What is machining surface quality? Meaning of machining surface quality
- source:GERHOLD CNC Machining
05 ～ 0.
15mm) , but having huge effect to the performance characteristics of machine spare parts; Of the spare parts wear away, corrode and exhaustion is destroyed begin from spare parts surface, especially modern industry production makes machine forward nicety is changed, high speed is changed, muti_function way develops, the mechanical part that the job plays in condition of high temperature, high pressure, high speed, tall stress, any blemish of exterior layer can quicken the invalidation of the spare parts. Accordingly, must take machining surface quality seriously. One, the treatment quality of the spare parts of meaning machine of machining surface quality points to treatment precision not only, still include to machine exterior quality, it is the token of integrality of condition of layer of the surface after the spare parts is machined. The surface after machining, always put in the deviation of proper microcosmic geometry form, mechanical function also produces the physics of exterior layer change. Accordingly, the geometrical feature that machining surface quality includes to machine the surface and exterior layer physics are mechanical function the content of two respects. (One) the microcosmic geometry feature of the surface of treatment of geometrical feature that machines the surface basically includes exterior surface roughness and surface wave to spend two parts to comprise, if pursue 5, 1 is shown. Exterior surface roughness is a surface that is apart from L to be less than 1mm tiny ripple; Surface wave is spent is to point to wave be apart from L the surface wave grain between 1 ～ 20mm. Normally the circumstance falls, when L/H (wave be apart from / wave height) ﹤ 50 when for exterior surface roughness, l/H=50 ～ 1000 when spend for surface wave. 1. By the appearance of cutting tool and cutting the plasticity in the process is out of shape and basically the element such as vibration causes surface roughness of surface of exterior surface roughness, it is to point to the error of microcosmic geometry appearance that already processed the surface. 2. Surface wave is spent basically is the periodic appearance error that causes by the low frequency vibration of the machining complex in machining a process (graph 5, 1 in L 2/H 2) , interpose at appearance error (﹥ of L 1/H 1 1000) with exterior surface roughness (﹤ of L 3/H 3 50) between. (2) the physics that machines exterior layer is mechanical the physics of function surface layer is mechanical the treatment sclerosis that function includes to express facing, leftover stress and the metallographic that express facing organize change. Because suffer cutting force and hot integrated effect,mechanical spare parts is in in treatment, the physics of exterior layer metal is mechanical mechanical function produced the physics that function belongs to at basic gold relatively to change. Graph 5, 2a place shows the change that expresses direction of facing edge deepness for the spare parts. The outerest generate have oxidation film or other compound, absorb, ooze enters aeriform particle, call adsorption layer. It is to reduce a layer below adsorption layer, it is the plasticity that causes as a result of the action of cutting force is out of shape area, its upside is the fiber layer that chafe as a result of the extruding of cutting tool and arises. The action of heat in metal cutting also can make material of workpiece surface layer arises to change reach grain size to change. 1. The treatment sclerosis of surface layer uses the treatment sclerosis of exterior layer commonly the deepness of sclerotic layer and sclerotic degree N come assess: N= [(H-H 0) / the H in type of of ％ of L00 of H 0] × -- what facing expresses after treatment is microscopical hardness; H. -- of raw material microscopical hardness. 2. The metabolic that exterior layer metallographic organizes is machining a process (especially grinding) below medium high temperature action, temperature of workpiece surface layer is elevatory, when the photograph that exceeds material when temperature becomes bit more critical, with respect to the change that can produce metallographic to organize, reduce spare parts performance characteristics greatly, this kind of change includes grain size, appearance, precipitate and recrystallization to wait. The change that metallographic organizes basically decides through microstructure observation. 3. of stress of exterior layer remains is in treatment process, because plasticity is out of shape, the influence that the volume that the change that metallographic organizes and temperature cause changes, exterior layer can produce leftover stress. It is qualitative mostly to the judgement of leftover stress at present, it depends on to the influence size of spare parts performance characteristics its direction, size and distributinging state. 2, exterior integrality the development as science and technology, taller and taller to the performance characteristics requirement of the product, a few important parts need to work below condition of high temperature, high pressure, high-speed, express any blemish of facing, affect the character of service of the spare parts directly, to get used to the development of science and technology, the idea of exterior integrality advanced in the field that researchs exterior quality, basically have: (one) the geometrical feature of the spare parts after exterior form appearance basically describes treatment, it includes exterior surface roughness, surface wave to spend wait with grain. (2) exterior blemish it is to point to treatment apparently occurrence macroscopical crackle, bruise and corrode a phenomenon to wait, have very big effect to the use of the spare parts. (3) microcosmic organization and the of metallurgy chemistry function that express facing basically include microcosmic crackle, microcosmic tissue corrode between change and brilliant etc. (4) mechanical function basically includes exterior layer physics the size of stress of remains of layer of deepness of exterior layer sclerosis and degree, surface, distributing. (5) the reflectivity that the of feature of other project technology of exterior layer basically includes attrition character, light, conductivity and permeability. CNC Milling