MANUFACTURING
On 11th November, 2015, we were taken to the firm "Al Chishty Engineering Works L.L.C. This is the factory in which we performed the manufacturing of our punch with the help of CNC and the Manual Lathe.
The steps that were required to get our final product are as shown below:-
1) Rough and Normal Turning:-
This is the process by which we first removed the rusted, outer layer of our punch to get the inner shiny surface and then we reduced the diameter of the whole punch to 0.9 cm, which is the diameter of our punch's main body. We did it in the CNC Lathe machine and the tool that was used was the usual turning Single Point cutting tool. It was held in the tool post in lathe and the specimen was held in between the jaws of the chuck and the tailstock. The video of the process is given below:-
2) Knurling:-
This is the process by which we did the diamond knurling so that we have a comfortable grip for holding the punch. It was done in CNC lathe and the tools used for doing it were two knurling rollers which were held in the tool post. One of them did the knurling one way and the other did cross knurling to produce the diamond pattern. The photos and video of the process are shown below:-
3) Normal and Taper Turning:-
First, by using Normal turning we reduced the pin length diameter of the punch from 0.9cm to 0.32cm and then using Taper turning we made the slope between the main body and the pin length. It was done in CNC lathe and the same tool was used to perform both the processes. These tools were same Single Point cutting tools use during the previous turning processes. The videos of the process are shown below:-
4) Facing:-
We used this process inorder to first flaten out the two ends of our punch and then to perform the chamfering at the back end's circumference of our punch. This was the only process that we performed through Manual Lathe as our CNC lathe, using the saddle. The tool that we used was the usual Facing tool, which is very similar to the turning tool but has a different zero angle of it's cutting tip. The photos and video of the process are shown below:-
5) Finishing:-
This is the process by which we smoothened our punch's sides and edges by using a sandpaper. Also a cooling liquid was poured throughout the turning to produce a smooth and shiny surface after machining. The photos and video of the process are shown below:-
6) Heat Treatment:-
For heat treatment we performed 2 different processes on our punch. These are as follows:-
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Quenching: By this process we improved the hardness of our punch but it also increased the brittleness of it. For it we first placed our punch in the Muffle furnace and allowed it to heat upto a temperature of 800 degress celcius when it becomes red hot. then we placed it in mild cold water and allowed it to be quenched for about 15 minutes as seen in the pictures.
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Tempering: By this process we improved the strength of our punch and reduced the brittleness. For performing this process we took out the punch from water and used a flame of "Methylacetylene and Propadiene" to heat the pin length of the punch to a temperature of 300 degrees celcius, after quenching it. This temperature we recognised by observing the colour of steel until it started to turn blue and then left it to slowly cool at room temperature for a day, as seen in the pictures.
7) Testing:-
For testing we were given a high carbon steel slab and were asked to hammer our punch on it and test if it breaks or deforms. Our punch deformed very minutely and a cause of this could've been that the tempering wasn't done perfectly as we couldn't be sure as at what shade of blue the 300 degress temperature is reached. The pictures are given below:-
