section for reference
• Created the mounting features as per design guidelines in the industry and with master sections
• Draft analysis & Tooling analysis is applied
• Created of parting lines and checked tooling feasibility

RESULT

 

Finally,the Interior trim of the Car interior door trim is designed using the given A Class Surface as the Input and B and C Class Surfaces are created with respect to the A Class Surface for the components listed down below:

• Straight Arm Rest
• Inclined Arm Rest
• Upper Map Pocket
• Lower Map Pocket
• Lower Substrate

Each component has a uniform thickness of 2.5mm.The components' surfaces (A, B & C) pass for Drafting analysis.The Plastic features follow the design guidelines and pass for the Lifter draft analysis.Clearance is provided on the Flanges, allowing for the Heatstakes to arrest and form an Assembly.Some regions in Lower Map Pocket and Lower substrate fail for draft analysis irrespective of determining the right tooling direction with the compass method.Therefore, we can conclude that the surfaces of those components have to be re altered by the Class A designer.