A hammer is a tool that strikes an object to make it move or deform. A hammer consists of a hammer head and a handle. According to the material of the hammer head, the hammer is divided into steel (iron) hammer and soft-headed hammer. Hammer, plastic hammer and rubber hammer commonly used in automobile maintenance. Plastic hammer and rubber hammer are commonly used in engine maintenance. If you knock on the cylinder head during disassembly, it will not deform. Main function of hammer: Hammer, also known as hammer or hand hammer, belongs to hammering tools. It is mainly used for hammering chisel, punch and other tools, or knocking the workpiece, so that the workpiece is deformed, displaced and vibrated, thus achieving the purpose of correction and shaping. Hammer can be divided into round head hammer, square hammer and sheet metal hammer. According to the different shapes of hammers, hammers can be divided into hammers, soft-faced hammers (wooden hammers, rubber hammers, plastic hammers) and so on. It depends on the material of the hammer. The specifications of the hammer are generally expressed by mass, such as 0.25kg, 0.5kg, lkg. Types and functions of hammers: 1) Most hammers are forged from carbon tool steel. Hammers commonly used in automobile maintenance include round head hammer, square hammer, sheet metal hammer and so on. Round-headed hammer is the most commonly used hammer, with a flat head at one end and a round head at the other. Flat head is used for punching, temporary tools and other hammering tools, while round head is used for willow joint and hammering gasket. Square hammer, also known as sledgehammer, is made of high carbon steel, which is mainly used for heavy knocking and is not commonly used in automobile maintenance; The sheet metal hammer is wedge-shaped, which is mainly used in the corner where sheet metal shaping or round head hammer can't reach. It is forbidden to directly hit the mating surface and vulnerable parts with a hammer, because the hammer will damage parts made of low hardness materials, such as aluminum shell or cylinder head. 2) Soft-faced hammer (soft-headed hammer) Soft-faced hammer is mainly used to hit parts that are not allowed to leave marks or are easily damaged. According to the different materials used in the hammer head of soft-faced hammer, it can be divided into rubber hammer, plastic hammer and wooden hammer. Many soft-faced hammers are filled with metal, such as lead or copper, to increase inertia. Soft-faced hammer is mainly used in automobile assembly process, which is used to knock parts to form better cooperation between parts. How to use the hammer: 1) Selection of hammer handle Most hammers are equipped with handles when they are purchased. If you choose to install the handle yourself, pay attention to the thickness of the handle and the size of the hammer. The center line of the hammer head should be perpendicular to the center line of the hammer head, and the direction of the maximum elliptical diameter of the hammer head should be consistent with the center line of the hammer head. 2) Grip method of the hammer (1): Hold the hammer handle with the five fingers of the right hand, with the thumb close to the index finger, the tiger's mouth aligned with the direction of the hammer head (the long axis direction of the wooden handle ellipse), and the tail end of the wooden handle exposed15 ~ 30 mm. During the process of knocking and swinging the hammer, the five fingers always hold the hammer handle. (2) Loosening grip: Only the thumb and forefinger hold the hammer handle all the time, and the other three fingers relax in the order of little finger, ring finger and middle finger when swinging the hammer; When knocking at the door, fold it in the opposite order and hold it down. The advantage of this method is that your hands are not easy to get tired, and the percussion is strong. Don't hold the hammer handle too close to the hammer head, try to be close to the handle end, because it will be more labor-saving and flexible to knock. 3) Swing method In actual operation, there are three kinds of swing methods according to the different requirements of hammering force of the workpiece being processed. (1) Wrist swing: When swinging the hammer, only the wrist action is used to hammer, so the hammer force is small. Grip hammer is usually used for machining work that requires less hammering force. (2) Elbow swing: When swinging the hammer, the wrist and elbow swing together to complete the hammering action with strong impact. Hold the hammer loosely, which is a common method of swinging the hammer. (3) Swing arm: When swinging the hammer, the wrist, elbow and arm will move together, and the hammer passes behind the ear, with the greatest hammering force. It is suitable for work that requires a large hammering force. Note: (1) Before using the hammer, you must wear protective glasses to prevent debris from flying into your eyes. (2) Before use, check whether the handle is installed firmly and whether there are cracks, so as to prevent the hammer from falling off and causing accidents. If the hammer is loose, you can wedge it up. If the handle is cracked or damaged, it should be replaced with a new handle immediately, and it is forbidden to continue using it. (3) It is very dangerous to use a hammer with broken appearance. When hit, the metal on the hammer may fly out, causing an accident. (4) When hammering baskets, punches and other tools, you must wear protective glasses.