Project 2

WIRING HARNESS ROUTING AND FLATTENING ON THE BACKDOOR OF A CAR

Aim

The project aims to route the wiring harness on the given backdoor of a car and prepare a flattened view drawing in the CATIA V5 by applying all packaging rules and following the industry standards and design guidelines.

Introduction

Wiring harness design and Routing

Wire harnesses are a mixture of wires that are bundled together to form a wire harness. Wire harnesses range in complexity from a few individual wires going point to point to hundreds of individual wires, multi-conductor cables and welded wires all forming a complex wire harness used to transmit power and all types of data. Wire harness designs are highly customizable, as harnesses are typically designed to suit specific applications. They may need to be concealed behind walls, fit within electrical boxes, or conform to other space constraints. Precise measurements of the environment, power demand, and lengths must be taken during design to prevent costly mistakes and ensure proper safety and functionality of the final product.

A wiring harness routing structure includes a wiring harness routing member configured to be attached to a vehicle body and a protector that accommodates and holds a wiring harness. The protector has a recess shape in which the protector is opened in one direction in a sectional view. At least one of the wiring harness routing members and the protector includes a fixing mechanism that fixes the protector to the wiring harness routing member. The protector and the wiring harness routing member are configured to be integrated via the fixing mechanism.

Real-life Image of wiring harness routing in the backdoor of a car

Image credential: open source

Wiring harness flattening

Electrical Harness Flattening operation is used for converting the 3D format of the wiring harness geometrical bundles into associated 2D drawings, which will be taken as a reference during the various stages of manufacturing, assembling, installation and servicing of wiring harness.

Once a product is ready to manufacture, its design must be precise or it risks costly errors and delays. Collaboration is the essential key to successful documentation and design between harness designers and manufacturing. CATIA – Electrical Wire Harness Flattening provides automatic and complete flattening of 3D Electrical Harnesses for manufacturing documentation in a concurrent engineering environment.

Real-life Image of wiring harness routing in the backdoor of a car

Image credential: open source

DESIGN METHODOLOGIES

Study and understand the wiring harness requirements for the backdoor of a car and identify the connectors and other components

• Open the cad file of the backdoor and identify the position of electrical components such as tail lights, wiper motor mounting area etc where the wiring harness routing is to be done.
• Decide the type of connectors, clamps, supports and external components going to be used for the backdoor routing.
• Understand the concept path of the main branch of the bundle that is going to be connected with the electrical parts of the backdoor.

The input cad file of backdoor of a car

Define the connectors as electrical part

• Download the neutral data file (step file / igs file) of the connectors from the given source (TE connectivity website) and open it in the CATIA part workbench.
• Identify the faces of the connector connection point, bundle connection point and the mechanically locking sides of the connectors.
• Create the geometries like center points of the connector connection point and bundle connection point by selecting appropriate edges and create an axis on the connector connection point by placing the Y axis towards the connector connection point (mating point) direction and the X axis pointing towards the side of the locking mechanism. The same axis direction should be followed for the compatible mating part.
• Now switch to the electrical part design workbench and define the model as an electrical connector part by using the define connector command.
• Define the connector connection point by giving the representation as the back connector connection point, selecting the face of contact, coincidence direction as Y axis and orientation direction as X axis.
• By using the define bundle connection point command select the face of the bundle entry side and the bundle center point to define the bundle connection point of the connector.
• Now the connector part file is converted into the electrical part file with all electrical properties.
• Follow the same steps for converting all connectors into electrical.

Selected connectors for the wiring harness routing of the backdoor and defined the connectors as electrical part

Define the fir tree clips electrically

• Study the fir tree clips model and understand how the bundle is passed through it and identify the entry, exit, base and mechanically connected faces.
• Fir tree clips are bidirectional components and we have to define the points and planes along three parameters, entry face, exit face and base face.
• Switch to the electrical part design workbench and define the fir tree model as an electrical support by using the define support part command.

Electrically defined fir tree clips

Create a new product file for the wiring harness assembly context, adding the relevant components to each product file and convert the geometrical bundle assembly file into an electrical bundle

• The main product file for the wiring harness assembly context is opened and then add new product file for geometrical bundle assembly under it.
• Open the geometrical bundle assembly in a new window and switch to the mechanical assembly workbench and add all the relevant connectors, fir tree clips, etc required for the harness assembly routing.
• Position the connectors and other components to the desired location by using various commands available in the mechanical assembly workbench.
• Switch to the electrical harness assembly workbench and activate the geometrical bundle command and select the geometrical bundle assembly file from the tree structure then it will convert the geometrical bundle assembly file into an electrical assembly file.

Product file of the backdoor assembly context with geometrical bundle assembly product file and the relevant components for routing

Wiring harness mounting strategy and selection parameters

• Mounting strategy and selection parameters for components, terminals, wire, protection devices, should be strictly followed clearance management while routing

Some of the Harness branching rules are,

• Branch length should be greater than 50mm
• Minimum distance between clamp and nearby branching point should be 25mm.
• Minimum distance between two breakouts should be 25mm.

Routing the wiring harness assembly

• By using the multi-branchable document command available in the electrical harness assembly workbench and adjust the options available likes, connector diameter, bend radius ratio, build mode, and with the help of routing objects options define the routing by adding the desired electrically defined components and adjust the tangency if required to get the proper bundle connection between connectors.
• It is always recommended to use multi-branch routing during the wiring harness assembly.
• We can add branches or split the existing branches by double-clicking the multi-branch-able command then it will automatically switch into the wiring harness installation workbench from there we can add a branch point on the existing bundle to the required position.
• Again go to the multi branch-able document command and select the appropriate electrically defined components and bundles to create sub-branches in the assembly.

Routed wiring harness assembly product file of the backdoor

Adding protective covering (corrugated tubes) to the bundles

Equivalent protective coverings (corrugated tubes) are added to the main bundle and for sub-branches

Check for the bundle continuity and bundle warnings in the wiring harness assembly and resolve them

• Under the edit command select the search icon (binocular symbol) a pop-up window will appear to select the advanced option and arrange the options available by selecting, workbench as electrical, type as bundle segment and attribute as fully connected.
• A pop-up window will appear, while selecting it as false and selecting the search button it will show all the discontinued bundles in the assembly. If we select it as true, it will show a fully interconnected bundle throughout the assembly.
• Bundle warnings are mainly due to the inappropriate bend radius given to the bundle this can be solved by adjusting the position of connectors, adjusting the bundle break point for sub-branches, reversing the tangency of the bundle, adding extra slag, etc.
• It is recommended to maintain the tentative bend radius always less than that of the computed bend radius of bundles.

Checked for the bundle continuity and bundle warnings in the geometrical bundle assembly when the query was set as false

Checked for the bundle continuity and bundle warnings in the geometrical bundle assembly when the query was set as True

Create a new product file for wiring harness flattening, initial settings and adding the relevant components

• Open a new product file for the wiring harness flattening process and switch to the electrical harness flattening workbench.
• Select the harness flattening parameters command a pop-up window appears to do the initial settings like, algorithm as coarse, angle mode as regular, minimum angle between two branches, flattening orientation, flattening scaling, synchronization, link and drawing options.
• Now open the input file of the wiring harness geometrical bundle product in a new window and check for the bundle continuity and all the components in the wiring harness assembly are electrically defined.
• Switch to the new product file for the wiring harness flattening and make the window as Tile vertically then we can import the input file to the new product file by selecting the geometrical bundle product tree structure using the extract command and the other window will be closed automatically.
• The imported file will automatically have the suffix .ehf file, this means it is successfully imported into the electrical harness flattening workbench.
• By selecting the appropriate plane and all bundles in the assembly we can flatten them by using flatten command and then adjust the position, angles, etc if required by using various commands available in the electrical harness flattening workbench then save all the files in one folder for the proper and smooth operations.

New product file for wiring harness flattening and the geometrical bundle set file and make the window as Tile vertically

Extracted the geometrical bundle set file successfully and shows .ehf file on the suffix of the file name

Flattened view of the electrical harness geometrical bundles

Adjust the position, angles, etc by using various commands available in the electrical harness flattening workbench and adding protective coverings to the bundles to get the appropriate view

Create a drawing file and convert the electrical harness to a 2D drawing

• Open a new drawing file by using the file toolbar and thereby selecting new and type has drawing. Make initial settings like, standard, paper size, view type, etc available in the pop-up window.
• We can add the front view of the flattened wiring harness assembly to the drawing workbench by selecting the front view command and selecting the appropriate flatten surface from the electrical harness flattening workbench
• Right click on the border of the design sheet and go to the properties and view option then enable 3D wireframe and mark as is always visible from the dress-up feature.
• To enable the 3D views of the connector we have to switch into the electrical flattening workbench and by double clicking, the flattening parameters from the tree structure adjust the graphic replacement of the device to 3D projection and again add a new front view into the drawing.
• We can also add a frame and title block into the drawing by using the toolbar insert, drawing, frame and title block.

A new drawing file was opened and added the front view of the flattened wiring harness assembly by adjusting the dress-up features to get a fully informative drawing associated with the 3D model

Conclusion

The concept design of wiring harness routing for the backdoor of a car is developed by following all the design guidelines and best practices as per industry standards and thus understand the critical role of wiring harness routing in automobile industries in “connecting” a variety of components to relay information and electric power.