Study Mech

  Q-5. Mention the design guidelines to be followed in low quantity production. Ans: In any product, manufacturing and assembly cost is a very important consideration. It affects the overall cost in a significant manner. However during the design phase, with some consideration in product design, production cost can be reduced.  In case of low quantity production. Design guidelines to be followed in low quantity production:   During the design phase, it is good to use standard components in design. Because of low quantity production, using non-standard components may significantly increase the cost. For lower quantity production, worst case tolerance can be used. Providing loose tolerance may reduce part rejection in the inspection phase, hence maximum parts can be approved. If too tight tolerance is not necessary, then try to provide more tolerance range. Hence, it also eliminates the use of a special finishing process and reduces post processing cost. In case of low qua...

  Q-4. What is redesign? What are the steps to be followed to reduce the cost in the existing part or assembly? Ans: Concept of redesign refers to changing or improving the existing product characteristic by design or material improvement. Product may be a single part of an assembly. Based on market requirements or to take advantage of new facilities, it's necessary to redesign products.  Steps to be followed to reduce the cost in the existing part or assembly:   Product development starts from design. During the design phase, the product should be designed in such a way that it can be easily manufactured with existing facilities. Hence, excess cost can be reduced. Assembly or part manufacturing cost can be reduced by choosing the right manufacturing process for the product. Also, selection of the manufacturing process is based on material, quantity of product  and other design parameters,like dimensions, tolerance etc. Using too tight tolerance leads to extra proce...

  Q-3. Briefly explain the mathematical modelling of any one of the manufacturing processes. Ans:   Mathematical model of polymer extrusion process : Polymer material consists of long chain molecules. In extrusion of thermoplastic polymers, important parameters are Material flow and type of flow Heat transfer in flow Residence time Mixing of particles in flow in multiple polymers, etc. To analyse these parameters, mathematical models are useful. Using governing equations and boundary conditions (B.C), a model is created and a solution is obtained for particular B.C. Governing equations:   To model any flow and thermal transport in the manufacturing process, conservation of mass, conservation of  energy and the force momentum balance equation is used. The equations are as follow, Where, ρ is density,  t is time, T is temperature, V is the velocity vector, μ is dynamic viscosity, F is body force, p is pressure, Cp is specific heat at constant pressure, β is coeffi...

  Q-2.Consider any one of the metal forming operations and list out the important parameters involved during the process. Ans: Rolling is a metal working process. In rolling, the metal stock or billet is passed through a pair of rolls to reduce the thickness. During the rolling process, the width of the stock remains constant. The important parameters involved during the rolling process are, Diameter of rolls. Friction generation between workpiece and roll surface & Neutral plane position. Deformation resistance of metal and temperature of billet, etc. Diameter of rolls: In the rolling process, rolling force is directly proportional to the diameter of roll. Rolling force increases as the roll diameter. As a decrease in diameter of roll, length of arc of contact  also decreases. Hence, smaller diameter roll provides uniform reduction in thickness of billet. Hence, small diameter rolls are generally used in rolling purposes.  Larger rolls are used as back up rolls, hen...

  What is Additive Manufacturing? As the name suggests, Additive Manufacturing (also known as 3D printing) is a group of manufacturing techniques , which manufacture parts by adding successive layers of material with the help of computer control systems. Various materials that can be used in additive manufacturing (AM) are plastic, metal, concrete, also human tissue. In the additive manufacturing process, Computer-Aided Design (CAD) is created and utilized to manufacture 3-Dimension (3D) objects. Various CAD-CAM software is required to Design, Analyze, and Manufacture parts. Once CAD data is produced, Slicing software slices the design in different layers (as required by different  AM processes), and then data utilized to manufacture required material parts. Different terms like “3D printing” and “rapid prototyping” are also casually used to describe Additive manufacturing, but each one is a subset of additive manufacturing. Hence in the simple sense, Additive manufacturing te...

In human civilization, making different things is an essential activity. Today the word manufacturing we used to describe this activity. The word manufacturing comes from the Latin word manus (hand)  and factus ( make), together it means "made by hand" . Technically we can define manufacturing as a physical or chemical process that we use to alter the geometry, properties, and/or appearance of any substance/ raw material to make desire parts or products. Manufacturing includes the assembly of different parts and components. The process to accomplish manufacturing involves the use of machinery, labor, tools, power, etc. In human evolution, a lot of techniques and processes discovered in manufacturing. Based on how we process raw material, we can simply divide it into subtractive manufacturing, Forming, and Additive manufacturing. 1. Subtractive manufacturing (material removal process)   As the name suggests, subtractive manufacturing involves cutting away or subtract unnec...

Quenching also called Hardening, is a heat treatment process in which steel is heated up to austenite temperature (above it's critical temperature), hold for some time and then cooled in water, oil or molten salt (rapid cooling). Due to rapid cooling, it results very hard structure - martensite (hardest form of Steel). fig.- steel component quench in oil. Due to hardening process hardness of steel increases and bitterness also increases. (brittleness increases hence hardened Steel nay not directly use). Quenching is always follow by tempering process. Due to rapid cooling in hardening process metal shape shrink, internal residual stresses are setup. That's the reason why hardening is follow by tempering.

Normalizing ( Air quenching) is a heat treatment process in which steel is heated 40°-50° C above re-crystallization temperature , hold for some time and then air cooled to the room temperature. It is one of the heat treatment process which is used for ferrous materials only.  Fig. - air cooled steel components This treatment refine the grain structure and increase uniformity of micro-structure and propertied of hot rolled steel.   Normalizing process  use to remove internal stress. It gives rise to the bainite, martensite and perlite. Normalizing require less cost than annealing due to air cooling. Due to normalizing, hardness of steel increase and ductility decrease.

Annealing (Softening)  is a heat treatment process in which steel is heated beyond the critical temperature (to   𝛾 -iron ) (or above recrystallize temperature), maintaining a suitable temperature for a suitable amount of time and then allow slow cooling (furnace cooling). Fig.- full annealed steel knife Purpose of annealing :   To relive the internal stresses To increase ductility ( hence toughness also increase) To reduce hardness Refinement of grain structure Improve plasticity, hence facilitate machining and cold deforming processes. In annealing, slow cooling result in formation of spherical carbide and coarse perlite, which are very soft product. Type of annealing : Full annealing Process annealing Spherodise annealing Diffusion annealing ( Homogenizing or Uniform annealing)

know the Heat Treatment...! Heat treatment is defined as the operations involving the heating and cooling of a metal or an alloy within a solid-state to obtain desire properties (physical or chemical) without change composition. The heat treatment process is carried out to change the grain size, modified the crystal structure of the material, and relieve the stress set up in the material after hot or cold working. Heat treatment also uses in many manufacturing processes, eg. glass working. The heat treatment process is performed in the furnace or oven with a controlling the environment of step-by-step heating and cooling within a specific period of time, apart from this the gases are used to control the furnace environment in some processes.  Fig.1 - Heat treatment process of gears Heat treatment consists of heating of metal near of above re-crystallization temperature of the material, hold for a particular time, and then finally cooling the metal in some medium which may be air, ...

latest in AM Car maker BMW group  opened  € 15 million Additive manufacturing facilities in Oberschleissheim, just outside Munich .  Demonstrating AM parts at BMW   The facilities will be utilized as central hub for production, R&D and training purpose. BMW is already leader in industrial scaled 3D printing and printed more than 3,00,000 automobile components last year. The Additive Manufacturing campus allows 80 workers running about 50 industrial AM system, including metals and plastic. Speaking at the opening ceremony, BMW AG Board Member Milan Nedeljković said: “Additive manufacturing is already an integral part of our worldwide production system today, and an established part of our digitalisation strategy. In the future, new technologies of this kind will make production even faster and allow us to benefit even more fully from the potential of toolless manufacturing.”