What is baling wire elongation?

Elongation is a measurement of how far a wire will stretch before it breaks. A wire’s elongation is expressed as a percentage, and is determined through tensile testing, where a sample of the wire is stretched until it breaks. The elongation percentage is calculated by measuring the change in length of a wire at the point of failure relative to its original length.

For example, a 10 inch wire with 10% elongation can stretch 1 inch before failing.

While under stress, a wire can undergo elastic or plastic elongation. Plastic elongation results in a permanent reshaping or deformation of the wire, whereas elastic elongation will result in the wire returning to its original shape after the force is removed.

In the recycling industry, sufficient elongation helps minimize wire breakage to effectively bale and secure materials that are prone to expansion such as rubber tires, cardboard, and foam.

The relationship between tensile strength and elongation

Tensile strength and elongation are distinct physical properties of wire. Tensile strength measures how much weight a wire can handle before it breaks, while elongation measures how much the wire will stretch before it breaks. The two don’t correlate, meaning that greater tensile strength does not necessarily mean a wire will have greater elongation, and vice versa.

For example, our 10 gauge black annealed box wire has an elongation of 25%, whereas our 11 gauge high-tensile wire has an elongation of just 11% while being significantly stronger.

What is baling wire elongation used for?

Elongation measures how much a wire can stretch before breaking. Wire with higher elongation is preferable for applications where materials might shift or change shape. In the recycling industry, increased elongation is important for expandable materials such as paper, foam, and cardboard.

Factors that affect elongation

Elongation values are the result of several factors including:

• Carbon grade. Higher carbon grade steel, used for hi-tensile wire, is less elastic.
• Manufacturing. A cold drawing process decreases wire elongation.
• Heat treatment. The annealing process increases a wire’s ductility and elongation.

How to measure elongation

To measure elongation, a tensile test stretches a wire to the breaking point as follows:

1. A sample of the wire is cut. Its length and diameter are measured.
2. The ends of the sample are securely gripped using a tensile testing machine.
3. A constant, external force is applied to the sample. The force is gradually increased until the wire breaks.
4. The maximum load of the sample is measured and recorded.
5. The elongation value is then calculated based on the change in wire length before failure.

Baling wire elongation and tensile strength chart

Here is a chart of the tensile strength, load strength, and elongation rate for each of our baling wire product categories.

Properties	Regular galvanized wire	Hi-tensile galvanized wire	Black annealed wire	Single loop black annealed bale ties	Single loop galvanized bale ties	Double loop bright bale ties	Double loop galvanized bale ties
Elongation	12%	7%–11%	25%	12%	12%	4%	4%
Tensile strength	75,000–95,000 psi (517.10–655 MPa)	145,000–175,000 psi (999.74–1206.58 MPa)	65,000–78,000 psi (448.21–537.79 MPa)	80,000–95,000 psi (551.58–655 MPa)	80,000–95,000 psi (551.58–655 MPa)	220,000 psi (1516.85 MPa)	220,000 psi (1516.85 MPa)
Load strength	402–1,832 lbs	1,256–1,832 lbs	565–1,118 lbs	402–1,074 lbs	402–1,074 lbs	1,060–2,150 lbs	1,015–2,040 lbs