Cable harness

[
car audio cables.]

A cable harness, also known as a wire harness or wiring loom, is a string of cables and/or wires which transmit informational signals or operating currents (energy). The cables are bound together by clamps, cable ties, sleeves, electrical tape, conduit, a weave of extruded string, or a combination thereof.

Commonly utilized in automobiles, as well as construction machinery, modern-day cable harnesses provide several advantages over loose wires and cables. For example, many automobiles contain many masses of wires which would stretch over several kilometers if fully extended. By binding the many wires and cables into a cable harness, the wires and cables can be better secured against the adverse effects of vibrations, abrasions, and moisture. By constricting the wires into a non-flexing bundle, usage of space is optimized, and the risk of a short is decreased. Since the installer has only one harness to install (as opposed to multiple wires), installation time is decreased and the process can be easily standardized. Binding the wires into a flame-retardant sleeve also lowers the risk of electrical fires.

Production

Cable harnesses are usually designed digitally according to geometric and electrical requirements. A diagram is then provided(either on paper or on a monitor) for the assembly preparation and assembly.

The wires are first cut to the desired length, usually using a special wire-cutting machine. After this, the ends of the wires are stripped to expose the metal (or "core") of the wires, which are fitted with any required terminals and/or connector housings. The cables are assembled and clamped together on a special workbench, or onto a pin board ("assembly board"), according to the design specification, to form the cable harness. After fitting any protective sleeves, conduit, or extruded yarn, the harness is either fitted directly in the vehicle or shipped.

In spite of increasing automation, in general, cable harnesses continue to be manufactured by hand, and this will likely remain the case for the foreseeable future. In part, this is due to the many different processes involved, such as:
*routing wires through sleeves,
*taping with fabric tape, in particular on branch outs from wire strands,
*crimping terminals onto wires, particularly for so-called "double crimps" (two wires into one terminal),
*inserting one sleeve into another,
*fastening strands with tape, clamps or cable ties.

It is clearly difficult to automate these processes. In spite of this, these processes can be learned relatively quickly, even without professional qualifications. Thus, manual production remains more cost effective than automation. For certain vehicles, such as HGVs, there are also a large number of variants (due to different configurations and the length of the vehicles), which produce very small batch sizes (as low as 1). However, the number of variants has been decreasing in recent years due to the use of data bus technology, such as a CAN bus, in conjunction with intelligent control units. In spite of this, different variants are produced on the same assembly board. Even here, man has an advantage over machine, since he can change over to the different variants (no "re-programming" being required).

Pre-production, however, can be automated in part. This affects:
*Cutting individual wires (cutting machine),
*crimping terminals onto one or both sides of the wire,
*partial plugging of wires prefitted with terminals into connector housings ("module"),
*soldering of wire ends (solder machine),
*twisting wires.

Testing the electrical functionality of a cable harness can be done with the aid of a test board. The circuit diagram data is pre-programmed into the test board, where harnesses can be tested individually or in multiple numbers. [ [http://www.cirris.com/harness/tester/index.html easy-wire™ Harness testing board and software] ]

Cable harnesses in sound engineering

The cable harnesses used in sound engineering (stage and studio) for carrying audio signals are also called multicores.

References