Hemming Machine

Hemming machines are also called hemming presses, which are similar to seaming machine as the two are similar metalworking processes in which a sheet metal edge is rolled over onto itself. Hemming process on hemming machines is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials. Hems are commonly used to reinforce an edge, hide burrs and rough edges, and improve appearance quality. Some may mistaken the term hemming machine as sewing machine for another sector, but here the term hemming machines we referred to is in the metal forming industry. Hemming machine in the forming sector is similar with seaming machines but not related to the sewing process.
 
The same, seams are commonly used in the food industry on canned goods, on amusement park cars, in metal roofing, and in the automotive industry. In sum, in the field of metal forming sector, a hemming machine is similar to seaming machine as the two are similar metalworking processes in which a sheet metal edge is rolled over onto itself. With the similar methods, there are some different nuances between the two. For instance, hemming is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials.


The Rolled Edge Processing

The hems are commonly used to reinforce an edge, hide burrs and rough edges, and improve appearance. Similarly, seams are commonly used in the food industry on canned goods, on amusement park cars, in metal roofing, and in the automotive industry. Seaming and hemming are both metal forming machineries, and the roles of these two are also important for product manufacturers to deal with the final output of the object quality in the final stage.

When processed with a good hemming machine, the processed metal parts are with better quality and improved functionality. For metal working industry, metal forming takes a large portion of work piece processing due to its fast speed compared with the long stand cutting process conducted by cutting machine such as turning center, milling machine, machining center, etc. In fact, with the die well managed, a punch mechanism can work very well to produce light objects in a short period of them. Punch press, by itself, is definitely the ideal one for this process that it is a type of machine press used to cut holes in materials through the die and the punching objects as the planned working routes.


Operation and process

Hemming machines can be small and manually operated or be controlled by either numerical controller or computer numerical controlled system (such as NC or CNC controller). Its fixture parts may hold one simple die set or two to even integrate die sets. In such case, the combined die sets are designed as a multi-station forming stop with turrets.

Like some other cases, a hemming machine for joining an inner sheet metal panel is designed with an outer sheet metal panel, which comprises a hemming tool which contains an electromagnetic coil positioned to electromagnetically crimp and weld the outer sheet metal panel to the inner sheet metal panel, in which a backing die positioned outside the inner metallic sheet, and the outer metallic sheet opposite the electromagnetic coil as is designed. This metal forming process is simple but with many critical key technology that determine the final outcomes.

Cold heading is another case that can be done with cold temperature among the metal forming inventory. In metal forming sector, cold heading is a metalworking process which incorporates the forging, extruding and upsetting process, which is specifically performed in the cold state, resulting in cold working. The cold heading process typically makes a near net-shape work piece, which indicates the fact that the final product is almost finished although it can also create the final product less plating. An important consideration in cold heading is the tendency for the wire to buckle if its unsupported length to diameter ratio is much too high. Furthermore, cold working or cold forming is referred to any metalworking process in which the processed metal is shaped below its re-crystallization temperature, which is usually at the ambient temperature level.


Physical Laws

The physical natures seem contrasted with hot working techniques like hot forging but are not. For hot forming process, there are also many advantages because through the heating process, the particles inside the work piece are completely rearranged due to the increased temperature of the targeted work piece. However, cold forming still is welcomed as it is good to other phases. Therefore, cold forming techniques are often categorized as four major groups. Firstly, it is the squeezing process. Secondly, it is the bending method. Thirdly, it is the drawing mechanism. Last but not least, it is the shearing procedure. All these four are generally having their own advantages of being simpler to carry out than hot working methods.

Aside from these pure forming processes, some other forming process involves the cutting process, such as the blanking. In the metal forming sector, sheet metal blanking can be made by hydraulic or pneumatic driven machineries, since the drive selection is made depending on the sheet thickness and other specifications. Nowadays, many of the hydraulic presses are commonly used in the metalworking sectors for many kinds of forming operations, such as clinching, forging, molding, punching, blanking, deep drawing, and other metal forming operations onto a wide variety of metal materials.

With the press machines, the cycle time of the production procedure could be shortened in a large scale, and at the mean time, within an acceptable tolerance values regarding the output. Because compared with metal cutting processing, the procedure of metal forming offers faster shaping process that makes mass production feasible and practical. With a good sheet metal blanking machine, the process of sheet blanking could be made smoother for onsite operators in the production lines for the following forming procedure, rendering productive achievements.

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