The shearing machine generally comes in two types: mechanical and hydraulic.
The work principle of a mechanical shear is nearly the same as that of a mechanical press. However, the mechanical shear produces excessive noise, has no overload capacity, and is very difficult to adjust the blade gap. This type of machine, over time, has been phased out.
The hydraulic shearing machine can be further divided into the swing beam type or guillotine type. In the cutting process, the blade of the swing beam type shearing machine swings in a circular arc. This type of movement demands a circular arc blade whose making process is rather complicated. Moreover the blade needs extra iron pad for compensation. Thus the blade gap is inaccurate and the resulting plate is not as good as desired. Due to the arc movement, the blade can not be made into a rectangular shape but in an acute angle, which will cause severe wear to the blade. The best nationwide swing beam shear manufacturers are the Tianshui Machine Tool Company and Shanghai Punching and Shearing Machine Works. The guillotine shear has overcome the shortcomings of the swing beam shear. However, there are only a few factories that are capable of manufacturing the guillotine shear. These factories include the Wuxi Jinqiu Machinery Company, Wuxi Shenchong Forging Machine Company, Huangshi Metal Forming Company, and many other famous companies that import guillotine shears from the LVD Company in Belgium.
The making of a press brake requires more advanced techniques compared with that of a shearing machine. When it comes to the bending machine, the first two brand names that spring to the professionals' mind must be Amad and Huangshi. Those two brands mainly manufacture traditional, classic press brakes. As far as the writer is concerned, nowadays' press brakes are mainly hydraulic powered. At present, the F-type and G-type are among the most commonly used press brake machines in China. The F-type press brake should belong to the traditional types. It adopts the built-in adjustable block stop to achieve accurate positioning. However, the built-in design makes it very difficult to resist bias load, therefore early press brake often comes with a balance valve. The over complicated hydraulic system also poses great challenges to machine cleaning and maintenance. The latter G-type press brake machine is designed with increased performance based on the F-type. It employs the outer slid plate for mechanical positioning. Compared with the F-type, the G-type has simpler structure and allows more convenient machine testing. By adding an iron pad to the blade, angle difference between the two planes of upper and lower blades is no longer is problem even for non-professionals.
A third variety of the press brake is the H-type. This type of press brake machine has a unique lever structure which is quite different from the first two types. The lever can maximize the pressing force, thus making the machine well suitable for large tonnage applications. Meanwhile, the electro-hydraulic numeric control system can accurately position a piece of metal for high precision pressing. Compared with other press brakes with the same tonnage, this H-type machine is more cost-effective. However, a pitiful fact is that there are few factories in China who are able to produce this type of machine. Even fewer is the number of people who know the H-type press brake. For all the writer knows, the Accurpress Company in Canada and one obscure manufacturer in China are capable of making the H-type machine. The quality of their machine is fairly satisfactory. What's more, one company I knew has once converted the Accurpress press brake with 320T in weight and 4.2 meters in length into a 6-meter-long machine whose performance is rather good.