What is a Ferrule?
What is a Ferrule? I ask myself this question thinking specifically of the small metal tube with a colored insulated plastic end where you can insert wire strands and crimp the tube securely to the wire. To answer this question, I decided to do an internet search to see what I could find describing a ferrule. However, I quickly realized that there is a wide variety of components known as ferrules that are very different from each other and provide many different purposes.
Ferrule Definition
For example, dictionary websites in general provide two main definitions for ferrules:
- 1. A ring or cap usually of metal put around a slender shaft to strengthen it or prevent it from splitting.
Or, - 2. A usually metal sleeve used for joining or binding one part to another (such as pipe sections or the bristles and handle of a brush).
So, when I looked at all this information I confirmed that “a ferrule is a ferrule is a ferrule” is not true. Ferrules come in different shapes, forms and materials, are used for many purposes and the differences can keep adding on.
Here’s a Few Examples of Items I Found that are also known as Ferrules:
- The metal sleeve holding the eraser securely on a pencil
- The metal band that secures a paint brush bristles to the handle
- The plastic sleeve located at the bottom of most golf clubs just above the club head
- The metal band used to prevent the end of a wooden instrument from splitting
- The compression fittings that attach plumbing tubing or pipes have ferrules in them
- The cap at the end of a cane or an umbrella
- The normally plastic collar at the tip of a pool cue stick that secures the tip to the stick
- And many many more…
We could go on naming components known as ferrules but for this blog, the ferrules we are referring to are the ones used for wire termination. These “wire ferrules” are used for electric or electronic wiring and for the specific purpose of providing a very nice, clean and safe termination for wire strands, which in turn provide an efficient and safe connection to a terminal block.
The Z+F ferrules provided by AutomationDirect and seen above, consist of a tin-plated copper tube with a polypropylene-fluoropolymer insulating collar at the cable insertion end. These ferrules are available in a variety of collar colors and tube sizes designed to accommodate wires ranging from 20 AWG to 1 AWG. (1) The wire is stripped to the approximate length of the ferrule tube and inserted into the (2) ferrule while ensuring that all wire strands slide into the tube. Then the ferrule is (3) crimped on the metal tube portion with a crimp tool leaving a (4) nice tight hold on the wire strands and providing an easy way to insert the crimped portion into a terminal block to easily and effectively secure it with the set screw.
The crimping tools are available in hexagonal or square profile and provide crimps that have the same cross-sectional area. Choosing what profile to use depends on the shape of the hole where the wire will be inserted. Square crimps fit better in rectangular holes while hexagonal crimps fit better in round holes.
These wire ferrules are also available in twin wire models. The twin wire ferrules have a larger insulated collar that allows you to insert two wires into the ferrule tube to be crimped tightly and securely together using a properly sized ferrule (must allow space for both wires).
The main advantages of wire ferrules are:
- To make a nice, clean and secure connection to a terminal block
- Prevent wire strands from spreading out of a terminal possibly causing a short
- Provides 100% contact to wire
Z+F is the pioneer of the insulated wire ferrule and also developed the tests that UL uses for testing wire ferrules. Z+F insulated wire ferrules are UL tested and approved (file E333905). There are many wire ferrules available out there, but not with the quality materials and ratings that Z+F provides. Try Z+F wire ferrules on your next project and see for yourself.
