Corrugated Tubing Overview
Corrugated tubing is a versatile plastic hard pipe known for its excellent compressive strength, mechanical protection, abrasion resistance, and electrical insulation properties.
While its thermal protection and heat radiation resistance are moderate, its noise reduction capabilities are somewhat inferior to those of adhesive tape.
The corrugated cross-section allows for superior axial bending performance, enabling it to maintain flexibility while withstanding strong impacts.
Material Composition and Properties
The wall material of the corrugated tubing is composed of thermoplastic insulating materials, which confer commendable electrical insulation properties.
Under various temperature ratings, particularly in high-temperature environments, its excellent heat resistance, flame retardancy, and thermal stability provide substantial protective benefits.
During assembly, the use of tooling fixtures facilitates convenient installation, highlighting its favorable installation characteristics.
Applications in Automotive Wiring
The primary materials used for corrugated tubing are polypropylene (PP) and polyamide (PA), specifically nylon 6. While PA exhibits superior flame resistance and abrasion resistance compared to PP, the latter excels in resistance to bending fatigue.
Typically, corrugated tubing used in vehicle body wiring harnesses is rated for temperatures between 105 and 125 degrees Celsius, predominantly utilizing PP material.
In contrast, the corrugated tubing employed in engine harnesses is rated between 125 and 150 degrees Celsius, often incorporating modified PP and PA6 materials.
Types and Structural Forms
There is a wide variety of corrugated tubing models, categorized by wave structure. Common types include the German standard type, high oscillation type, Japanese wave type, French wave type, Korean wave type, and the American universal wave type.
By structural form, corrugated tubing can be divided into open corrugated tubing and closed corrugated tubing. In automotive wiring harness processing, open corrugated tubing is favored to ensure ease of assembly.
Additionally, based on electromagnetic shielding performance, corrugated tubing can be classified into standard corrugated tubing, which lacks electromagnetic shielding, and specialized corrugated tubing, which provides such shielding.
Temperature Ratings and Flame Retardancy
The temperature ratings for corrugated tubing range from T1 to T6, with T1 at 85 degrees Celsius, T2 at 105 degrees Celsius, T3 at 125 degrees Celsius, T4 at 150 degrees Celsius, T5 at 175 degrees Celsius, and T6 at 200 degrees Celsius. Different vehicle models and usage locations necessitate varying flame retardancy requirements.
Currently, major automotive manufacturers are imposing increasingly stringent flame retardancy standards, with many requiring a minimum of zero-level flame retardancy.
Dimensions and Usage in Harsh Environments
The dimensions of corrugated tubing generally fall between an inner diameter of 3 to 40 millimeters, with common sizes for automotive wiring harnesses including 7.5, 10, and 12 millimeters.
Due to its excellent mechanical protection properties and cost-effectiveness, corrugated tubing is extensively utilized in both vehicle body and engine wiring harnesses, particularly in applications outside the closed cabin of vehicles.
For instance, in the chassis wiring harnesses of commercial vehicles such as trucks, where wiring is often exposed to harsh environmental conditions, the risk of dust and particulate infiltration is significant.
Consequently, there is a heightened demand for protective materials that offer superior abrasion resistance, leading to a preference for high-performance corrugated tubing.