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Stainless Steel Laminate Quality Problem Analysis

The stainless steel laminate is composed of two or more layers of resin-impregnated fiber or fabric with a combination of overlapping and hot pressing. Laminate is one of the laminate products. Laminated products can be processed into various kinds of insulation and structural parts, widely used in motors, transformers, high-voltage electrical appliances, electrical instruments and electronic equipment. Laminated products can be plates, tubes, rods or other shapes.

With the development of electric industry, high insulation. High strength, high temperature resistant and suitable for the use of all kinds of laminated plastic products. The copper clad laminates used in the printed circuit have also been developed rapidly due to the need for electronic industry. Our electrical and electronic laminate products are gradually developed after liberation. The thermosetting layer in China has formed a complete series.

The performance of laminated products depends on the base material and adhesives and forming process. According to its composition, characteristic and heat resistance, laminate products can be divided into the following two kinds.

(1) organic substrate laminated products -- wood pulp insulation paper, cotton fiber paper, cotton cloth, etc. as reinforcing materials. Long-term use of temperature can reach 120 ℃, and developed the synthetic fiber products to strengthen material.

(2) inorganic substrate laminated products - reinforced materials with inorganic glass fiber cloth and alkali glass fiber felt. Long-term use of temperature is 130 ~ 180 ℃, can reach even higher temperature, vary with adhesive resin.

Laminated plastic products are divided into laminate, laminated tube, laminated rod and molded laminate. The printed circuit with copper foil laminate and the capacitance casing with capacitive sleeve for high voltage appliances are two kinds of special laminated plastic products.

Laminate application

Phenolic laminated paper board has high mechanical strength, good resistance to moisture and heat resistance, good electrical performance (poor cloth board), easy to process, and widely used in electrical products. Phenolic laminated paper, cloth, board density is about 1.35 g / ㎝ & sup3; It's about half as light as aluminum and is used in aviation and other structures.

Phenolic laminate products are resistant to chemical corrosion, organic solvents, organic acids, and dilute inorganic acids, which are suitable for many chemical equipment and are generally not applicable to alkaline media.

Laminated cardboard can withstand the sawing, drilling, cars, milling, planing, such as processing, after processing should not appear crack and slag, thickness under 3 ㎜ punching processing, cold stamping without heating, general model subject to preheat after punching. It is used for insulation components of high and low voltage electrical and electronic industries.

Cloth plate processing performance is better than cardboard, glass cloth laminated board, bonding strength and impact strength is higher than the cardboard, but big water imbibition, electrical insulation decline after moisture absorption, and easy to mildew, not suitable for hot and humid areas use. Therefore, it is generally used to make the insulation structural parts of low voltage electrical appliances such as gasket, slot wedge, screw, etc. Glass cloth laminated board is a lot of more phyletic, the performance also varies with the adhesive resin, compared with other laminate, glass cloth plate has higher mechanical strength and heat resistance, under the effect of high temperature, bending, and impact strength are reduced, but still higher than the gummed paper plate and adhesive plate.

Melamine glass sheet with high strength, arc resistance and flame resistance, especially for Marine electric appliances. Epoxy phenolic glass cloth plate, organic silicon epoxy glass cloth laminated board, diphenyl ether glass cloth board, polyimide glass cloth plate, poly (amino imide glass cloth plate, etc., good dielectric properties, and high heat resistance and flame resistance, so it is a kind of excellent dielectric insulation. The most widely used is epoxy phenolic glass cloth plate.

The glass cloth board is widely used in electric, construction, chemical, electronic, airplane, aerospace, automobile, electric locomotive and Marine industries due to its various excellent properties.

Quality problem analysis

The quality problem of laminates is a comprehensive reflection of resin, gluing and pressing process quality. Although the suppression is the last key process of laminates, the quality of the semi-finished products produced in the previous process will have a direct impact on the quality of the laminate. Therefore, it is necessary to carry out a detailed and comprehensive analysis of the quality problems of the laminates, so as to find the exact causes, take effective measures to solve them in time, and improve the quality of laminate.

(1) the phenomenon of surface hemp hole tends to appear in thin plates, mainly in the form of adhesive paper cloth, especially in table fabrics, with small amount of glue, low soluble resin content and poor fluidity of resin. The second is that the pressure is unevenly compressed. The individual case is that the preheating time is too long and the pressure is low. So for sheet material when it is important to pay special attention to the tape of soluble resin content cannot be on the low side, and use good table fabric, it is best to thin plate and thick plate collocation to suppress together, in order to increase the flexibility of the billet, uniform heating, compression. If because of the limitation of product specification, only thin plate task, the pad paper should be thickened some and must change frequently, the preheating time cannot be too long, the pressure should heel. In addition, the hot plate temperature should not be too high.

(2) the surface uneven, stare blankly this phenomenon occurs when the resin content, soluble larger small pasteboard, due to the small resin liquid, glue dispensing quantity uneven phenomenon easy to reflect on the surface of the laminate present uneven and stare blankly phenomenon. So when the glue must pay attention to the glue amount control even, material note each piece of material upside down to 180 °, make up caused by uneven glue, glue such surface condition can be improved.

(3) the cracking and cracking of laminate plates mainly occurred in the thick paper and cloth board, and the laminates with more than 5mm are cracked. Epoxy phenolic glass cloth plate is not easy to crack, it is the adhesive strength of glue. Laminate crack has much to do with resin adhesive force, when the aging material sandwiched into the laminate, the laminate will craze, therefore, gummed paper cloth material work shall be conducted, the aging material selected, can not be mixed in the blank. In addition, the adhesive paper cloth is too small and uneven, too low or too low pressure, too easy to cause cracking.

(4) the surface color depth in the middle, surrounded by white Volatiles, mainly gummed paper cloth around the preheat the volatiles Yi Yi, central residual volatiles, so surrounded by white and color depth in the middle. This can be determined by the voltage resistance of the center of the plate in the middle of the plate. Therefore, it is more serious to prevent the moisture absorption of adhesive paper, especially the soluble resin content of the paper cloth and the corresponding increase in the low molecular material produced in the heat pressure. Trials show that low molecular content greater than water influence, practice shows that tape do not produce white cloth volatiles under 4%, less than 6% of the control preheating can not produce white or rarely white, more than 6% of white lace is bigger.

(5) surface fracturing is mainly the pressure of the resin to suppress the pressure in the flow, so it is necessary to strictly control the pressure and pressure of the adhesive tape on the flow glue. The pressure of epoxy phenolic glass fabric is more than 7MPa (70kgf/cm&sup 2;). It will crush the glass cloth.

(6) thickness deviation is larger surface area of rubber reinforced material itself, cause uneven glue or gluing machine imperfection caused a certain position, large amount of glue gummed paper cloth liquidity, preheating uneven heat transfer of hot plate, soluble resin content, resin flow pressure too fast. So substrate thickness deviation cannot too big, the amount of adhesive tape cloth should be uniform, reducing the content of soluble resin, should pay attention to when the materials will be part of the gummed paper cloth upside down to 180 °, preheat pressurized shoulds not be too fast. Be careful to exclude pipes and hot sheets.

(7) the thickness deviation of laminar thickness deviation is generally thin in the middle thickness, which is mainly caused by the corrugated edge of the steel plate. Therefore, the steel plate should be taken care of, and the edges should be reused after leveling. There is also a thin phenomenon of large deviation, which is mainly caused by high temperature, low temperature and hot plate tilt. So should pay attention to when the materials will be part of the tape cloth upside down to 180 °, staggered pipeline imports and exports, preheat the note row of hot plate, pipe water, in case of hot plate temperature is high, while the temperature is low, at the same time, often should check the hot plate tilt and repair in time. The thickness deviation and the thickness of the middle thickness are thin, which is mainly caused by the deformation of the central depression. The hot plate should be repaired.

(8) when the sheet slims out, the sheet cloth slides out of the steel plate, especially when the epoxy phenolic glass cloth plate is pressed. It is commonly referred to as "runner". Causes of the run of material is more, such as resin adhesive was greater than the tender, uneven glue on both sides, prepares materials not neat, charging, preheat flow when pressure too high and hot plate itself run material can produce uneven phenomenon, run material can create personal equipment accident, must pay attention to prevent. When preparing materials, use the same batch of adhesive paper cloth, the amount of glue and the solubility are basically consistent, the blank is laid out, the loading is positive, and the pressure is gradually increased. In case of running conditions, the steam should be turned off to cool down, but the pressure should be kept enough to observe the slip and adjust after stabilization, and then gradually to continue to suppress the steam temperature.

(9) sticking steel plate or surface spray Mainly mold release agent is not appropriate, the release agent, such as zinc, calcium, barium stearate, less dosage of oleic acid and so on, or outer mold release too little and uneven and easy to stick steel plate, quantity more or wipe wet feeding easy generation after demoulding agent spray. So we will strictly control the release agent dosage, need clean outer mold release agent, such as floor wax, silicon rubber, mold release agent concentration to allocate appropriate, to rub evenly, form a thin layer, after being dry feeding again. In addition sticking steel plate and steel plate surface quality, the surface is bright and clean degree of poor or processing is not enough, is easy to stick steel plate, sometimes because of careless work using ontology material as table fabric, also can produce the phenomenon of sticking steel plate.

(10) laminate warp too much This kind of phenomenon often occurred in 7 ~ 15 mm thick board, the cause of the warp is complex, such as uneven gummed paper glue quantity, suppression of heating, cooling speed is too fast, the discharge temperature is too high, unreasonable collocation program, etc., but mainly because of internal stress. Therefore, the internal stress should be reduced as far as possible, such as heating or cooling, slow to the steam or cold water to prevent the laminate from being hot or cold. Should have sufficient cooling time, cannot shorten arbitrarily, when the water pressure is insufficient should extend the time appropriately. The collocation plan should pay attention to the laminate plate to be heated evenly, the material is to be transferred to a few times as far as possible, which is good for reducing warping.

(11) the resistance to voltage failure is mainly the thin plate, because the thin-plate resistance voltage is higher than the thickness plate, and when the heat treatment process is cancelled, the thin-plate resistance often fails to meet the standard requirements. Thin plate breakdown voltage has a great relationship with the volatiles of adhesive paper cloth. It has been proved that when the volatiles of 3020 adhesive paper are qualified under 4%, the volatiles are not stable at 4.5%~ 5%, and the acceptance rate of 5% is very low. It is generally effective to use thermal drying of laminated plates with nonconforming voltage, but some of them have low voltage and low voltage. Hot work is large, so the paper cloth should be kept in a dry storage, not damp.