previous definition (17.03.2011 21.03)
Blast finishing uses the high-velocity impact of particulate media to clean and finish asurface. The most well known of these methods is sand blasting, which uses grits of sand (S1O2) as the blasting media. Various other media are also used in blast finishing, including hard abrasives such as aluminum oxide {AI2O3) and silicon carbide (SiC), and soft media such as nylon beads and crushed nut shells. The media is propelled at the target surface by pressurized air or centrifugal force. In some applications, the process is performed wet, in which fine particles in a water slurry are directed under hydraulic pressure at the surface.
(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.662)
new definition
This method of finishing is used after machining and heat treating to impart a dull finish to molding surface. On a vertical or near-vertical molding areas, such roughness may prevent easy ejection.
With products made from low-density polyethylene (LDPE) and a few other plastics (e.g., polyurethane (PU), etc.), ejection is actually improved by some roughness of the molding surface. If a shiny surface is required, buffing after blasting is required. Such roughness wears off with use, and the molds will require occasional roughing of the surface to keep operating without ejection problems.
Four grades of aluminum oxide (grit) for sand blasting are commonly used; they are #80 (coarsest), #120, #180, and #240 (finest). Other grades are also available. (Sand blasting is regularly used to remove oxides after heat treat.)
(Herbert Rees, Mold Engineering, pp405,406)
2 - Buckling (failure mode)
previous definition
When a column is under F axial load it stays put. If we increase the force over time, there will be a critical load where the column will bend from the axis this is called buckling.There are 4 types of bucking
Column(Axial) Buckling, Radial Buckling, Pressure caused Buckling and Torsional Buckling.
Think of a column of a material where E is elasticity modulus and I is the moment of inertia, L is the lenght of column. There is an equation between F and the properties of material which tells that there is a critical F load of buckling.
F=(pi)^2*E*I/L^2
(Prof Dr Mustafa Savcı Prof Dr Alaeddin Arpacı, Mukavemet, p.299)
new definition
Buckling failure occurs when, because of a critical combination of magnitude and/ord point of load application, together with the geometrical configuration of a machine member, the deflection of the member suddenly increases greatly with only a slight change in load. This nonlinear response results in a buckling failure if the buckled member is no longer capable of performing its design function.
(Jack A. Colling, Failure of materials in mechanical design, p13)
3 - Anisotropy ( material )
previous definition
As a result of plastic deformation, the grains have elongated in one direction and contracted in the other. Consequently, this piece of metal has become anisotropic, and thus its properties in the vertical direction are different from those in the horizontal direction. The degree of anisotropy depends on the temperature at which deformation takes place and on how uniformly the metal is deformed.
Anisotropy influences both mechanical and physical properties of metals. For example, sheet steel for electrical transformers is rolled in such a way that the resulting deformation imparts anisotropic magnetic properties to the sheet. This operation reduces magnetic-hysteresis losses and thus improves the efficiency of transformers.
(Kalpakjian S. Schmid S.R.,Manufacturing Engineering and Technology Sixth Edition in SI Units, p. 50)
new definition
One aspect of material behaviour that we have not addressed yet except in passing is the influence of lack of isotropy. Recall that isotropy means that the material stiffnesses are identical or constant (iso) in all directions when observed or measured at a point. In contrast, anistotropy means that the material stiffnesses are not the same in all directions when measured at a point. That is, if we look in different directions from the same point in the material, do we perceive different stress-strain behaciour in some way, shape, of form? What's the level of that dissimilarity? That level is reflected in the types of anisotropy that are observed. If the material is simply called anisotropic, then in every direction we look, we'll perceive a different behaviour.
(Robert Millard Jones, Deformation Theory of Plasticity, p68)
4 - Swift Cup Test ( material )
This method of finishing is used after machining and heat treating to impart a dull finish to molding surface. On a vertical or near-vertical molding areas, such roughness may prevent easy ejection.
With products made from low-density polyethylene (LDPE) and a few other plastics (e.g., polyurethane (PU), etc.), ejection is actually improved by some roughness of the molding surface. If a shiny surface is required, buffing after blasting is required. Such roughness wears off with use, and the molds will require occasional roughing of the surface to keep operating without ejection problems.
Four grades of aluminum oxide (grit) for sand blasting are commonly used; they are #80 (coarsest), #120, #180, and #240 (finest). Other grades are also available. (Sand blasting is regularly used to remove oxides after heat treat.)
(Herbert Rees, Mold Engineering, pp405,406)
2 - Buckling (failure mode)
previous definition
When a column is under F axial load it stays put. If we increase the force over time, there will be a critical load where the column will bend from the axis this is called buckling.There are 4 types of bucking
Column(Axial) Buckling, Radial Buckling, Pressure caused Buckling and Torsional Buckling.
Think of a column of a material where E is elasticity modulus and I is the moment of inertia, L is the lenght of column. There is an equation between F and the properties of material which tells that there is a critical F load of buckling.
F=(pi)^2*E*I/L^2
(Prof Dr Mustafa Savcı Prof Dr Alaeddin Arpacı, Mukavemet, p.299)
new definition
Buckling failure occurs when, because of a critical combination of magnitude and/ord point of load application, together with the geometrical configuration of a machine member, the deflection of the member suddenly increases greatly with only a slight change in load. This nonlinear response results in a buckling failure if the buckled member is no longer capable of performing its design function.
(Jack A. Colling, Failure of materials in mechanical design, p13)
3 - Anisotropy ( material )
previous definition
As a result of plastic deformation, the grains have elongated in one direction and contracted in the other. Consequently, this piece of metal has become anisotropic, and thus its properties in the vertical direction are different from those in the horizontal direction. The degree of anisotropy depends on the temperature at which deformation takes place and on how uniformly the metal is deformed.
Anisotropy influences both mechanical and physical properties of metals. For example, sheet steel for electrical transformers is rolled in such a way that the resulting deformation imparts anisotropic magnetic properties to the sheet. This operation reduces magnetic-hysteresis losses and thus improves the efficiency of transformers.
(Kalpakjian S. Schmid S.R.,Manufacturing Engineering and Technology Sixth Edition in SI Units, p. 50)
new definition
One aspect of material behaviour that we have not addressed yet except in passing is the influence of lack of isotropy. Recall that isotropy means that the material stiffnesses are identical or constant (iso) in all directions when observed or measured at a point. In contrast, anistotropy means that the material stiffnesses are not the same in all directions when measured at a point. That is, if we look in different directions from the same point in the material, do we perceive different stress-strain behaciour in some way, shape, of form? What's the level of that dissimilarity? That level is reflected in the types of anisotropy that are observed. If the material is simply called anisotropic, then in every direction we look, we'll perceive a different behaviour.
(Robert Millard Jones, Deformation Theory of Plasticity, p68)
4 - Swift Cup Test ( material )
previous definition (better)
In the sweep cup test, a deep-drawn cup is used to determine the limiting draw ratio of blank size to cup diameter. It is obtained with a 50mm diameter flat bottom punch and a draw die appropriate for the thickness of the specimen. A circular blank is cut to a diameter smaller than the expexted draw limit. Lubrication is provided by two oiled polyethylene disks, one on each side of the blank. The blank is drawn to maximum punch load, which occurs before the cup is fully formed. Successively larger blanks are drawn until one fractures before being drawn completely through the die. The diameter of the largest blank that can be drawn without fracturing, divided by cup diameter, determines the limiting draw ratio. (Aluminum and Aluminum Alloys, ASM Specialty Handbook, p.232)
new definition
In the sweep cup test, a deep-drawn cup is used to determine the limiting draw ratio of blank size to cup diameter. It is obtained with a 50mm diameter flat bottom punch and a draw die appropriate for the thickness of the specimen. A circular blank is cut to a diameter smaller than the expexted draw limit. Lubrication is provided by two oiled polyethylene disks, one on each side of the blank. The blank is drawn to maximum punch load, which occurs before the cup is fully formed. Successively larger blanks are drawn until one fractures before being drawn completely through the die. The diameter of the largest blank that can be drawn without fracturing, divided by cup diameter, determines the limiting draw ratio. (Aluminum and Aluminum Alloys, ASM Specialty Handbook, p.232)
new definition
Circular blanks were deep drawn into flat-bottomed cups. Blank diameter was increased in small increments until the largest blank size that could be successfully drawn was determined, the critical blank diameter. In addition, some blanks were surface ground prior to testing to allow different thickness and clearence combinations to be evaluated. All the blanks were belt polished to a 400 to 800 nm. surface finish and then etched with a grid pattern to allow surface strain measurements to be made after drawing.
(ASTM International,Formatibility of Metallic Materials,p152)
5 - Mild Steels (material)
previous definition
Mild steel has less than 0.30% carbon. It is generally used for common industry products, such as bolts, nuts, sheet, plate, and tubes, and for machine components that do not require high strength. (Kalpakjian, Smith; Manufacturing Engineering and Technology 4th Edition; pg. 146)
new definition
Mild steel is quite a different material from the steel that is used for knives and tools. This tool steel is capable of taking a temper and hardening. Mild steel is produced of uniform quality and very reliable, and it is admirably adapted to stand the rather rough treatment in the shipyard, necessary in the formation of a ship's structure. A property of mild steel, which has frequently been found of immense service, is its capability of bending without fracture. There are many cases on record of steel ships having recieved severe injuries to the skin plating, but remaining quite intact. With wrough iron as formerly used, which is not so ductile, fracture is much more easily obtained.
(Edward Atwood, War-Ships, p10)
(ASTM International,Formatibility of Metallic Materials,p152)
5 - Mild Steels (material)
previous definition
Mild steel has less than 0.30% carbon. It is generally used for common industry products, such as bolts, nuts, sheet, plate, and tubes, and for machine components that do not require high strength. (Kalpakjian, Smith; Manufacturing Engineering and Technology 4th Edition; pg. 146)
new definition
Mild steel is quite a different material from the steel that is used for knives and tools. This tool steel is capable of taking a temper and hardening. Mild steel is produced of uniform quality and very reliable, and it is admirably adapted to stand the rather rough treatment in the shipyard, necessary in the formation of a ship's structure. A property of mild steel, which has frequently been found of immense service, is its capability of bending without fracture. There are many cases on record of steel ships having recieved severe injuries to the skin plating, but remaining quite intact. With wrough iron as formerly used, which is not so ductile, fracture is much more easily obtained.
(Edward Atwood, War-Ships, p10)
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