Development of Door trim panel

DEVELOPMENT OF DOOR TRIM PANEL

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.

ABSTRACT

The project report deals with the steps and procedures followed while developing plastic trims for cars door from a class A surface provided, using CATIA V5 surface workbench. It explains the method I followed for creating the main tooling axes, side core axes, Class B surface, Class C surface and final closed body creations. It also explains the draft analysis performed to check the manufacturability of the products using injection moulding. Various plastic door trims such as map pockets, armrest, lower substrate etc were successfully developed in this project.

For this door trim panel development we need to collect the relevant data for ex:-all class A surfaces of parts which are a part of door trim. and required feature profile data etc…,

To fallow the given master section for the attachment features.

INTRODUCTION

The door panel covers internal parts like the window regulator, the power window motor, and the wiring. It is attached to the sheet metal part of the door. It is designed differently based on the design of the sheet metal part of the door. Besides its aesthetic look, it also has many functional features attached to it such as an armrest, bottle holder, speaker attachment, etc. In older cars, door panels used to be made out of cardboard and upholstered with material that matches the rest of the upholstery within the cabin. On the other hand, most modern cars have door panels made from plastic.

OBJECTIVE

• Here I received class A surface of a car door’s plastic trims. My objective is to develop the class A surface received into manufacturable product design following the OEM design standards using CATIA V5 surface workbench.

STEP BY STEP PROCEDURE:

• CLASS - A SURFACES:

A-class surfaces are those free form surfaces, which are visible to us (interior/exterior), having an optimal aesthetic shape and high surface quality. Mathematically class-A surfaces are those surfaces which are curvature continuous while providing the simplest mathematical representation needed for the desired shape/form and does not have any undesirable waviness. This is the reason why in design industries Class-A surfaces are given more importance. In automotive design, a class-A surface is any of a set of freeform surfaces of high efficiency and quality.

• CLASS - B SURFACES:

Class-B surfaces are the secondary surfaces that can be seen sometimes, but are less important, such as the inside of your glovebox, ash tray, etc. These must be smooth and "error-free" as well, but are not held to the standards that class-A surfaces are.

• CLASS - C SURFACES:

Class C surfaces are the backside surfaces that can have tool marks, flash and other imperfections without hurting appearance, function, etc.

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 analyzed element where the deviation from the draft direction at any point, corresponds to specified values.
• The maximal draft analysis accuracy is 0.01 deg. According to the graphic card performance, this accuracy can be debased.
• The different mapping analyses of the same surfaces cannot be displayed simultaneously, even if you have set the mapping analyzes in no show. You need to visualise them one after the other.

OTHER ATTACHMENT FEATURES

• Dog houses
• Heat stakes
• Flanges
• Locators
• Ribs

• DOG HOUSE :

Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting features. Sometimes other engineering features like snaps; locators etc. are mounted 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 a B-surface.

• HEAT STAKING :
  Heat Staking is a pulsed-heat process to join two or more parts out of which one at least is made of plastic. The process is to deform the plastic material using heat and force at a set process time. The bond is made by partially de-forming the plastic part in order to fix the other.
  Heat Staking makes it easy to bond metal to plastic and is commonly used in high volume/low cost applications such as automotive, IT and consumer appliances.

Heat Staking Benefits:

• Similar and dissimilar materials may be joined: metal to metal, plastic to plastic, metal to plastic
• Accurate control operating within a small process window
• Local heating resulting in no damage to surrounding materials
• Processing of glass-filled materials
• No mechanical vibration
• Many heat-stake shapes are possible through custom designed tools.

Materials best suited for Heat staking:
Heat staking technology is ideal for most native and blended thermoplastics on the market today, as well as the most robust glass and/or other- filled plastics. It produces high quality results when used with any of the following materials:

• Polycarbonate (PC)
• Polypropylene (PP)
• Polystyrene (PS)
• Acrylonitrile butadiene styrene (ABS)
• Nylons (GFN or Nylon 6/6)
• Ultem (GFN or Nylon6/6)
• FLANGES:

A flange is a protruded ridge, lip, or external or internal rim that increases strength. A flange allows for easy attachment and transfer of contact force with another object. They help with stabilizing and guiding the movements of a machine or, in this case - your access door

• LOCATORS:

Locators are use to arres the degree of freedom , If it a xy , yx based component we will able to arres the x,y freedom. we are having 12 number of degree of freedom so using of locators to lock it. It is having two different types ,they are two way locator and four way locator.

• RIBS:

Ribs are used to strengthen the walls of your mould without increasing wall thickness which means that you minimise the problems that come into play when the wall thicknesses have to be increased. In essence, if the wall is too thick, warping and sinking can result so that the entire design may need to be rejected.

PARTS INVOLVED IN DOOR TRIM PANEL:

• INCLINED ARM REST
• LOWER SUBSTRATE
• MAP POCKET
• BOTTLE HOLDER

STEP 1:Creation of class A surface:-

Class-A surfaces are those free form surfaces, which are visible to us (interior/exterior), having an optimal aesthetic shape and high surface quality. Mathematically class-A surfaces are those surfaces which are curvature continuous while providing the simplest mathematical representation needed for the desired shape/form and does not have any undesirable waviness. This is the reason why in design industries Class-A surfaces are given more importance. In automotive design, a class-A surface is any of a set of freeform surfaces of high efficiency and quality.

PART NO.	INSTANCE NAME	CLASS A
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
PART 4	BOTTLE HOLDER

STEP 2:-Creation of tooling axis& Draft analysis

• Due to the complexity of the geometry, the Bisecting method won't be accurate and also takes too much time and effort.
• Therefore, it is best to go with the Compass Method:
  • Insert > Analysis > Feature Draft Analysis
  • Simply place the compass on the largest flat surface.
  • Check the Analysis.
  • Tilt the Compass by Orientation or Rotation about an axis to get the desired result.
• After finalizing the orientation, lock the compass direction.
• Create a Line, this will be our Reference Axis:
  • Line > Point-Direction > Select Point > Select Direction (Compass Direction)

Colour	Description	Value
Green	Core Side	Above 3 degrees
Blue	Parting Line	0 degrees
Red	Cavity Side	Below 0 degrees

Tooling axis:-

PART NO.	INSTANCE NAME	TOOLING AXIS
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

STEP 3: B SURFACE CREATION

Note: Depending 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.

Perform the following operations in the order:

EXTRACT	Choose the respective A surface and extract with no propagation option.
UNTRIM	The extracted surface will possess the specific trimmed. Untrim to get the basic geometry.
EXTRAPOLATE	The surfaces have to overlap each other in order to facilitate trimming therefore extrapolate it up to the required dimension.
TRIM	Trim the surfaces according to the required geometry.
OFFSET	Now, Offset the Trimmed geometry by the value of the thickness of the component. This Offset is our B Surface. Note: Offset the Silent Fillet separately and then trim with the bucket
FILLET	Extract the Fillet surface from Class A. Untrim to get the basic Geometric shape. Measure the uniform radius of the surface. Apply Fillet to the respective edges to get the desired finish.

Note: The fillet radius of the Class B offset is altered to maintain the uniform thickness throughout the geometry.

Offset direction	Fillet Radius
Inward	Initial Radius - Thickness
Outward	initial Radius + Thickness

CLASS B SURFACES:

PART NO.	INSTANCE NAME	CLASS B
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

STEP 4: C SURFACE CREATION

C surface is the part of the geometry that connects Class A with B surface.

Rules to be followed. for C surface creation:

• 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.

Perform the following operations in the order:

MULTIPLE EXTRACT	Extract only the Boundary by Tangential selection.
CURVE SMOOTH	We need minimum Parting lines as possibles, so smoothen the extracted boundary.
SWEEP	The C surface is swept with the Line option along the Drafting Angle Direction. Guide Curve: Select the Smoothened Curve Draft Direction: Select the Tooling Axis Draft Angle: 3 Degrees
MULTI-SECTIONS SURFACE	In places like Fillets where the Sweep option doesn't work, we can fill in the gap using MSS. Choose the Sections. Then choose the Guide Curve along which we can drag the profile.
EXTRAPOLATE	The Sweeps at the edges need to overlap in
JOIN	For our future reference, we can Join all the C surface sweeps as one single entity.

CLASS C SURFACE:-

PART NO.	INSTANCE NAME	CLASS C
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

STEP 5: CLOSED SURFACE

• First Trim/Join Class A with Class C.
• Then Trim with Class B and keep the respective surfaces.

PART NO.	INSTANCE NAME	CLOSED SURFACES
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

STEP 6: CLOSED BODY DRAFT ANALYSIS

All the 3 class surfaces must pass in this analysis.

Insert > Analysis > Feature Draft Analysis

Note: Ensure you have the Material view mode ON.

• Define the Draft direction using the "Compass" option.
• Drag the Axis system representation close to the model and align it along the tooling axis.
• "Lock" the Draft direction.
• Set the Colour scale

Colour	Description	Value
Green	Core Side	Above 3 degrees
Blue	---	0 degrees
Red	Cavity Side	Below 0 degrees

• Place the Analysis Tool (Arrow Icon) anywhere on the model and review the colours on the feature.
• If any feature (especially C surface) 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.

STEP 7: ASSEMBLE THE ALL THE CLOSED PARTS

STEP 8: PLASTIC FEATURE: DOG HOUSE

DEFINITION

• It is a feature used:
• To avoid sink marks.
• Solve length issue.
• Provide strength and assembly.

DESIGN GUIDELINES FOR DOG HOUSE

DRAFT ANALASYS FOR DOG HOUSE

STEP 9: PLASTIC FEATURE: HEAT STAKE

GUIDELINES FOR HEAT STAKE DESIGN

Diameter	There are no standards for Dia, it depends on the manufacturer. The dimension is altered in such way that sink marks are avoided.
Thickness	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.
Height	Height of Heatstake < Height of Locator Since Fixing occurs after Locating.
Draft	0.5 degree.
Flat plate	Dia of Flat Plate = 2.5 x (Dia of Heat Stake).
Clearance	0.1mm to accommodate for clearance.
Spacing	65-100 mm

GUIDELINES FOR RIB DESIGN TO SUPPORT HEAT STAKES

Draft	0.5-1.5 Degrees If it is more, then the rib will be too narrow at the top and mold wouldn't fully fill the rib.
Thickness	(0.4-0.5) T at the base of the rib. The larger the area of the base of the rib, the more heat retained. Retained heat causes more shrinkage. This leads to Sink marks as well. Minimum 0.75mm at the Tip of the Rib. Molten material won't reach any further.
Fillet	Maximum radius = 0.25 mm. Due to the less thickness of the rib we need to maintain a small fillet radius, or else we'll get ribbon formation.
Height	Height ≤ 5T Taller ribs are prone to buckling.
Base Rib Root Dia	D ≤ 30% of Deviation from Thickness. Greater than that causes Sinkmark.

Operations to be followed:

Extrude	Create a straight line sketch using the surface as support. In the Surface workbench, Extrude the line in the direction of the Tooling axis.
Thickness	Go to the Part workbench and add Thickness to the extruded surface. We now have a solid rib of definite volume and density.
Draft	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.
Boolean	Boolean Add/Union Trim the Rib to the Coin holder body.
Fillet	We provide rounded corners at edges to facilitate easy flow rate and avoid Flowlines.

STEP 10: PLASTIC FEATURE:LOCATOR

STEP 11: TRANSLATION 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.

STEP 12: BOOLEAN OPERATION

• 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

STEP 13: CLEARANCE FOR HEAT STAKES PROVIDED ON FLANGES

• 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.

PART NO.	INSTANCE NAME	FLANGES
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

STEP 14: FINAL DRAFT ANALYSIS

Insert > Analysis > Feature Draft Analysis

Note: Ensure you have the Material view mode ON.

• Define the Draft direction using the "Compass" option.
• Drag the Axis system representation close to the model and align it along the tooling axis.
• "Lock" the Draft direction.
• Set the Colour scale

Colour	Description	Value
Green	Core Side	Above 0.5 degrees
Blue	Parting Line	0 degrees
Red	Cavity Side	Below 0 degrees

• 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.

PART NO.	INSTANCE NAME	FINAL DRAFT ANALASYS
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

STEP 15: PLASTIC FEATURE: PUSH PIN

DEFINITION

• It is a feature that facilitates:
• Locating and Arresting components of an Assembly.
• Providing Alignment in Mating Parts.
• Acting as a stopper or guide for various mechanisms.

DESIGN GUIDELINES FOR PUSH PIN

Operations to be followed:

Positioned Sketch	Draw the Boundary of the sketch to be revolved.
Revolve/Shaft	Revolve the sketch about it's axis.
Pad	There are some slots in the revolved geometry to facilitate as guideway for locating and arresting. Create a Rib sketch and then Pad it.
Boolean Remove	Remove the Padded rib from the revolved geometry to get the desired shape of the pushclip.
Chamfer
Fillet	We provide rounded corners at edges to facilitate easy flow rate and avoid Flowlines. Min. Radius = 0.25 mm

RESULT

• The A surface of the following components converted to a solid body:
• Arm Rest
• Map Pocket
• Lower Substrate
• Bottle holder
• 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.

PART NO.	INSTANCE NAME	FIRST ANGLE VIEW	TREE STRUCTURE
PART 1	INCLINED ARM REST
PART 2	LOWER SUBSTRATE
PART 3	MAP POCKET
‘ PART 4	BOTTLE HOLDER

FINAL LOOK OF DOOR TRIM ASSEMBLY

We get the following Desirable Outcome for Draft Analysis:

Green	Class A and C Has a Projection, falls into the Core side.
Red	Class B. Has a depression, falls into the Cavity side.

Note: 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.

CONCLUSION:

By the given master sections and class A reference surface by use of these surfaces we are developed a car door trim by the help of some of attachment features and all the parts can assembled and push pins were also inserted and the final part should be analysed .

Hence, the creation of a plastic car door trim by using CATIA V5 surface workbench successfully.