Mechanical processing characteristics of three kinds of composite materials

Mechanical processing characteristics of the three kinds of composite materials Source: China Polypropylene Net - Website of China Fiber Net Add Anyone: amy69 Add time: 2009-5-18

First, glass steel

FRP is a common name for glass fiber reinforced thermosetting resin matrix composites and it is a hard-to-cut material. FRP has phenolic resin base, epoxy resin base, unsaturated polyester resin base and so on. The main component of the glass fiber filler is SiO2, which is hard and wear-resistant, has high strength and heat resistance, and has poor cutability to plastics that use wood powder as filler. Different resin matrix, machinability is not the same. Epoxy resin base is harder to cut than phenolic resin base. Tests have shown that the cutting tool material of FRP is the most severely damaged by high-speed steel. P-type and M-type hard alloys also wear large, and K-type wear is minimal. In class K, the K10 with the least cobalt content is the most resistant to wear, and the use of diamond or cubic boron nitride tools to cut FRP can greatly increase production efficiency. When selecting the geometric parameters of the tool, r0=20~25° for glass fiber reinforced plastic sheet material, molding material and winding material with high glass fiber content; for filament winding material, make r0=20~30°. Due to the high resilience of FRP, the rear corner should be selected to have a large value, so that a0=8~14°; the minor declination angle is smaller, and the surface roughness can be reduced, and the finishing car is 6~8°. Processing of delaminated, fluffed coiled tubing and fiber-wrapped FRP should use a 6 to 15° blade angle. When cutting v = 40 ~ 100m/min, f = 0.1 ~ 0.5mm / r, aP = 0.5 ~ 3.5mm, fine car aP = 0.05 ~ 0.2mm.

Second, thermoplastic resin matrix composites

The basic processing features of the machining of thermoplastic resin matrix composites are:

1) Add coolant when processing to avoid overheating, overheating will melt the workpiece;

2) using high-speed cutting;

3) The cutting tool must have a sufficient capacity of flutes;

4) Use a small amount of back knife and a small amount of feed;

5) The turning tool should be ground to a certain inclination to minimize the cutting force and thrust of the tool;

6) Twist drills for thermoplastic composites;

7) Tungsten carbide or corundum cutters, or special high-speed steel cutters for plastics should be used;

8) The workpiece must be properly supported (back pad) to avoid delamination caused by cutting pressure;

9) When precision machining, consider the plastic memory and the room temperature of the processing workshop;

10) The cutter head and cutter must be sharp, and the blunt cutter can increase the cutting force on the workpiece.

Third, metal matrix composites

The most important feature of metal matrix composites (MMC) is good molding performance, which can basically meet the requirements after molding. However, with the expansion of the application of composite materials, especially the application of MMC in the industrial and aerospace fields, the processing and finishing of such materials is increasingly important. For example, large SiC/Al plates manufactured in the US need to be cut by water jet and fixed on the metal matrix composite beams with standard steel connectors. The volume percentage used for tactical missiles is 25% for SiC particles and 2124 for aluminum matrix composites. The blanks must be processed by diamond tools before they are applied. This results in secondary processes such as water cutting, drilling and turning.

Traditional cutting, turning, milling, grinding and other processes can generally be used for MMC, but the tool wear is more serious and tends to increase as the volume fraction and size of the reinforcement material increase. And the ability of large particles or fibers to resist shedding is stronger, so the tool is more stressed. Therefore, for some single-fiber-reinforced MMCs, it is often necessary to use diamond-tipped or diamond-embedded tools. For short fiber or particle composites, tungsten carbide or high speed steel tools are also sometimes used. The strength of the reinforcement also has an effect on tool wear. The higher the strength of the general reinforcement, the more difficult it is to cut. It was found that silicon carbide whisker reinforced aluminum matrix composites are more difficult to process than other aluminum matrix composites. For most MMCs, using sharp tools, proper cutting speeds, large amounts of coolant/lubricant, and large feeds can be very effective. In general, diamond tools are better than hard alloys and ceramic tools and are more suitable for high-speed turning. Conversely, if carbide tools are used, the tool life is long if the turning speed is low. Wire saws can also be used to cut MMCs, but generally they are slow and can only be cut straight.

Because composite materials and traditional materials have different characteristics, the cutting process of composite materials is essentially different from metal materials. Therefore, the experience and knowledge gained from processing traditional materials cannot be directly applied to the processing of composite materials, and new methods must be adopted. Study its processing performance.

First, glass steel

FRP is a common name for glass fiber reinforced thermosetting resin matrix composites and it is a hard-to-cut material. FRP has phenolic resin base, epoxy resin base, unsaturated polyester resin base and so on. The main component of the glass fiber filler is SiO2, which is hard and wear-resistant, has high strength and heat resistance, and has poor cutability to plastics that use wood powder as filler. Different resin matrix, machinability is not the same. Epoxy resin base is harder to cut than phenolic resin base. Tests have shown that the cutting tool material of FRP is the most severely damaged by high-speed steel. P-type and M-type hard alloys also wear large, and K-type wear is minimal. In class K, the K10 with the least cobalt content is the most resistant to wear, and the use of diamond or cubic boron nitride tools to cut FRP can greatly increase production efficiency. When selecting the geometric parameters of the tool, r0=20~25° for glass fiber reinforced plastic sheet material, molding material and winding material with high glass fiber content; for filament winding material, make r0=20~30°. Due to the high resilience of FRP, the rear corner should be selected to have a large value, so that a0=8~14°; the minor declination angle is smaller, and the surface roughness can be reduced, and the finishing car is 6~8°. Processing of delaminated, fluffed coiled tubing and fiber-wrapped FRP should use a 6 to 15° blade angle. When cutting v = 40 ~ 100m/min, f = 0.1 ~ 0.5mm / r, aP = 0.5 ~ 3.5mm, fine car aP = 0.05 ~ 0.2mm.

Second, thermoplastic resin matrix composites

The basic processing features of the machining of thermoplastic resin matrix composites are:

1) Add coolant when processing to avoid overheating, overheating will melt the workpiece;

2) using high-speed cutting;

3) The cutting tool must have a sufficient capacity of flutes;

4) Use a small amount of back knife and a small amount of feed;

5) The turning tool should be ground to a certain inclination to minimize the cutting force and thrust of the tool;

6) Twist drills for thermoplastic composites;

7) Tungsten carbide or corundum cutters, or special high-speed steel cutters for plastics should be used;

8) The workpiece must be properly supported (back pad) to avoid delamination caused by cutting pressure;

9) When precision machining, consider the plastic memory and the room temperature of the processing workshop;

10) The cutter head and cutter must be sharp, and the blunt cutter can increase the cutting force on the workpiece.

Third, metal matrix composites

The most important feature of metal matrix composites (MMC) is good molding performance, which can basically meet the requirements after molding. However, with the expansion of the application of composite materials, especially the application of MMC in the industrial and aerospace fields, the processing and finishing of such materials is increasingly important. For example, large SiC/Al plates manufactured in the US need to be cut by water jet and fixed on the metal matrix composite beams with standard steel connectors. The volume percentage used for tactical missiles is 25% for SiC particles and 2124 for aluminum matrix composites. The blanks must be processed by diamond tools before they are applied. This results in secondary processes such as water cutting, drilling and turning.

Traditional cutting, turning, milling, grinding and other processes can generally be used for MMC, but the tool wear is more serious and tends to increase as the volume fraction and size of the reinforcement material increase. And the ability of large particles or fibers to resist shedding is stronger, so the tool is more stressed. Therefore, for some single-fiber-reinforced MMCs, it is often necessary to use diamond-tipped or diamond-embedded tools. For short fibers or particle composites, tungsten carbide or high speed steel tools are also sometimes used. The strength of the reinforcement also has an effect on tool wear. The higher the strength of the general reinforcement, the more difficult it is to cut. It was found that silicon carbide whisker reinforced aluminum matrix composites are more difficult to machine than other aluminum matrix composites. For most MMCs, using sharp tools, proper cutting speeds, large amounts of coolant/lubricant, and large feeds can be very effective. In general, diamond tools are better than hard alloys and ceramic tools and are more suitable for high-speed turning. Conversely, if carbide tools are used, the tool life is long if the turning speed is low. Wire saws can also be used to cut MMCs, but generally they are slow and can only be cut straight.

Because composite materials and traditional materials have different characteristics, the cutting process of composite materials is essentially different from metal materials. Therefore, the experience and knowledge gained from processing traditional materials cannot be directly applied to the processing of composite materials, and new methods must be adopted. Study its processing performance.

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