Black annealed wire manufacturing process

Black annealed wire is manufactured the same way that all baling wire is made, with one key difference. The wire undergoes the usual wire drawing process, in which it is drawn through a series of dies to reduce its diameter and achieve the desired gauge. The difference is that after the wire undergoes an annealing process where it is heat treated to relieve internal stresses and increase ductility. 

The manufacture of black annealed wire involves the following steps:

1. Purchasing low-carbon steel billets
2. Wire drawing
3. The annealing process
4. Cooling
5. Surface coating (optional)
6. Cutting and coiling

The annealing process improves the wire’s ductility, elongation, and smoothness, making it more workable. At BWD, we offer black annealed wire by the box, stem, or as single loop bale ties in a variety of gauges.

Our black annealed wire manufacturing process proceeds as follows.

Purchasing the steel

We purchase rods made of 100% American steel from trusted, family-owned mills. Low-carbon grades (1018) are used since lower carbon content produces softer, more flexible wire.

Preparation and drawing

First, the wire rods undergo mechanical descaling to remove rust and mill scale.

Then, we run our wire through a heavy-duty bull-block continuous wire drawing machine. The wire is run through progressively smaller dies to increase wire gauge (decrease diameter) and achieve the desired size.

Annealing

The three stages of annealing are:

1. Recovery. The internal stresses and physical properties of the metal are recovered. The wire is heated to a specific temperature, which softens it and removes irregularities in the internal structure. 
2. Recrystallization. The wire is heated to a temperature above its recrystallization temperature but below its melting point. This temperature is maintained for a set period of time, during which deformed grains are replaced with stress-free grains.
3. Grain growth. The wire is then air-cooled to allow the newly formed grains to harden into the desired crystalline structure and complete the process. The cooling process affects the wire’s microstructure, allowing atoms to arrange themselves in a more regular manner, ultimately leading to reduced hardness and increased ductility.

The material may lose some of its strength during this stage, but it can be regained through subsequent quenching or tempering.

Surface coating

After the annealed wire has been cooled, a surface coating is often added (This is optional, but BWD coats all of their annealed wire products.). Surface treatments can improve corrosion resistance, aesthetic appearance, and magnetic properties of the wire.

We apply oil and wax to our black annealed wire. This layer of oil smooths the wire, helping it feed through high-volume baling machines. It also acts as a protective layer that increases the wire’s lifespan.

Cutting and coiling

The finished wire is then cut or coiled. Baling wire products are often sold by weight, so the lengths we cut vary depending on the gauge of the wire and whether it will be sold by the box or stem.

Advantages and disadvantages of annealing

The advantages of annealing include:

• Improved mechanical properties. Annealing improves the structural integrity and flexibility of wires, making them more workable and better suited for baling applications that require flexible, ductile wire.
• Enhanced electrical and magnetic properties. The heat treatment process improves conductivity and magnetism, which makes annealed wire a good choice for electric fencing.
• Stress reduction. By relieving internal stresses built up during the drawing process, annealing reduces the risk of fatigue, fracturing, or cracking over prolonged periods of use.

The disadvantages of the annealing process include:

• Time-consuming. Depending on the temperature specifications and composition of the wires or other materials being annealed, a longer gradual cooling process may be required.
• Precise temperature control. To avoid thermal shock which could cause fracturing of the crystal lattice, annealing requires precise control and monitoring of temperatures during both the heating and cooling processes.
• Loss of tensile strength. Some annealing processes result in a notable loss of tensile strength, however, the elastic quality of annealed wire can often compensate for this. Tensile strength can also be recovered through additional processes.

What is annealed wire used for?

Black annealed wire is often used for the following applications:

• High-volume baling operations. The smooth feed of black annealed wire is ideal for use with two-ram horizontal balers that process large quantities of materials in the recycling industry.
• Baling expansive materials. The flexibility of annealed wire makes it a great choice for baling materials that are prone to expanding. This includes rubber tires, cardboard, and foam.
• Mill-size bales. These bales require either the elasticity of black annealed wire or the strength of high-tensile wire. 
• Other applications. The construction industry, agriculture industry, and packaging industry use black annealed wire for fencing, to bind materials, to enhance structural support, and more.

Black annealed wire specifications

We sell:

• Black annealed box wire
• Black annealed stem wire
• Black annealed single-loop bale ties

Our annealed products feature the following specifications.

Country of manufacture	Tensile strength	Elongation	Finish	Box size	Carbon Grade	Gauge sizes	Wire diameter	Box sizes	Stem sizes
USA	65,000–78,000 psi (448.21–537.79 MPa)	12%	Wax coating	50 or 100 lbs	1018	9–12	0.077–0.135 inches	300’ (50 lb box), 800’ (100 lb box)	39,083 feet–64,011 feet