Study On Surface Wettability Of Textured Tool Materials

Cutting is one of the most widely used machining methods.During metal cutting,severe friction can cause serious tool wear and accelerate tool failure.Therefore,the severe wear should be reduced in actual application process.The addition of lubricant is one of the most common methods of reducing grinding and cooling in the cutting process.This thesis based on surface wettability and studies the wettability of the textured tool.And the effect of on friction and wear properties were studied under liquid lubrication conditions.High-speed steel tools,PCBN tools,PCD tools,ceramic tools,coated tools and carbide tools were selected as the tool sample materials.After the tool samples were ultrasonically cleaned,Fish scale and linear scale texture were prepared on the surface by a pulsed fiber laser machine.And the laser processing power was 14 W and the scanning speed was 100 mm/s;The number of scans was 1;Then,the surface topography and surface roughness of the tool without texture and its corresponding textured tool were investigated.The roughness of the tool surfaces and its corresponding textured tool surfaces were obtained and compared.The results show:(1)The processed fish scale micro-texture or linear type Micro-texture can increase the roughness of the tool surface,and the degree of increasing varies according to the materials.When processing the fish scale micro-texture on the surface of six different tool materials,Among the fish scale textured tools,the surface roughness of PCBN tool is the smallest,ceramic’s roughness tool is the largest;And when processing the different pitches linear micro-texture on the tools of six different materials,the roughness of the tool surface was also significantly increased,and as the pitch of the texture increases,the surface roughness generally decreases.That is,for the linear textured tools,the denser the linear micro-texture was,the higher the surface roughness was.The linear micro-texture intensive degree is negatively correlated with the tool surface roughness.(2)For the six tool materials,when the fish scale micro-texture is processed on the surface,the surface roughness increases more than the linear micro-textured tools.The contact angle of the tool surfaces and the corresponding textured tool surfaces were measured by using contact angle measuring instrument under different measuring reagent conditions(deionized water,lubricating oil and cutting fluid).The influence factors of contact angle such as tool materials,texture morphology and measurement reagent selection,surface roughness were studied.The experimental results show:(1)Processing micro-textures(fish scales and straight lines)on the surface of six different material tools,when the measuring reagent is deionized water and cutting fluid,the contact angle of some textured tools will be reduced,others will increase;When the measuring reagent is lubricating oil,all the contact angle of the textured tool reduced;(2)When processing the linear micro-texture on the surface of six different material tools,due to the measurement of different direction,the contact angle measurement of the linear texture has a directional difference,the contact angle when the observation direction is parallel to the linear texture direction is significantly larger than the contact angle of the observation direction perpendicular to the linear texture direction;(3)When processing linear micro-texture of 200 μm,300μm and 400 μm on the tools,the contact angle of the textured tools are significantly different.And when the measuring reagent is lubricating oil,The contact angle is related to the degree of texture density.The denser the texture,the smaller the contact angle.When the measuring reagent is deionized water and cutting fluid,the contact angle of the tool surface is not related to the texture density;(4)for different tool materials,The effect of surface roughness on the contact angle is not obvious.For the same kind of tool material,when the measuring reagent is lubricating oil,the contact angle of the tool surface conforms to the wenzel state,that is,the higher the roughness,the smaller the contact angle;When the measuring reagent are water and cutting fluid,the contact angle of the tool surface does not conform to the wenzel state,and the relation between contact angle and roughness are not obvious;(5)When selecting different measurement reagents for contact angle measurement,whether for the surface of the non-textured tool or textured tool,the spreadability order of the three liquids on the tool surface is Lubricating Oil>Cutting Fluid>Water.Using the prepared textured tools,the friction and wear test was carried out under the condition of dry friction,oil lubrication,and the cutting fluid.And the surface wear morphology and elements were analyzed by scanning electron microscope SEM and EDX;The results show:(1)Under dry friction conditions,the average friction coefficient of the non-textured surface of the six tool materials is larger,and the surface wear is more serious.The average friction coefficient order ranked from high to low of the dry friction conditions is:High-speed steel Tools,PCD tools,coated tools,ceramic tools,carbide YG6,PCBN tools.And the six tool materials under dry friction conditions,the friction curve begins to slowly rise after the steady friction state,the friction coefficient remains stable.(2)Under different lubrication conditions,whether for lubricating oil or cutting fluid lubrication,the non-textured surface wear and the average friction coefficient of different tool materials are mainly determined by the nature of the material itself,and the relation with contact angle is not obvious.And when the lubricant changes,the friction coefficient is in the same order;For the same tool material,the surface wettability affects the surface friction and wear performance.And the average friction coefficient and surface wear degree associated with the surface contact angle,the larger the surface contact angle,the smaller the average coefficient of friction and the lighter the surface wear.