Factors Influencing Carbon Fiber Heating Tube Lifespan

Carbon fiber heating tubes are a novel type of electric heating element that differ from traditional metal wire heating tubes. They utilize carbon fiber as the heating element material and quartz tubes as the outer shell. Their advantages include a long service life, high electrothermal conversion rate, infrared radiation heating, acid and alkali resistance, and resistance to thermal shock. These tubes are widely used in industrial tunnel furnaces, industrial ovens, industrial dryers, and are gradually replacing halogen heating tubes and resistance wire heating tubes in household heaters.

Carbon fiber heating tubes can be categorized into many types based on their shape, quartz tube material, and processing technology. The main classification methods include:

1. Heating element material
2. Gas filling within the quartz tube
3. Outer quartz tube
4. Wiring method
5. Overall shape of the heating tube

With over a hundred different names, we will not list each one here. Instead, we will focus on the factors that affect the performance and lifespan of linear carbon fiber infrared heating tubes.

Currently, the most common forms of carbon fiber heating elements include carbon felt, carbon fiber woven tape, and spiral-shaped heating wires. Each type has its advantages and applications, benefiting users in different ways.

When using carbon fiber felt as the heating element, there are minor issues with power instability. This mainly stems from the manufacturing process, as the inherent characteristics of carbon fiber felt make it difficult to ensure uniform thickness. Additionally, the precision control during cutting also poses challenges, leading to power instability in the heating element.

When processing carbon fiber woven tape, the fibers can be easily pulled and broken, causing burrs at the output of the heating element. This can create bright spots at break points during usage. However, using multiple strands of carbon fiber woven into a spiral can enhance the electrical characteristics of the heating element, reduce surface temperature, and significantly extend the lifespan of the heating tube.

During the production of carbon fiber heating elements, the carbon fiber raw yarn is first woven into ropes or tapes, then wound around a mandrel to form a spiral-shaped heating wire. After winding, the heating wire undergoes heat treatment, resulting in two types of carbon fiber heating tubes: hollow and solid (with a core rod).

Hollow carbon fiber heating tubes, where the core rod is removed after the filament is set, rely heavily on the amount of adhesive used during the fixing process.

1. Excessive Adhesive:
   • Can create impurities post-heat treatment, causing contamination inside the quartz tube, affecting the appearance.
   • Makes the heating wire too rigid, leading to brittleness and potential breakage or damage during subsequent processes like threading or sealing.
2. Insufficient Adhesive:
   • Can cause burrs or loose strands, leading to breakage at defect points during operation.
   • Results in insufficient rigidity, causing the heating wire to lose its spiral shape and contact the outer quartz tube, shortening its lifespan.
3. Uneven Adhesive:
   • Leads to localized bright spots during operation, affecting the lifespan of the heating tube.

The thickness of the heating wire plays a significant role in the lifespan of the heating tube. For tubes with the same power, a thinner heating wire means shorter carbon fiber length and lower winding density, resulting in a relatively shorter lifespan. Parameters such as the number of turns and pitch of the spiral also directly impact the lifespan. Optimal selection requires practical experience from the manufacturer, with the understanding that higher material usage increases the production cost.