Crimping pliers (crimpers) are a specialized tool, without which it is impossible to properly connect electrical wires in a car. Not only the stability of the on-board electronics, but also safety depends on the reliability of the crimp: poor contact can lead to overheating, a short circuit or even a fire. However, many car owners still use a soldering iron or twister, not realizing that professional crimping is 3 times stronger and more resistant to vibrations.

In this article we will look at what there are crimping pliers for terminals and lugs, how to choose them correctly for specific tasks (from wiring repair to alarm installation), and we will also show unique crimping techniques that are used by craftsmen at service stations, but are rarely mentioned in instructions. You'll learn why cheap "universal" crimpers often ruin terminals, how to avoid common mistakes, and which tool models are worth their price in 2026.

Types of crimping pliers: which tool for which tasks

All crimpers are divided into categories according to type of crimped connections and operating mechanism. An error in choosing a tool can lead to deformation of the terminal or poor contact. Let's look at the main types:

  • 🔧 For non-insulated terminals — used for crimping open ferrules (NSHVI, NKI, NShP). They have sockets for standard sizes from 0.5 to 50 mm². Suitable for repairing automotive wiring, where sleeves are often required.
  • 🛠️ For insulated terminals - crimp terminals with plastic insulation (for example, molex or duplex). They are equipped with special grooves that do not damage the insulation, but reliably fix the metal part.
  • ⚡ For coaxial connectors — highly specialized pliers for crimping RG cables (used in car antennas and multimedia systems). They have a hexagonal profile for uniform pressure.
  • 🔄 Universal — with replaceable matrices for different types of terminals. Convenient for workshops, but require precise adjustment. Often there are models with adjustable crimping force.

It is worth highlighting hydraulic pliers — they are used for crimping thick cables (from 70 mm²) and are used mainly in freight transport or when upgrading electrical systems (for example, installing a winch). Such tools are expensive (from 15,000 ₽), but they give uniform force up to 10 tons, which is critical for high-voltage connections.

⚠️ Attention: Pliers for RJ-45 telephone connectors Not suitable for automotive terminals! Their mechanism is designed for thin stranded wires, and not for a thick copper core, which is used in the on-board network. Forced crimping with such a tool will lead to microcracks in the terminal.
📊 What type of terminals do you crimp most often?
Non-insulated (NSHVI, NKI)
Isolated (Molex, Duplex)
Coaxial (RG cables)
Universal (different types)
I don't squeeze it myself

Key selection parameters: what to look for before buying

When choosing crimping pliers, car owners often focus only on price, missing out on technical nuances. Here 5 criteriathat are really important:

  1. Matrix material - the best option: hardened tool steel (labeling Cr-V or HRC 58-62). Cheap pliers made of soft metal become deformed after 50-100 crimps.
  2. Mechanism type:
    • 🔗 Articulating pliers system - simple, but requires physical effort.
    • 🔄 Lever mechanism - reduces effort by 30-40%, but takes up more space.
    • ⚙️ Ratchet mechanism — the most accurate, used in professional models (for example, Knipex 97 53 08).
  • Section range — for automotive wiring, 0.5–16 mm² is sufficient. If you plan to work with power cables (for example, for an inverter), take a model that supports up to 35 mm².
  • Presence of a latch — locks the pliers in the closed position, preventing accidental damage to the terminals in the bag.
  • Handle ergonomics — rubber pads reduce fatigue during long-term work. Budget models often have plastic handles that slip in your hands.

    • Manufacturers sometimes indicate in the specifications crimping force in kilograms, but this parameter is secondary. Much more important pressure uniformity: for example, ticks JTC 4026 develop 2 tons, but due to the uneven matrix they can pinch the terminal on one side. Before purchasing, check the reviews for any “distortions” after crimping.

    Parameter Budget pliers (up to 2000 ₽) Professional (from 5000 ₽)
    Matrix material Carbon steel Hardened Cr-V steel
    Crimping accuracy ±0.3 mm ±0.05 mm
    Resource (number of crimps) Up to 500 From 5000
    Weight 200–300 g 400–600 g
    Warranty 6 months 2–5 years
    💡

    Before purchasing, check the pliers for “play” of the matrices: slightly move the jaws to the sides. If a gap of more than 0.1 mm is noticeable, the tool will quickly fail under load.

    TOP 5 crimping pliers for motorists in 2026

    We analyzed reviews from craftsmen and tool tests to create a rating of pliers that have the best price/quality ratio. The list includes models for different tasks - from wiring repairs to installing additional equipment.

    • 🥇 Knipex 97 53 08 - the best professional choice. The ratchet mechanism guarantees uniform crimping, and the dies are made of chrome vanadium steel withstand up to 10,000 cycles. Suitable for terminals 0.5–16 mm². Price: ~8,500 ₽.
    • 🥈 JTC 4026 — universal model with 6 matrices for non-insulated and insulated terminals. Comfortable rubber handles and locking in the closed position. Minus: weight 580 g. Price: ~3,200 ₽.
    • 🥉 Jonnesway T10047 - a budget option with good ergonomics. Suitable for terminals 0.5–10 mm². Matrices from CR-MO steel, but the resource is limited to 2,000 crimps. Price: ~1,800 ₽.
    • 🔧 WSK TS-7B - specialized pliers for coaxial connectors (RG-58, RG-59). Equipped with a hexagonal matrix for uniform pressure. Price: ~2,500 ₽.
    • 💰 Stayer 3445-20 - the most affordable option (from 900 ₽) for rare use. Suitable for terminals 0.5–6 mm² only. The matrices are not removable, which limits versatility.

    For installation of alarm or radio optimal JTC 4026 — it covers 90% of the required sections. If you are doing professional wiring repair, it’s better to take it right away Knipex: Its price is worth it due to its durability and accuracy.

    ⚠️ Attention: Brand pliers IEK (popular in hardware stores) are not suitable for automotive terminals! Their dies are designed for soft aluminum wire, rather than the copper strands used in machines. When crimping, such pliers often “tear off” the insulation.

    Step-by-step instructions: how to properly crimp terminals

    Even expensive pliers will not save you from poor contact if the crimping technology is broken. Follow this algorithm to avoid common mistakes:

    Remove the insulation from the wire (length of bare core = terminal depth + 1 mm)|

    Clean the core from oxides (use WD-40 or fine sandpaper)|

    Select the terminal according to the wire cross-section (permissible play - no more than 0.2 mm) |

    Check the pliers for the presence of grease in the hinges (add if necessary Litol-24)

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    Step 1. Stripping the wire. Use stripper (insulation stripping tool) rather than a knife - this will prevent cuts to the core. For stranded wires, twist the wires before crimping to prevent them from fraying. The length of the exposed part should be equal to terminal sleeve depth plus 1 mm (for stock).

    Step 2. Selecting a matrix. On most ticks, the size of the nest is marked with a color or number. For example:

    • 🔴 0.5–1.5 mm² - red mark
    • 🔵 2.5–6 mm² - blue mark
    • 🟢 10–16 mm² - green mark

    If the clamps are universal, check that the matrix matches the terminal type (insulated/non-insulated).

    Step 3: Crimping. Place the terminal with the wire into the matrix until it stops. Squeeze the handles of the pliers smoothly, without jerking. For ratchet models (for example, Knipex) you will hear a click - this is a signal of a complete crimping cycle. Do not open the pliers until you hear a click!

    Step 4. Quality check. Pull the wire along the axis of the terminal - it should not come out. Inspect the sleeve: it should have uniform dents without cracks. If the terminal is deformed on one side, repeat the crimping process with proper alignment.

    What to do if the terminal is not crimped completely?

    If the pliers do not converge all the way, the reasons may be the following:

    1. The matrix socket is selected incorrectly (take one size larger).

    2. The wire core is too thick for this terminal (take a terminal with a spare cross-section).

    3. There is not enough lubrication in the joint of the pliers (add graphite lubricant).

    4. The matrices are worn out (replacement or purchase of new pliers is required).

    Common mistakes and how to avoid them

    Even experienced auto electricians sometimes make mistakes when crimping, which lead to unstable operation of the equipment. Here TOP-5 misses and ways to prevent them:

    • ❌ Using a soldering iron instead of crimping. The solder joint is fragile and does not tolerate vibration well. In a car, such contact will be destroyed in 1–2 years. Solution: crimp + heat shrink.
    • ❌ Crimping “by eye” without checking the cross-section. A 2.5 mm² terminal on a 4 mm² wire will lead to overheating. Solution: use caliper or a correspondence table.
    • ❌ Repeated crimping of one terminal. This weakens the metal and can cause cracks. Solution: If the crimp is unsuccessful, cut off the terminal and take a new one.
    • ❌ Ignoring insulation after crimping. Exposed contacts oxidize and corrode. Solution: use heat shrink tube or electrical tape 3M Scotch 2228.
    • ❌ Crimping of stranded wire without tinning. Thin wires are flattened, reducing the contact area. Solution: Before crimping, solder the end of the wire or use spade clamp tips.

    Pay special attention crimping power cables (for example, for a winch or inverter). Here, errors are fraught not only with equipment failure, but also with fire. For such tasks use hydraulic pliers and double crimp: first the sleeve, then the insulation.

    💡

    The most common cause of poor contact is a mismatch in the cross-section of the wire and the terminal. Even if the terminal “fits” onto the core, the crimp will be unreliable. Always check the table for compliance!

    Crimping vs soldering vs twisting: which is more reliable in a car

    There is ongoing debate among car owners about which method of connecting wires is better. Let's look at the pros and cons of each option in relation to automotive wiring:

    Method Pros Cons Where to apply
    Crimping

    ⚡ Fast (10 seconds per connection)

    ⚡ Vibration resistance

    ⚡ No risk of overheating (unlike soldering)

    ❌ Requires quality pliers

    ❌ Not all terminals are suitable for stranded wires

    		 Basic wiring, alarm, radios
    Soldering

    🔥 Maximum conductivity

    🔥 Suitable for thin wires

    ❌ Fragile connection (breaks due to vibrations)

    ❌ Risk of insulation overheating

    ❌ Requires skills

    		 Repair of printed circuit boards, thin signal wires
    Twist

    ✅ No tool needed

    ✅ Fast in the field

    ❌ Oxidizes in 3–6 months

    ❌ High contact resistance

    ❌ Prohibited by PUE (Electrical Installation Rules)

    		 Temporary repairs (up to 1 month)
    Welding

    🔧 Durability like a solid wire

    🔧 Corrosion resistance

    ❌ Requires special equipment

    ❌ Risk of insulation damage

    		 Critical circuits (such as starter)

    For 90% of tasks in the car are optimally crimped. Soldering should only be used for thin signal wires (for example, when repairing climate control), where minimal signal loss is important. Twisting is permissible only as a temporary solution - for example, if a wire has frayed on the road and you need to get to a service station.

    Interesting fact: In the aviation industry, crimping is even used for high-voltage cables. They use it there special terminals with gas-tight seal, which can withstand pressure and temperature changes from -60°C to +150°C. Automotive terminals are, of course, simpler, but the principle of reliability is the same.

    Caring for crimping pliers: how to extend their service life

    Even expensive pliers will fail within a year if they are not properly cared for. Follow these rules to make your tool last longer:

    • 🧴 Lubrication. After each use, apply to the hinge graphite lubricant or WD-40 Specialist. This will prevent corrosion and reduce wear.
    • 🧹 Cleaning. Remove metal dust from matrices soft brush (do not use sandpaper!). Dust increases friction and reduces crimping accuracy.
    • 🔧 Storage. Keep the pliers in case or foam trayto avoid impacts. Hardened steel dies are brittle and can break if dropped.
    • 🔄 Calibration Check for ticks once a year crimp uniformity: Crimp the test terminal and inspect it under a magnifying glass. If the dents are asymmetrical, adjustment or replacement of the dies is required.

    If the pliers begin to “creak” when working, this is a sign joint wear. Do not ignore this signal: further operation without repair will lead to matrix skew and defective crimps. In workshops, such a tool is sent to preventive maintenance every 6 months.

    ⚠️ Attention: Never use crimpers to cut wire! This deforms the cutting edges of the dies and reduces the crimping accuracy. For cutting take side cutters or wire cutters.

    FAQ: answers to frequently asked questions

    Is it possible to crimp aluminum wires with automotive pliers?

    No, aluminum requires special pliers with trapezoidal matrix, since aluminum is softer than copper and deforms differently. When crimping an aluminum wire with standard pliers, the terminal may “cut through” the wire, which will lead to a break. Aluminum is not used for automotive wiring (only copper), so there is no need for such pliers.

    How to crimp a terminal without pliers (in the field)?

    As a last resort you can use hammer and flat screwdriver:

    1. Place the wire terminal on metal anvil (for example, a vice).
    2. Gently hit the edges of the terminal with a hammer and a screwdriver, evenly distributing the force.
    3. Check the connection for strength (pull the wire).
    Important: This method is only suitable for temporary repairs! As soon as possible, redo the connection using normal pliers.
    Why does the terminal get hot after crimping?

    Terminal heating indicates bad contact, which arises for three reasons:

    • Insufficient crimping area (the terminal is too large for the wire).
    • Oxidation of the wire (before crimping, you need to strip the wire!).
    • Defect of the pliers matrix (uneven pressure).
    Solution: Redo the connection by selecting the terminal according to the cross-section and cleaning the core alcohol or WD-40.
    Which pliers are suitable for crimping bolt lugs (NB)?

    For NB tips (for example, NB-4 or NB-10) you need pliers with hexagonal matrix, which ensures uniform compression around the perimeter. Suitable models:

    • Knipex 97 52 06 (for NB 4–10 mm²)
    • JTC 4028 (universal, with socket for NB)

    Please note: NB tips require double crimp - first the sleeve, then the insulation.

    How to check the quality of crimping with a multimeter?

    Connect the multimeter in mode calls to the two ends of the wire. There must be resistance less than 0.1 Ohm. Then pull the wire and repeat the measurement - if the resistance increases, the crimp is unreliable. Also check contact resistance between the terminal and the wire: it should not exceed 0.05 Ohm.