What is tensile strength for baling wire?

Tensile strength is a mechanical property that defines the maximum amount of pulling or stretching stress a material can withstand without breaking or deforming. 

Baling wire is used to secure bundles of commonly recycled materials (plastic, foam, office paper etc.) and agricultural products (straw and hay). 

Why is tensile strength important for baling wire?

Tensile strength for baling wires is important because it ensures:

• Secure binding. Tensile strength ensures baling wire can hold together compressed materials in a secure, tightly bound bale.
• Resistance to breaking. Baled materials can exert excessive force on the baling wire, and sufficient tensile strength is essential to ensure it can resist the force without breaking. This is particularly important during transportation and handling.
• Efficient baling. Baling machines exert significant force, so baling wire needs to have the tensile strength to withstand the baling process without breaking our deforming.

What contributes to wire tensile strength?

The tensile strength of a wire is influenced by the material’s composition, processing, and internal molecular structure.

While it may seem smart to buy the strongest possible wire, high-tensile wire is more expensive. If you don’t need the extra strength, why spend the extra money?

Factors that contribute to a wire's tensile strength include:

• Purity of the material. Higher carbon grades increase tensile strength. We use 100% American steel in our wire manufacturing process.
• Manufacturing processes. Annealing, quenching, and galvanizing can alter the wire's microstructure, consequently affecting its tensile strength.
• Diameter of the wire. Wire gauge influences tensile strength. Lower gauge wires generally have greater tensile strength.
• Temperature. As wire is heated, its tensile strength can diminish.
• Material selection. Steel, copper, aluminum, and other materials have different molecular structures, which offer different tensile strengths.

How do you measure the tensile strength of a wire?

To perform a tensile strength test, the following steps are followed:

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 and the corresponding elongation of the sample are measured and recorded.
5. The tensile strength values are then calculated based on the recorded data.

Elongation values

Elongation indicates a wire’s ability to stretch before breaking. Elongation is a measure of the length that a baling wire can stretch before failing or breaking. It is calculated as the increase in sample length divided by the original sample length, reported as a percentage.

By evaluating wire for elongation, recyclers can make well-informed baling wire selections for their operations. A higher elongation percentage indicates better ductility, which means that the wire can undergo more stretching. Wires with higher tensile strength are typically less elastic.

How to choose wire gauge size

Wire gauge plays a major role in determining wire strength. Gauge choice should revolve around factors such as the type of materials being baled (cardboard, plastic, metal), the type of baling equipment used, and the size and density of bales.

To find the best wire for your baler, consult your baling machine manufacturer. This section highlights the wire gauges commonly used to bale various materials in different baling machines.

Horizontal balers

• Cardboard: 11–13 gauge
• Newspaper: 12–13 gauge
• Plastic shrink wrap: 11–12 gauge
• Other plastics: 11–12 gauge
• Foam: 11 gauge

Vertical balers

• Cardboard: 12–14 gauge
• Newspaper: 12–13 gauge
• Plastic shrink wrap: 13–14 gauge
• Other plastics: 12–13 gauge
• Foam: 11 gauge

Automatic baling machines

• Cardboard: 10–12 gauge
• Newspaper: 10–12 gauge
• Plastic shrink wrap: 10–12 gauge
• Other plastics: 10–12 gauge
• Foam: 10–11 gauge

Wire tensile strength chart

This chart displays the tensile strengths and load strengths of our products.

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
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)	75,000–95,000 psi (551.58–655 MPa)	75,000–95,000 psi (551.58–655 MPa)	220,000 psi (1516.85 MPa)	220,000 psi (1516.85 MPa)
Load strength	402–1,074 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