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【Popular Science】A Complete Guide to Standard Selection and Crimping Process of Tubular Cold-Pressed Terminals!
- Categories:Industry News
- Author:Guangdong Deke Electric Co., Ltd.
- Origin://m.hymfwq.com/
- Time of issue:2026-09-10 16:28
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【Popular Science】A Complete Guide to Standard Selection and Crimping Process of Tubular Cold-Pressed Terminals!
- Categories:Industry News
- Author:Guangdong Deke Electric Co., Ltd.
- Origin://m.hymfwq.com/
- Time of issue:2026-09-10 16:28
- Views:
Equipment R&D engineers are often plagued by customer complaints about loose wiring and intermittent open circuits. Procurement teams seek standardized terminal specifications for convenient bulk warehousing and management. Field electricians prioritize wiring that does not damage conductors, secure crimping, and effortless operation. Compact tubular terminals address pain points for all three groups: bundling multi-stranded flexible wires, enabling visual wire gauge identification via insulated sleeves, and compatibility with a full range of automatic ratchet crimping tools. They serve as core components for standardized wiring in industrial control, equipment and wiring harness projects.
Combined with the international standard DIN 46228, UL486E crimp pull-out force specifications and mass production test data from workshops, this article fully sorts out the selection logic, color coding, category differentiation, pin length matching, and three mainstream crimping processes for tubular terminals.
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I. Why Tubular Terminals Are Mandatory for Industrial Wiring
Conventional multi-strand flexible wires consist of dozens of fine copper filaments twisted together. When directly connected to screw terminals, the copper strands tend to fray, get crushed and broken, resulting in partial poor contact. Long-term power-on operation may lead to heat buildup, excessive voltage drop and even equipment failure. Featuring a tinned solid copper sleeve structure, tubular terminals fully gather and compact the entire bundle of copper strands, enabling multi-strand flexible wires to deliver stable conductive performance comparable to solid single-core wires. They offer multiple advantages over the traditional tin-dipping method for wire ends:
1. Eliminate welding hazards : High temperatures during tin dipping may burn the wire insulation. Soldering inside compact cabinets carries risks of fire and short circuits. Cold-pressed tubular terminals involve no high heat throughout the process, suitable for operations inside enclosed electrical control cabinets.
2. Protect conductor integrity : The sleeve evenly encapsulates all copper strands. Fine copper wires will not be severed when screws are tightened, preventing wire breakage under long-term vibration conditions.
3. Standardized wiring dimensions : Uniform pin length of sleeves ensures full insertion of wire copper cores into terminals, preventing electric leakage caused by exposed copper strands.
4. Facilitate subsequent maintenance : Insulated sleeves are color-coded by wire gauge. Technicians can quickly match the corresponding current rating during inspection and modification, lowering the risk of maintenance errors.
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II. Color Coding System for Insulated Sleeves of Tubular Terminals (DIN Standard)
There are two major globally adopted color coding systems: the Telemecanique (France) code and the Weidmüller (Germany) industry code. The domestic industrial control and equipment sector uniformly follows the DIN 46228 standard. The colors of insulated sleeves are not for decoration, but serve as visual identifiers for wire cross-sectional areas.
Core function: On-site technicians can identify wire sizes directly by sleeve color without caliper measurement. This unifies standards for procurement, assembly and maintenance, and streamlines drawing documentation and spare parts management for long-term projects.
Key distinction between systems: The sleeve color for the same wire gauge differs between the German and French standards. Standards must be unified during bulk procurement to prevent mismatched installation on the production floor. The DIN 46228 German color scheme applies to most industrial control equipment and PLC terminal blocks used domestically.
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III. Structures and Application Scenarios of Four Major Types of Tubular Terminals
1. Non-insulated Shoulderless Tubular Terminals Featuring no plastic insulating sleeve and consisting merely of a copper metal sleeve, they occupy minimal space.
Application scenarios : Wiring positions with extremely limited space where insulating sleeves would interfere with the arrangement of adjacent terminals. Commonly used for prefabricated short harnesses inside 13A plugs and RCBO residual current circuit breakers.
Limitations : Manual wire threading is difficult, and fine copper strands tend to fray. They are only suitable for factory-prepared short wires rather than on-site mass wiring.
2. Pre-insulated Single-Wire Tubular Terminals (Mainstream Type Widely Used in China) Equipped with an integrated plastic insulating shoulder. The sleeve guides flexible wires into the metal sleeve during threading, greatly reducing the difficulty of wire insertion, and is applicable to conventional fine wires ranging from 0.14 to 16 mm².
Advantages : Low operation threshold, visual wire gauge identification, and prevention of short circuits between adjacent wires. The preferred option for wiring harnesses of PLCs, control cabinets and instruments.
3. Double-Wire Tubular Terminals (Dedicated for Parallel Connection of Two Wires) The cross-sectional area of the metal sleeve cavity is twice that of single-wire terminals. The oval insulating sleeve can accommodate two complete insulated wires simultaneously. They are available in insulated and non-insulated versions.
Application scenarios : Parallel connection of common power supplies for buttons on industrial control panels, multi-wire convergence inside HVAC and lighting controllers. In the German standard system, 2.5 mm² double-wire terminals uniformly adopt blue insulating sleeves.
4. Pin Sleeves with Multiple Length Options (For Different Wiring Depths) Terminals of the same wire gauge are supplied with metal pins of various lengths to fit PCB posts and terminal blocks of circuit breakers with varying insertion depths.
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IV. Comparison of Three Mainstream Crimping Processes (in accordance with UL486E Pull-Force Standard)
The crimp profile directly determines terminal pull-out strength, vibration resistance and long-term electrical stability. There are three mainstream types in the industry: hexagonal, quadrilateral and trapezoidal, compatible with different working conditions and crimping tools.
1. Hexagonal Crimping (First Choice for High-Reliability Industrial & Automotive Applications) The sleeve is wrapped under uniform six-sided compression, achieving full contact between copper strands and the metal sleeve. Per UL486E pull-force tests, its pull-out strength is 15%–30% higher than quadrilateral crimping for the same wire gauge (the standard pull force ≥250N for 0.5mm², ≥2300N for 6mm²).
Core advantages : Uniform stress distribution without local stress concentration, greatly reducing the risk of metal fatigue cracking. It features minimal resistance drift under high/low temperature and continuous vibration environments.
Application scenarios : New energy wiring harnesses, automotive electronic control systems, high-power industrial control cabinets and long-term outdoor equipment.
2. Quadrilateral Crimping (General-Purpose for Low-Cost Static Equipment) Formed by four-sided compression. Mould and tooling costs are lower, yet stress concentrates on the four edges. The sleeve may deform and contact resistance rise under prolonged cyclic vibration. With the same conductive cross-sectional area, it requires a larger hole diameter for round wiring posts compared with hexagonal crimped terminals.
Application scenarios : Static control wires for home appliances, indoor low-voltage fixed wiring and non-vibration civil equipment.
3. Trapezoidal Crimping (Moderate Tolerance for Simple Assembly Scenarios) It imposes lower requirements on wire gauge matching accuracy than quadrilateral and hexagonal crimping. However, the jaw size must be strictly matched to the wire gauge; otherwise, incomplete crimping and loose copper strands may occur.
Application scenarios : Small simple instruments and low-frequency signal thin harnesses.
Example : 2.5 mm² insulated terminals come with standard pin lengths of 8 mm / 10 mm / 12 mm / 18 mm; high-power sleeves for 16 mm² are available with extended pin lengths of 15 mm / 21 mm. Extended pins are designed for recessed PCB terminals inside equipment housings to ensure full insertion of copper cores into conductive contact areas.
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V. Selection Guide for Mainstream Professional Crimping Tools
1. Automatic Ratchet Crimping Pliers (Compatible with Quadrilateral / Hexagonal Crimping)
Lightweight ergonomic handles with a built-in automatic size adjustment mechanism. The tool automatically engages the corresponding crimping cavity once the terminal is inserted, with no manual gear switching required. Ideal for mass harness fabrication in workshops.
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2. Compact Front-End Crimping Pliers (For Confined Spaces)
The crimping jaw is located at the front end of the pliers, suited for wiring applications with limited wire length and narrow routing inside control cabinets.
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3. Multi-functional Trapezoidal Crimping Pliers
Compatible with all sizes of insulated and non-insulated tubular terminals, suitable for sporadic wiring work by electricians and small processing factories.
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VI. Selection Summary
Though tiny in size, tubular terminals are critical components ensuring the reliability of electrical connections.
Core selection logic:
1. Static, civil-use and low-cost wiring → Quadrilateral crimping + standard pre-insulated single-wire tubular terminals;
2. Industrial control, automotive and high-power equipment subject to vibration → Hexagonal crimping with extended-pin insulated terminals;
3. Double-wire parallel connection and common circuits on panels → Dedicated double-wire tubular terminals;
4. Confined cabinets and short wires for on-site repair → Compact front-end crimping pliers.
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Guangdong Deke Electric specializes in mass customization of full-range tubular terminals. Manufactured in strict compliance with DIN46228, RoHS and UL standards, our products deliver stable electrical conductivity and resistance to salt spray corrosion. The portfolio covers insulated and non-insulated single-wire and double-wire series ranging from 0.14 mm² to 35 mm². We provide technical support including terminal selection guidance, crimping process specifications and pull-out force testing, catering to wiring harness demands across industrial automation, new energy, instrumentation and home appliance industries.
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