Perpetual motion machine

Perpetual motion machine
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.

Farewell to Burrs

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.

 

but highly possible to cause burrs at the end of the flat surface.
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.

To manually remove the burrs with pneumatic deburring tool led to the uneven chamfers.
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.
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.

Thread Before and After Plating (Part 2)

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 M13.2×0.3-6H. Then, the threads need to pass the inspections of the enlarged customized M13.2×0.3-6H +0.02/-0mm plug gauge before plating. After plating, the internal threads need to pass the inspections of a standard M13.2×0.3-6H 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.

 

When it comes to manufacture pre-plated thread, we have to leave some room for plating during CNC processing.
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.

 

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

Design Matters (Part 4) – Uneven sheet materials

Uneven sheet materials
Too thin of too thick, uneven sheet materials can be a huge problem.

 

Generally speaking, when it comes to deciding the thickness of sheet materials, the unevenness is often a concern. It then becomes necessary for the sheet materials to have additional thickness, so that we can machine the materials to the required dimensions and at the same time ensure the accuracy of the reference surface and the relative dimensions. Whether the sheet materials are rolled metals or extruded plastics, they all need molds for manufacturing purpose. However, mold precision goes down with time, which could lead to the poor quality of the sheet material surface, as well as the uneven material thickness.

 

Case Study on Uneven Sheet Materials

Recently, APPORO machined a batch of panels by milling, of which mostly are Eurorack & Modular Synthesizers, and delivered them to our Japanese customer. After assembling the panels, they found out the assembly acrylic plates were not completely coplanar with the panels, and turned to APPORO for solutions. APPORO digged into the situation and then figured out it was due to the uneven thickness of the acrylic plates, which resulted in the height gap between the metal panels and the acrylic plates.

 

The uneven thickness of the acrylic plates resulted in the height gap between the metal panels and the acrylic plates.
The assembly acrylic plates were not completely coplanar with the panels due to uneven thickness.

How We Solve Unevenness?

The panels are 1.6mm thickness steel plates with drilled holes, milled grooves, and after powder coating. While the acrylic plates are 3.0mm thickness amber transparent acrylic, of which the outer areas were to milled into 1.4mm in height. Usually, the rest areas with extra 1.6mm lump of the acrylic plates could perfectly match the steel panels. However, only few suppliers provide amber transparent acrylic, and therefore the quality and precision of the molds are not satisfying. Consequently, those so-called materials with 3.0mm thickness are actually with thickness around 2.6-3.2mm, which are of considerably unstable quality. What’s more, even we can find the inconsistent thickness across one plate. After the discussion, our customer agreed to accept the panels with the 1.5-1.8mm gap between the unmilled and the milled surfaces. So, APPORO offered the solutions below for this problem:

1.) Cut the materials into plates from the 3.0mm thickness acrylic sheet materials. Then, checked the thickness of every sheet material, and eliminated the materials with thickness less than 2.70mm and over 3.0mm.

2.) Milled the parts into 1.2mm in height, with at least 1.5mm to 1.8mm lump on the top. So, after the assembly the acrylic sheet might be 0.1mm lower than the panel surface, which could still meet the assembly requirement of the customer.

 

Finally, the technical team of APPORO conquered the difficulties in production, assembly, and etc., helping our customer deal with the tricky situation. Again, APPORO won the trust of our customer and also the opportunities of further cooperation. If you are undergoing similar problems during design or assembly process, send us an email for the technical discussion with APPORO. APPORO will assist you of advancing in the product design.

 

Learn more about the importance of design in CNC manufacturing:

Design Matters (Part 1) – Shrinkage

Design Matters (Part 2) – Coating

Design Matters (Part 3) – Warping

Burr and Deburr

Burr and deburr
Burr and deburr

We probably all heard about this old saying in our lives: “To err is human, to forgive divine.” Of course we are not going to talk about making mistakes and forgiving people here. It is that the saying perfectly matches the topic we are about to discuss this time: burr and deburr. A burr refers to a small piece of material left on the part after processing. No matter what manufacturing method we are using, burrs sometimes are inevitable. Take die casting parts for example, burrs are likely to form on the shut-off surface. Besides, drilling can also result in burrs around the hole.

 

Why we have to remove the burr?

Even though it is small, a burr can possibly result in functionality problem of a workpiece, assembly failure, and even injury of assembly operators or customers. Especially for some parts the surface is extremely critical, burrs will not be allowed. In that way, deburring process will be necessary. Therefore, how to remove the burrs without harming the functionality of the parts then reflects the techniques of a manufacturer.

 

Generally, there are 5 kinds of different deburring methods: manual, electrochemical, thermal energy, cryogenic, and mechanical. Among these 5 methods, manual deburring is most common process as it is more cost-effective. Here, APPORO has a case study on manually deburring the die casting parts.

 

Case study on deburring the die casting parts

There is a zinc die casting project that APPORO has been cooperating with one customer on for several years. According to the drawing of this item, there is a hole with slope end on the shut-off surface. So, this design increases the possibility of having burrs on its edge. Because APPORO already noticed that situation, when we moved to the mass production process, we always examined every part carefully and removed the burrs on it. The customer has always been content with the quality all this time.

 

To remove the burrs by chamfering
Burrs were aroound the end of the hole

 

However, recently the customer placed an order of these zinc die casting parts again. After the die casting process, we used tumbling to remove the burrs, and then reamed the parts so the dimensions could be within the tolerance. However, when we were inspecting the parts, we found out that the parts were still with burrs. Because the burrs were around the hole end, we knew the root cause was that the reamer had already worn down. As a result, we changed the reamer instantly and deburr the parts again by chamfering. The situation was thus well solved. Of course, there was no influence on the quality of these zinc die casting parts. And, eventually, our customer was satisfied with them. APPORO pays attention to every trivial detail, so we can always offer the best quality to our customers.

 

Are you looking for a reliable manufacturer that can help produce your parts without burrs? No matter what needs you have, APPORO will strive to meet your expectations. Contact APPORO for a free project review and get a RFQ today!

 

If you haven’t had the drawing for your project, you can also learn more about: How to Make Your Own CAD Drawing?

Design Matters (Part 3) – Warping

Undoubtedly, part warping is a nightmare for both manufacturers and customers. It can affect the functionality of a part or lead to assembly failure. Generally, part warping is due to residual stress, which can be highly relevant to the choice of materials, dimensions of the part, and manufacturing conditions.

 

Warped part can be straightened.
Warped part is mainly caused by the residue stress of the material

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Design Matters (Part 2) – Coating

Thickness of Coating do play an important role on functionality of the part.
Coating do play an important role on functionality of the part.

Previously on Case Study we discussed material shrinkage as an important factor to be considered in the design before production. Apart from material shrinkage, there are still far more factors you have to be aware of in your design. That being said, devil is in the details. Especially when designing an assembly part, you have to pay extra attention, or assembly failure can be foreseen. Coating then is a topic worth a discussion.

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Design Matters (Part 1) – Shrinkage

Shrinkage is a physical phenomenon mostly happening to molding parts made by plastic injection and die casting.
Shrinkage is a physical phenomenon mostly happening to molding parts.

It is always exciting to carry out new projects. However, before moving on to the production process, you have to make sure that your design already includes all the factors that might have influences on your parts. This time, APPORO would like to share with you how material shrinkage happens, and how it can affect your parts.

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Diamond Knurling Operation on CNC Lathe

Knurling is to feature patterns onto the CNC machined components.
Knurling is to feature patterns onto the CNC components.

As mentioned previously in “Cross Knurling Profile DIN 82-RGV”, knurling is a manufacturing process to feature straight, crossed, angled, diamond-like lines or pattern onto the CNC components. Usually, we use DIN 82 knurling specification standard for most CNC machining cases. If diamond knurling is required, we shall use DIN 82-RGE which is featured with diamond-like 30° cross male knurling. Also, we may consider DIN 82-RGV which is featured with cross knurling pattern as an alternative for customized purpose.

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Effects of CNC Machining on Part Distortion

With recent increase in demand for more ultra precision machining designs for improving performance requirements, we are facing a great challenge in this kind of CNC machining services. Generally speaking, the greatest challenge when machining these components is part distortion. For instance, removing material up to 80 % on CNC machines to produce monolithic components replacing multi part assemblies has become common in aerospace, automobile, precision instrument industries. These kind of components might have similar appearance features such as thin wall, very long length, etc.

What Is Part Distortion?

Part distortion is defined as the deviation of part appearance from original shape after released from the fixture. Generally speaking, distortion could come from several variables such as type of material, inherent residual stresses in bulk material, residual stresses induced from CNC machining, part design, etc. In the most cases, the dominant factor of part distortion is the inherent residual stresses in the part. In general, these inherent residual stresses usually come from different manufacturing processes, i.e. quenching, stretching forging, extrusions, casting, welding, machining, forming, and etc.

CNC Machining Part Distortion
Residual stresses induced from CNC machining may cause parts deforming.

 

How Can I Minimize Part Distortion?

Distortion is a common challenge in manufacturing industrial components. The suggestions to minimize or eliminate distortion shows as below:

1.) The length to thickness ratio of the part design is lower than 10:1.

2.) Pre-heat treating the metal part prior to manufacturing for stress relieve. For instance, the general stress relieve condition for AISI 4340 alloy steel is at 650-670°C for 2hrs, slow cooling furnace.

3.) As per our experience of CNC machining service, distortion increases with the cutter size at constant feed, speed, depth of cut and material removal rates.

4.) Considering that WEDM process involves being fully-submerged, it imposes nearly no stress on the metal part.

 

With optimized manufacturing process flow, we are able to minimizing any deformation on all the CNC machined parts. Also, to select the suitable cutting tools and CNC machining parameters is of utmost importance. Note that the choice of cutting tools size is key to strike the balance between the productivity and geometrical constraints of the component. By the way, you can learn more about:

1.) Larger Corner Radii Reduced CNC Machining Cost

2.) 4 Things That Will Impact Your Manufacturing Costs