What makes a good crimp? Understanding crimp quality for reliable electrical connections

Crimping is one of the most widely used methods of creating electrical connections, but it’s also easy to get wrong. Poor crimping can cause high resistance, overheating, intermittent faults and even complete circuit failure.

A good crimp creates a gas-tight, mechanically strong electrical connection that remains reliable for years, even in demanding industrial environments.

Whether you're working in manufacturing, panel building, maintenance or installation, understanding crimp quality is essential for electrical safety, performance and long-term reliability.

Why crimping is important

A properly executed crimp connection:

• Delivers low electrical resistance
• Prevents wire pull-out
• Withstands vibration and mechanical stress
• Reduces moisture ingress and corrosion
• Maintains consistent performance under load

Crimping is often preferred over soldering in industrial applications because it is faster, more repeatable and better suited to high-vibration environments.

1. Correct wire preparation for crimping

Good crimping starts with proper wire preparation.

Correct strip length

The stripped wire length must match the terminal barrel depth.

• Too short → incomplete connection
• Too long → exposed conductors and risk of short circuits

Undamaged wire strands

Ensure strands are:

• Straight
• Intact
• Free from nicks or cuts

Damaged strands reduce conductivity and weaken the crimp connection.

Our very own brand, UniStrand, provides the perfect wire for consistent, reliable crimping performance - offering uniform conductor quality and precision manufacturing that helps ensure every connection meets the highest standards of durability and safety. See for yourself below:

2. Matching crimp terminals, tools and wire size

Crimp quality depends on using the correct combination of:

• Crimp terminal type (insulated, non-insulated, heat shrink, ferrule, lug)
• Wire size (gauge / cross-section)
• Crimp tool and die profile

Incorrect matching can result in:

• Under-crimping → loose, high-resistance connections
• Over-crimping → damaged conductors or cracked terminals

For consistent results, ratchet crimping tools are recommended, as they apply controlled, repeatable force.

3. Gas-tight crimp connections explained

A high-quality crimp forms a gas-tight connection, also known as a cold weld.

This process:

• Eliminates air gaps between strands
• Prevents oxidation and corrosion
• Locks the wire and terminal together

Gas-tight crimps are significantly more reliable than soldered joints in high-vibration applications such as machinery, vehicles and HVAC systems.

4. Correct crimp shape and profile

Different crimp terminals require specific crimp profiles:

• Insulated terminals → “W” or oval crimp
• Non-insulated terminals → “B” crimp
• Heat shrink terminals → uniform crimp for sealing
• Bootlace ferrules → square or hexagonal crimp

Using the wrong crimp shape can lead to poor contact, strand damage or reduced mechanical strength.

5. Crimp strength and pull test

A reliable crimp must withstand mechanical stress.

Pull test check:

The wire should not pull out under moderate force. Failure indicates:

• Incorrect crimping force
• Wrong tool or die
• Incorrect wire size
• Poor wire preparation

Strong crimps are critical in:

• Industrial equipment
• Automotive systems
• Robotics
• HVAC installations
• Moving or vibrating applications

6. Strain relief and insulation support

Insulated crimp terminals provide two functions:

• Electrical connection (conductor crimp)
• Mechanical support (insulation crimp)

Proper strain relief prevents flexing and fatigue at the termination point - a common cause of failure in electrical systems.

7. Visual inspection of crimp quality

A quick visual check helps confirm a good crimp.

Look for:

• Fully compressed terminal with no cracks
• No exposed wire beyond the terminal
• Even, clean crimp indentation
• No movement or looseness
• Correct insulation positioning

If a crimp looks incorrect, it should be replaced.

What makes a good crimp?

A good crimp connection is:

• Gas-tight
• Mechanically strong
• Electrically efficient
• Consistent and repeatable

Achieving this requires correct wire preparation, matched tools and terminals and controlled crimping force.

High-quality crimping improves reliability, reduces downtime and ensures safe, efficient electrical performance - making it essential in modern industrial applications.

If selecting the right cable or wire is a limiting factor in achieving a strong crimp, we’re here to help with our dedicated cable campaign