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AbstractWire Harness is the interconnecting wiring in the
vehicle for the transmitting electrical power and signals in the
electrical system. Over the years the number of components to be
connected and hence the number of circuits has increased many
folds. This has made the wire-harness design as the most complicated
task in the vehicle design and wire harness (electrical system )
integration with the other aggregates a difficult job. Many CAD tools
and design software have evolved from computer companies. But
they have not resolved major issues faced by vehicle OEMs and the
wire-harness manufacturers. In fact, the requirements of vehicle
manufacturers are not clear to the other agencies and this results in
wire-harness development as a major bottleneck in any vehicle
development program. An overview is given on the importance of the
wire-harness design and the impact it will have on the success or
failure of the final product VEHICLE when it reaches the
customer.
KeywordsWire Harness, Automobile.
I. INTRODUCTIONHE increase in the electrical and electronic content in the
automobiles has resulted in the wire harness design
becoming more and more complex. From the simple function
of electrical power distribution and transmitting signals, it has
become a networking of multiple controllers with a vast range
of sensors , actuators and their interfaces. Many luxury
features used only in high-end vehicles for safety and comfort
have now become standard across all makes and models. With
the availability of more electronic components suitable for
automobile applications the gadgets on the vehicles are
multiplying with every new model introduced in the market.
II.RELATED WORKThis Procedure and Guidelines issued by NASA [1]
establishes guidelines for the Product Design Team (PDT)
providing support for the design and development of
spaceflight electrical harnesses. The P & G is marked as
COMPLIANCE is MANDATORY which signifies the
importance of wire harness design for any space mission. The
same level of weightage is being given in the field of
automotive designs as the number of safety requirements of
electrical and electronics units needs to be taken care at design
stage of vehicle development.
Mr. Ajay Pradhan is Asst Professor with D Y Patil College Of Engineering,
Akurdi, Pune e-mail:[email protected]
III. BACKGROUND DETAILA.Principles Of Wireharness DesignThe wire harness design is usually last component to be
finalized on the vehicle proto-type. Various design changes
are done to meet requirements of access, serviceability and
robust design. But the inherent flexibility in the routing and
adaptability to other system items, results in the design of wire
harness being changed to incorporate feedbacks from different
agencies.The following general principles are used in the process of
wire harness design;
- Design to cost
- Optimum lengths & routing / branches
- Protection from Thermal and mechanical damage
- Water proof or sealed connectors in critical areas to
avoid contact corrosion
- Design to assembly
- Access to serviceable parts / troubleshooting
- Design for manufacturing of wire harness
- Minimum bending radius
- Poke yoke / mistake proofing
- Splice position / joints
B.Conventional Methods Of DesignThe normal practice followed by vehicle manufacturers was
to define the overall specifications of the electrical system and
then prepare the circuit diagram for the subsystems. The
compiling of the subsystems will result in the total vehicle
level electrical circuit which will be used to design the wire
harness requirement of the particular vehicle. The following
process flow is used to define the design inputs and outputs
for this purpose;
Design Inputs
- Wire Harness Design manual- Vehicle level Electrical circuit schematic
- Layout on vehicle
- Feature list
- Component details
- DFMEA
Design Outputs
- Wire harness drawing
- Bill of material
- 3D bundle layout
- Digital interference check
Current Trends in Automotive Wire
Harness Design
Mr. Ajay Pradhan
T
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- Prototyping
- Validation process
IV. PROPOSED SYSTEMA.Manufacturing Challenges In Wireharness DesignIn spite of all technological advances in the field of
automotive assembly line; the manufacturing of wire harness
is still done manually and at the most using semi-automaticmachines for a few operations. The wide variations in the
layout from one model to another and also in versions for the
same model has resulted in almost no standardization of
design. Each OEM follows a different philosophy in selecting
the components and making the layout for the vehicle. [ 3]
The major challenges faced by wire harness manufacturer
in todays automotive industry are;
- Variety of connectors / terminals: The connectors are
proprietary items of the manufacturer and rarely they can be
duplicated / copied due to IPR issues. This results in no
commonality in the connector and terminal designs and at
vehicle level there is little scope to reduce the variety. Thesystems and components on the vehicle for different electrical
systems come from global sources who will not allow the
connector design changes in already validated product.
- No Standardization: Connectors used for a same function
vary across models and vehicle platforms. Similarly, vehicle
OEM should have the connector, terminal and wire standards
to bring uniformity in design and drawings.
- No regulation: Unlike the functional components as
lamps or safety components as horns, wipers; wire harness
design is not required to meet any regulatory requirement.
However, deficiencies in design can cause serious hazards on
the vehicle and protection has to be in-built for the wire
harness.
- Insufficient protection to wires: The vehicle environment
may require certain branches of wire harness with special
insulation or protection. Identifying the requirements in
advance and implementing in the design necessitates a lot of
forethought / experience on the part of the wire harness
designer.
- Manual checking of W/H: The process of wire harness
assembly uses a assembly board and at the end to the line the
connectors are manually plugged into matching components to
check the circuit continuity and correct insertion of wires. If
any fault is reported then tracking the problem and rectifying
it is done manually.Harness assemblies are becoming increasingly complex,
making the process of manual insertion result in higher scrap
rates and additional quality control issues. [4]
- Tier II suppliers of raw materials: The wire harness
manufacturer depends on a number of sources to get his raw
materials and any deviations in quality affects the final
performance of the wire harness and its reliability.
- Handling issues (Mechanical damages): The wire harness
needs to undergo many stages of handling from the
manufacturing to getting assembled on the vehicle.
B.Future Trends In Wire Harness Design :The wire harness design in interlinked with the trends in the
overall vehicle development. However, to increase the
efficiency of the wire harness design in terms of cost and time,
the use of CAD tools dedicated to the process of wire harness
design have come into the market over the years. The features
in the packages address some of the steps in the design which
were done manually or on the prototype wire harness to freeze
the design; The major highlights of the software packages are
listed below;
- Standardization and increased productivity through
design
- Modular design
- Sneak analysis / Voltage drop testing / Fuse blowing test
- Simulation of circuits
- Design rules Checks
- 3D modeling in CAD & flattened wire harness design for
manufacturing
- Recycling of wire harness material at end of life.
- Generate the BOM for the wire harness
A cost benefit analysis can help you determine when awiring harness should and should not be used. [5] [7]
C.Cad Tools Used In Wire Harness Design :Harness drawings can be produced in either 2D or 3D
format using CAD software; however, a 2D format lends itself
better to harness construction since the 1:1drawing is normally
attached to the harness board as a template. A 3D format,
while very explicit, does not lend itself to this application.
There are, however, drawing packages that produce both 2D
and 3D versions from the same native file. [5] [6]
Software packages from trademarks below are used by
different vehicle OEMs and wire harness manufacturers to
bridge the gap between design of the wire harness and
manufacturing them as per the design.
- ZUKEN
- MENTOR GRAPHICS [2]
- EMBASSY etc.
V.CONCLUSIONThe reliability of the electrical system can be gauged from
the robustness of the wire harness layout and the consistency
of the supplies received from the wire harness manufacturer.
If the controls on the assembly of wire harness ensure that the
fitment is exactly identical as per the fitment drawing
specified by the designer, the electrical faults due to wireconnections get totally eliminated. Similarly, if the quality
checks at wire harness manufacturer are enabling an error free
and zero defect wire harness, the vehicle assembly clearance
for electrical system faults will be almost nil on assembly line.
The wire harness contributes to almost 30% approximate
cost of the total Electrical system but is responsible for more
than 50% of the problems faced in the Electrical system.
Hence, the significance of the proper design of the vehicle
wire harness is self justified.
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REFERENCES
[1] Design and Development Guidelines For Spaceflight ElectricalHarnesses ; Procedures and Guidelines NASA Directive No.565-PG-
8700.2.1B Nov 2005
[2] JOHN P. WILSON, MENTOR GRAPHICS MODELING REAL-WORLD DESIGN CHALLENGES WITH MODERN VEHICLE
HARNESS DESIGN TOOLS MGC 12-10 TECH9450-w ; 2010
[3] Eli sa Pou yanne, Business dev Mgr Mentor Graphics Driving wiringharness design data toward manufacturing. Pg No. 2-11
www.cfibermfg/Wiring harness guide
[4] PATRICK BOYER, Harness Automation project Mgr, KOMAX corp.Benefits of fully-automated wire harness assembly. Pg No. 13-15
www.cfibermfg/Wiring harness guide
[5] Darrell Fernald, Engineering Mgr Copper Interconnect Building wiringharnesses to save costs in chassis and racks. Pg No. 17-22
www.cfibermfg/Wiring harness guide
[6] Jingkui Ruan; Xueliang Zhou Research on CAD/CAPP integratedsystem for automobile wiring harness Mechanic Automation and
Control Engineering (MACE), 2011 Second International Conference on
Digital Object Identifier: 10.1109/MACE.2011.5988240Publication
Year: 2011 , Page(s): 5146 - 5149
[7] Forde, C. The architecture and analysis of the XK8 electricalsystemThe Electrical System of the Jaguar XK8 (Digest No.:
1996/281), IEE Colloquium on Digital Object Identifier:
10.1049/ic:19961455 Publication Year: 1996 , Page(s): 7/1 - 711
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