Mechanical tools

.Name the fuels used in hand forging . qualities of a good forge fire . the correct method of placing stock in fire For heating metals to be forged, different types of fuels are used. Fuels are combustible materials capable of generating heat energy. Forge furnaces are fired with petroleum gas, producer gas, oil, coal and charcoal. For hand forging, the hearths are heated with soild fuels like coal or charcoal with low sulphur content. For heating tools steels charcoal is preferred as the fire burns more evenly when charcoal is used. Heating and metal stock For efficient heating, the way in which the fire is maintained is important. Thr fire which is maintained on the top surface will be thin and not suitable for heating the metal to carry out forging. The fire should come from deep in the hearth. The forge fire should be maintained clean i.e, free from ash, clinkers and dust. Clinkers is formed as the coke burns. This settles down at the bottom of the hearth and solidifies. Accumulati...

. function of a forge . the parts of a forge and state their functions . identify the forge tools and state their uses The forge supplies heat for raising the temparature of the metal to be forged. Parts of a forge and their uses Hearth The hearth is the main part where the heating of the metal takes place. It is prepared with refractory (fire) bricks and clay. Tuyers The forced air is sent through the tuyers to burn the fuel. The tuyer covered with refractory materials to avoid melting. The air also passes through a cooling tank. Cooling tank To keep the tuyer cool always, the cooling tank is filled with cold water. Air valve The air valve is used to regulate the supply of air to the hearth Blower The blower supplies air to the forge for burning the  coal or coke. The blowers are operated manually or by electric Power. The blower is fixed independently to each forge or it supplies ait to a number of forges which are controlled by independent air valves. Hood and chimney Smoke and...

  The necessary of preheating high speed steel The hardening process of high speed steel High speed steels get their name from the fact that they may be operated as cutting tools at much higher speeds than is possible with plain carbon tool steels. Since the maximum hardness of high speed steels is  obtained on tempering at high temparatures, they can be operated as cutting tools in the same temparature range without loss of hardness. That is the rise in temaprature due to friction will not reduce the temper of the tool pointas it cuts into the steel. Tool steels are often annealed for softening before machining or forming, and also for obtaining grain refinement. An nealing Soak at 900° C for about four hours. Then cool slowly at not more than 20°C per hour to 600°C. It may then be cooled to room temparature in still air. Hardening Pre -heat to 850°C slowly to prevent cracking. Then heat rapidly to approximately 1250°C depending upon the alloy used. This rapid heating reduces...