Friday, November 5, 2010

CrazyEngineers Forum - Mechanical & Civil Engineering

CrazyEngineers Forum - Mechanical & Civil Engineering

Sand casting processes

Posted: 05 Nov 2010 05:43 AM PDT

Sand Casting Processes
For Case(A):
Bottom board is placed either boundary moulding from or on the floor making the surface even. The drag moulding flask is kept upside down on the bottom board. Dry facing sand is sprinkled over the board. Rest of the drag flask is completely filled with back up sand and uniform the rammed to compact the sand. The remaining of sand should be done properly. So as to compact it to hard , which makes the escape of gases difficult not to lose.
So that mould could not have enough strength . After the ramming is over , the excess of sand in the flask is completely scraped using a flat bar to the level of the flask edges. Now with a vent wire which is a wire of 1-2mm diameter with a pointed end, vent holes are made in the drag to he full depth flask as well as to the pattern to facilitate the removal of gases during casting solidification. This complete the preparation of the drag.


For case B:
We finished the drag flask is now rolled over to the bottom bolt exposing the pattern and cope of the pattern is placed over the dragged pattern.

For case C:
The cope flask on the top of the drag is rotated aligning again with the help of the pins. A screw pin for making the screw passage. The sand is thoroughly rammed and excess sand scrap and vent holes are made over all in the cope as in the drag. The screw pin and the riser pin are carefully with drawn from flask the mould is now ready.
for more details

http://engineeringhut.blogspot.com

Manufacturing processes

Posted: 05 Nov 2010 05:26 AM PDT

Topic: Tool design(Mechanical Engineering)

Manufactuing Processes:
Introduction:
Manufacturing involves turning raw material to finished products, to be used for various purposes. There are a large number of processes available. These processes can be broadly classified into four categories.
1: Casting processes
2: Forming processes
3: Fabrication processes
4: Material removal processes
Casting Processes
These processes only processes where the liquid metal is used. Casting is also the oldest known manufacturing process.
Basically it consists of inducing the molten metal into a cavity of mould of the required form and allowing the metal to solidify.The object after solidification removed from the mould. Casting processes are universally used to manufacture a wide variety of products. Casting is the most flexible and cheapest method and given high strength of rigidity to the parts which are difficult to produce by other manufacturing processes.
The principle process among these sand casting where sand is used as the raw material. The process is equally suitable for the production of a small batch as well as on a large scale.Some of the other classified casting processes for specialized need are
·Shell mould casting
·Precision mould casting
·Plaster mould casting
·Permanent mould casting
·Die casting
·Centrifugal casting
Forming Processes:
These are solid state manufacturing processes involve minimum amount of material wastage. In forming process metal may be heated to temperature which is slightly below. This solidify temperature and large force is applied such the material flows and act in desired shape. The desire shape is controlled by means of a set of tool ties and dies, which may be closed during manufacturing.
These processes are normally used for large scale production rates. These are generally economical and in many cases improve the mechanical properties. These are some of the metal forming processes.
·Rolling forging
·Drop forging
·Press forging
·Upset forging
·Extrusion forging
·Wire forging
·Sheet metal operation
Fabrication Processes
These are secondary manufacturing processes where the starting raw materials are produced by any one of the previous manufacturing processes desired. Its assembly involve joining pieces either temporary or permanent. So that they would be perform the necessary function. The joining can be achieved by either or both of heat and pressure joining materials.
Many of the steel structure construction, we see are first rolled and then joined together by a fabrication process are
·Gas welding
·Electric arc welding
·Electrical resistance welding
·Thermo welding
·Brazing welding
·Soldering welding
·Cold welding
Material removal processes:
These are also a secondary removal manufacturing process, where the additional unwanted material is removed in the form of chips from the blank material by a hard tools so as to obtained the final desired shape.
Material removal is normally a most expensive manufacturing process. Because more energy is consumed and also a lot of waste material is generated in this process. still this process is widely used because it deliver very good dimensional accuracy and good surface finished. Material removal process are also called machining processes. Various processes in this category are
·Turning
·Drilling
·Shaping and planning
·Milling
·Grinding
·Broaching
·Sawing
·Trimming

for more details just click here
http://engineeringhut.blogspot.com
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