View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
Get link
Facebook
X
Pinterest
Email
Other Apps
Tolerance & Fits
Get link
Facebook
X
Pinterest
Email
Other Apps
-
Tolerance
It is defined as, "the magnitude of permissible variation of a dimension or other measured value from the specified value".
Purpose ↠ permit dimensional variations of components, performance, specification and design.
As the permissive tolerance goes on decreasing, the manufacturing cost to achieve it goes on increasing exponentially.
Classification of Tolerance:
Unilateral tolerance ↠ If tolerance distribution is only one side of the basic size.
Bilateral tolerance ↠ When tolerance distribution lies on either side of the basic size.
Compound tolerance ↠ When tolerance is determined by established tolerances on more than one dimensions.
Geometric tolerance ↠ Used to indicate the relationship of one part of an object with another.
Classification of Geometric Tolerance:
Form tolerance ↠ group of geometric tolerance applied to individual features (includes straightness, circularity, flatness, cylindricity).
Orientation tolerance ↠ type of geometric tolerance used to limit the direction/orientation of a feature in relation to other (includes perpendicularity, parallelism, angularity).
Positional tolerance ↠ group of geometric tolerances that controls the extent of derivation of the location of a feature from its true position (includes position, symmetry, concentricity).
Fits
It is defined as, "the relationship between the two mating parts that are to be assembled i.e. the hole and the shaft w.r.t the difference in their dimensions before assembly".
Manufactured parts are required to mate with one another during assembly.
Ideally fits is required for proper functioning of mating parts.
Allowance ↠ intentional difference between the maximum material limits (LLH and HLS) of two mating parts.
Types of Fits:
Clearance Fit ↠ The largest permissible diameter of the shaft is smaller than the diameter of smallest hole.
Interference Fit ↠ The minimum permissible diameter of shaft exceeds the maximum allowable diameter of hole.
Transition Fit ↠ Occurs when two tolerance mating parts are sometimes interference fit and sometimes clearance fit when assembled.
References:
Material from Class Lectures + Book named Fundamentals of Modern Manufacturing Materials, Processes and Systems by Groover + My knowledge.
TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = 𝛼 (T m – T o )L Where, C t = the correction for temperature, in m. 𝛼 = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the tempe...
Projection: The term Projection is defined as: Presentation of an image or an object on a surface. The principles used to graphically represent 3-D objects and structures on 2-D media and it based on two variables: Line of Sight. Plane of Projection. Line of Sight & Plane of Projection: Line of sight is divided into 2 types: Parallel Projection Converging Projection & A plane of projection is an imaginary flat plane upon which the image created by the lines of sight is projected. Orthographic Projection: When the projectors are parallel to each other and perpendicular to the plane of projection. The lines pf sight of the observer create a view on the screen. The screen is referred to as the Plane of Projection (POP). The lines of sight are called Projection lines or projectors. Rules of Orthographic Projection: Edges that are parallel to a plane of projection appear as lines. Edges that are incl...
Diffusion It is defined as, " The transportation of one atom from one state into other state " . Used for hardening of surfaces like die parts, gear, bolt, machine element. Hardening can be done using Temperature-Heat treatment ( diffusion couple ). There are two types of diffusion: Inter-diffusion ↔ in which atoms tend to migrate from region of high concentration to low concentration . Self-diffusion ↔ in which atoms migrate within a solid. Diffusion Mechanism There can be two conditions of moving atoms Empty spaces between adjacent sites. Atoms have sufficient energy to break bond with neighbors atoms which cause lattice distortion during displacement. If we rise temperature, small fractions of atoms is capable of diffusive motion (which cause lattice distortion). Types of Diffusion 1. Vacancy Diffusion It is defined as, " interchange of an atom from a normal lattice position to the adjacent vacant lattice site " . Extent of vacancy diffusion is a function...
Comments
Post a Comment
HI, we wI'll contact you later