Study On The Adhesion Mechanism Between Moulds With Biomimetic Coupling Non-smooth Surfaces Processed By Laser And Parts

The moulds are very important effect in the developing industry. Compared with working circumstances of moulds, it is found that the adhesion between mould and part can affect the quality and producing efficiency of products. In the process of de-moulding, because the adhesion between mould and part is too large, on one hand, it results in the de-moluding difficulty and the distortion of parts, even coming into being many waste products; on the other hand, it shorten the life of mould. Therefore, reducing the adhesion between mould and part is one of the measures which enhance the quality and producing efficiency of products and depress the producing cost.According to the traditional theory, the smoother is the surface of mould, the smaller is the adhesion force between mould and part, the smaller is the resistance during the process of de-moulding. And then workers have their best to heighten the processing precision of mould surface and play down the roughness degree. Whereas the higher precision process is not only increase the producing cost, but also the impact of the adhesion force reducing is unconspicuous. The bionics study found that the surfaces of some biology in the nature have an evolution through hundreds of millions years, in order to adapt existent environment and content existent requirement, some biology always select the smallest energy consumption and material consumption to content the most environment adaptability, the environment adaptability is brought by coupling superficial morphology, cuticle structure and component of biology, it makes the biology surfaces have some unique properties and functions. Such as the leaves of lotus and paddy, they exist in the silt. In order to adapt this condition, their surfaces have formed a coupling double rough structure with micron-scale and nano-scale by uninterrupted evolution, the structure makes leaves super-hydrophobic and self-cleaning. As well as earthworm and dung beetle exist in the soil. In order to content exist requirement, their surfaces have formed unique non-smooth structure by unceasing evolution, the structure makes them have dragged reducing function in the soil.Founded on the revelation of biology with non-smooth characteristics and composing mechanism. The paper base on bionics mechanism, and design four kinds of biomimetic coupling non-smooth morphology of concave, horizontal stria, vertical stria, graticule. Making use of laser process technique, the surfaces of mould samples are processed four kinds of biomimetic coupling non-smooth morphology. Both 45P#P steel and high speed steel are selected as mould materials. Aluminum and aluminum alloy, magnesium and magnesium alloy, polymer are selected as part materials. Preparing the mould sample/part couple by the method of melting casting, measuring the adhesion force of mould sample/part couple by the electronic universal test machine, studying on effect of different non-smooth morphology, different mould materials, different part materials on the adhesion force between mould samples and parts; Simultaneity, observing the interface of the mould sample/part couple by the optical microscope, analyzing the mechanism of mould sample/part couple; In addition, measuring static angle contact of water droplet on biomimetic coupling non-smooth surfaces, analyzing the wetting property of biomimetic coupling non-smooth surfaces, and discussing effect of the wetting property on the adhesion between mould samples and parts.The conclusions are gained as follow:1. The adhesion forces of mould samples with biomimetic coupling non-smooth surface are obviously lower than those of the mould samples with smooth surface. The biomimetic coupling non-smooth surfaces can effectively decrease the adhesion force between moulds and parts, the maximal decreasing extent of the adhesion force attain to 23.9%, the minimal decreasing extent of the adhesion force attain to 2.4%.2. Under the condition of the same material mould and the same material part, for the parts of alloy, the adhesion forces between mould samples and parts decrease in sequence of smooth, concave, horizontal stria, graticule, vertical stria. For the parts of polymer, the adhesion forces between mould samples and parts decrease in sequence of smooth, horizontal stria, graticule, vertical stria, concave.3. Under the conditions of the same non-smooth morphology and the same material part, the adhesion forces between mould samples of 45P#P steel and parts are lower than those between mould samples of high speed steel and parts.4. Under the same condition of the same non-smooth morphology and the same material part, for Al, Al-13%Si, Al-20%Si, the adhesion forces between mould samples and parts increase in turn; for Mg, AM50, AZ91D, the adhesion force between mould samples and parts decrease in turn; for LDPE, HDPE, PP, the adhesion force between mould samples and parts decrease in turn.5. The contact angles of water droplet on biomimetic coupling non-smooth surfaces are obviously larger than those of water droplet on smooth surface. It shows that the wetting property of biomimetic coupling non-smooth surface is worse than that of smooth surface. With different biomimetic coupling non-smooth morphology, the wetting property of mould surfaces is different, and the wetting property turns worse in sequence of smooth, concave, stria, graticule. The worse wetting property has a beneficial effect on reducing the adhesion between part and mould surface; With different material mould, the wetting property of mould surfaces is different, the wetting property of 45~# Psteel mould surface is worse than that of high speed steel mould surface, so 45~# steel mould have a beneficial on reducing the adhesion between part and mould.6. The reason of the adhesion force reducing is that biomimetic coupling non-smooth structure can make the wetting property of mould surface worse, the contact angle of melting part liquid on mould surface increase, the spread of melting part liquid on mould surface is baffled, air aperture is formed at non-smooth unit of the contact interface between biomimetic coupling non-smooth mould samples, the existence of air aperture lessens the actual contact areas between mould samples and parts, in favor of reducing the adhesion between mould samples and parts.