In this article, it will be attempted to present a quick overview of the different generative processes. Since this area is growing and many processes are still not fully matured, only brief descriptions can be presented. However, the process stereo lithography was the first GMP to be developed and commercialized by 3D Systems Inc. and will be discussed in more [...]
In the case of conventional silicon micromachining, the aspect ratio cannot be large because of limitations inherent in etching. Generally, the depth to which machining can be done is limited to a few tens of microns only. This imposes severe constraints for developing three-dimensional microsystems. To produce three-dimensional micro devices with high aspect ratio components, deep etch lithography is necessary. [...]
Specific Heats of a Gas: Formula, Constant Pressure, Ratio and Heat Capacity! Specific Heats of a Gas: The specific heat capacity of a substance may be defined as the quantity of heat required to raise the temperature of unit mass of the substance by one degree. The unit of specific heat is J/kg-°C. Since this unit is small it is [...]
Thermodynamic Processes and Equations! A process is a change in the state of a gas as a result of flow of energy. During this flow a change takes place in properties of the substance such as pressure, volume, temperature and also the energy quantities such as internal energy, heat and work. The five important processes commonly dealt with in engineering [...]
In this article we will discuss about the processes used for joining metals. Learn about:- 1. Welding 2. Brazing 3. Soldering 4. Gas Cutting Process and Equipment or (Oxyacetylene Gas Cutting Process). 1. Welding: In olden days, in order to join two pieces of metals, riveting was done. But nowadays for joining two pieces of metals welding is done. So, [...]
Welding is broadly classified into two types: I. Plastic Welding: In this case the two pieces of metals to be joined are heated to plastic state and welding is completed by forcing them. In this case no filler material is added. II. Fusion Welding: In this case the two pieces of metal are heated and brought to molten state and [...]
The three thermally active and overlapping stages during annealing are: 1. Recovery 2. Recrystallisation 3. Grain Growth. The first two stages of annealing are caused by the stored cold- worked energy. Grain growth, the third stage of annealing, occurs if annealing is continued after recrystallisation has completed. In this stage, the recrystallised grains grow in size at the expense of [...]
The most extensively used method is conventional hardening for quenching in a single medium. The disadvantage of this method, however, is that the cooling rate in the martensitic transformation range will be very high. It will differ only slightly from the rate on the upper zone of super-cooled austenite of low stability and, therefore, cracks, distortion and other defects may [...]
In this article we will discuss about the classification of metal forming processes. 1. Compressive Forming Processes: In these processes the plastic state is reached by application of uni-axial or multi-axial compressive forces. Examples are forging, extrusion, rolling, indenting, coining, etc. (Fig. 2.2) shows the stress states in the material during rolling, forging, coining and extrusion processes. In the rolling [...]
There are a number of processes, described below, which may be called unconventional forming processes or high energy rate forming processes. In these processes, unconventional sources of energy such as Explosive Forming, Electro-Hydraulic Forming, Magnetic Pulse Forming, Petro-Forge and Drop Hammer and Dynapak etc., are used. The release of energy is at extremely high rate and hence the name high [...]