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Performance analysis of cable ties, buckles, brackets and protective tubes in automotive wiring harnesses

by | Mar 26, 2024

Wire harness fixation design is a very important item in the wire harness layout design. Its main forms include tie ties, buckles, and brackets.

1 tie

Cable ties are the most commonly used protective material for wire harness fixation, and are mainly made of PA66. Most of the fixings in the wire harness are completed with cable ties. The function of the tie is to fasten the wire harness and secure it firmly and reliably to the body's sheet metal holes, bolts, steel plates and other parts to prevent the wire harness from vibrating, shifting or interfering with other components and causing damage to the wire harness.

Although there are many types of cable ties, they can be divided into the following types according to the type of sheet metal clamping: clamping round hole type cable ties, clamping waist round hole type cable ties, clamping bolt type cable ties, clamping steel plate type cable ties, etc.

The round hole type cable ties are mostly used in places where the sheet metal is relatively flat and the wiring space is large and the wiring harness is smooth, such as in the cab. The diameter of the round hole is generally 5~8 mm.

The waist-shaped round hole type cable tie is mostly used on the trunk or branches of the wire harness. This kind of cable tie cannot be rotated at will after installation, and has strong fixation stability. It is mostly used in the front cabin. The hole diameter is generally 12×6 mm, 12× 7 mm)

Bolt-type cable ties are mostly used in places where the sheet metal is thick or uneven and the wiring harness has irregular direction, such as firewalls. The hole diameter is generally 5mm or 6mm.

The clamping steel plate type tie is mainly used on the edge of the steel sheet metal to clamp the sheet metal to smooth the transition of the wire harness and prevent the edge of the sheet metal from scratching the wire harness. It is mostly used in the wire harness and rear bumper located in the cab. The thickness of the sheet metal Generally 0.8~2.0mm.

2 buckles

The function of the buckle is the same as that of the tie, both of which are used to secure and protect the wiring harness. The materials include PP, PA6, PA66, POM, etc. Commonly used buckle types include T-shaped buckles, L-shaped buckles, pipe clamp buckles, plug-in connector buckles, etc.

T-shaped buckles and L-shaped buckles are mainly used in places where the wiring harness wiring space is small due to the installation of exterior decoration or where it is not suitable to drill holes for the wiring harness itself, such as the edge of the cab ceiling, which is usually a round hole or waist round hole;

Pipe clamp type buckles are mainly used in places where drilling is not suitable or impossible, such as engine bodies, which are generally tongue-shaped sheet metal;

The connector buckle is mainly used to cooperate with the connector and is used to fix the connector on the car body. It is usually a round hole, a round hole or a key hole. This type of buckle is more targeted. Generally, a certain type of clip is used to fix the connector on the car body. The buckle can only be used for the corresponding series of connectors.

3 bracket guard

The wiring harness bracket guard has poor versatility. Different bracket guards are designed differently for different models. The materials include PP, PA6, PA66, POM, ABS, etc., and generally the development cost is relatively high.

Wire harness brackets are generally used to fix connectors, and are often used where different wire harnesses are connected;

The wire harness guard is generally used to fix and protect the wire harness, and is mostly used on the wire harness located on the engine body.

B. 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 the wire harness can not only ensure the quality of the wire harness, but also reduce costs and improve economic benefits.

1 bellows

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 point 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.

PP corrugated pipe has a temperature resistance of 100°C and is the most commonly used type in wire harnesses.

PA6 corrugated pipe has a temperature resistance of 120°C. It is outstanding in flame retardancy and wear resistance, but its bending resistance is lower than that of PP material.

PPmod is an improved type of polypropylene with a temperature resistance level of 130°C.

TPE has a higher temperature resistance level, reaching 175°C.

The basic color of the corrugated pipe is black. Some flame-retardant materials are allowed to be slightly gray-black. Yellow can be used if there are special requirements or warning purposes (such as airbag wiring harness corrugated pipes).

2 PVC pipes

PVC pipe is made of soft polyvinyl chloride, with inner diameters ranging from 3.5 to 40. The inner and outer walls of the pipe are smooth and uniform in color, which can have a good appearance. The commonly used color is black, and its function is similar to that of corrugated pipes. PVC pipes have good flexibility and resistance to bending deformation, and PVC pipes are generally closed, so PVC pipes are mainly used at the branches of wiring harnesses to make smooth transitions of wires. The heat-resistant temperature of PVC pipes is not high, generally below 80°C, and special high-temperature resistant pipes are 105°C.

3 fiberglass casing

It is made of glass yarn as the base material, braided into a tube, impregnated with silicone resin, and dried. It is suitable for wire protection between electrical appliances that are prone to high temperatures and high pressures. It has a temperature resistance of over 200°C and a voltage resistance of up to kilovolts. above. 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.

4 tape

Tape plays a role in bundling, wear-resistant, temperature-resistant, insulating, flame-retardant, noise reduction, and marking in wire harnesses. It is the most commonly used type of wire harness wrapping materials. Commonly used tapes for wire harnesses are generally divided into PVC tape, flannel tape, and cloth tape. 4 types of base glue and sponge tapes.

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. It 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, coated with high peel strength solvent-free rubber pressure-sensitive adhesive, no solvent residue, corrosion resistance, noise reduction performance, hand-tearable, easy to operate, temperature resistance 105 ℃. 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, etc. High-quality acrylic flannel tape can provide good temperature resistance, oil resistance and aging resistance. Made of high-quality polyamide flannel, high viscosity, no hazardous substances, corrosion resistance, balanced unwinding force, and stable appearance.

Fiber cloth-based tape is used for high-temperature-resistant winding of automotive wiring harnesses. Through overlapping and spiral winding, smooth, durable and flexible automotive wiring harnesses 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. Because the base material has high strength and oil and temperature resistance, it is an ideal product for use in the engine area. It is composed of a high-quality polyester cloth 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 various thicknesses, densities and colors, it can be rolled or die-cut into various shapes. The tape has excellent weather resistance, conformability, cushioning, sealing and superior adhesion, and is widely used.

Velvet sponge tape is a wire harness protection material with good performance. Its base layer is a layer of flannel combined with a layer of sponge, and is 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.