post processing of pre-pressed blanks
The manufacturing costs of turned parts in large series can be reduced by reducing machine processing times and reducing the use of materials. A classic approach reducing machining times on the CNC machining center is the use of form plates, another approach is the use of CNC machining centers with several spindles, the so-called multi-spindle machine. Our company takes a further approach by using specific manufacturing technologies to develop an optimized and near-end-shape blank. We work with a network of extrusion presses to choose the supplier with the right technology, depending on the requirements of the part. The advantage at PENTACON as a "neutral" user of optimized semi-finished products in large-scale machining compared to the processing manufacturer of the semi-finished products is: You get the "tailor-made" and cost-optimal blank as well as processing from a wide technological spectrum and supplier network. As a rule of thumb, starting from a machining volume of 25%, a price advantage compared to off-the-shelf production can be achieved.
Since the blank is partially reshaped in parts or designed close to the final contour, a machining-related allowance of around 0.1 to 0.5 mm usually remains for the machining depending on the contour. The CNC machine tool can turn this oversize in one chip and saves a considerable cycle time compared to bar machining. Depending on the component, however, it must be weighed how far the final shape is approached and, as a result, additional pressing stages and thus more complex and expensive tools and systems may be necessary. A simple or form-compatible geometry thus enables a more productive and cost-effective forming process. Based on our many years of experience, we decide where the cost of the entire process with blank and machining lies. Furthermore, there are significantly fewer chips that would otherwise be included in the material price calculation as a direct material price. In addition, extrusion changes the strength properties. In particular, the yield strength and hardness increase. This technology enables strength properties to be achieved even for steels with a low carbon content, which are otherwise only achieved through the use of alloyed steels.
The basic formability or production of the geometrically optimal blank is an interplay of geometry and material, which is often also described with the parameter degree of deformation. In general, it can be said that with very easily formable steels, more difficult geometries can be realized in the same process. When considering the benefits of this technology, one has to consider the material in question early on in the development phase, because not every material can be cold formed easily. For cold extrusion or cold upsetting, for example, steels are suitable as far as possible, which have a high elongation when soft-annealed. Selection of good cold-formable steels: C4C, C8C, C10C, C15C, 42CrMo4, 35B2, 38B2, 19MnB4 (without claim to completeness) In the steels listed above, the boron-alloyed steels represent a specialty. These raw alloys are characterized by good formability in the raw state and a comparatively high strength after heat treatment. These steel grades are used, for example, across all industries for fasteners.
If cold forming reaches its limits in terms of geometry and material, so that a stable process can no longer be ensured in the forming tool, the alternative is to consider the semi-hot forming technology as an alternative. In the case of semi-hot forming, the component is inductively “preheated” to a point where the degree of forming is reduced in line with production, but the structure has not yet been changed similarly during hardening. The higher process costs can be compensated by reducing the amount of machining and the use of materials. This process holds the greatest potential for difficult-to-machine and cost-intensive special alloys. Examples from the field of semi-hot forming: 1.4108, 1.4429, 1.4435
Folgende Materialien setzen wir erfolgreich ein:
The bar and extruded part are compared. This shows the material saved. At the same time, the material strength increases significantly through extrusion.