Data Center

Fusion Splicing vs Mechanical Splicing

Matt Hurst

When compared to mechanical splicing, fusion splicing is fast becoming the preferred option for fiber termination.





By using a fusion splicer – a machine that precisely aligns two fiber ends before “fusing” or “welding” them together using an electric arc – the installer can ensure an excellent connection. Fusion splicing can be performed as a single fusion (fusing just one fiber at a time) or as a mass fusion (fusing 12 fibers in a single operation).


Mechanical splicing doesn’t permanently join two fibers together; instead, it precisely “holds” them together, enabling light to pass from one fiber to the other.


Advantages of Fusion Splicing vs Mechanical Splicing

Fusion Splicing Mechanical Splicing
Variable Cost per Splice $0.50 - $1.50 $10 - $30
Insertion Loss < 0.1 dB 0.2 dB - 0.75 dB


  • Lower Cost

    Fusion splicing typically costs more upfront due to the investment required to add a fusion splicing machine to your toolkit, but it offers a lower variable cost per fusion splice: $0.50 to $1.50 per splice.

    Mechanical splicing doesn’t require a large upfront investment in tools, but it has a higher variable cost at $10 to $30 per splice. The more splicing you do, the less cost efficient mechanical splicing will be due to its high variable cost per termination.

    In the past, some data center installers have been hesitant to try fusion splicing simply due to the expenses associated with the purchase of fusion splicer tooling. In recent years, however, we’ve experienced significant cost decreases in splicer tools, as well as increased availability of low-cost splicer rental options.

  • Superior Performance

    With mechanical splicing, the typical insertion loss (IL) is higher – between 0.2 dB and 0.75 dB – because the two fibers are simply aligned and not physically joined. (Insertion loss is the loss of signal power resulting from the insertion of a splice in optical fiber.)

    Because fusion splicing provides a continuous connection between two fibers, it offers lower insertion loss and better performance. The typical loss in fusion splicing is < 0.1 dB, providing better protection against cable failure and weak signals.

Additional Considerations for Fusion Splicing

Before you deploy fusion splicing instead of mechanical splicing, there are two important factors to consider:

  • Proper storage of protective heat shrink splice sleeves

By heat shrinking a protective sleeve over the finished splice, the splice is protected against moisture and other environmental hazards – but the heat shrink splice sleeves must be stored correctly in order to be effective and protect the fragile joints.

  • Proper slack management for 250µm, 900µm or ribbon fiber

Proper slack management for 250µm, 900µm or ribbon fiber must also be provided to enable future termination of damaged connectors.


To address these two challenges, Belden offers an FX UHD Splice Cassette that supports all common splice protection sleeves and integrates splicing and field-termination slack storage into the cassettes. Completely interchangeable and flexible, it can be combined in the same patch panel with other products because it matches the form factor of the entire Belden FX UHD family.

Belden can help you leverage the advantages of fusion splicing to quickly reduce costs and maximize system uptime in your data center. Find simple solutions to your data center challenges here.