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Case Study

    Stainless steel could last longer with passivation treatment.       One of the most frequently asked questions from our customers is that why stainless steel needs passivation(*Ref) treatment when it already has good anti-rust quality. It seems that workpieces after passivation treatment only look more polished and completely degreased on the surface. Actually, if we only degrease and dry the workpieces without passivation, there is no obvious difference visually. Therefore, here APPORO would like to thoroughly discuss and introduce passivation treatment from the perspective of professionals.     What is passivation treatment?   Passivation treatment refers to a chemical post-treatment in order to enhance the inherent anti-corrosion quality of stainless steel, which is different from the traditional metal pickling that removes oxide layers on the surface, and from the chemical film treatment before coating. After passivation treatment, there will be a protective oxide film on the surface of the stainless steel workpiece. This invisible film is extremely thin. Its thickness is smaller than 0.0000001 inch, around 1/100,000 the thickness of human hair. Generally speaking, workpieces after passivation treatment are clean, bright and rust-proof on the surface.   Basically, this oxide film forms naturally when the workpieces get exposed to the oxygen in the air after manufacturing, polishing, or acid cleansing process. Under ideal conditions, the surface of the workpiece will be totally covered with the oxide film. But it will also be covered with iron particles from cutting tools or the rust on them, or the ferrous particles during manufacturing. Although these manufactured stainless steel items are seemingly smooth and clean on the surface, under certain conditions these invisible and scattered particles could possibly lead to the corrosion and do damage to the quality of the protective oxide film on the surface that previously formed. Sometimes rusty spots could even be identified.   Besides, as to smoothly remove the iron chippings from the cutting tools, AISI 303, so-called free cutting stainless steel, sulfides are added. However, the sulfides on the surface also could result in rust and rusty spots after the exposure to certain environment.     When do we need passivation treatment?   Overall, there are several inevitable factors during manufacturing that could sometime cause rust and rusty spots on the surface. If the application requirement of the workpiece is rather strict, such as environment with high salinity, strong acid/base, corrosive chemicals, high temperature, or high humidity, passivation treatment is recommended. Or the material could be replaced with medical grade stainless steel AISI 316L. This grade of stainless steel is often used in some of the harshest environments such as medical industry, food, energy, construction and agricultural industries.   *Ref: Learn more about Passivation ...
  Perpetual motion machine remains a dream unattainable.       As a manufacturer, APPORO has quite an understanding of design of machine tools and the way they work. We figure how to optimize our CNC manufacturing procedures and to enhance the efficiency all the time, so as to reduce the manufacturing costs. Hence, when knowing there is so-called machine design which could conserve energy or enhance efficiency, APPORO surely looks into its operating principle in details and evaluates if it matches its advertised performance. Not surprisingly, the actual test result often falls short. Speaking of that, several well-known scams in history also adopted this kind of conceptual design, claiming to have created perpetual motion machine(*Ref) to defraud.     What is a Perpetual Motion Machine?   Perpetual motion machine refers to a machine that does motions constantly and works without energy input. There are two major categories in terms of perpetual motion machine. The first kind violates the first law of thermodynamics as it does work without energy sources. The first law of thermodynamics states conservation of energy, indicating the total energy stays constant in an isolated system, and that no extra energy emerges in that system. Any machine that claims to produce energy from nowhere falls into this category.   While the first kind of perpetual motion machine was proved to be impossible, discussions about the second kind of perpetual motion machine were put on table right away. Its design makes use of the energy outside of the isolated system such as heat and wind energy, striking the balance so that the system could operate perpetually. However, energy would eventually be exhausted from the working machines. The just balance could only be reached if there is energy input, so it still failed to forever motion without additional energy.     After Perpetual Motion Machine   The idea of perpetual motion machine has existed for centuries. Based on the scientific understanding nowadays, it remains a dream unattainable. However, there are still a lot of “scientists” engaged in the invention of perpetual motion machine, one after another. Basically these “scientists” are:   1.) Rookies: They barely know a thing about the concept of perpetual motion machine. They often mistake certain device for perpetual machine, which, in fact are device that absorb energy in the dark. For example, human body.   2.) Genuine scientists: They hold the firm belief that science has to be challenged all the time, thinking that thermodynamics could also be wrong or should be revised, as Newton’s law of motion was revised by theory of relativity quantum mechanics. It is never easy to overthrow a law, but their attitudes are admirable. These people are the most likely to invent perpetual motion machine.   3.) Fraud: Even in this era of information explosion, we can still see those who claim to have invented perpetual motion machine. They use sophisticated physics terms and fancy words to convince other to take their scientific results and defraud them of investment. But, until now, all perpetual motion machines are proved to be fraudulent.     Will The Dream Come True?   Perpetual motion machine has always been the dream in the field of science. Just like alchemy for development of chemicals, as many efforts are put into this probably impossible techniques, many relevant techniques are then created. As a pragmatic CNC manufacturer, although we might not believe the concept perpetual motion machine would be ever realized, we could not deny the fact that the progress of science and mechanic design derives from the constant efforts of researchers. Holding the same attitude, APPORO will non-stop updates and introduces new techniques and shares more case studies, hoping to have in depth academic exchange and to contribute to the manufacturing field.     *Ref: Learn more about Perpetual motion. ...
It is inevitable to have burrs on the cutting or hole-drilling edge during the milling while milling parts. The size of burr is usually relevant to tool wear condition, feeding and rotary speed, material properties, cutting fluid, etc. The left burrs on the workpiece not only could get operatives scrapped, but also could lead the dimensions exceeding the tolerance. Therefore, CNC manufacturers all regard burrs as a huge enemy against workpiece quality. Previously, APPORO shared a case study on deburring the die casting parts. In that case, burrs formed on account of reamer wearing, and after APPORO promptly renewed the reamers, conducted a full inspection, and removed the burrs, we coped with the quality crisis.   Most burrs on the end/edge of the parts could be removed on the CNC machine through chamfering(*Ref). However, some have to be manually removed as the burrs are where the machine can hardly perform, resulting in the high overall manufacturing cost. If you ever encounter the above situation, take a look at two concrete cases below. See how APPORO make excellent use of decades of experience in CNC manufacturing to overcome all kinds of challenges.     Across Milling Burrs   Basically, milling is about cutting round bar materials into required ID/OD dimensions with high-speed rotary tools. If we are to mill flat surface onto the cylindrical side of round bar materials, the CNC milling machine should be installed with driven tool holders, where face milling cutters are mounted. When it comes to the step of face milling on the side, the round bar stops spinning and aligns the face milling cutter with the part to be machined. Then, the milling cutter starts spinning in right/down or left/right direction to side mill the workpieces, until the depth and width across flats are as required.     We use two cutters to precisely and quickly face mill the rod, but highly possible to cause burrs at the end of the flat surface.       From the poppet stem photo above, the head of this OD 8.0 mm workpiece features 7.0 mm width across flats. In other words, the surface has to be 0.5 mm in-depth on one side. First, APPORO used two cutters with 7.0 mm space in-between to face mill the 8.0 mm OD with symmetry from the end of the workpiece, in the same direction with the axis. The processing was precise and quick, but highly possible to cause burrs at the end of the flat surface, which was also around the edge of finish part of the workpiece. As there were not sufficient tool holders in that CNC lathe machine, it was impossible to remove the burrs on the machine. In that way, APPORO could only manually remove the burrs with a pneumatic deburring tool. However, the inconsistent force exertion led to the uneven chamfers and the disqualification.     The inconsistent force exertion led to the uneven chamfers marked by red arrows. The undercut marked by red circle is very rough due to the fact that the cutting tool is worn out.       When APPORO reviewed all the milling process, we decided to substitute a better CNC lathe machine with more functions, installing face milling tools in its driven tool holders on the side. So, we can machine the 7.0 mm across flats directly. When the 0.5 mm deep surface is completed on one side, the C axis of the lathe machine rotates by 180 degrees and machines 0.5 mm deep surface with an end mill. In the following, APPORO uses the chamfering tool to remove the burrs from the four edges. After this adjustment, APPORO stays away from the risk of inconsistent force exertion of manual deburring and enhances the production efficiency.     To mill the across flats and remove the burrs directly on a powerful CNC lathe machine.       Burrs from Hole Drilling on Slopes   Generally, after hole drilling, noticeable burrs formed around the edge of the exit surface. If there is still enough space around the hole, chamfering to deburr is still available. However, if the exit surface is not perpendicular to the hole, meaning that the exit surface is a slope or curve, chamfering is not an option to deburr. Here are some alternative plans we can adopt:   1.) Blast Using the momentum of the high-pressure gas to strike the surface of the workpiece. Available to polish the surface and deburr with evenness and efficiency. However, after blasting the surface could turn slightly matte.   2.) Tumble The tumble theory applied to have tooling rub against the workpiece with high frequency. Available to polish the surface and deburr with evenness and efficiency. Unavailable for overlong/overweight workpiece or workpiece with external thread.   3.) The universal deburring tool A unique chamfer tool with its cutter and spring attached. It allows removing the burrs around the edge on both ends at a time. Unavailable for hole under 3mm ID.   Can’t figure out how to deal with the nightmare of burrs? It is time to contact APPORO now. APPORO is going to help you overcome all the problems in manufacturing, based on our experience for decades in this field!   *Ref: Learn more about Chamfering.  ...
The trade war between China and the US has been constantly escalated, which draws opposite sides of opinions from experts in all fields. On one side, many think tariffs limit the benefits of free trade, raising the cost of living, and failing to bring positive effects on the manufacturing in the US. On the contrary, the others believe the trade war is beneficial for the US economy, as it brings back more job opportunities of manufacturing to the US. No matter what the future will be like, we have to put the emphasis on currently the two most impactful tariffs: a 25 percent tax on steel and 10 percent tax on aluminum. The impacts of them could be everywhere, starting from Coke, vehicles to industrial equipment and other high-end manufacturing.     Tariff Avoidance Strategies   In the aspect of the manufacturing industry in Taiwan, the trade war leads to the rise of all kinds of costs. For example, materials, manufacturing, and sales are all influenced, directly or indirectly. Here are the strategies most corporations adopt:   1.) Reduce the cost of supply chain   2.)Switch to another supplier with lower cost   3.) Revise design and change manufacturing way to cut down manufacturing cost, and lead in industry 4.0 with automation (and unmanned factory)   4.) Stand still and stick to the current operating strategy, while bearing the enormous pressure of continuing raising costs during the trade war.     As the trade war continues, although it does not force corporations to shift back their massive production to the US, due to the fact that the labor cost in the US is still higher than it in China or countries oversea. Gradually, it apparently accelerates the speed of which corporations move out their production from China. Since 2019, many CNC manufacturers in Taiwan have indeed received orders from China, most of which are from the purchasing offices in China. These purchasing offices are assigned by their parent companies in the US tor purchase from Taiwan or Southeast Asian countries. Although in the first half of year the accumulated exports of Taiwan slightly dropped, however, in certain industries such as IT industry the accumulated exports are constantly growing.         Taiwan's exports highly rely on China market but also influenced by tariffs.   (Ref:     In the trading storm between these two great and conflicting countries, CNC manufacturers in Taiwan might benefit from the transferred order temporarily, in the meantime, we should also figure out how to prevent ourselves from being dragged into the storm next time.  ...
Unified National is a standard commonly used by the United States and Canada in for Inch Screw Threads where the flanks of the V have an angle of 60° to each other. At first, UN(*Ref) only included four basic categories: UNC, UNF, UNEF, UNS, and then UNJ and UNR were gradually added to the standard.     UN Thread Classes   According to UN standard, there are three different classes (1A, 2A, and 3A) when it comes to external threads, and for internal threads there are three as well (1B, 2B, and 3B).   1A and 1B: Refers to the thread fitting with the most loose tolerance, where there is a huge allowance. This class of thread fit is applicable to easy assembly and disassembly.   2A and 2B: The major class in the industrial and commercial applications, such as machine screws and fasteners. This class of thread fit is interchangeable and stable in regard to quality and assembly.   3A and 3B: Applied to commercial products with high quality, this class of thread fit requires compact assembly with an extremely small allowance. Therefore, 3A/3B thread fitting is usually seen in crucial design with safety requirement in commercial or aerospace industry products.     The UNJF-3A adjustable thread gauge is with an extremely small allowance.     As for external threads, the tolerance of 1A class thread fitting is larger than it of 2A class fitting by 50%, and by 75% than it of 3A class fitting. Samely, for internal threads, the tolerance of 1B class fitting is larger than it of 2B class fitting by 50%, and by 75% than it of 3B class fitting. Taking the 5/16”-18 UNJ-3B thread as an example to show how to read UN thread specification, the 5/16” stands for the major diameter, the 18 UNJ suggests that there are 18 threads per inch in the UNJ threads, and the 3B refers to the finest class of the UNJ internal threads.     Trivia about lathe UNJ threading   In the following, APPORO is going to introduce UNJ threads. Initially released December 1965, the military specification MIL-S-8879 is mainly applied to aerospace fasteners. There are internal thread and external thread specifications when it comes to UNJ threads, which based on the pitch can be categorized into UNJC, UNJF, UNJEF, and UNJS. UNJ threads are different from UN threads in the respects below:   1.) external threads: The roots of regular UN threads will be V shape bottoming, while the roots of UNJ thread are strictly specified to be semicircular bottoming. This kind of circular roots can slow down the wear rate of sharp cuts during processing and increase the fatigue strength of threads.     2.) internal threads: In order to assemble with the semicircular bottoming of external thread, the minor diameter of an UNJ internal thread will be slightly larger than it of a regular UN internal thread. As internal threads are rather unlikely to break from the internal stress, there is no specifications for the major diameter roots of UNJ internal threads to be semicircular bottoming.     3.) The symbol for all UN external threads is “A”, while for all UN internal threads is “B”. In addition, for J series threads usually the required thread class is 3A/3B, which is the highest fit, and the second most common thread class for J series threads is 2A/2B. On the other hand, for UN threads the thread class is commonly 2A/2B.         In the process of lathing UNJ external threads, sharp cuts should be equipped according to the specified root radius (between 0.15011 pitch and 0.18042 pitch), so that the roots of the external threads could be smooth semicircles in a row in shape. As the roots of an external UNJ thread are special semicircles in shape, its minor diameter is slightly larger than it of a regular external UN thread, and that is why it could not match other Inch Screw Threads of the same specifications. For example, if we drive an ⅜”-16 UNC nut with an ⅜”-16 UNJ screw, the minor diameters of these two would interfere with each other, resulting in the assembly failure. However, using a larger tapper to manufacture the internal thread of the ⅜”-16 UNC nut could prevent the minor diameters from interfering and avoid other assembly problems.     On the contrary, if we would like to drive an internal UNJ thread with a regular external UN thread, since there is no specifications about the major roots of an internal UNJ thread being semicircles in shape, basically an internal UNJ thread could match an external UN thread of same specifications. The difference between an internal UNJ thread and an external UN thread is that the minor diameter of an internal UNJ thread, as known as the size of its tap-drill hole, is larger; therefore, the minor diameter of the internal UNJ threads could match the semicircular shape external roots of the external UNJ threads. For instance, under some special circumstances, there will not be any problems driving an ⅜”-16 UNJ nut with an ⅜”-16 UNC screw.     In comparison with hundreds of thousands of thread specifications and applications, thread manufacturing and inspection are rather simple. However, their importance is often underestimated, leading to assembly failure and possibly affecting the overall product equality. Find yourselves a CNC expert with thread manufacturing proficiency and experience like APPORO so that the quality of your products are guaranteed!       *Ref: Learn more about Unified Thread Standard  ...
    To use NO GO of the standard thread gauge for the inspection criterion for threads before plating. After plating, the threads have to pass the standard thread gauge inspections.       How to Control the Thread Size Before Plating?   As it is mentioned previously, the goal of OD control can be easily reached under stable CNC processing. Generally, after CNC processing, the threads of a non-plated component have to pass the thread gauge inspection so as to pass the QC inspection. Nevertheless, for components that need to undergo plating process, the manufacturing and inspection procedures will be different from the former. According to the requirement of our Swiss dental equipment supplier client, APPORO has to be discreet than ever for inspections. See the examples below:   Based on the required plating film thickness, APPORO has to leave some room for it during CNC processing, and use the pre-plated thread gauges for inspections. See the photo below. If the required plating film thickness is 1-3um, the major, pitch, and minor diameters should all be +0.02/-0mm larger than the standard dimensions when manufacturing the internal thread M13.2x0.3-6H. Then, the threads need to pass the inspections of the enlarged customized M13.2x0.3-6H +0.02/-0mm plug gauge before plating. After plating, the internal threads need to pass the inspections of a standard M13.2x0.3-6H plug gauge. Once they pass the inspection, they can be approved for shipment. If there is an external thread on the plated component, after CNC processing, the pre-plated ring gauge inspection will be necessary. And then, the inspection of a standard ring gauge should then be conducted.     What we can do without pre-plated gauges?   However, the customized pre-plated plug/ring gauges are all expensive, which are only needed for components that demand extremely high precision, but not for all components. With the long time CNC manufacturing experience, APPORO suggests to use NO GO of the standard thread gauge for the inspection criterion for threads before plating. That is, the threads could perfectly screw in the NO GO of the standard thread gauge without loosing. After plating, the threads have to pass the standard thread gauge inspections, a.k.a. GO and NO GO inspections.     This inspection is more available for components with plating film under 5um thickness. For components with plating film over 5um thickness, as its plating is for anti-corrosion purpose, and the precision requirement of it is usually lower. Even the ready made standard screws and nuts can be the inspection tools. Or, before plating the threads should be able to screw in the NO GO of the standard thread gauge but slightly loose. And then, the threads should pass the GO and NO GO inspections after plating.     Plating and thread making are common techniques when speaking of CNC manufacturing components. Before and after different procedures, the concern will also be different. APPORO has devoted long time and and much efforts to CNC processing techniques, systematically learning from the processing experience in this field and turning it into application to increase the manufacturing efficiency and yield rates. Should you have any technical questions relevant to controlling size before/after plating, do not hesitate to contact us.     Learn more about thread gauge measurement:   Thread Gauge for instant measurement ...

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