1.What is called a surface roughness? A: The surface roughness refers to the microscopic characteristics of the part geometry machining surface by a small distance and the valley thereof. It is a microscopic geometry errors.

2.How to generate surface roughness? A: The surface of the part by machining or formed by other methods, since the processing of the material to plastic deformation, mechanical vibration, friction and other reasons, there is always a geometry error.

3.What is the impact of surface roughness of the parts? A: The surface roughness of the mating parts of the friction and wear properties, fatigue strength, and corrosion resistance between the parts and the like have a major impact.

4.At present, China's "surface roughness" What are the main national standard? A: GB / T 3505 2000 term surface and surface roughness parameters; GB / T 1031-1995 Surface roughness parameters and their values; GB / T 131-1993 mechanical drawing surface roughness symbols, codes and injection method.

5.What is known as the actual profile? A: Yes, the plane intersects the resulting actual surface contours. According to the different phases of the cross-sectional direction, it can be divided into horizontal and vertical contour actual actual profile. When assessing and measuring surface roughness, except otherwise indicated, usually according to the actual lateral contour, texture and processing the profile section that is perpendicular to the direction of.

6.What is called the sampling length? A: The length of the baseline period for determining a surface roughness characteristics. The rougher the surface, the sample length should be greater. Sampling provisions is to limit the length and reduce the impact of errors on other geometric shapes surface roughness measurement results. Within the sampling length, typically includes five or more peaks contour and contour valley. The value of the length of the sample selection, see GB / T 1031-1995 Surface roughness parameters and their values.

7.What is called the evaluation length? A: Yes, in order to outline the necessary assessment of a length, and may include one or more sampling length. Due to the presence of the part surface machining unevenness, in order to fully reflect reasonably measured surface roughness characteristics, need to assess several sampling lengths. Evaluation of the length of the selected value, see GB / T 1031-1995 Surface roughness parameters and their values.

8.What is called the baseline? A: The assessment of surface roughness parameters numerical size of a reference line called the baseline. Baseline Two: Least Squares midline contour and contour arithmetic average midline.

9.What is known as contour least squares midline? A: The least-squares center line profile within sampling length, so that each point on the contour square contour offset and a minimum line.

10.What is called the arithmetic average midline contour? A: The arithmetic average centerline profile within sampling length, the actual profile is divided into upper and lower parts, and so on, an equal area under the line.

11. The basic parameters for which assessment? A: The three basic evaluation parameters for the height parameter, which outline the arithmetic mean deviation (Ra), microscopic roughness ten point height (Rz) and outline the maximum height (Ry); the other three as an additional assessment parameters that outline microscopic roughness the average distance (Sm), the outline of a single peak average spacing (S) and the profile bearing length ratio (tP).

12.What is known as contour arithmetic mean deviation (Ra)? A: In the sample length, measured on the contour of each contour point to the arithmetic average of the absolute value of the middle distance, Ra larger the value, the rougher the surface. Ra can objectively reflect the geometry of the measured profile. Ra value can be measured directly with an electric meter contour, but not intuitive.

13.What is called microscopic ten point height of irregularities (Rz)? A: In the sampling length, the five largest profile peak height and the average of the five largest valley depth and the average value. Rz larger the value, the more the surface roughness. Rz surface roughness height parameters for assessing a relatively good intuitive and easy measurements on optical instruments, but reflects the measured geometry of the outline feature has limitations.

14.What is referred to as the maximum contour height (Ry)? A: within sampling length distance contour peaks and valleys line between the lines. Peak line and the bottom line in the sample refer to length, parallel to the center line and contour line through the highest and lowest points. Parameters Ry, simple measurement, when measured surface is very small, not suitable for Rz, while Rz evaluation, may be Ry.

15.Evaluation of surface roughness height parameters (Ra, Rz, Ry)) How to determine the allowable values? A: See GB / T 1031-1995 Surface roughness parameters and their values.

16.Surface roughness symbols, codes when, and what is its significance? A: The basic symbol indicates surface may be obtained by any method. When no roughness parameter values or for instructions (for example: surface treatment, local heat treatment condition, etc.), apply only to simplify the code tagging.
17.Surface roughness symbols, codes when, and what is its significance? A: The basic symbols plus a dash to indicate the surface is obtained by removing material. For example: turning, milling, drilling, grinding, cutting, polishing, etching, EDM, gas cutting and the like.

18.Surface roughness symbols, codes when, and what is its significance? A: The basic symbols plus a small circle, represents the surface is obtained without removing material. For example: casting, forging, stamping deformation, hot rolling, cold rolling and powder metallurgy. Or for maintaining the original condition of the supply surface (including retaining the status of the procedure).

19.Surface roughness symbols, codes when, and what is its significance? A: The way to get any kind of surface with roughness Ra of the upper limit value of 3.2μm.

20.Surface roughness symbols, codes when, and what is its significance? A: The surface of the material obtained by removing the roughness Ra of the upper limit value of 3.2μm.

21.Surface roughness symbols, codes when, and what is its significance? A: The surface roughness without removing material obtained by the method, the upper limit value of Ra 3.2μm.

22.Surface roughness symbols, codes when, and what is its significance? A: The surface of the material obtained by removing the roughness Ra of the upper limit value of 3.2μm, the lower limit value of Ra 1.6μm.

23. Surface roughness symbols, codes when, and what is its significance? A: The way to get any kind of surface with roughness, Ry upper limit value of 3.2μm.

24. Surface roughness symbols, codes when, and what is its significance? A: The surface roughness without removing material obtained by the method, the upper limit of Rz value of 200μm.

25. Surface roughness symbols, codes when, and what is its significance? A: The surface of the material obtained by removing roughness Rz upper limit value of 3.2μm, the lower limit of Rz value of 1.6μm.

26. Surface roughness symbols, codes when, and what is its significance? A: The surface of the material obtained by removing roughness, Ry upper limit value of 3.2μm, the lower limit value of Ry 12.5μm.

27. When the surface roughness of the label you want to pay attention to what? A: When the height of the selected parameters Ra, can be omitted when their code labels, choose Ry, when Rz, the code can not be omitted. Given the pattern of the surface roughness of the surface after the completion of the code is the requirement, usually just pouring symbol and parameter values ​​can be allowed. As part of the functional surface with special requirements (grain processing, allowances and other additional requirements), it can be marked or on behalf of the relevant parameters (symbol) in the number of basic symbols around.

28. How surface roughness symbol painting? A: Figure 1 Figure 1 d '= h / 10; H = 1.4h; h is the height of the font.

29. Surface Roughness methods are there? Example 1 A: Figure 2. Figure 2 Surface roughness generation (symbol) number should be noted in the visible contour, dimension lines, extension lines, or on the extension line. Symbol tip must point from the outer surface of the material.

30. Surface Roughness methods are there? A: Figure 3 Figure 3 center hole work surface, keyways the face, chamfer, fillet surface can be simplified labeling.

31. Surface Roughness methods are there? A: Figure 4 Figure 4 gear, involute spline, thread and other work surfaces are not shown tooth (teeth) Tagging shape when.

32. Surface Roughness methods are there? A: See Figure 5 Figure 5 of the same surface have different surface roughness requirements shall draw dividing lines with a thin solid line, and note the corresponding surface roughness symbols and sizes.

33. Surface Roughness methods are there? A: The need to represent at local heat treatment or partial plated coating, application crude dotted line drawn its scope and marked the appropriate size, or it can be requested in writing injection surface roughness symbols.

34. Surface Roughness methods are there? Example 6 A: see FIG. 7 parts of the continuous surface 7 and repeating elements (holes, grooves, teeth, etc. ......) and a surface of the coupling surface of thin solid lines are not consecutive, the generation (symbol) No. marked only once.

35. Surface Roughness methods are there? A: Figure 8 Figure 8 parts requirements at the same time most of the surface, in the upper right corner of the unified label, and note "rest" word. To simplify the label, or location restrictions, we can simplify the code labels, omitting injection method may also be used, but must explain the significance of these simplified generation (symbol) number in the vicinity of the title bar. When using a unified and simplified labeling labels, code and text should be other surface Note graphic symbols and text on 1.4 times.

36. The surface roughness parameters and the provisions of the note written by the position of how to provide? A: Figure 9 Figure 9

37. How to choose the surface roughness? A: The choice of surface roughness is necessary to meet the functional requirements of the use of parts of the surface, but also consider the economics of processing.

38. When determining the surface roughness of analogy, generally based on the height parameter to select what principles? Answer: the same parts, the surface roughness of the work surface should be less than the non-working surface. The surface roughness value should be less than the non-friction surfaces friction surface; the surface roughness of rolling friction surface should be less than the sliding friction surface; high velocity, pressure unit surface roughness value should be small. By cyclic loading surface and can lead to stress concentration sites (such as rounded corners, trenches) surface roughness values ​​should be selected to be small. Combined with the nature of the required high surface, with the mating surfaces and small gaps requires reliable connection overloaded by interference fit surface should take a smaller surface roughness. With the same properties, the smaller the size of the parts, which should be as small surface roughness. The same accuracy class, small size than large size, surface roughness than the shaft hole is smaller. For the mating surface, the size tolerances, form tolerances, surface roughness should co-withered, have a certain relationship in general.

39. When the surface roughness Ra of 50-100μm, the surface shape of what features, how to apply? A: The shape of the surface is characterized by visible marks applied to the machined surface roughness, seldom used. Casting, forging, gas cutting up rough this requirement.

40. When the surface roughness Ra of 25μm, the surface shape of what features, how to apply? A: The shape of the surface features visible marks applied to the machined surface roughness, seldom used. Casting, forging, gas cutting up rough this requirement.

41. When the surface roughness Ra of 12.5μm, what shape the surface characteristics, how to apply? A: The shape of the surface is characterized by micro-see marks, applied to the rough surface of the more precise level, a wider range of applications, such as the surface of the shaft surface, chamfering, screw holes and rivet holes, washers and other contact surface.

42. When the surface roughness Ra of 6.3μm, wherein the surface shape of what, how to apply? A: The shape of the surface features visible traces of processing, semi-rough surface is applied to the free surface, frame, box, clutch pulley side cam side and other non-contact with the bolt head and the rivet head in contact with the surface, and all axes undercut hole, generally binding surface, such as shutters.

43. When the surface roughness Ra of 3.2μm, wherein the surface shape of what, how to apply? A: The shape of the surface is characterized by micro-see traces of processing, used in semi-finished surface, box, frame, cover up, sleeve, etc., and other parts of the mating connector without the required surface, the surface of the blue, we need to pre-knurled machined surface, not all of the outer surface of the spindle of the contact and the like. Turning the surface roughness is basic cutting method is more economical to achieve.

44. When the surface roughness Ra of 1.6μm, wherein the surface shape of what, how to apply? A: The shape of the surface to see the traces of processing characteristics, high quality requirements applied to the surface of the surface, medium-sized machine tool work surface (ordinary precision), the combination of machine tool spindle box and cover the joint surface, medium-size flat belt pulley and V-belt pulley work surface, the sliding bearing bush pressed into the hole generally slow rotation of the journal. Non-aeronautical mating surface, some important parts of aerospace products.

45. When the surface roughness Ra of 0.8μm, wherein the surface shape of what, how to apply? A: The surface shape is characterized by recognizable traces of machining direction, applied to medium-sized machine tool (ordinary precision) sliding rail surface, rail clips, pins and tapered cylindrical surface of the pin, the general accuracy of the dial, to be polished chrome outer surface of the speed rotation of the journal, the positioning pin pressed into the holes and the like. Mating surface is common values, it is important with the Department, the heavy equipment, grinding economy.

46. When the surface roughness Ra of 0.4μm, wherein the surface shape of what, how to apply? A: The shape of the surface characteristics of the micro-machining marks distinguish the direction of applied medium-sized machine tool (to improve accuracy) sliding guide surface, the working surface of the slide bearing, and the main surface of the fixture element drill sets, crankshaft and camshaft journal work, indexing plate surface, journal and sleeve high speed under working face and the like.

47. When the surface roughness Ra of 0.2μm, wherein the surface shape of what, how to apply? A: The shape of the surface is characterized by non-identified traces of machining direction, used in precision machine tool spindle taper hole, the top conical surface; binding surface of the small diameter precision spindle and the spindle, piston pin bore of the piston, and the support surface requires airtight surface. Leaf Basin aeroengine blade and the surface of leaf.

48. When the surface roughness Ra of 0.1μm, wherein the surface shape of what, how to apply? A: The shape of the surface is characterized by dark glossy surface, used in precision machine tool spindle box with holes in the sleeve, the equipment in use to bear the friction surface, such as rails, groove surfaces, surface holes with hydraulic drive, the valve face, the inner surface of the cylinder, piston pin surface. General mechanical design threshold. Grinding uneconomical.

49. When the surface roughness Ra of 0.05μm, the surface shape of what features, how to apply? A: The shape of the surface is characterized by bright shiny surface, applied special precision roller bearing rings, ball and roller surface, medium-accuracy meter gap in the mating parts of the work surface, measure the surface workload regulations and the like.

50. When the surface roughness Ra 0.025μm, what shape the surface characteristics, how to apply? A: The surface shape is characterized by a mirror-like surface gloss, applied special precision bearing rings raceways, with the surface of the ball and roller surface, high pressure pump plunger and plunger sleeve to ensure airtight bonding surface height and the like.

51. When the surface roughness Ra 0.012μm, what shape the surface characteristics, how to apply? A: The surface shape wherein mist mirror, used to measure the surface of the instrument, meter of mating parts work surface height accuracy gap size exceeds the amount of block work surface 100mm and so on.

52. When the surface roughness Ra 0.008μm, what shape the surface characteristics, how to apply? A: The shape of the surface characteristics of a mirror, applied to the amount of block work surface, high-precision measuring instruments measuring surface, optical measuring instruments metal mirror and so on.

53. Surface roughness Ra> when 10-40μm, economical processing methods for which several? A: economical solutions for the roughing, rough planing, rough milling, drilling, hair filing, sawing.

54. Surface roughness Ra> when 5-10μm, economical processing methods for which several? A: economical solutions for the car, plane, milling, boring, drilling, crude hinge.

55. Surface roughness Ra> when 2.5-5μm, economical processing methods for which several? A: economical solutions for the car, plane, milling, boring, grinding, pulling, scraping rough, rolling.

56. Surface roughness Ra> when 1.25-2.5μm, economical processing methods for which several? A: economical solutions for the car, plane, milling, boring, grinding, pulling, scraping, pressing, milling.

57. Surface roughness Ra> when 0.63-1.25μm, economical processing methods for which several? A: economical solutions for the car, boring, grinding, pulling, scraping, precision reaming, grinding teeth, rolling.

58. Surface roughness Ra> when 0.32-0.63μm, economical processing methods for which several? A: economical solutions for the fine hinge, fine boring, grinding, scraping, rolling.

59. Surface roughness Ra> when 0.16-0.32μm, economical processing methods for which several? A: economical solutions for the grinding, honing, lapping, super finishing.

60. Surface roughness Ra> when 0.08-0.16μm, economical processing methods for which several? A: economical solutions for the grinding, polishing, general polishing.

61. Surface roughness Ra> when 0.01-0.08μm, economical processing methods for which several? A: economical solutions for the ultra-fine grinding, precision polishing, mirror grinding.

62. The surface roughness Ra when ≤0.01μm, economical processing methods for which several? A: economical solutions for the mirror grinding, Superfinishing.

63. Threaded surface roughness parameters Ra value How to choose? A: coarse thread accuracy rating for four when, Ra is 0.4-0.8μm. When coarse thread precision grade is 5, Ra is 0.8μm. When coarse thread precision grade is 6, Ra is 1.6- 3.2μm. When fine tooth common thread accuracy rating for 4, Ra is 0.2-0.4μm. When fine tooth common thread precision grade is 5, Ra is 0.8μm. When fine tooth common thread precision grade is 6, Ra is 1.6-3.2μm.

64. Bonding surface roughness parameters Ra value How to choose? A: The combination forms a bond, moving along the groove at the hub, Ra is 0.2-0.5μm. Bound form a bond, the axial movement of the trough, Ra is 0.2-0.4μm. Bound form a bond, fixed at, Ra is 1.6μm. Bound form trough axis, moving along the groove at the hub, Ra is 1.6μm. Bound form groove axis, moving along the axis of the groove, Ra is 0.4-0.8μm. Bound form trough axis, fixed place, Ra is 1.6μm. Combination in the form of a hub groove, moving along the groove at the hub, Ra is 0.4-0.8μm. Combination in the form of a hub groove along the axis of the groove move, Ra is 1.0μm. Combination in the form of a hub groove, fixed at, Ra is 1.6-3.2μm. Note: Non-working surfaces are Ra 6.3μm.

65. Rectangle Spline surface roughness parameters Ra value How to choose? A: The internal splines at the outer diameter, Ra is 6.3μm. Internal splines, the inner radius, Ra is 0.8μm. Internal splines, key side, Ra is 3.2μm. External splines, outside diameter, Ra is 3.2μm. External splines, an inner diameter of at, Ra is 0.8μm. External splines, key side, Ra is 0.8μm.

66. Gear surface roughness parameters Ra value How to choose? A: The site for the tooth surface accuracy rating for five when, Ra is 0.2-0.4μm. When parts of the tooth surface accuracy level to level 6, Ra is 0.4μm. When parts of the tooth surface accuracy grade 7, Ra is 0.4- 0.8μm. When parts of the tooth surface accuracy rating of 8, Ra is 1.6μm. When parts of the tooth surface accuracy grade nine, Ra is 3.2μm. When parts of the tooth surface accuracy grade 10, Ra is 6.3μm. When the cylindrical portion of the precision grade is 5, Ra is 0.8- 1.6μm. When the cylindrical portion of the precision grade is 6, Ra is 1.6-3.2μm. When the cylindrical portion of the precision grade 7, Ra is 1.6-3.2μm. When the cylindrical portion of accuracy class 8, Ra is 1.6-3.2μm. When the cylindrical portion of the precision grade nine, Ra is 3.2-6.3μm. When the cylindrical portion of accuracy grade 10, Ra is 3.2-6.3μm. When the site is an end precision grade is 5, Ra is 0.4-0.8μm. When the site is an end precision grade is 6, Ra is 0.4-0.8μm. When parts of the end face accuracy grade 7, Ra is 0.8-3.2μm. When parts of the end face accuracy grade 8, Ra is 0.8-3.2μm. When parts of the end face accuracy grade nine, Ra is 3.2-6.3μm. When parts of the end face accuracy grade 10, Ra is 3.2-6.3μm.

67. Worm surface roughness parameters Ra value How to choose? A: The site for the worm tooth surface accuracy rating for five when, Ra is 0.2μm. When parts of the worm tooth surface accuracy rating for 6, Ra is 0.4μm. When parts of the worm tooth surface accuracy grade 7, Ra is 0.4μm. When parts of the worm tooth surface accuracy grade 8, Ra is 0.8μm. When parts of the worm tooth surface accuracy grade nine, Ra is 1.6μm. When parts of the worm gear accuracy rating for the top five is, Ra is 0.2μm. When parts of the worm addendum accuracy class 6 is, Ra is 0.4μm. When parts of the worm addendum accuracy rating of 7 is, Ra is 0.4μm. When parts of the worm addendum accuracy rating of 8 is, Ra is 0.8μm. When parts of the worm addendum accuracy rating for 9 to, Ra is 1.6μm. Note: The site for the tooth root worm, Ra are 6.3μm. When the worm wheel portion of the tooth surface accuracy rating for 5, Ra is 0.4μm. When the worm gear tooth surface precision parts for the grade is 6, Ra is 0.4μm. When the worm wheel portion of the tooth surface accuracy grade 7, Ra is 0.8μm. When the worm gear tooth surface sites of accuracy class 8, Ra is 1.6μm. When the worm wheel portion of the tooth surface accuracy grade nine, Ra is 3.2μm. Note: The site for the worm gear tooth root, Ra are 3.2μm.

68. Sprocket surface roughness parameters Ra value How to choose? A: The site for the general accuracy of the working surface of the fastener when, Ra is 1.6-3.2μm. Parts of high precision work surface fastener when, Ra is 0.8-1.6μm. Precision parts for the bottom teeth when general, Ra is 3.2μm. High-precision parts for the bottom teeth when, Ra is 1.6μm. Precision parts for the addendum when general, Ra is 1.6-3.2μm. High-precision parts for the addendum when, Ra is 1.6-6.3μm.

69. Pulley surface roughness parameters Ra value How to choose? A: The site for the working surface of the pulley diameter of the pulley ≤120mm, Ra is 0.8μm. When the portion of the working surface of the pulley diameter of the pulley ≤300mm, Ra is 1.6μm. Parts of the working surface to the pulley diameter of the pulley> is 300mm, Ra is 3.2μm.

70. Hydraulic components surface roughness parameters Ra value How to choose? A: The site for the piston pump crank, piston office, Ra is 1.6-0.8μm. Site for the rod journal, bearing, journal at the center, Ra is 0.4μm. A piston outer cylindrical portion, the side surface, Ra is 0.8μm. Site for the piston pump rod hole, cylinder, slide valve bushing, plunger, piston at, Ra is 0.8-0.4μm. Parts of slide valves, high pressure pump plunger valve, valve seat place, Ra is 0.2-0.1μm.

71. Mating surface of the sliding bearing surface roughness Ra parameter values ​​How to choose? A: The part of the axis of the tolerance level IT7-IT9, Ra is 0.2-3.2μm. Parts of the axis at the tolerance level IT11-IT12, Ra is 1.6-3.2μm. Site for the hole tolerance level IT7- IT9 place, Ra is 0.4-1.6μm. Site for the hole tolerance class IT11-IT12 place, Ra is 1.6-3.2μm.

72. Combined with tapered surface roughness parameters Ra value How to choose? A: The site for the outer conical surface of the sealing junction, Ra is ≤0.1μm. Parts of the outer surface of the centering cone junction, Ra is ≤0.2μm. Other parts of the conical outer surface of the junction, Ra is ≤1.6-3.2μm. Conical surface portion of the inner seal junction, Ra is ≤0.2μm. Parts of the inner surface of the centering cone junction, Ra is ≤0.8μm. Other parts of the surface of the inner cone junction, Ra is ≤1.6-3.2μm.

73. Surface roughness labeling methods are there? Specification 1 A: The surface roughness of the direction in code numbers, and symbols must figure below specified dimensions. Surface roughness labeling methods are there? A specification 2: Surface roughness symbols with a horizontal line shall be under the Note icon.

74. Surface roughness labeling methods are there? A: The tip must point symbols from the outer surface of the material, use up a unified code Note roughness pattern in the upper right corner, in front of filling "rest" word.

75. Tagging surface roughness which A: When all the same surface roughness can be unified in the top right note pattern. Figure 13 Figure 13

76. Surface roughness labeling methods are there? A: There are different surface roughness on the same surface, shall draw dividing lines with a thin solid line.

77. Surface roughness labeling methods are there? 6 A Specification: Continuous surface and repeating elements (holes, slots, teeth, etc.) surface and a discontinuous surface with a thin solid line connection, the surface roughness of the code marked only once. Figure 15 Figure 15

78. Surface roughness labeling methods are there? 7 Specification A: When a small place or inconvenience when labeling, code can lead to marked. Figure 16 Figure 16

79. Surface roughness labeling methods are there? A specification 8: To simplify labels or label position is limited, can be marked to simplify the code, omitting injection method may also be used (figure below), but it should be near the title bar of a simplified code meaning.

81. Surface roughness labeling methods are there? 9 A. Specification: local heat treatment or parts need to plating (coating), the application range of its crude dotted line drawn and labeled the appropriate size can also be requested in writing injection surface roughness symbols. Figure 18 Figure 18

82. Surface roughness labeling methods are there? Specifications 10 A: Working surface of the center hole, keyway working face, chamfer, fillet surface roughness code, press FIG simplified standard method. Figure 19 Figure 19

83. Surface roughness labeling methods are there? Specification 11 A: When working surface of the gear, involute spline, thread, etc. are not shown tooth (teeth) shape, surface roughness can code the following figure marked manner. Figure 20 Figure 20

84. When the surface roughness of the other identification code is, what is its meaning? A: The sampling length should be marked on the long side below the horizontal line represents the symbol sampling length I = 2.5mm.

85. When the surface roughness of the other identification code is, what is its meaning? A: When the roughness obtained by the specified processing method, text annotation can be used in the long side of the horizontal line above the symbol.

86. When the surface roughness of the other identification code is, what is its meaning? A: The need to control the surface machining grain direction, can raise grain direction symbol to the right of the symbol.

87. When the surface roughness of the other identification code is, what is its meaning? A: The allowance shall be marked on the left side of the symbol indicates allowance of 2mm.

88. When the surface roughness of the other identification code is, what is its meaning? A: indicates plating (coating) surface roughness of coated label before.

89. When the surface roughness of the other identification code is, what is its meaning? A: indicates plating (coating) marking surface roughness after coating or other surface treatment.

90. The surface roughness affects the choice of which features a variety of? A: The surface roughness of the impact on the various functions: such as the coefficient of friction, wear, fatigue strength, impact strength, corrosion resistance, contact stiffness and vibration resistance, the gap clearance fit, interference fit in the bond strength was measured accuracy, thermal conductivity, electrical conductivity and contact resistance, sealing, adhesive strength, paintability, coating quality, resistance to fluid flow, light reflection properties, food hygiene, appearance, quality metallizing, lubrication of the steel sheet for press Wait.

91. The surface roughness have any effect on the choice of mating nature? A: The impact of the performance with reliability and stability. For clearance fit, since the initial wear, the summit will soon wore off, the gap increased; interference fit, assemble timely pressure will squeeze flat crest, reduce the actual effective interference, in particular, more cooperation on the small size It is significant. Thus, with the nature of the high stability requirements of the joint surface, with a small gap with the movable surface, solid and reliable connection requirements, interference fit to bear the load of a large value of Ra is lower, the same size smaller than the tolerance level of the large size (especially 1 class 3 tolerance level), the same tolerance level of axial ratio hole! "the value is smaller, and the same with the nature, the size of the smaller parts, its Ra value is smaller.

92. The surface roughness have any effect on the choice of wear? A: The parts of the surface after processing, due to the presence of valley, are just some of the peak of the contact surface contacts, thereby reducing the contact area than the pressure increases, increased wear. Therefore the Ra value, the friction surface than the non-friction surfaces, the rolling movement of the friction surface than the high velocity of the sliding friction surface, the friction surface of the pressure unit to be smaller.

93. The surface roughness have any effect on the choice of contact stiffness? A: When the two surfaces in contact, because the actual contact area over a portion of the contact area, the stress per unit area is increased, when the external force, contact deformation is easy to produce, and therefore, reduce the reference value Ra contact stiffness high binding member.

94. Surface roughness choose confrontation fatigue strength have any effect? A: Part rougher the surface, the more sensitive to stress concentration, leading to fatigue failure of parts, therefore, subject to cyclic loading surface and some can lead to stress concentration, such as rounded corners, Ra value at the lower groove. The surface roughness degree of influence on the part of the fatigue strength of the material varies with the impact on the cast iron is not obvious, for higher strength steel is the greater the impact.

95. The surface roughness have any effect on the choice of impact strength? A: The impact strength of the steel surface with a surface roughness Ra value is reduced for an improved, at low temperatures, particularly evident.

96. The surface roughness have any effect on the choice of measurement accuracy? A: Because there are microscopic surface roughness, measurement, measuring rod in peak physical contact, although the measuring force is small, but the contact area is small, the force per unit area is not small, thus causing a certain degree of contact deformation. Since the microscopic surface roughness of a certain valley and downs, such as the measurement between the probe and the surface to be measured relative to the slide, which makes measuring rod also measured surface with undulating valley fluctuate, affecting the value shown there fluctuation.

97. The surface roughness have any effect on the choice of sealing? Answer: no relative sliding static sealing surface, microscopic roughness valley too deep, the sealing material after preloading that can not be completely filled, while leaving a gap, resulting in leaks. The more the surface roughness, the more severe leak. There is relative sliding movement of the sealing surface, due to the relative motion, the microscopic roughness is generally 4-5μm, more favorable for storing lubricating oil, such as the surface is too smooth, is not conducive to store oil, it will lead to friction and wear. In addition, the seal is good or bad and processing grain direction is also related.

98. The surface roughness of choice against corrosion have any effect? A: The surface roughness is corrosive gases or liquids tend to accumulate on the surface of the part, and to parts of the surface layer penetration, increased corrosion, therefore, Ra value in a corrosive gas or liquid under the conditions of the work surface of the part to be smaller.

99. What choice of surface roughness on the metal surface coating quality? A: workpiece galvanized, chromium, copper after its microscopic surface roughness depth of not more than double the pre-plating, and nickel plating, plating is reduced compared to the previous half. Because the tensile stress generated when a rough surface capable of absorbing coating metal layer is cooled, it is not easy to crack, it must be before the metallized surface has some roughness.

100. The surface roughness have any effect on the choice of the vibration and noise? A: Vice surface rough motion machinery and equipment, the operation will produce vibration and noise, especially in high speed rolling bearings, gears and engine crankshaft, camshaft and other parts, such phenomenon is more obvious. Thus, the secondary motion surface roughness Ra value is smaller, the more moving parts smooth silent.