Progressive Crumb Supply - Shredder Comparison

Component	Progressive Crumb Supply	Competitors
Type of Hydraulic Drive	Closed loop hydraulic drive The system works at very high pressures and therefore with small displacement can develop a very high torque. The components with small displacement can react immediately to the requirements of the blades. These closed circuits can guarantee very high efficiencies.	Open loop hydraulic drive This systems works at lower pressures and therefore requires components with much larger displacement. The components with large displacement are much slower to react to the requirements of the blades. These open circuits are not very efficient.
Constant-power machine operation	This system allows for constant power shredder operation: when the load on the blades increases because of very tough material, the pumps displacement are reduced proportionally to the rising pressure. Since the power used is proportional to pressure and displacement, a very regular electric motor operation is obtained without heavy overloading. Thus the hydraulic shredder, with a relatively low installed power, is able to process very tough materials.	Very rigid system in which the shredder works at max. speed and max. torque constantly. The motors installed in these shredders must be overdesigned compared to the closed loop system because in case a higher cutting force is required, this will not be available.
Sidewalls	Made of machined steel contoured to the shape of the blades. This allows the blades to scrape of any shredded particles and avoid any "dead" areas in the shredding chamber where material could accumulate.	In some cases - straight steel walls - this is an economical solution which may cause some shredded particles to be stuck in the upper and lower part which may eventually exert pressure on the shafts flexing them toward each other. If this occurs the blades will tend to scrape each other causing a loss in the available cutting force of the blades. In extreme cases the shafts or sidewalls have been known to be damaged.
Shafts configuration	Hexagonal - this solutions guarantees a very strong support to the blade allowing an easy removal.	Sometimes KEYWAY are used - this solution is a lot cheaper to machine but is also much weaker since the contact area with the blade is greatly reduced. Since the shaft is exerting the pressure on the two keyways, these may deform creating great difficulty in removing the blades. The blades are not interchangeable and each blade must be designed for the specific individual position on the shafts. In case of hexagonal shafts, blades with 3 or 6 hooks should be avoided since the hooks will grab the material at the same time causing the shredder to work in an irregular manner If these number of hooks cannot be avoided and the spiral blade setting is required for the smooth working of the shredder each blade must also in this case be designed for the specific individual position on the shafts.
Blades treatment	Made in a special through-tempered steel - this means that the blades have the same steel characteristics in the core and in the external surface. Thus the hardeness of the core is the same as that of the external surface. With this treatment, the blades may be grinded down many times (also 5 times) before they need to be replaced. The hardeness under the grinded surface will be of the same hardeness as the original external surface.	Sometimes surface treatments are used - these blades cannot last as long and may have to be replaced when worn down increasing the maintenance costs of the shredder. These blades may also be re-built but the cost to carry out this operation is very expensive. This is a difficult operation to carry out. It is a poor solution to have blades made of two different steels which do not always adhere to each other very well. This is especially true for the heavy work required by the shredder blades which must resist against some tough and sometimes abrasive materials. If the coating is worn down, within a very short time the rest of the blade made of mild steel will
Blade diameter Hook height	The blades have a larger diameter and taller hook so that they can better grip the material being shredder. To obtain a more aggressive gripping capability, the blades are also positioned slightly above the shredding area, in many instances this feature will avoid having to use a ram in the hopper to press the material on the blades.	Usually the blades have a smaller diameter and they are normally placed well inside the shredding chamber, this may create some difficulty while shredding certain materials.
Cleaning fingers (sectors)	They have almost the same thickness as the blades in order to avoid that the shredded material may recirculate on the shafts. They follow the contour of the sidewalls. These cleaning fingers are designed to slide on rails so that they may be adjusted as close as possible to the blade thickness when they are sharpened.	These fingers are welded or bolted to sideplates which are fitted on the sidewalls of the shredding chamber. When the cleaning sectors are much thinner than the blades and will allow some types of materials to wrap around the shafts.
Extra-end protections	Additional solid steel plates with extra Teflon seals placed at both ends of the cutting shafts which assure the complete separation of the gearbox and the bearings from the shredding area. These additional steel parts are an integral part of the shredding chamber, they are not just fastened to the chamber. These are especially useful when handling liquid material which can be polluted or abrasive.
Front bearings lubrication	Bearings are lubricated in oil bath, this guarantees a constant lubrication and easier inspection through the spy glass.	Grease bearings a more economical solution since it does not require that a special oil housing is created. The bearing are not as well cooled off as the bath oil and they could overheat. In case they are not periodically controlled or replaced the grease may "dry" out causing the bearing to damage the front flange. Some front flange component must be dismantled for this type of inspection to be carried out.
Electronic Control	Electronic board - designed by SATRIND for the working of the shredder with the most popular functions (intermitted working, cycle time, number and count of reversals, connection for consensus to other equipment, etc..) This board can be connected to a PLC in case the shredder must be integrated in a complex plant. The board is connected to a transformer in the control panel designed to deliver a 24V power supply. There is no memory required for this electronic board, therefore if electrical power is removed, it will not be affected. The advantage of this Electronic Board is that in case of any malfunction, it can be very easily, economically and quickly substituted with a new one.	PLC - Programmable Logic Controller This components requires that any adjustments or maintenance must be carried out by a specialized technician who must know the specific programmable logic which has been used in the design of the PLC. Most PLC 's are powered by battery, should the batteries go dead, all the PLC memory could be lost requiring it to be newly programmed by a specialized technician. The type of programmable control logic used could become a problem to identify on older models.