Combined fineblanking and forming operations rationalise series production of functional sheet metal parts.
The stamping of sheet metal of various compositions and thicknesses has for many years been one of the most important series production processes available in the metalworking industries. But the stamping process itself is only half the story because a number of subsequent processes are required to turn the pressed parts into functional, ready-to-use components. There is, however, an alternative manufacturing method known as fineblanking which has been successfully in use for over forty years. Today, the increasing number of integrated functions and forming operations and rising production costs are making the proven fineblanking process look more and more attractive. Because the blanking and forming technologies are combinable, considerably fewer operations are necessary compared to conventional machining production processes. The result is a high quality, three-dimensional functional part manufactured from a strip of sheet metal in a single process that is ready to use on removal from the fineblanking press.
The chain of processes involved in sheet metal working has changed radically over the last twenty years. Whereas in the past, every single operation such as cutting out blanks, punching holes and break-outs, production of threaded extrusions or forming operations had to be carried out separately on a different machine, today medium to large sheet metal parts are processed in small and medium runs, for example on a laser stamping machine and a die bending press. Large series of small and functional parts on the other hand are still produced on a press as in the past, although today’s presses are high-performance automatic machines that are generally equipped with a progressive tool. In this respect, although various methods and processes have been continuously optimised, this essentially always started out from the “old basis”.
However, there is certainly no further scope for big surge in productivity and reproducible quality - and more importantly for
increase in value added, for which reason this “old basis” is coming under increasing cost pressure despite all the advances made. The only way out of this vicious circle is systematic rethinking and an unbiased search for alternatives. The main thing is to subject all relevant aspects and influencing factors to strict and systematic examination, which in many cases also entails breaking taboos or at least “questioning” them. Some of the questions that need to be asked are: Does a plastic part still have to be made of plastic in the future, or would it not be possible to replace it with a multifunctional sheet metal part that is cheaper to produce? Does the part really need to be a complex moulding or forging, or wouldn’t a function-integrated sheet metal assembly be better and also save material and working time as well as machines and tools? Another question is whether it is absolutely necessary to make a multifunctional sheet metal assembly out of sheet metal parts produced by a process of blanking, stamping, laser processing, bending, coining, deburring, coating and joining, or whether it would not make more sense to opt for complete finished production by means of fineblanking or combined fineblanking/forming as an alternative to these time-consuming operations.
Fineblanking is the obvious answer. Put simply, in the fineblanking process every press stroke produces ready-to-install sheet metal parts with repeatable accuracy requiring at most deburring when used for very special applications. Many functions can be designed into components and assemblies made of every possible kind of steel, copper, aluminium and alloy material. This reduces the number of mechanical components within an assembly just as the number of individual operations up to. Consequently, though this also means that several machines, presses and jigs as well as moulds and tools etc. can be dispensed with, so that looking at the equation as a whole, the initially higher investment in a fineblanking system plus peripheral handling equipment and tooling system is offset by a considerably higher level of cost-efficiency.
Although fineblanking is similar to conventional stamping or shearing, it allows series production of precision parts with cleanly sheared edges, with no diebreak and without the need for any further machining. The parts can be manufactured in a single operation, thanks to the integration of forming or stamping operations. The triple-force principle of the tool and press used in fineblanking and in the combined fineblanking/forming process guarantees high dimensional accuracy, excellent flatness and precise shape. This way no further machining or finishing operations are required even for technically demanding precision components that are used in mechanical and electromechanical drives and powertrains.
The production of a gearwheel provides a good illustration of the potential savings that are possible in materials and machining operations if fineblanking or a combination of fineblanking and forming are used in preference to machining. Machining usually entails the following operations—cutting the blank, cutting the inside hole, piercing windows/holes, straightening/levelling, machining the outer diameter to the finished size, machining the tooth crests on the outside diameter, hobbing the gear teeth, drilling holes, chamfering and deburring/finishing. By contrast, fineblanking consists merely of only fineblanking, chamfering the tooth crests and deburring/finishing. Since modern progressive tools or modular tools can combine all sorts of different fineblanking and forming operations, the sheet metal parts can be produced in a single press stroke. In practice this leads to cost savings of up to 70 percent or more depending on the lot size, and the number of functions that are integrated and the number of mechanical components previously needed to achieve the same performance or today’s increased performance can be eliminated.
The combination of fineblanking and forming also opens up further potential for creative and alternative solutions for designers and manufacturers, leading in turn to real productivity and cost benefits and competitive advantages. With combined fineblanking/forming the forming of the main outside and inside contours of a flat sheet metal part can be enhanced by such additional processes as bending, countersinking, semi-piercing, coining, offsetting, deep drawing and joining. This means that the design of parts can be individualised for integrated functions, which reduces the number of different parts in an assembly or device and cuts production and assembly costs. The full technical and rationalisation potential of fineblanking / forming technology comes into play with multifunctional parts which, in many cases, more or less replace conventional technical parts and allow their production equipment to be dispensed with.
Fineblanked and formed parts are to be found in every area of working and private life. They help produce handy and efficient household and consumer appliances, provide efficiency and safety in automotive engineering and ensure dynamically powerful and accurately repeatable movements and operations in powertrain assemblies and drive equipment. Products range from the classic fineblanked parts such as scissors and knives, robust components for pliers and electric tools, drive elements and gears for gearboxes, mechanical or electromechanical ratchets and adjuster mechanisms in vehicles, to special components for sports equipment and medical engineering. In all these applications fineblanking and forming technology ensure that performance, safety, long life, comfort and low maintenance are in harmony with the required cost efficiency in production.
