Wrapping Materials for Wiring Harness: Corrugated Pipe, PVC Pipe, Tape

The automobile wiring harness is fixed on the entire car body, and damage to the wiring harness directly affects the performance of the automobile circuit. Here we introduce the characteristics and usage scenarios of various wrapping materials for automobile wiring harnesses.
Automotive wiring harnesses should have high and low temperature resistance, resistance to temperature and humidity cycle changes, vibration resistance, smoke resistance and industrial solvent resistance. Therefore, the external protection of the wire harness plays a vital role. Reasonable external protection materials and wrapping methods for wire harnesses can not only ensure the quality of wire harnesses, but also reduce costs and improve economic benefits.

Corrugated tube wrapping automobile wiring harness

1-Corrugated pipe
Corrugated pipes occupy a larger portion in wire harness wrapping. The main characteristics are good wear resistance, high temperature resistance, flame retardancy and heat resistance in high temperature areas. The temperature resistance is generally between -40~150℃.
According to the bandaging requirements, it is generally divided into two types: closed bellows and open bellows.
Closed-end corrugated pipes combined with wire harness clamps can achieve good waterproofing effects, but are more difficult to assemble. Open corrugated pipe is commonly used in ordinary wiring harnesses and is relatively easy to assemble. According to different wrapping requirements, corrugated pipes are generally wrapped with PVC tape in two ways: full wrapping and spot wrapping.
According to the material, corrugated pipes commonly used in automobile wiring harnesses are divided into four types: polypropylene (PP), nylon (PA6), polypropylene modified (PPmod) and triphenyl phosphate (TPE). Common inner diameter specifications range from 4.5 to 40.
1. PP corrugated pipe has a temperature resistance of 100°C and is the most commonly used type in wire harnesses.
2. The temperature resistance of PA6 corrugated pipe reaches 120℃. It is outstanding in flame retardancy and wear resistance, but its bending resistance is lower than that of PP material
3. PPmod is an improved type of polypropylene with a temperature resistance level of 130°C.
4. TPE has a higher temperature resistance level, reaching 175℃.
The basic color of the bellows is black. Some flame retardant materials are allowed to be slightly grayish black. Yellow can be used if there are special requirements or warning purposes (such as airbag wiring harness bellows).
The material of PVC pipe is soft polyvinyl chloride, and the inner diameter ranges from 3.5 to 40. The inner and outer walls of the tube are smooth and the color is uniform, which can achieve a good appearance effect. The commonly used color is black, and its function is similar to that of bellows.
PVC pipes have good flexibility and resistance to bending deformation, and PVC pipes are generally closed. Therefore, PVC pipes are mainly used at the branches of the wiring harness to make a smooth transition of the wires. The heat-resistant temperature of PVC pipes is not high, generally below 80°C, and special high-temperature resistant pipes are 105°C.

Fiberglass casing wrapping automotive wiring harness

2-Fiberglass casing
Using glass yarn as the base material, it is braided into a tube, impregnated with silicone resin, and then dried. It is suitable for wire protection between electrical appliances that are prone to high temperatures and high voltages. It has a temperature resistance of over 200°C and a voltage resistance of over 1,000 volts. The commonly used color is white. It can be dyed into other colors (such as red, black, etc.) according to different requirements of customers. The diameter specifications range from 2 to 20. This tube is generally used for fusible wires in wiring harnesses.

Tape wrapping car wiring harness

3-Tape
The tape plays a role in binding, wear-resistant, temperature-resistant, insulating, flame-retardant, noise reduction, and marking in wire harnesses. It is the most widely used type of wire harness wrapping materials. Commonly used tapes for wiring harnesses are generally divided into four types: PVC tape, flannel tape, cloth-based tape and sponge tape.
PVC tape is a roll-shaped adhesive tape made of insulating polyvinyl chloride film as the base material and evenly coated with pressure-sensitive adhesive on one side. Has good adhesion, durability and electrical insulation properties. After the tape is unrolled, the film surface is smooth, the color is uniform, both sides are flat, and the temperature resistance is around 80°C. It mainly plays the role of bundling in wire harnesses.
Commonly used flannel tape is made of polyester non-woven fabric as the base material and coated with high peel strength solvent-free rubber pressure-sensitive adhesive. No solvent residue, corrosion resistance, noise reduction performance, tearable by hand, easy to operate, temperature resistant to 105°C. Because its material is soft and corrosion-resistant, it is very suitable for use in wiring harnesses in interior noise reduction parts of cars, such as instrument panel wiring harnesses. High-quality acrylic flannel tape can provide good temperature resistance, oil resistance and aging resistance. Made of high-quality polyamide flannel, with high viscosity, no hazardous substances, corrosion resistance, balanced unwinding force, and stable appearance (no curling).
Fiber cloth-based tape is used for high-temperature-resistant winding of automotive wiring harnesses. Through overlapping and spiral winding, a smooth, durable and flexible automotive wiring harness can be obtained. Made of high-quality cotton fiber cloth and strong rubber-type pressure-sensitive adhesive, it has high viscosity, no hazardous substances, can be torn by hand, has good flexibility, and is suitable for machine and manual use.
Polyester cloth-based tape is specially designed for high-temperature resistant winding of wiring harnesses in automobile engine areas. Due to the substrate’s high strength and oil and temperature resistance, it is an ideal product for use in the engine area. Made of high-quality polyester fabric base with high oil resistance and strong acrylic pressure-sensitive adhesive.
Sponge tape is made of low-density PE foam as the base material, coated with high-performance pressure-sensitive adhesive on one or both sides, and composite silicone release material. Available in a variety of thicknesses, densities and colors, and can be rolled or die-cut into a variety of shapes. The tape has excellent weather resistance, conformability, cushioning, sealing and superior adhesion, and is widely used.
Velvet sponge tape is a good wire harness protection material. The base layer is a layer of flannel combined with a layer of sponge, coated with a specially formulated pressure-sensitive adhesive. It plays the role of noise reduction, shock absorption, and wear-resistant protection. It is widely used in instrument wiring harnesses, ceiling wiring harnesses, and door wiring harnesses of Japanese and Korean cars. Its performance is better than ordinary flannel tape and sponge tape, but the price is also more expensive.

4- Rubber parts
Rubber parts are mainly distributed at the interface between the engine and the cab, the interface between the engine room and the cab, the interface between the 4 doors and the carriage, and the entrance of the fuel tank. Depending on the material, natural rubber, neoprene, silicone rubber, EPDM rubber, etc. are commonly used.
Among them, natural rubber has good elasticity and mechanical strength, excellent flexural resistance, high tear strength and good cold resistance. The disadvantages are that it has poor aging resistance, is not resistant to oil and ozone, and is flammable. Neoprene has good ozone resistance, heat aging resistance, oil resistance, strong flame retardancy and self-extinguishing properties. However, its low temperature resistance is not very good and it is difficult to process.
Silicone rubber has excellent heat resistance, cold resistance, dielectric properties, ozone resistance and atmospheric aging resistance, and has a wide application temperature range. The disadvantage is that the tensile strength and tear resistance are poor. EPDM rubber has good weather resistance, ozone resistance, heat resistance, corrosion resistance, acid and alkali resistance, high strength and high expansion rate. The disadvantage is that the adhesiveness is poor and the elasticity is not as good as natural rubber. Due to its good overall performance, EPDM is currently the first choice for automotive rubber parts.