Wire Processing is commonly known by it’s basic processes: wire measure to length and cut, wire stripping and crimping of a terminal to one or both ends of the wire. These hook up wires by themselves form an electrical connection in an electrical device. Multiple wires are grouped together to form a wire harness with multiple connections. Wire Harnesses are typically held together with cable ties and/or enapsulated in sheathing such as convoluted plastic tube, heat shrink or tape.
As a wire assembly becomes more complex and as new materials are introduced, additional processing becomes necessary. These processes are unique and are performed on either single or multi-process machines mounted on a bench top or an automation system. This article will cover some of these special processes that are used in a wire harness.
There are a range of methods to splice two or more wires in an assembly. These methods range from manual processes such as solder and loose piece splice clips to more automated processes such as reel feed splices and ultrasonic wire splicing. Different industries may embrace a specific method of splicing. For example, the aerospace industry uses solder sleeves as a primary splice method where the automotive industry almost exclusively uses ultrasonic.
Ultrasonic welding uses high frequency vibration and pressure to create a metallurgical bond. The vibration of the materials causes a scrubbing motion which dislodges contaminants such as oxidization and small traces of oils used in the manufacturing process. The result is a bond that has very low electrical resistance. The material does not reach a melting temperature and does not depend on materials with similar melting points. As a result small wire splices as well as large cross sections can be bonded together. The ultrasonic weld process is also used to seal copper tubes for refrigeration, wire to terminal connecting and a great number of electrical and electronic connections.
Wire Splicing using a semi-formed splice like the ETCO autoband is another method to attach leads together as part of wire harness assembly. Splice terminals are low costs and provide a tight compression crimp around the wire.
Heat Shrink Processing
Heat Shrink tube as mentioned in the introduction, is used for encapsulation of a wire harness or portion of a harness. It is also used as an insulator over terminals and isolating connectors to eliminate shorts from bare conductor material (wire and terminals) touching one another.
The standard method of shrinking heat shrink tube is a heat gun. Heat guns are a manual process which requires an operator to present the heat gun to the assembly or the assembly to the heat gun. In cases of long runs of heat shrink, the operator must pass the heat gun over the tube at a steady rate. Other methods are heat shrink ovens which have a hood and conveyor with heated elements and a blower. The tube to be shrunk is loaded to the conveyor and passes through the oven at a set processing speed. Both processes above use heated elements which consume a high level of energy and attract high energy costs. With long runs of heat shrink, processing time is long.
The Focus Lite processing machines from Judco Mfg use energy efficient quartz halogen bulbs and mirrored surfaces to reflect and focus light energy to a central location. Tube is shrunk quickly and efficiently with fraction of the energy. Several models for processing shrink tube up to 1.5″ diameter and 16″ in length. The FL30 is shown in the video above.
Laser Wire Stripping
Wire stripping is a common processing method as outlined in the introduction. Contact wire stripping with a blade if not set up properly can make contact with the wire which could result in a small nick in the wire. Even with a proper set up there is a risk of putting an indent in a strand even if the surface of the strand is not compromised. Some industries such as aerospace are shifting to non contact wire stripping. Laser wire stripping is an emerging technology for applications requiring non contact wire stripping. Specially effective with irregular shaped wire profiles. The wire pictured in the video above is a twisted pair Teflon coated wire, common in aerospace applications. Hand held, bench top and automated processing configurations are possible.
Weather Seal Application
Environments where water or moisture exist require extra protection. Connectors which reside in these environments will use a weather seal to seal off the opening to a connector body. The seal is inserted over a stripped wire and the terminal is crimped over the seal. The seal is crimped to the insulation support portion of the terminal. Terminals designed for weather seals will have an over sized insulation crimp to properly capture the seal. Assembly methods include manual loading, bench top loading, combination seal insertion, strip and crimping and fully automatic assembly on a cut, strip and terminate machine. The Schaefer SSM pictured at the left is mounted to a fully automatic processing machine such as the Megomat 800 six station processing machine.
With over 30 years of experience in processing wire and cable assemblies with state of the art technology, Wire Process Specialties is equipped to provide these or other solutions to your wire processing problems. Connect Your Way to WPS to find out more.