Definition Of Flatness Error
Contents |
marked with Prussian blue and the other surface rubbed over it. The distribution of colour over the other surface gives a rough idea of high and low points on the surface. This method is usually suitable for small plates and not for large surfaces. Mathematically, flatness error of a surface states that the definition of flatness tolerance departure from flatness is the minimum separation of a pair of parallel planes which will just contain definition of flatness in metrology all points on the surface. The deviation of a large surface such as surface table or machine table from the true plane may be determined by surface flatness definition the use of either a spirit level or an auto-collimator. The principle of the method is same, whether the apparatus used is auto-collimator or spirit level. According to IS : 2063—1962, a surface is deemed to be flat within a given range of
Define Flatness
measurement when the variation of the perpendicular distance of its points from a geometrical plane (this plane should be exterior to the surface to be tested) parallel to the general trajectory of the plane to be tested remains below a given value. The geometrical plane may be represented either by means of a surface plane or a family of straight lines obtained by the displacement of a straight edge or a spirit level or a light beam : Flatness deviations (errors of flatness) are indicated as define flatness problem follows : (i) … µor mm per metre when convexities are allowed as well as concavities ; (ii) concave to … |x or mm, when, between the ends, only concave surfaces are allowed ; and (iii) convex to … \x. or mm, when, between the ends, only convex surfaces are allowed. It is well known that a surface can be considered to be composed of an infinitely large number of lines. The surface will be truly flat only if all the lines are straight and they lie in the same plane. Let us study the case of rectangular table. From Fig. 7.4, it is obvious that all the generators (lines) are straight and parallel to the sides of the rectangle in both the perpendicular directions. Even then it is not truly flat, but concave and convex along two diagonals. Thus for the verification of a surface to be truly flat, it is essential to measure the straightness of diagonals in addition to the lines parallel to the sides. Thus the whole of the surface is divided by straight lines as shown in Fig. 7.5. The end lines AB and AD etc., are drawn away from the edges as the edges of the surface are not flat but get worn out by use and can fall off little in accuracy. The straightness of all these lines is determined and then those lines are related with each other in order to verify whether they lie in the same plane or not. In above setting of the lines, it should
be sure to respond. Need Help? Are you looking for technical support or have a sales-related question? Use any of our fast and friendly services to meet your needs: email flatness meaning sales or technical support, contact our regional offices, or chat live with us. We
Flatness Checking Method
have set your country to United States Change We have set your country to United States Please select your shipping
Flatness Definition Mechanical Engineering
country to get started. This will allow Edmund Optics to display the most accurate regionalized product, pricing, and contact information for the country to which you are shipping. You can change this selection at http://what-when-how.com/metrology/flatness-testing-metrology/ any time, but products in your cart, saved carts, or quote may be removed if they are unavailable in the new shipping country. Select Your Country China European Union France Germany Japan Singapore South Korea Spain Taiwan United Kingdom United States --------------- Algeria Andorra Angola Antigua and Barbuda Argentina Australia Austria Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia Botswana Brazil Brunei Darussalam Bulgaria http://www.edmundoptics.com/resources/application-notes/optics/understanding-optical-specifications/ Burkina Faso Burundi Cambodia Cameroon Canada Canary Islands (Spain) Cape Verde Central African Republic Chad Chile Colombia Comoros Costa Rica Cote d'Ivoire Croatia Cyprus Czech Republic Democratic Republic of the Congo Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Estonia Fiji Finland French Guiana Gabon Gambia Georgia Ghana Gibraltar Greece Greenland Grenada Guatemala Guernsey (UK) Guinea Guinea-Bissau Guyana Honduras Hong Kong Hungary Iceland India Indonesia Ireland Israel Italy Jamaica Jersey (UK) Jordan Kazakhstan Kenya Kiribati Kuwait Kyrgyzstan Latvia Lesotho Liechtenstein Lithuania Luxembourg Macedonia Madagascar Malawi Malaysia Maldives Mali Malta Mauritania Mauritius Mexico Micronesia Moldova Monaco Mongolia Montenegro Morocco Mozambique Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger North Ireland (UK) Norway Oman Pakistan Palau Panama Papua New Guinea Paraguay Peru Philippines Poland Portugal Qatar Republic of the Congo Reunion Romania Russia Saint Kitts and Nevis Saint Lucia Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Slovakia Slovenia Solomon Islands South Africa South Sudan Sri Lanka Suriname Swaziland Sweden Switzerland Tajikistan Tanzania Thailand Togo Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Tuvalu Uganda United Arab Emirates Uruguay Uzbekistan Vanuatu Vatican City Venezuela Vietnam Zambia United States Change EDMUN
straightness and flatness of travel of linear bearings and stages. Just how straight and flat? What levels of precision are achievable? In this technical note, we http://www.pi-usa.us/blog/straightness-and-flatness-of-air-bearings/ will discuss several aspects: the error motion over full travel, impacts on error motion, the repeatability of the error, and the short-term errors. 2. Definitions: what is straightness and flatness? Define our coordinate system. See Figure 1. X = axis of motion for a linear stage. Figure 1 Straightness error motion (“straightness”) is defined as error motion in the Y direction. As the stage travels definition of along the X axis, the motion deviates from the perfect line by some amount. Flatness error motion (“flatness”) is defined as error motion in the Z direction. As the stage travels along the X axis, the motion deviates from the perfect line by some amount. Figure 2. Typical error motions 3. Error motion over full travel The first specification we discuss is the total error definition of flatness motion over full travel. This measurement is usually specified in “microns TIR.” TIR means Total Indicator Reading. When TIR is used, we are specifying the peak-to-peak measurement of error motion. We do not assume symmetry about a zero reference. In Figure 3, we see the straightness error plotted over 220mm of travel. The TIR reading is 0.3 µm. Air bearing stages can typically achieve better than 1 µm flatness and straightness TIR for every 200mm of travel. See detailed product spec sheets for actual specifications. Figure 3. PIglide LC 230mm travel, straightness over full travel 4. Error motion impacts Besides the inherent quality of the stage or bearing itself, straightness and flatness error motions of air bearings can be affected by several outside influences. 4.1 Quality of the mounting surface Air bearing stages require a very rigid, clean, flat surface for mounting. Any irregularity in the surface, debris, burrs, or dirt, can have a noticeable impact on the stage’s error motion, particularly flatness. In Figure 4, we see the difference in flatness for a stage mounted to granite surface plate of high quality vs. mounted to an optical breadboard. The breadboard mounting