Crimping terminals is a common wire assembly process dating back several decades. Over the years processing methods and procedures were established and improved to assure optimum crimp quality and electrical conductivity of the wire to terminal connection. This article will cover the common crimp types, crimp methods used to provide a quality wire to terminal connection and migration path from manual processing to automation of the crimp process.
Crimp Types
Closed Barrel: Closed barrel terminals have a round crimp barrel that surrounds the wire being crimped. There are two typical open barrel configurations, formed by progressive stamping process with a seam where the two sides come together and form a circle and solid machines connector where the crimp barrel is seamless, normally produced on a screw machine. Closed barrel terminals come insulated or non-insulated and are in loose form or on a reel. Examples of closed barrel terminals include rings, quick connects, ferrules and solid pins used in aerospace applications.
Open Barrel: Open barrel terminals are generally U shaped prior to crimping and are crimped around the terminal in a B shape or overlapped. Open barrel terminals are generally available mounted on a reel but in some cases are available in loose form for lower volume processing. In addition to a barrel for the wire, some open barrel terminals include an insulation support for applications for additional strain relief (from vibration or wire movement). Open barrel terminals normally are un-insulated but in some cases have a partially loaded insulator pod which is inserted over the terminal during the crimp process.
An example of this terminal type is the ETCO pre-insulated terminal series.
Crimping Methods
Hand Tools: A hand tool is used in low volume or prototype crimp applications. Tooling in a hand tool can be fixed and non-removable from the hand tool frame or can be removable. Crimp dies are available for open barrel and closed barrel terminals A reliable method of crimping wire to terminals with good repeatability. As volumes increase, repeated processing of terminals with hand tools can cause strain on an operator.
Bench Top Crimping: Crimping terminals with bench top crimping equipment provides moderate volume processing of loose piece and reel mounted terminals.
With loose piece terminals, the terminal and wire are hand loaded to a crimp nest and the operator cycles the press using a foot pedal or palm button.
Wezag CS200 Carpenter Accu-Crimp 62
Reel mounted terminals are processed using a crimp press and applicator. The applicator has a mechanical or pneumatic feed which positions the terminal on the crimp anvil. The operator presses a foot pedal and the crimp press cycles, forming the terminal over the wire and advancing the next terminal for further processing. A wide range of applications can be processed with bench top crimping equipment by the utilization of different press tonnages and applicators/die sets (fixed and quick change).
Automated Crimp Processing: Automated processing adds a wire cut and strip element to the crimp process. The most basic form is the stripper-crimper which adds a wire stripping unit to a bench crimp press to strip the end of the wire and presenting the wire to the crimp nest for crimping.
Automated crimp centers process the wire from its source in a barrel or reel, cut and strip the wire to length and present it to a crimp press for crimping. Reel fed applicators are the same as the bench top type. In the case of loose piece terminals, a vibratory bowl is used to orient the terminals and present to the crimp press for crimp processing.
Manual to Automated Crimp, a Migration Path
As volumes increase, the need to automated also increases. On occasion, the increase is dramatic, requiring a greater step through the automation migration path. But normally the increase is controlled and slower so migration can take a multi step approach over time.
Hand Tool to Bench Top Migration: Migrating from a hand tool to power assisted bench top crimping requires a bench top crimping platform like the Accu-Crimp 62 or electric powered CS200 from Wezag Tools (both pictured above).
Heavy Duty Applications use higher tonnage to provide the power needed toprocess large terminals. The Wezag UP60 is pneumatic powered and provides over 7 tons of crimp force.
Non-Fixed hand tool die sets may be removed and compatible with bench top crimping units. This reduces the overall cost of the migration from hand tools to powered bench top equipment.
Bench Top to Automated Process Migration: Migrating from a bench top to automated processing machine like the Primo XLT or Uno multi-station machines is simple and straightforward. Mini style applicators used in a bench press application as pictured above can be mounted directly from a bench top press to the press on the automation system. Some applications require a different feed cam to feed the terminal on the press downstroke to allow for the robotic arm to swing into position with no interference from the terminal.
However, in the case of loose piece terminals, separate presses with integrated vibratory bowl fed systems may be required as they are not a standard set up on an automated machine.
Loose Piece to Reel Mounted terminal Migration: Converting from loose piece processing to reel fed terminals requires a crimp press and applicator as described above. The first step is determining the compatible terminal on reel equivalent. If a quick change mini applicator can be used, then the crimp press can be quickly changed from one terminal type to another simply by switching out the terminal applicator.
Crimp Process Validation and Control
Assuring an adequate quality and repeatable crimp and crimp process is common among all crimping methods. Non Destructive and Destructive crimp testing is used as pre-process and in-process validation methods. For more information on crimp quality process and validation, please refer to our three part series which can be found on our News Channel: Part One (crimp validation), Part Two (In Process Crimp Monitoring) and Part Three (Machine Process Capability and Calibration).
Wire Process Specialties has over 30 years of experience in processing of wire and cable including crimp technology. Connect Your Way to WPS. Our vision is to help our customers reduce processing costs and increase production efficiency.
