TR: THE INCLINED SHEAR 
CONTINUOUS FEED SHEAR

The reasons for preferring the open box and continuous feeding system for shearing scrap as opposed to classical and traditional systems with a manual pre-compression phase before the automatic shearing cycle are:
• The possibility of shearing particularly long materials, with lengths exceeding the size of the feed box.
• The lower routine maintenance costs due to less wear and fewer cylinders  
• The use of a single operator to simultaneously load and control the operation of the shear
• Less space occupied due to the compactness of the shear and its limited dimensions
• Absence of production downtime related to the preparation of the scrap to be sheared.
Unlike inclined shears, in conventional shears the time required for the return of the main cylinder and the opening of the wings at the end of the cycle must be taken into account.

In contrast, inclined and continuous-feeding shears present difficulties and shortcomings such as:
• The impossibility to produce scrap bales,
• The lower density of the sheared material is due to the distribution of the vertical compression force over three compression stages. In fact, density is achieved by vertical compression and not by lateral compression. Lateral compression simply reduces the size of the scrap by stopping at a predefined position, while density (weight of the occupied volume) is achieved by the vertical compression which stops when the maximum compression force is reached. The vertical compression force, in inclined shears, is distributed over at least three compression stages, whereas in conventional shears the compression is concentrated on the surface of the vertical clamp, which is much smaller than the vertical clamp in inclined shears.
In order to achieve a shear density equal to that of traditional shears, inclined shears need at least 3 times the force of the traditional shear baler.
• The maximum shear length is defined by the external positive stop but is not certain and constant because it is left to the action of gravity and the movement of the inclined base(if present), which rather than "pushing" it allows to "slide" the scrap to be sheared.
• The depth of the compression stages of the vertical clamp limits the maximum cutting length and prevent the bulky material to slide freely.
• A special attention that the operator must give to loading the scrap into the feeding box. The scrap must be loaded and distributed in such a way that it does not "float" in the feed box without slipping, and in such a quantity and size that it impeed the shearing of the material for overload,
• The shearing rejection for excess of scrap at the guillotine, since there is no longitudinal pusher, causes the machine to temporarily stop in order to free the blades from the material that produced the overload (an inconvenience that occurs more frequently with machines with limited cutting force) .
• The limitation of not being able to shear certain categories of scrap, due to the opening of the flippers and the clamp and the limited flexibility of the system to adapt to certain types of material.
• The loading height, which makes it difficult for the operator to view the inside of the feeder box, to correctly distribute the scrap in the loading area and to control the work phases,
• The difficulty of maintenance operations on the inclined parts of the structure, which forces operations that are not easy when replacing a part that must be mounted in inclined seats and not vertical seats.  

With regard to the productivity of continuous-feeding shears, for the same working parameters (installed power, force, pump oil flow rate, etc.), it should be noted that open-box shears are unbeatable in shearing long material and pre-packaged bales, while they are not facilitated, compared to traditional shears and in particular those with oscillating wings, when they are faced with those materials that due to their shape and size require flexibility of movement in the pre-compression phase in preparation for shearing.
It is true that open-feeding box shears are in continuous operation and do not have the dead times of manual pre-compression of the scrap, the return of the main cylinder and the opening of the wings at the end of the cycle, but it is also true that traditional systems, once the pre-compression box is closed, for each cutting cycle do not have the dead times of closing the flippers, the dead times of movement of the inclined plane, the overstroke times of the three-stage vertical clamp.
The choice between the two working systems for scrap preparation, traditional (with pre-compression box) or continuous feeding (with open box), is therefore left to the needs of the user, who must valuate the limits and merits of the two different systems in relation to their own needs, scrap types, available space, investment size....