Month: June 2021

During the manufacturing of metal workpieces it’s often necessary to machine threads. Usually when workpieces have to be mounted or assembled to other parts, screw connections are unavoidable. Generally, there are two different ways to create threads: cutting (‘taps’), which is the most popular method, and forming (‘forming tools’).

OTEC has developed several surface finishing processes of threading tools. With OTEC’s stream finishing machines with Pulsfinish, OTEC’s pulse drive, the tools can be processed reliably, quickly and economically according to the tools’ requirements. The principle of pulse finishing system is based on the precisely defined and rapidly repeating relative movement between media and workpiece. Here the clamped workpiece is immersed in the media stream of the rotating drum where it is quickly accelerated to a speed of over 2,000 rpm. Then it is decelerated and accelerated once again. The differing speeds resulting from the inertia of the media in the drum and the rapid change of workpiece speed give rise to an extremely intense and precisely controllable abrasive effect. 

Compared to conventional processing methods, OTEC’s pulse finishing process has far fewer steps. Deburring, smoothing and rounding of the edges all happens in one step, which leads to both time and cost savings. A surface treated with the OTEC process also improves the adhesion of the subsequent coatings and extends the tool life. 

When dealing with cutting tools, taps generally need a deburring process after tool grinding. With the conventional brushing method, all burrs can never be removed, which negatively affects the later coating process. Non-removed burrs break off and create uncoated areas that wear more quickly. With OTEC’s stream finishing machines with pulse drive (Pulsfinish), workpieces can be deburred within several seconds to several minutes. 

Cutting edges can be rounded to a defined measurement. By setting the parameters container and workpiece rotation speed as well as the immersion angles the geometry of the taps can be modified in order to match the requested and optimal shape. 

When processing forming tools, the main task is to evenly smoothen the entire tool surface. A smooth surface reduces the formation of material in the forming grooves and reduces the friction between the tool and the material to be deformed. Depending on the requirements, the defined rounding of certain functional edges is also necessary. By using a surface finishing process developed by OTEC, it’s possible to achieve these requirements. Compared to competing processes like shot blasting, the OTEC process is both cost effective and at the same time quite flexible, as it can be adapted to different workpiece shapes. Using this finishing process, the deformation forces can be reduced by about 60%.

OTEC’s stream finishing machines with pulse drive (Pulsfinish) make it possible to work with high energy and small and abrasive media. The finishing target is achieved in about one to two minutes, depending on the size of the tap and the requested result. The media used is also smoothing the surface of the tools, which improves the coating behavior and tool life. The process is very flexible and adapts to every dimension and shape of taps. OTEC’s stream finishing machines are highly cost effective since the wearing of the media used is low and additionally, a single machine is able to process a large number of workpieces at the same time. 

Contact us today to request sample processing for your threading tools.

Cutter bodies such as drilling, milling and rotary bodies are used for machining processes and serve as holders for inserts. Cutter bodies are available in different lengths and shapes and are manufactured of hardenable steel from which the cutter body is first milled, then deburred, hardened and ground to size. Finally, the polishing or coating of the surface follows e.g. with hard chrome. The coating is intended to prevent corrosion, but is quickly removed by the chips produced during cutting.

The deburring and polishing of cutter bodies has usually been carried out by brushing or blasting. The results obtained using this method are often inconsistent and inaccurate. For instance, if the contact surface for the insert is not absolutely flat, it will have a negative impact on the cutting process itself. Additionally, non-removed burrs can affect the stability during the cutting process. With OTEC’s SF series of stream finishing machines, tool bodies can be perfectly deburred and polished with repeatable and reliable results. In contrast to manual machining, OTEC’s stream finishing machines deliver consistently perfect results. Depending on the initial quality and the size of the workpieces, the typical processing times for polishing are between five to eight minutes. Thanks to OTEC’s patented pulse finishing technology, it’s possible to reduce an initial roughness from Ra 0.2 – 0.5 µm to Ra 0.03 – 0.05 µm. 

For surface processing, two main tasks are involved in the production of cutter bodies: Deburring after milling and polishing after hardening and grinding. The reliable removal of burrs is important for optimum fit of the inserts on the cutter body. A burr-free and flat support surface is important for stability during the cutting process and prevents chipping of the insert. The subsequent polish removes the oxide layer formed during hardening, thereby improving the visual appearance and upgrading the part for sale. The perfectly polished, smooth surface not only affects the appearance of the tool but also the functionality. Due to the polish, the surface is closed, compacted and significantly smoothed. The extreme smoothness offers less attack surface for corrosion and ensures a better chip flow in the flute. A specific surface treatment can thus significantly increase the efficiency of the cutter tool.

To learn more about OTEC’s stream finishing machines or request sample processing, contact us today.