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Servo Motor

 
What Is a Servo Motor?

Servo motor is a general term for a motor that can freely determine its displacement while incorporating an encoder. The word “servo” is derived from the word “servant” (slave), indicating that it operates as specified. Servo motor is often used in robots and processing machines.

Uses of Servo Motors

Servo motors are almost never seen in household applications, but they are widely used in industrial applications.

One example is assembly robots in automobile factories. Servo motors can be used to assemble a large number of parts quickly and accurately.

Robots with servo motors are also used for painting and welding in automotive plants. Depending on the program, they can reproduce the same motions accurately and quickly.

Precision industrial equipment, such as semiconductor manufacturing equipment and medical devices, also requires high repeatability and accuracy. Many servo motors, both large and small, are used in production equipment.

Principles of Servo Motors

Permanent magnet synchronous motors are the most widely used small AC servo motors in use today. A synchronous motor consists of a rotor, stator, bearings, and a casing.

The rotor of a permanent magnet type synchronous motor has a permanent magnet attached to it, and the stator winding surrounds the rotor in a circular pattern. Wires connected to the stator windings from the outside conduct alternating current to the stator windings.

The stator winding becomes an electromagnet when the current flows through it. As the AC current changes phase with frequency, the electromagnet also changes polarity with time.

The rotor, on the other hand, rotates in response to the phase change of the stator because the polarity of the permanent magnet is fixed. This is the principle of rotational operation of servomotors.

Most servomotors are small in size and capacity. However, induction motors are sometimes used for large-capacity servo motors.

The most important feature of servo motors is that they come with an encoder. The encoder provides feedback of motor displacement to the control equipment.

A dedicated control device is used to power the servo motors. The control device reads the encoder signal and can control the number of revolutions, speed, etc.

Dedicated control devices for servo motors are called servo drivers or servo amplifiers and are sold by motor manufacturers.

Other Information on Servo Motors

1. Difference Between Servo Motors and Stepping Motors

Stepping motors can easily and accurately control the angle and speed of rotation with pulse signals because the amount of rotation is determined by a single pulse. Although the structure is simple and inexpensive, it can be out of synchronization under sudden load and has low torque and high noise level at high rotation speeds.

Servo motors, on the other hand, use a sensor to detect rotation and send feedback signals to the driver. The control signal is compared with the feedback signal and the output is adjusted so that there is no difference, thus enabling fine control.

They rotate more smoothly than stepping motors and are stable, even under high torque, high rotation, or sudden load. On the other hand, motors and drivers are complex and expensive, and since they are controlled by comparison with feedback signals, there is a delay in response to changes in output. Servo motors are used when frequent starting and stopping is required, or when fine control is desired, such as very low speed or reverse rotation. 

2. Servo Motors Torque

Servo motors torque is divided into rated torque and instantaneous maximum torque. Rated torque is the torque output at the motor’s rated output and rated rotation speed. During normal operation, the motor is used at or below this torque.

Instantaneous maximum torque is the maximum torque that can be output in a short period of time, which reduces the time required for acceleration and deceleration. It can generate 3 to 5 times more torque than the rated torque, but continued use of the motor at the instantaneous maximum torque will shorten its service life.

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Laser Module

What Is a Laser Module?

Laser ModulesA laser module is a set of devices that produce a laser light source, which is required for various devices that operate using lasers.

Today, there are many devices that use lasers, and in particular, laser light sources are indispensable for measurement devices, position detection devices, and various sensors. Most lasers used for measurement purposes are blue, green, or red lasers in the visible light range, but there are also lasers used for processing purposes that deviate from that wavelength range, and they are classified from Class 1 to Class 4 according to the degree of danger they pose.

Uses of Laser Modules

Applications of laser modules vary depending on the wavelength, but in general, they are used for measurement purposes, pointers, light sources for DVD pickups, wiring of semiconductor parts, and mark printing on resin materials and other materials.

Red lasers are mainly used in measuring instruments, such as microscopes and interferometers. For this reason, many laser modules that can stably emit red lasers for measurement equipment are now commercially available. Light sources in the visible light range are relatively safe as long as they are not greatly amplified, so they are also used in laser pointers and projectors.

On the other hand, lasers of various wavelengths are used in laser processing machines. Depending on the wavelength, the materials that can be processed and the damage to the workpiece will vary.

Principle of Laser Modules

The principle of the laser module lies in the use of elements suitable for the wavelength and phase of the laser light required, and in the utilization of the physical transition of energy levels of the elements, called induced emission.

To obtain light of a specific wavelength, a medium composed of an element is prepared. When this element lowers its level from the excited state, it emits a certain amount of electromagnetic energy, and a light source with a wavelength corresponding to that energy is obtained.

In order to align the phases of this light source in the laser module, it is necessary to drop the levels of many excited elements at once. This is done by using a physical phenomenon called induced emission. Induced emission is a phenomenon in which, when light equivalent to the energy difference between the excited level and the defined level of the element is incident, the electrons in that area also emit energy in response to the incident light. This phenomenon will result in light of the same phase.

In order to perform many induced emissions at the same time, the laser module is configured to extract a laser light source of a certain wavelength by repeating the cycle of excitation of the entire element to an excited state at once and induced emission.

Other Information on Laser Modules

1. Class Classification of Laser Light Sources

Laser light sources are classified according to their safety management, and are classified according to the stage from Class 1 to Class 4. For example, Class 1 is not a safety issue and no special measures are required, but Class 4 is a high power laser that handles CW of 0.5W or more, and there are concerns about burns and damage to the skin and eyes, even if the light is reflected.

Adequate safety measures, including protective equipment, are required, and products are usually labeled with a warning label corresponding to the laser class. Some products are equipped with protective covers, including interlocks, so that even Class 4 lasers can be handled as Class 1 lasers. 

2. Examples of Laser Module Wavelengths

Laser modules are commercialized in a variety of wavelength values. Visible light is handled with a lower limit of purple around 380 nm and red around 780 nm, depending on the application, and red lasers are widely used for pointer applications and measuring instruments.

On the other hand, a typical example of a laser source for processing applications is the CO2 laser, which has the longest wavelengths of 10.6um and 9.6um.

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Vacuum Furnace

What Is a Vacuum Furnace?

Vacuum FurnacesA vacuum furnace is a furnace capable of vacuum heat treatment processing.

Since the object is heated in a vacuum furnace, the surface of the object can be processed without oxidizing it. Decarburization is prevented and the luster of stainless steel and other materials can be maintained after heat treatment.

Also, because of the high surface cleanliness, bonding of dissimilar metals can be processed cleanly. A major feature of this process is that distortion can be reduced because of the gradual cooling process from heating to cooling.

This processing method emits less carbon dioxide and reduces variation in dimensions and hardness. In some cases, heat treatment is performed in a Vacuum Furnace with nitrogen gas flowing through it.

Uses of Vacuum Furnace

Vacuum furnaces are mainly used for processing metals and semiconductors.

The following are examples of vacuum furnace applications:

The following are also examples of products manufactured in vacuum furnaces:

  • High-grade steels for carbide tools
  • Materials for electronic products such as magnets and capacitors
  • Automotive parts and industrial machinery parts

Metals that require special features are fabricated in vacuum furnaces. Metals treated in vacuum furnaces are characterized by high luminosity, and surface oxidation and impurities can be reduced.

Vacuum furnaces have many advantages, but they also have the disadvantage of high maintenance and initial installation costs.

Principle of Vacuum Furnaces

Vacuum furnaces use a combination of oil rotary pumps and turbo molecular pumps to exhaust the air inside the furnace and maintain a high vacuum. Heating in the absence of oxygen in a high vacuum prevents oxidation.

1. Vessel Material

Stainless steel is generally used as the furnace vessel material; it can be heated to 1,000°C to 2,300°C and is heated by metal heaters such as tungsten, molybdenum, and silicon carbide.

Smaller furnaces are also available in which the object is heated in a tubular furnace made of alumina or quartz glass. Kanthal wire is used as the heater material, and the furnace can heat up to 700°C to 1,600°C.

2. Cooling Method

Cooling methods include natural cooling, gas cooling, and oil cooling. For high temperatures, the vessel is double-layered and water-cooled. High temperatures are measured externally with a radiation thermometer.

In a standard vacuum furnace, heating and cooling are performed in the same chamber.

 Structure of Vacuum Furnaces

Vacuum furnaces perform heat treatment of heat-treated products through the three processes of conveyance, heating, and cooling. There are two main types of furnaces, the “one-chamber type” and the “multi-chamber type,” depending on the type and purpose of the heat-treated parts.

1. One-Chamber Vacuum Furnace

In the one-chamber type vacuum furnace, the operator transfers and places the product to be treated in the furnace, and the heating and cooling processes are performed in a single chamber. Since the heating and cooling processes are performed in the same room, the furnace must be able to withstand sudden temperature differences. Heat-resistant stainless steel or carbon materials are used for the heater and structural components.

Because of its simple structure, the lineup of furnaces is extensive, ranging from small to large sizes. For cooling, natural cooling or inert gas cooling with nitrogen or other inert gases is used to prevent contamination of the furnace interior and heat-treated products. The cooling gas outlet structure and stirring fan enable uniform cooling with minimal contamination.

Therefore, it is suitable for processing products that are sensitive to surface contamination or deformation. On the other hand, the disadvantage is low productivity because the next product to be heat-treated cannot be loaded until the previous treatment is completed.

2. Multi-Chamber Vacuum Furnace

The multi-chamber type vacuum furnace has a structure in which the conveying, heating, and cooling processes are performed in two or more chambers. Heating and cooling are basically completed automatically, as per the settings once the product is fed into the transfer chamber. It is possible to control the temperature in each zone, or to set up multiple heating chambers for small batches and stagger the processing time.

The above innovations can improve productivity. By making cooling in a separate chamber, liquid refrigerants with high cooling capacity, such as oil, can be selected. High cooling capacity can be maintained because the cooling chamber is not heated.

Even metallic materials with low hardenability and sensitive to cooling rates can be cooled to a high level of performance. On the other hand, cleaning is required after heat treatment due to contamination of the treated material by the refrigerant. There is also a risk of distortion and cracking due to the high cooling rate.

Other Information on Vacuum Furnaces

Carbon Components of Vacuum Furnaces

Carbon components such as carbon graphite and C/C composite are used in Vacuum Furnaces. They are used for heating elements, structural materials, and heat treatment jigs.

Carbon materials have high heat resistance, up to 3,000°C. They are lightweight and have a low coefficient of thermal expansion. They are characterized by their light weight, low coefficient of thermal expansion, low deformation due to thermal fatigue, and low heat capacity.

Its light weight allows for increased loading capacity of heat-treated products and reduced setup load. The low deformation resistance also leads to lower running costs. The low thermal capacity and high energy-saving effect provide many productivity-enhancing benefits.

However, a disadvantage is that carbon volatilization during heating causes contamination of the furnace interior and heat-treated parts. The cooling method is also limited to gas cooling only.

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Conveyor Screw

What Is a Conveyor Screw?

Conveyor Screws

A conveyor screw is a conveyor that can transport granular objects by rotating helical screw blades.

It does not have a feeding function, and is a product made specifically for conveying only as a conveyor. Due to its structure, it is capable of transporting at an incline, and is characterized by its resistance to contamination by foreign matter and leakage of transported materials.

Taking advantage of the features of the screw wings, which are shaped like a series of spirals, it is possible to feed two or more substances at the same time and mix and transfer them while agitating, in addition to conveying. It can be used in combination with a feeder to supply a fixed amount, or to cool and heat at the same time.

Conveyor screws are efficient, compact, and can be used as part of a complex process. They are also easily installed and removed, and mobile products are available.

Uses of Conveyor Screws

Conveyor screws are used in a variety of industries for powder conveying applications because of their simplicity of construction and efficiency.

A typical industry is the building materials industry. They are used to mix and transport raw materials such as cement, sand, water, and crushed stone for the purpose of manufacturing concrete. It is one of the main raw materials for concrete and is widely used in construction and civil engineering projects.

In the food sector, it is used to transport agricultural products such as feed and grains. In the mining industry, it is used to transport cement and coal. In some cases, they are used for ash removal from boilers.

In the chemical industry, they are used to transport granulated chemicals. One example is the transport of calcium carbonate from tanks to mixing tanks. They are also used in the pharmaceutical and other fields, where they are responsible for mixing and conveying.

Principle of the Conveyor Screws

The principle of a conveyor screw is a machine that feeds material by rotating a helically bent feed screw (screw). A conveyor screw consists of a screw, housing, and drive unit.

1. Screw (Feed Screw)

The screw is a spiral-shaped part that feeds the material. As the screw rotates, the material is pushed forward.

The screw diameter and pitch (angle of rotation of the screw) are designed according to the type and amount of material to be conveyed. By adjusting the shape and rotation speed of the screw, the amount and speed of material being pumped can be controlled.

2. Housing

The housing is a cylindrical outer shell that covers the screw. It contains the material to be transferred. The shape and size of the housing are designed according to the size of the screw and the type of material to be transferred. The material to be transferred moves inside the housing along the screw’s spiral groove.

3. Drive Unit

The drive unit, such as an electric motor or engine, is used to rotate the screw. The drive unit rotates the screw to feed the material.

In most industrial applications, three-phase induction motors are used. Among three-phase motors, 200V products are most common. By using an inverter or other device, the rotational speed of the drive unit can be varied to change the conveying speed.

How to Select a Conveyor Screw

When selecting a conveyor screw, select the appropriate equipment based on the object to be conveyed and the distance to be covered.

First, the selection should be based on the material to be conveyed, such as powder or granules. In most cases, conveyor screws are used to transport powders, so other transport methods should be considered for liquids and other materials. The shape and material of the screw differs depending on the type of material to be conveyed.

Screw size and housing size also vary depending on the amount of material to be transported. We accurately ascertain the amount of material to be conveyed and select equipment with the necessary conveying capacity.

In addition, the range of application of conveyor screw is relatively short. Depending on the distance to be conveyed, multiple conveyor screws may need to be connected. It is necessary to consider the number and arrangement of the required conveyor screws according to the distance to be conveyed.

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Anchor Screw

What Is a Screw Anchor?

A screw anchor is an anchoring component that utilizes screws for fastening and securing purposes. In construction, anchors are essential for attaching base materials to other materials or for connecting new materials to existing ones. There are primarily two types of anchors: pre-attached and post-attached, with post-attached anchors being specifically referred to as “post-attached anchors.”

Uses of Screw Anchors

Screw anchors are widely used in construction to attach metal components to concrete foundations and structures. Their applications range from installing handrails and column legs in parking garages to bicycle parking facilities, signs, solar panels, vending machines, and water pipes. They also play a crucial role in adding earthquake-resistant features to older buildings, installing protective railings on bridges and roads, fenders and vehicle stops in harbors, and tunnel lighting.

Principle of Screw Anchors

Screw anchors are installed by first fixing the anchor to the base material, then attaching other components to the anchor’s threaded portion. Unlike typical screws that rely on axial force for their anchoring strength, screw anchors generate a fixing force through shear stress between the base material and the anchor. This shear stress arises from the engagement of the screw’s threads with the base material, providing resistance against separation forces.

Other Information on Screw Anchors

1. Types of Anchors

Beyond screw anchors, the construction industry recognizes three major types of anchors: metallic, adhesive, and others. Metallic anchors, including metal diffusion anchors, secure themselves by expanding against the base material. Adhesive anchors are fixed in place by an adhesive agent cured within a pre-drilled hole in the base material.

2. Failure Modes of Post-installation Anchors

Post-installation anchors, including screw anchors, may fail in one of three modes: rupture of anchor reinforcement (yield failure of the anchor), cone failure (failure of the base metal), or anchor pullout. The mode of failure is determined by the weakest link in the anchoring system, whether it be the material strength of the anchor, the strength of the base metal, or the anchorage strength itself.

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Switching Regulator

What Is a Switching Regulator?

Switching RegulatorsA switching power supply (SMPS) is a power supply that incorporates a highly efficient power conversion circuit called a Switching Regulator.

Electronic devices with ICs and microcontrollers require stable direct current with minimal voltage fluctuation. There are two types of regulated power supplies: linear power supplies and switching regulators, but linear power supplies have been the most common.

In the case of linear power supplies, the circuit is simple. It converts a 100 V AC voltage into a constant AC voltage and rectifies the AC current by utilizing the diode’s property of flowing forward current but not reverse current. It further uses a capacitor to smooth it out. However, this had the disadvantage that it did not allow power supplies to be made smaller or more efficient.

Switching regulators have solved this problem. While linear power supplies convert commercial alternating current to voltage and then rectify it, switching regulators do the exact opposite: they rectify commercial alternating current to DC and then convert it to voltage.

Then, by switching on and off, it is converted into pulse wave AC and fed into a high-frequency transformer, which is the mechanism of switching regulator.

The feature of switching power supplies is that they are smaller and lighter, but their circuits are more complex.

Uses of Switching Regulators

Compared to conventional linear power supplies, switching regulators have much more complex circuits, but they have the advantage of being extremely compact due to the use of ICs for the stabilization circuit.

The large and heavy power transformer (a device that uses electromagnetic induction to convert the height of AC power voltage) is not installed, as in the case of a simple power supply, and this has made it possible to reduce the size and weight.

Because of this compactness and light weight, applications for switching regulators include AC adapters for cell phones. They are also highly compatible with small electronic devices such as PCs and tablets, which are often carried around.

Recently, in order to further promote miniaturization, high-power and high-efficiency GaN devices have been incorporated into switching regulators for AC adapters to realize even smaller AC adapters compared to conventional Si devices.

Principle of Switching Regulators

The principle of switching regulators is the opposite of the conventional linear power supply. Linear power supplies use a transformer to convert commercial current to voltage and then rectify it, whereas switching regulators first rectify commercial alternating current to DC and then convert it to voltage. However, once rectified, voltage conversion cannot be performed using a transformer.

Therefore, in switching regulators, the rectified current is converted into pulse-oriented AC by high-speed switching of semiconductor elements such as transistors and MOS FETs, and then fed into a high-frequency transformer. This increases the number of components and circuits required and makes them more complex, but this complexity is the key to switching regulators.

There are several types of control methods for switching regulators, the most common of which is the PWM (pulse width modulation) method. PWM is a method of stabilizing voltage by adjusting the on-time of the switching on/off cycle, or the width of the pulse wave, so that the area of each pulse is the same. Switching regulators can also be said to increase efficiency because the output can be adjusted by switching on and off.

In addition, since the pulses of switching regulators are high-frequency, ranging from tens to hundreds of kHz, the transformer can be small and lightweight. However, high frequencies increase the loss of the iron core, so a ferrite core is used. This improves power supply efficiency and saves energy.

The ferrite core has a core rod made of a material called ferrite that is attached to the cable so that it wraps the cable. This absorbs the magnetic field generated by the high-frequency noise current flowing through the cable and converts it into heat, thereby reducing noise.

The weak point of switching regulators is the generation of noise due to high-speed switching, which is expected to be reduced by ferrite technology.

Other Information on Switching Regulators

1. Frequency of Switching Regulators

Switching regulators convert the output voltage to a specified voltage value by adjusting the ON/OFF time of the switching operation using semiconductor elements. The frequency of the signal that controls this switching is called switching frequency. 

2. Reason Why 24V Voltage Is Often Used

In electrical products that use switching regulators, the output voltage required for the power supply is often 24 VDC. The reason for this is that control circuits require that voltage, although there are various theories.

One theory is that since DC was once often powered by batteries, it was determined by an integral multiple of the 1.5V of a dry cell battery cell. In small devices, 6V, 9V, 12V, etc. are also used, but these are also integer multiples of 1.5.

In the days before PLCs (programmable controllers) replaced control circuits used in factory automation, circuits consisted of electromagnetic relays, and the voltage was used to turn on the relays.

As a remnant of this, 24V is still often used today. There are also other reasons such as the fact that 24 VDC is more resistant to noise environments. 

3. Noise in Switching Regulators

Switching regulators use switching elements to turn current on and off at high speed, so it is inevitable that they generate high-frequency noise.

The history of the development of switching regulators has been one of increasing efficiency and at the same time, noise suppression has been a must. Modern switching regulators are equipped with various noise suppression measures.

Switching regulators are themselves a source of noise. Noise is not only added to the output power line, but also becomes electromagnetic waves that affect electronic equipment.

The following methods are available for noise suppression:

  • Reflection
    Using inductors and capacitors as filters to prevent noise components from being transmitted
  • Absorption
    Absorbing noise with ferrite cores, etc. and converting it into heat or other energy
  • Bypass
    Dropping noise to ground with capacitors, etc.
  • Shield
    Radiated noise components are dropped to the ground with a metal case or absorbed with a ferrite material or other radio wave absorbing material.

4. Detailed Examples of Noise Suppression for Switching Regulators

The most common types of noise are common mode noise and differential noise.

Common mode noise
This is noise that leaks through parasitic capacitance generated between the switching regulator circuit board and the equipment chassis and returns to the power supply side through the GND as a loop path.

Differential Noise
In this case, the noise is current noise from a noise source entering the switching regulator circuit in series with and returning to the power supply side via the power supply line. As the name implies, the direction of each noise current at the positive and negative poles of the power supply is opposite and is also called normal mode noise.

It is called differential noise because the direction of the noise current at the positive and negative poles of the power supply is the same for each.

Generally speaking, common mode noise is the more radiated of the two types of noise, but countermeasures must be taken for both if the allowable noise level is exceeded. The first method is to shorten the cable length of the path or to use stranded cables.

For more serious countermeasures, a noise filter must be added. Choke coils are effective against common-mode noise. A bypass capacitor to ground, called a pass capacitor, is also used. Differential noise suppression is achieved by connecting capacitors between power lines flowing in opposite directions.

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Zirconia

What Is Zirconia?

Zirconia

Zirconia is the generic name for zirconium oxide, an oxide of zirconium.

Its chemical formula is ZrO2, and it is classified as a ceramic. Its extremely high melting point and heat resistance make it suitable as a raw material for cutting and polishing tools and refractories. Zirconia is also used in dental materials and ceramic knives as a familiar example.

Uses of Zirconia

Zirconia has a high melting point and is resistant to chemical erosion, making it suitable as a material for cutting and polishing tools and refractories such as crucibles and furnaces. Zirconia is also used in ceramic knives because of its hardness, flexibility, and strength.

Among zirconia materials, tetragonal zirconia is used as a raw material for ceramics and as grinding balls for electronic components.

Cubic zirconia also has oxygen ion conductivity and is used as a solid electrolyte membrane in fuel cells.

Principles of Zirconia

Zirconium is an element with atomic number 40, and its oxide, zirconium oxide, is called zirconia and classified as a ceramic. At room temperature, it forms the most stable monoclinic crystal structure, but as the temperature is increased, the material changes sequentially to tetragonal and cubic crystals.

Properties of Zirconias

Zirconia (ZrO2) has a melting point of about 2,700°C. It has many features such as low thermal conductivity, heat resistance, corrosion resistance, and high strength. On the other hand, zirconia is susceptible to degradation due to changes in crystal structure and volume caused by changes in temperature.

Oxides such as yttrium oxide (Y2O3), calcium oxide (CaO), cerium oxide (CeO2), and magnesium oxide (MgO) are suitable stabilizers for zirconia. By adding these oxides to react and form a solid solution in the crystal structure, the stable existence of cubic crystals at room temperature becomes possible. Zirconia with a stable cubic crystal at room temperature is called stabilized zirconia or partially stabilized zirconia.

1. Stabilized Zirconia

Stabilized zirconia is a good conductor of oxygen ions at high temperatures due to its high oxygen vacancy lattice. It is also chemically stable and is being investigated as a solidification base material for high concentration TRU waste.

2. Partially stabilized Zirconia

Partially stabilized Zirconia is generally made by reducing the amount of oxide added compared to stabilized zirconia.

Other Information on Zirconia

1. Dental Applications of Zirconia Ceramics

When 3 mol% yttrium oxide is added to partially stabilized zirconia, Y-TZP (Tetragonal Zirconia Polycrystal), which has almost 100% tetragonal crystals at room temperature, is used as a dental material. Zirconia is a highly hard material, which makes it less workable when fully sintered.

For this reason, zirconia products used for dental applications are generally made by cutting blocks in a semi-sintered state, which is relatively easy to process, followed by full sintering.

2. Zirconia manufacturing method

There are two main methods of zirconia production: wet refining and dry refining. The raw materials for both methods are zirconium ores such as zircon and adelite. The first process in the wet refining method is to melt the selected ores with caustic soda, and then decompose. After further processes such as washing and filtration, the resulting zirconium hydroxide is calcined and pulverized to produce zirconia powder. In the dry refining method, on the other hand, the ore is crushed to remove impurities and then beneficiated repeatedly to produce pure zirconia.

3. The difference between Zirconia and metals

The difference between zirconia and metals is that zirconia is an oxide of zirconium metal, which is a ceramic due to covalent bonds stronger than metallic bonds.

  • Resistance to corrosion
    Metals tend to combine with corrosive elements in the environment, such as oxygen and sulfur, and corrode relatively easily, but zirconium rarely corrodes.
  • High hardness and heat resistance
    Zirconium is formed by covalent bonds that are stronger than metallic bonds, making it extremely hard, strong, and difficult to deform, and its high melting point (1,855°C) also makes it highly heat resistant.

On the other hand, unlike metals, zirconia is not ductile and does not elongate, making it vulnerable to strong impacts, and in some cases, it may crack.

4. Difference between Zirconia and Silica ceramics

Zirconia has become widely used in dentistry in recent years, as mentioned above, because of its hardness, flexibility, and non-corrosive properties compared to metals. However, silica-based ceramics have the disadvantage of being hard but easily fractured when compared to real teeth.

Zirconia is so hard that it is called an artificial diamond, and its hardness is about 10 times that of conventional ceramics, making it extremely durable. However, in recent years, the variations have increased, and in dental applications, it is also being used in front teeth, which requires a high level of aesthetics in dental applications.

5. Disadvantages of Zirconia in dental applications

Although dental zirconia is white in color and esthetic, it is less transparent than silica ceramics, and the lack of color variation has been considered a demerit. Recently, however, the number of variations has increased, and zirconia is now being used for anterior teeth, which requires a high level of aesthetics in dental applications.

However, zirconia is extremely hard, about 10 times harder than ceramics, and if the bite is incorrectly adjusted, it can shave the teeth to which it is being meshed, which is a demerit that needs to be improved. In addition, to its hardness of zirconia, it makes it difficult to process and shape manually by dentists, and because it is shaped by a computerized machine, it is less precise than ceramics.

Finally, another disadvantage is the high cost of treatment. This is due to the high price of high-quality zirconia itself used in dentistry and the fact that it is an out-of-pocket treatment not covered by insurance, but this is a point that should be improved in the future.

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Jumper

What Is a Jumper?

JumpersA Jumper is a generic term for a metal wire, metal terminal, or pin that shorts two points on a breadboard or PCB.

A breadboard is a board on which electronic circuits can be built simply by inserting electronic components and jumper wires into the holes. Each of the electronic components that make up a circuit has a specific role, and these components must be connected correctly for the circuit to work properly.

Jumpers make it easy to directly connect two points on a circuit.

Uses of Jumpers

There are two types of jumpers commonly used: one is a conductor type jumper wire and the other is a set of jumper pins and a jumper switch.

1. Jumper Wire

Jumper wires are used to easily build circuits in combination with breadboards. They are useful in electronic construction because they can be used to build circuits simply by inserting components and jumper wires into holes in the breadboard, eliminating the need for complicated soldering

2. Jumper Pins and Jumper Switches

Jumper pins and jumper switches are two small components that come as a set and are used to switch the circuit operation on the PCB or to expand the functionality of the PCB. The signal connection destination is switched by inserting or removing jumper switches from the jumper pins depending on the application.

This is used not only to switch or expand functions, but also to disconnect circuits with abnormalities. Jumper pins are sometimes called pin headers. A jumper switch is sometimes called a jumper cap.

Principle of Jumper 

Jumpers utilize the property that an electric current flows (short-circuiting) when metals make direct contact with each other.

1. Jumper Wire

A jumper wire is a simple metal wire. The ends are often shaped for easy connection to a breadboard. Some are shaped like sockets to connect to jumper pins on the PCB.

Wires other than the connection part are covered with a vinyl sheath. Typical wiring thickness is about 1 mm. If the amount of current to be handled in a circuit is large, thicker wiring may be used to lower wiring resistance.

2. Jumper Pins and Jumper Switches

Most jumper pins take the form of metal terminals arranged in a regular pattern with a 2.54mm pitch. There are two types of jumper pin structures: the dip structure, which is suitable for inserting into a breadboard or PCB, and the SMD (Surface Mounted Device) structure, which is suitable for surface mounting on a PCB. These two types are used according to the circuit and PCB design policy.

The metal plug is covered by a plastic outer shell, which makes it easy to connect and disconnect with bare hands. Inside the jumper switch is wiring that shorts the jumper pins when they are inserted into two adjacent jumper pins.

Other Information on Jumpers

1. Precautions for Handling Jumpers

Jumpers are useful for testing circuits and creating experimental circuits because they allow you to easily switch circuit operations and add functions. However, if a jumper is set incorrectly, the operation of the circuit may become unstable or malfunction.

When using jumpers, it is necessary to check the expected circuit behavior and appropriate jumper settings every step of the way. 

2. Items on Which Jumpers Cannot Be Mounted

Due to their shape and size, jumpers cannot be mounted on PCBs for consumer devices such as smartphones, which require small size, high density, and low profile. In such devices, PCB designs may be made so that wiring can be switched with 0 Ohm resistors instead of jumpers.

On the other hand, desktop PCs and devices for industrial equipment often have plenty of space, and jumpers are usually installed on the PCB.

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Dispenser

What Is a Dispenser?

Dispensers

A jet dispenser is a device that dispenses a fixed amount of solution from a container. It is also simply referred to as a dispenser.

They are often used in industrial applications, such as applying adhesives to gasket materials or soldering small amounts of solder to electronic circuit boards. However, dispensers for hand washing detergents and alcohol sanitizers are commonly used for household purposes.

Dispensers are also named according to their method. The most common type is the air pulse dispenser, in which the solution is dispensed from a syringe.

Uses of Dispensers

The following are some of the main applications where dispensers are used.

  • Automobiles
    Automotive parts are made up of many components, which are again made of many small parts. When assembling parts such as instrument panels and bearings, dispensers are used to join the parts together.
    Some dispenser molds have a dispensing tip diameter of only a few millimeters so that even the smallest parts can be handled.
  • Electronic parts
    As with automotive parts, many electronic parts are very fine, so dispensers with thin tips are used.
    A typical example is soldering on electronic circuit boards. Conventionally, a method called screen printing has been used. Compared to the past, equipment has become smaller, and more precise parts are required. Since it is difficult for screen-printing to support miniaturization due to the shape requirements, soldering by dispensers is used.

Principle of Dispensers

The principle differs depending on the method, but here we introduce the air pulse method, which is a typical dispenser.

The air pulse system consists of an air source, piping, regulator, controller, and syringe.

First, compressed air is released from the air source. The compressed air travels through the piping to the regulator.

The regulator reduces the pressure of the compressed air and sends the air to the controller at a constant and stable pressure. The regulator is connected to the controller because sending compressed air directly to the controller side would result in damage to the components.

The controller regulates the pressure supply to the syringe. The condition of the supply is set by the operator.

When pressure is applied to the syringe, the solution in the syringe is dispensed.

Although the supply pressure is adjusted by the regulator or controller to be constant, in practice, there is a problem. As the solution in the syringe decreases, the dispensed volume also decreases. To reduce the dispensing volume variation, it is necessary to reset the conditions according to the remaining solution volume.

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Transfer Machinery

What Is Transfer Machinery?

Transfer MachineryTransfer machinery is a general term for equipment used to move goods and materials.

Specifically, there are various types of conveyor, elevator, pipeline, rail, and self-propelled types, depending on the shape and size of the object to be conveyed and the purpose of the conveyance.

Transfer machinery may refer to a single unit, such as a conveyor, a conveyor system integrated into a production system, or a conveyor system integrated into a logistics system, such as a warehouse, factory, or distribution system.

Transfer machinery is generally handled in the factory automation (FA) industry. In many cases, we offer not only single units but also optimal conveying systems for the objects to be conveyed, their contents, installation conditions, and so on.

Uses of Transfer Machinery

Transfer machinery is used to move goods and materials in distribution warehouses for the transportation industry, inventory control warehouses for the mail-order industry, warehouses that handle pickup, packaging, and shipping, production plants, and processing facilities. Movement includes horizontal, elevated, inverted, rotary, and fluidized movement, and conveyor units are used for each of these applications.

If the purpose cannot be achieved by the conveyor unit alone, they are combined and used in a system that performs the desired conveyance.

Principle of Transfer Machinery

1. Conveyor Transport

Conveyor units are available in belt, chain, and roller types. In the belt or chain type, the belt or chain is stretched around a certain section of the conveyor. In the roller type, rollers are placed at regular intervals over a certain section.

The belt, chain, or rollers are then rotated by a motor. By placing the object to be conveyed on the belt, chain, or rollers, the object is moved parallel to the belt, chain, or rollers.

2. Rail Transport

In the case of rail conveyance, rails are installed in the conveyance section. A container equipped with a drive unit is installed on the rail, and the container is driven while the object to be transported is placed inside the container.

3. Inverted Conveyance

In conveyance, it is sometimes necessary to invert the object to be conveyed in order to align the direction of the object. For example, bottles that are lying on their sides may need to be placed upright and their contents placed inside.

In such cases, a mechanism is needed to convey the object while inverting it.

4. Rotary Conveyance

In conveyance, there are cases where it is necessary to rotate the object to be conveyed in order to align the direction of the object. For example, labels on boxes flowing in an indeterminate direction may need to be aligned.

In such cases, a system that rotates the object to be conveyed is required.

5. Lifting and Lowering Conveyance

In some cases, conveyance may require moving an object up and down. For example, the object may need to be moved up and down from the height of a shelf to the height of a conveyor.

In such cases, a mechanism to raise or lower the object to be transferred by machinery is required, and equipment, such as a lifter or elevator, is used. 

6. Pipeline Conveying

In some cases, powder or granular materials are conveyed. For example, food flour or pellets of plastic material are moved in an unpacked state.

In such cases, a pipeline is installed in the conveyance section and gravity or air pressure is used to move the material through the pipeline. 

7. Self-Propelled Conveyance

Transfer machinery includes self-propelled automatic guided vehicles (AGVs), which can be programmed to travel along any route and do not require any transfer equipment along the route.

Therefore, AGVs are used in outdoor locations where it is difficult to set up Transfer Machinery.

Other Information on Transfer Machinery

Difference From Logistics

Although you may see articles that refer to transfer machinery as “logistics,” in reality, transfer machinery and logistics are two different things. Logistics is the centralized management of the entire flow of goods, including procurement, distribution, processing, and shipping.

In contrast, transportation may be a part of that process, but it does not cover the entire scope of the process.