Carbon Fiber SMC Molding Process

Core tips: Carbon fiber SMC is a sheet molding plastic formed by cutting carbon fiber, matrix resin, additives and other materials in accordance with a certain ratio, using professional molding processing equipment in accordance with a certain process

 

Refers to the carbon fiber SMC sheet according to the product size, shape, thickness, weight and other requirements of cutting material, and then the cut material superimposed into the heated metal mold cavity, according to the pre-set process molding conditions curing molding process;

 

SMC molding process has many advantages, such as it has simple operation, easy to achieve automation, short production beat, formable surface smooth structure complex products, etc., can be embedded metal molding, low waste, in addition to the application of carbon fiber SMC molding process to obtain products, its performance is also very good: Excellent mechanical properties, thermal stability, chemical corrosion resistance, heating low shrinkage and low water absorption.

 

① Mainly includes "pressure", "temperature" and "forming time", which is determined according to product thickness, material requirements, mold conditions, etc.

② The mold installation must be horizontal, and ensure that the installation position is in the center of the press table;

 

① To thoroughly clean the mold, and coated release agent, before adding material to use clean gauze to wipe the release agent, so as not to affect the appearance of the product quality. For the new mold, the oil must be removed before use.

② Heat the mold by closing the mold;

 

① Open the mold, use the contact thermometer to measure the upper and lower mold temperature of the mold cavity (Note: before, after, left, middle and right, measure several points to ensure that the mold surface temperature reaches the material requirements above the pressing temperature, the mold core temperature is lower than the mold cavity about 5 degrees);

② If the temperature is not reached, wait for the mold to continue heating;

③ If the temperature is reached, spray release agent to the upper and lower molds again.

① Feeding amount: the feeding amount of each product can be calculated according to the following formula when the first pressing: feeding amount = product volume * density 1.5g/c square meters;

②Feeding area: the size of the feeding area directly affects the density of the product, the flow distance of the material and the surface quality of the product, which is related to the SMC flow and curing characteristics, product performance requirements, mold structure and so on. The general feeding area is 70%-100%. Too small will lead to fiber orientation due to too long process, reduce strength, increase the degree of corrugation, and even can not fill the mold cavity;

③ Feeding position: feeding position and method directly affect the appearance, strength and directivity of the product. Under normal circumstances, the feeding position of the material should be in the middle of the mold cavity. For asymmetric complex products, the feeding position must ensure that the material flow reaches all ends of the mold forming cavity at the same time when forming.

 

When the material block into the mold cavity, start the machine, the press quickly down. When the upper anlower molds match, slowly apply the required molding pressure, after a period of time of heat preservation and pressure preservation, the product molding ends. The molding process parameters should be reasonably set according to the material characteristics combined with the conditions of the press.

The level of molding temperature depends on the curing system of the resin paste, the thickness of the product, the production efficiency and the complexity of the product structure. The molding temperature must ensure the smooth progress of the cross-linking reaction triggered by the curing system, and achieve complete curing. The molding temperature of carbon fiber SMC is generally between 130-140 ° C.

 

Generally speaking, the molding temperature chosen for products with large thickness should be lower than that for thin-walled products, which can prevent excessive heat accumulation inside thick products from being caused by excessive temperature. The increase of molding temperature can shorten the corresponding curing time;

 

On the contrary, when the molding temperature is reduced, the corresponding curing time needs to be extended. The molding temperature should be selected in the balance between the highest curing speed and the best molding conditions.

 

SMC molding pressure varies with product structure, shape, size and SMC thickening degree. Products with simple shapes need less pressure, and products with complex shapes need more pressure. The higher the thickening degree of SMC, the greater the molding pressure required, and the products with high appearance performance and smoothness requirements need higher molding pressure when forming. In short, the determination of molding pressure should consider many factors. In general, the molding pressure of carbon fiber SMC is between 10-25Mpa

 

The curing time (also known as holding time) of carbon fiber SMC at the molding temperature is related to its nature and curing system, molding temperature, product thickness and color. The molding time of carbon fiber SMC is usually between 10-15 minutes.

 

Since the SMC is a fast curing system, it is important for the press to close quickly. If the closing of the press is too slow after feeding, it is easy to precure patches on the surface of the product, or produce a lack of material, or the size is too large.

 

In the realization of rapid closure at the same time, the end of the press stroke should be carefully adjusted mold closing speed, mold distance from the closure of a certain distance, slow down the closing speed, conducive to exhaust.

 

① Open the upper die slowly, and confirm whether the product is stuck after rising to 10mm. After confirming that the product remains in the lower die, the upper die can be moved to the upper limit. Open the top die mechanism, slowly lift the product out;

② Check the appearance of the product, see missing materials, dirt, air holes, dry yarn, etc., such as no painting needs of the product will spill the raw edge repair can complete the product production.