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Extruders are widely used for a variety of conveyed goods in the food industry and the screws are usually ground and polished by hand, which is costly and time-consuming. Extruders move not only bulk goods but also viscous masses such as dough. A rough surface is prone to food residue and micro-organism deposits, which makes surface cleaning much harder. Additionally, sharp, unstable edges are problematic since they can repeatedly break off when under stress, leaving small fragments in the food. The only way to prevent this, and to guarantee uninterrupted production and food purity, is smooth, even surfaces in even the smallest angles, and rounded, stable edges. Typically, components used in the food industry are post processed in several steps, which can take several hours and is very costly. Since extruders can be heavy and unwieldy, the risk of injury from sharp edges is high.


The most efficient and cost-effective way to obtain evenly smoothed surfaces and rounded, stable edges is customized post processing using OTEC stream finishing technology: a mechanized, reliable, repeatable process for smoothing and edge rounding. Targeted, controlled processing ensures that the extruder screw can do its job unimpaired: no catching, no increased resistance and no deposit build-ups.


Schaaf Technologie GmbH manufactures screw extruders. Manually post processing the parts after turning and milling used to take the company around four hours. Recently Schaaf Technologie replaced all of this manual processing with OTEC’s efficient stream finishing process. 

According to Ron Hanke, Production Manager at Schaaf Technologie, “The OTEC stream finishing process means that we can process our screw surfaces automatically, evenly and consistently. The new process also improves tribological properties all-round, which in turn extends the service life of the parts by reducing friction. The process now takes just 30 minutes, and the time it takes for our employees to load the machine is minimal. We even obtain a better surface result than we did with manual finishing. The OTEC stream finishing process gives us a huge advantage in terms of both quality and time.”


OTEC’s stream finishing (SF) process, which was developed in-house, is ideal for particularly complex geometries. Components are clamped in a holder and lowered into a rotating container filled with an abrasive or polishing medium. The workpiece is also rotated to produce an even finish. This makes it feasible to achieve highly refined surfaces with roughness depths of up to Ra 0.01 µm even on the most complex geometries – all without manual strain or risk of injury. 

The enormous machining forces used in stream finishing can remove material faster and more precisely than any other type of surface processing. It is also easy to store and retrieve custom process programs, ensuring repeatability. 

OTEC’s latest innovation, the SF-HP, can even process large and heavy workpieces with a diameter and length of up to 650 mm and a maximum weight of up to 200 kg.


Work with us to identify exactly the right process for your components. Contact us today to request sample processing.

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Drag Finishing For The Tool Making Industry

In the drag finishing process, workpieces are clamped in specially designed holders. These holders are dragged in a circular motion through a process drum containing grinding or polishing granualate. This high-speed motion generates high contact pressure between the workpiece and the media, which quickly produces perfect results in the form of high-precision edge rounding, smoothing or a mirror-finish with results equivalent to those obtained by manual polishing.

One of the main applications for OTEC’s drag finishing machines is in the tool making industry. Some of the parts that can be processed using drag finishing include:

  • carbide cutters, thread-cutting dies, inserts and small broaches – processing these parts in a drag finishing or stream finishing machine reduces the risk of chipping. Precision rounding of the cutting edges and polishing the chip flutes increases tool life and improves cutting performance.
  • PVD and DLC coated workpieces – Stamping, forming and cutting tools are often coated with a carbide material in order to reduce wear. As a result, droplets can form on the surface of the tool. The drag finishing process selectively removes these droplets. Lubricant can be retained in the tiny holes and depressions left behind. This gives an improved film of lubricant on the surface of the tool, resulting in much less friction and reducing wear dramatically.
  • finishing of stamping and forming tools – the quality of stamping and forming tools can be improved considerably with the OTEC finishing process. Surface finishing lowers the coefficient of friction and thereby reduces wear at the surface of the tool. Polishing the forming surfaces can considerably increase the life of stamping and forming tools and improve tool performance. Smoothing the roughness peaks reduces the forces required and gives better flow characteristics during forming. In order to ensure that the quality of tools remains constant, regular repolishing is absolutely essential. Finishing in OTEC machines not only cuts down on expensive manual finishing work, but also delivers absolutely reliable and reproducible results.
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OTEC’s CF 50 Disc Finishing Machine’s New Design

OTEC’s CF 50 disc finishing machine now boasts a brand new compact design, with an optimized welded structure that guarantees reliable operation and a long service life. The updated design also features storage space for two compound containers and a waste water pumping station with a tray. The optimized spraying system with an additional rinsing nozzle enables process containers with the patented zero gap system to be filled quickly.

Another feature of the new design is a 7.5-inch color touch display for operating the machine that allows users to quickly and easily create, store and retrieve up to 5,000 programs. This makes operation extremely user-friendly. Thanks to the optional remote maintenance function, OTEC can carry out maintenance work on your machine without being onsite. It can also be set up for remote control if required, so you can be flexible in where you control the machine from. 

The CF 50 disc finishing machine is suitable for any rapid surface processing requirement involving larger fine blanked, turned, milled and punched parts as well as jewelry.

The OTEC CF Series disc finishing machine is the result of over 20 years of experience and pioneering innovation. Thanks to the optimal design of the containers and gap, our machine provides the ultimate in reliability and short process times.

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Stream Finishing For The Automotive Industry

In the automotive industry, the surface finish of individual components is crucial. So-called bulk goods are typically finished using disc finishing machines whereas sensitive parts that need to be finished to a greater degree of precision require the use of stream finishing or drag finishing machines. At OTEC, we offer a variety of finishing machines that meet the needs of the automotive manufacturing industry to ensure a perfect surface finish and increased service life of components.

OTEC’s stream finishing machines can be used to process cylindrical or near-cylindrical components – mainly the shell surface. With a wide choice of grinding and polishing media and a host of machine parameter settings, OTEC can provide the perfect process for almost any workpiece including gear wheels, crankshafts, camshafts, valves, spindle drives and other gear-type components. 

OTEC’s stream finishing process can help change the surface topography and adapt the surface microstructure of engine, motor and drivetrain component surfaces, contributing to

increased drivetrain efficiency in combustion engines and electric drives. The tribological properties of these engine, motor and drivetrain component surfaces are a critical factor in friction and wear behavior and have a huge impact on their performance. Achieving the perfect finish ensures minimal friction and wear. 

Some of the advantages of OTEC’s stream finishing machines include:

  • A reduced friction coefficient
  • An overall reduction in friction
  • Less wear
  • Increased internal compressive stress 
  • A more streamlined production chain since deburring and other techniques can often be replaced by stream finishing  

OTEC can develop a custom process designed specifically for your workpiece and application. Please send us a sample processing request if you would like to work with us. 

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OTEC’s Newest Stream Finishing Machine

OTEC is expanding its SF Series of stream finishing machines, with the addition of the SF-HP model, designed to accommodate larger and heavier workpieces. With its modern and compact design, the SF-HP was developed to round edges, polish, smooth and deburr large workpieces. This innovative machine can be used for applications across a variety of industries including aviation, machinery construction, forming tools, the energy, oil and gas industry, shipbuilding as well as the food industry.

Repeatable high-quality surfaces are guaranteed thanks to OTEC’s proven Streamfinish technology. Our unique, patented pulse finishing process is also integrated in the new SF-HP. Economical processing of large and heavy workpieces is now a reality. 

The new machine can process workpieces that are up to 650mm (25.5906 inches) in diameter and/or length and 200kg (440.925 lbs) in weight. Other features include a simple and intuitive user interface. Additionally, a variety of axis settings for the process head and spindle make almost any flow-through process media of the workpiece surface possible.

Some of the benefits of OTEC’s SF series stream finishing machines include: 

  • High efficiency and short processing times
  • A range of processing options depending on the requirements, including smoothing, high-gloss polishing, edge rounding and deburring.
  • User friendly operation through a multi-touch color display screen
  • Ergonomic machining of large and heavy workpieces through integrated automatic loading. 
  • Simple container changing enables multi step processes using different media. 
  • Improved tribological surface properties, which provide reduced friction and abrasion.
  • The highest surface qualities down to the smallest geometry. 

To see if OTEC’s new SF-HP stream finishing machine is right for you, please submit a sample processing request and we can develop a process specifically designed for your workpieces and applications. 

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Choosing The Right Media And Compounds For Disc Finishing

OTEC Präzisionsfinish GmbH recently hosted a webinar on how to select the best media and compounds for a disc finishing process. The webinar shared some of the benefits of choosing the optimal grinding chips and compounds for your process, including shorter processing times and obtaining the desired results more efficiently. 

The training also provided an overview of the different media that can be used with disc finishing machines, including plastic, ceramic and porcelain grinding chips. Additionally, during the webinar, best practices for choosing the ideal compounds for wet finishing processes were also discussed.

Possible applications for OTEC’s disc finishing machines include: 

  • In medical and pharmaceutical manufacturing, for surgical fasteners, bone screws, bone plates and milled parts, ear molds, dental implants and acrylic teeth.
  • For the automotive industry, in the manufacturing of pieces including gearbox and engine parts. 
  • In the jewelry and watchmaking industries,  for working parts of mechanical watches and polishing gemstones. 

To view this webinar on demand, please reach out to us via our inquiry form.

To see if OTEC can help implement or improve a disc finishing processing for you,  please submit a sample processing request.

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Stream Finishing For The Aerospace Industry

OTEC’s stream finishing machines can be a reliable, quick and cost effective alternative to manual finishing for the aerospace industry. Stream finishing can be used with servo valves, which are commonly used in aircraft flight control systems. These valves hydraulically operate aircraft ailerons, rudders and other control surfaces.

OTEC’s SF-Series Stream Finishing Machine

High friction and burr formation among a servo valve’s bushings and spools can lead to abrasion and wear, which can cause the valve to fail. Additionally, sharp or unevenly rounded edges can also impair a valve’s flow. When a servo valve needs to be replaced, it’s very important to guarantee consistency, safety and stability. These replacement parts are frequently post-processed by hand, which can be inefficient and unreliable. Manual processing is subject to human error and can be very time consuming and costly.

Servo valves are electromagnetically operated hydraulic ram valves consisting of a bushing, a spool and an electric control unit. The valve can open or close a variety of hydraulic circuits based on the position of the spool.

However, stream finishing servo valves with a consistent flow of media and strictly monitored parameters guarantees maximum process reliability and repeatability, which means a much lower rejection rate for parts. OTEC’s SF3/3 RLS stream finishing machine with an automatic workpiece loading system can process a component in 40 seconds flat. OTEC machines can pay for themselves in as little as two to three months. The pulse finishing process used with our stream finishing machines reduces cycle time by up to 96% compared to manual processing. Other benefits of OTEC’s high-precision processing include enabling the closest possible tolerance, which is critical for system tightness, and permitting a higher switching or stroke frequency, which significantly increases control accuracy. 

Before (Top) and After (Bottom) Stream Finishing

Pulse finishing, OTEC’s stream finishing innovation, has remained the fastest mass finishing process on the market since it was launched in 2013, with average process times of 60 seconds. Using very small grinding bodies compatible with the process, it produces precise, effective, ultra-consistent results even with complex workpieces. OTEC stream finishing systems are cost-effective, process-oriented solutions that combine easy automation with maximum process reliability.

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How To Get The Perfect Finish on Additively Manufactured Parts

Additive manufacturing, also known as 3-D printing, is becoming more commonplace in industrial manufacturing and a variety of components, ranging from jewelry parts, dental implants, earmolds and engine blades, are all being manufactured through this industrial production method. 

Since the 3-D printing process creates components by adding successive layers, 3-D printed parts have a distinctive surface structure characterized by striations, pores, fissures and cavities, which creates the need to improve their surface quality and  reduce the staircase effect. 

The conventional solutions are manual post-processing, solvent vaporizing, or mass finishing, for example, vibratory tumbling. However, all three of these methods can be very costly and time consuming. Fortunately, OTEC’s disc finishing machines offer a quick and cost-effective alternative when it comes to achieving the perfect finish on additively manufactured components. OTEC’s disc finishing machines produce homogeneous surfaces very quickly, without chemicals, by smoothing and polishing them.

OTEC CF Standard Series disc finishing machine

OTEC’s CF Series disc finishing machines are known for their application flexibility, repeatability and process reliability, which makes them ideal for getting the perfect finish for 3-D printed parts. The CF Series machines have a flexible workflow that allows workpieces and abrasives to be easily changed in each container. Thanks to a modular design, the machine allows you to run different post-processing steps in different containers simultaneously, regardless of whether the workpieces are the same. Additionally, the machine’s control unit lets you store and monitor workpiece-specific process parameters, so you can run them again with the press of a button. 

Compared with vibratory finishing, OTEC’s disc finishing machines have a much higher mechanical abrasion level. For manufacturers of 3-D printed parts, that means shorter process times – by a factor of five to ten. And unlike chemical smoothing, our CF machines do not use harsh chemicals such as solvents. They are safe to handle, simplify workflow and save you time. They’re also affordable to buy and operate, which cuts series production unit costs. 

Our CF Series machines reduce manual rework to the absolute minimum. That largely depends on the application in question and the finishing requirements. Generally speaking, repeatable, reliable mechanical processing with disc finishing cuts the cost of manual work by 80%. Only the final polish – for example with jewelry – needs to be done by hand.

CF processing example: 3-D printed workpiece made by SolidPro, before (left) and after (right) the CF process.
CF processing example: a 3-D printed plastic earmold after the CF process.  

If you need help finishing 3-D printed parts, please send us a sample processing request.

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Finishing Machines For Medical and Pharmaceutical Technology

OTEC USA’s latest webinar highlights different applications for our finishing machines within medical and pharmaceutical technology. 

This training provides an overview of several of our CF Series disc finishing machines, our HV 20 Tub Vibrator and our DF Pharma Series drag finishing machines. Some of the possible applications include use in the production of surgical implants, earmolds and dental implants, among others. 

All of OTEC’s machinery is reliable and cost-effective, while providing precise results.   

To request access to the full on-demand webinar, please contact us via our inquiry form: