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
Expandable Mold Castings
Get link
Facebook
X
Pinterest
Email
Other Apps
-
Expandable Mold Casting
A type of mold casting which is used once is broken to get the final product.
There are many types of expnadable mold casting which we discussed one by one.
1. Shell Molding:
Casting process in which the mold is a thin layer of sand held together by thermosetting resin binder.
Steps involved in this mold casting are:
A match-plate of cope and drag pattern is first heated at 230-315℃ and is placed over a boz containing sand mixed with thermosetting resin.
Bix is inverted so that sand and resin fall onto the hot pattern.
It causes the sticking of layer on this hot pattern.
Box is repositioned so to loose uncured particles.
2. Vaccum Molding or V-Process:
A type of molding process in which vaccum play the part of sand binder.
Steps involved in vaccum Molding are:
A thin sheet of heat-softened plastic is drawn over a vented pattern which contains small holes to facilitate vaccum forming.
Vaccum flask is then placed over it.
2nd sheet of plastic is placed over the mold.
Molten metal is then poured.
Pattern vaccum is released and the pattern is withdrawn.
When vaccum is released, sand loose its bounded state and fall away.
3. Investment Casting (or Lost Wax Casting):
Sand Casting in which pattern is made by injection mold is called investment casting.
Steps involved in investment casting are:
Produce master pattern which can produce master die and then wax pattern.
Assemble the wax pattern onto a common sprue.
Coat the cluster of tree with a thin layer of finely ground investment material called slurry.
Coat the cluster of coarse particles from an additional investment called stuccoing upto 8 layers.
Remove the wax pattern by heating and pour the molten metal.
Remove the solidified casting from the mold.
4. Evaporative Polystyrene Process (EPS) (or Lost Foam or Fill Mold or Evaporative Foam Process):
The sand casting in which mold of sand packed around a polystyrene foam pattern that vaporizes when the molten metal is poured into the mold.
Steps for EPS are:
Polystyrene beads are pre-heated and then introduce into heated-die cavity.
The foam pattern cluster is coated with a refractory material.
Dry the coating and then placed into a vented flask.
Molten metal is poured into the mold the pattern vapourizes and we get the final product.
Reference:
University Notes
Book Fundamental of Modern Manufacturing 6th Edition by Mikell P. Groover
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...
Types Of Lines And Its Uses: There are three types of types on the basis of thickness and they are: Visible Lines ↝ It represents features that can be seen in the current view. Hidden Lines ↝ It represents features that cannot be seen in the current view. Center Line ↝ It represents symmetry, path of motion, centers of circles,, axis of asymmetrical parts. Dimension and Extension Lines ↝ It indicates the sizes and location of features on a drawing. Placement Of Dimension Lines: Dimension should be outside the view. Dimension should be applied to one view. Dimension should be placed in a view that shows the distance in its true length. Dimension lines should be placed, in general 10 mm (1/2 in) away from the outlines from the view. Parallel lines should be placed uniformly. Values should be midway (auto centered) between the arrow heads, except when a center-line interferes. Dime...
Comments
Post a Comment
HI, we wI'll contact you later