月: 2022年12月

What Is Glue?

Glue is a material used to join substances together.

There are various types of glues, and they are selected according to the materials to be joined, the temperature at which they are used, and the time it takes for them to cure. The conditions under which glue cures also vary.

For example, some adhesives vary greatly in curing time depending on differences in temperature and humidity. In addition to the commonly known one-component glues, there are also two-component glues that cure by mixing the main agent and curing agent.

Uses of Glues

The main use of glue is to join objects together. Glues can bond various types of materials, such as metal, plastic, wood, glass, ceramics, stone, paper, cloth, leather, rubber, and foam, by selecting the appropriate adhesive for the application and object.

Common applications include machinery and automotive manufacturing, construction, electronics manufacturing, aerospace industry, and medical device manufacturing. They can also be widely used in home DIY and repair work, and in craft manufacturing.

Principle of Glues

Glue principles include mechanical, chemical, and physical interactions.

Mechanical Interaction
Glue penetrates into the pores and crevices of a material’s surface, where it cures and forms.
Chemical interaction
Glue and the object to be bonded share electrons between atoms, i.e., a chemical reaction that forms a covalent bond between the atoms.
Physical interaction
Glues are joined by intermolecular attraction, called intermolecular force or van der Waals force, which occurs when Glue and the object to be glued come close to each other on an atomic level.

Glues will function by combining one or more of these three types of interactions. Since impurities such as dirt and oil on the surface of the object can interfere with adhesion, the surface must be cleaned before bonding.

Types of Glues

Glues can be classified according to composition, shape, curing principle, and application. Below are cases classified by their curing principle.

1. Dry-Setting Glue

Glue is made by dissolving a solid adhesive component in a solvent. When the solvent evaporates from the glue, the glue solidifies, and the objects are bonded to each other. Generally, dry-setting glues are relatively inexpensive and easy to use, but they have the disadvantage of a strong solvent odor when organic solvents are used.

Woodworking glue is another type of dry-setting glue. This is a water-based emulsion of vinyl acetate resin. Because the solvent is water, it takes longer to cure, but it has the advantage of having almost no odor and being environmentally friendly.

2. Reaction Curing Type Glue

This is an adhesive in which a chemical reaction proceeds when the adhesive is removed from the container, applied to the object, and pasted together, causing the glue to harden and develop adhesive strength. Glues include two-component epoxy adhesives, one-component epoxy adhesives, and cyanoacrylate adhesives known as instant adhesives.

Two-component glues have excellent storage stability because the curing reaction is initiated when the main glue and curing agent are mixed. On the other hand, heat-curing glues and moisture-curing glues such as cyanoacrylate require careful attention in the storage environment because the curing reaction may occur in the container due to summer heat or moisture absorption. 

3. Light-Curing Glue

Light-curing adhesives are adhesives that cure by light. Irradiation with light, such as ultraviolet light, generates reactive radicals and ions, which initiate polymerization of the monomer, causing the Glue to harden. In the sense that they cure by chemical reaction, they can also be called reaction-curing glues.

UV-curable glues are used to bond tiny parts in electronic and optical devices. In addition to ultraviolet light, other light sources that trigger reactions in light-curing glues include visible light and electron beams.

4. Hot-Melt Adhesives

Hot-melt glues are melted by heating to bond objects together and then hardened by cooling to form a bond. This method has the advantage of high productivity due to the short time required for Glue application and curing. It is also considered environmentally friendly because it does not contain solvents.

Hot-melt type glues are available in stick-like stick, granular, and film forms, depending on the shape of the adhesive. Stick-shaped sticks of hot-melt glue are generally inexpensive and easy to use. On the other hand, granular and film-type hot melt glues require the use of specialized equipment and are relatively expensive, but the adhesion is more precise.

What Is a Polyurethane Elastomer?

Polyurethane elastomer, a synthetic rubber, is known for its excellent elasticity and rigidity. This polymer, characterized by urethane bonds, stands out for its superior mechanical strength and abrasion resistance, allowing for long-term usage. The properties of polyurethane elastomers vary significantly based on material composition and bonding methods.

There are two main types: polyester urethane rubbers (AU), which have ester bonds in the main chain, and polyether urethane rubbers (EU), with ether bonds. AU is known for its excellent oil resistance and mechanical strength but is susceptible to hydrolysis. Conversely, EU offers better resistance to hydrolysis and superior water resistance but has lower oil resistance and mechanical strength compared to AU.

Uses of Polyurethane Elastomers

Polyurethane elastomers are versatile, and used in applications like rolls, tires, conveyor belts, and sports shoe soles. Their abrasion resistance makes them ideal for belts in factories. However, caution is advised in acid or high-humidity environments due to potential deterioration. The material’s high elasticity is particularly beneficial in sports shoes, highlighting the wide range of applications achievable by varying the material composition and manufacturing process.

Causes and Countermeasures for Polyurethane Elastomer Degradation

Factors such as light, heat, oxygen, water, and microorganisms contribute to the degradation of polyurethane elastomers in natural environments. Light and heat can cause oxidative decomposition, breaking urethane bonds and degrading physical properties. Countermeasures include adding UV absorbers or antioxidants. Water-induced degradation, especially in polyester urethane rubbers, involves hydrolysis of urethane bonds. This can be mitigated by incorporating carbodimide compounds. Microbial degradation, often due to fungi, is more pronounced in polyurethane than other polymers. Polyester urethane rubber, in particular, is vulnerable, with degradation mechanisms often involving hydrolysis by microorganism-produced esterases.

Types and Manufacturing Methods of Polyurethane Elastomers

Polyurethane elastomers’ properties vary based on their types and manufacturing methods. The synthesis typically involves a polyaddition reaction between polyol, like glycol, and diisocyanate. The primary manufacturing methods are as follows:

Miracle Type

This common method involves forming a dough from raw materials, and then pouring and pressing it into molds. It’s straightforward and efficient but has drawbacks such as susceptibility to hydrolysis and variable material properties.

Thermoplastic Type

Also known as the injection method, this approach uses resin processing techniques. Polyurethane elastomer pellets are heated, melted, and injected into molds for molding. It’s cost-effective but requires expensive equipment, making it suitable for mass production.

Castable Urethane Type

In this method, liquid polyurethane elastomer is mixed with a curing agent and vulcanized in the mold. The resulting cross-linked polyurethane molecules provide high elasticity. This method is favored for its inexpensive setup and ability to process complex shapes, though it has lower manufacturing efficiency due to longer production times.

What Is a Hydraulic Accumulator?

A Hydraulic Accumulator is a device that converts the pressure energy of a fluid into other high-pressure fluid energy and stores it. It is mainly used in hydraulic and steam fluid equipment.

There are different devices in different technical fields depending on what is stored or accumulated. For example, in the computer field, accumulators temporarily store calculation results and are used for the next calculation; in the electric power field, storage batteries and accumulators; and in wind power generation, systems that circulate oil between windmills and generators to maintain balance.

In hydraulic and steam systems, the pressure energy of oil or steam is stored as nitrogen gas or steam pressure energy, and the gas is expanded to release energy when needed.

Uses of Accumulators

Accumulators are often used in hydraulic systems and steam boilers. In hydraulic systems, accumulators are installed in the high-pressure circuit leaving the pump, and the high hydraulic pressure during operation compresses the nitrogen gas sealed in the Accumulator. When the hydraulic pressure drops, the force of the nitrogen gas is used to raise the hydraulic pressure and maintain it.

In the boiler system, the steam accumulator stores the heat value of steam as high-temperature, high-pressure saturated steam when there is a surplus of steam, and delivers steam with reduced pressure when necessary. In addition, the boiler can operate efficiently and stably because the accumulator absorbs the imbalance between the time variation of steam usage and the steam generation of the boiler.

The use of accumulators in water pumps also softens sudden pressure fluctuations during shutdown and prevents water hammer. The main purpose is to use the energy of the stored gas in the accumulator’s container as an auxiliary power source in an emergency. It is also effective in absorbing and buffering impact pressure, buffering pressure rise in the pipe, and reducing wasteful power consumption of the system.

Principle of Accumulator

Gas accumulators mainly use nitrogen, which is pressurized and contracted or expanded to transfer energy in and out. In the case of hydraulic systems, accumulators are installed in the high pressure circuit leaving the pump.

Inside the Accumulator is a bag called a bladder, which separates the oil side from the gas side. Nitrogen gas is sealed in the bladder, and when the hydraulic pump is driven and the hydraulic pressure rises above the nitrogen gas pressure, the nitrogen gas is compressed.

When the pressure in the hydraulic system drops or the pump stops, the pressure energy of the nitrogen gas causes the bladder to expand to maintain hydraulic pressure. This also has the effect of reducing pulsations in the hydraulic pressure.

The bladder, which seals the nitrogen gas inside the container, is made of a rubber-based material that expands and contracts. The container is made of carbon steel, stainless steel, aluminum, or synthetic materials that are free from corrosion.

The capacity of the container ranges from 0.5 to 450 liters, and the maximum allowable pressure is about 990 atmospheres.

Bladder-type accumulators are characterized by fast energy release and the ability to store and release energy in fast cycles as needed. In addition, the equipment can be made compact, and maintenance is easy.

Other Information on Accumulators

1. Gases in Accumulators

Nitrogen gas is often used as the gas that stores energy in accumulators. Nitrogen gas is a nonflammable and inert gas, which prevents deterioration of the metal used in accumulators. Another advantage is that it is inexpensive and has no risk of explosion.

Since the pressure of nitrogen gas gradually decreases with repeated operation, it is necessary to periodically inspect the accumulators to ensure that the pressure has not decreased. If accumulators are used in the suspension, a drop in gas pressure will make it impossible to absorb shocks from the road surface, resulting in a poor ride quality. If the pressure is low, replenish nitrogen gas. 

2. Car System Using Accumulators

Accumulators are used in automobile suspensions and brakes. Accumulators, which act as gas springs, are used in special-purpose vehicles with large body weights and multi-axle vehicles, for which springs may not be able to absorb the shock. In addition, hydraulic suspensions using accumulators can raise and lower the vehicle body freely.

Accumulators are used in brakes to recover energy during braking. In hybrid vehicles, when energy is recovered by the motor, there is a discrepancy between the braking force required by the driver and that of the accumulator. To resolve this discrepancy, accumulators properly assist the motor to ensure optimal braking force.

What Is a Caulking Gun?

A caulking gun is a tool used to continuously apply small amounts of caulking material (also called sealant or sealant material) to fill various gaps.

It is called a caulking gun because it resembles a gun in shape, requiring the user to pull and hold a lever with a finger to dispense the caulking material.

Uses of Caulking Guns

The caulking material used to fill gaps in concrete or tile is often loaded in a cylindrical interchangeable container. One of these bottoms is formed by a conical nozzle, and the other by a raised-bottom surface.

The caulking gun is used to push this raised-bottom surface and dispense small amounts of caulking material from the nozzle.

Principle of Caulking Guns

Caulking guns can be broadly divided into the following three types

Manual Type

• This is the most common and inexpensive type and does not use power.
• By pulling out the rod that holds the container, setting it, and gripping the lever, the latch that pushes up the bottom of the container moves forward one frame at a time, pushing out the caulking material.
• The lever must be held at all times while the caulking material is being ejected, and a certain amount of grip and skill is required to apply an even amount of caulking material.

Electric Type

• The electric type has a small battery-operated motor that pushes the caulking material out, so it can dispense a consistent amount of caulking material regardless of the hardness of the caulking material.
• It is shaped like a gun and is used by pulling the trigger with the finger, so it uses very little force.
• The disadvantages are that the central unit is more expensive and heavier than the manual type.

Pneumatic Type

• This type uses compressed air to push out caulking.
• It is lighter than the electric type and more stable than the manual type.
• The disadvantage is the need for a compressor to make compressed air and to work with a connected hose.

Recommendations for Choosing Caulking Guns

Sealing is an essential part of the gap-filling process. Caulking guns were initially tools used in construction work and plumbing. In recent years, however, DIY has become popular and used in ordinary households.

Therefore, a novice handling a caulking gun for the first time may be at a loss as to which caulking gun to choose. Here are some recommendations for selecting a caulking gun to avoid making a mistake in choosing to caulk.

A typical sealant cartridge contains a 330 ml capacity. If you are working over a large area, you will need more cartridges. If you need a large amount of sealant, a large cartridge with a 600 ml or 800 ml capacity is suitable. We recommend that you purchase a caulking gun that is compatible with those cartridges.

Functionality is also an essential factor in choosing a caulking gun. If the caulking gun has a rotating body, it can be used in areas that are difficult to seal. Another advantage is that it eliminates the need to change posture or hold the gun in different positions depending on the area to be worked on, which improves work efficiency.

Dripping can cause the sealant to adhere to unexpected places and waste sealant. This is very inefficient and a cause of failure. Caulking guns that prevent dripping instantly release the pressure on the sealant by releasing the trigger.

The type of caulking gun determines other methods. Categorized as manual, electric, or pneumatic, caulking guns vary in price, lightness, and weight. To avoid mistakes, choose the right caulking gun for you.

How to Wash Caulking Guns

When sealant adheres to the caulking gun, it hardens. Therefore, it cannot be removed by ordinary washing with water. However, if you leave it as it is, the hardened solids will get in the way, and you may not be able to set the sealant the next time you work with it.

To wash the caulking gun, first, use disposable rubber gloves. This is because kerosene and solvents are suitable for removing sealant. Solvents, in particular, can be dangerous in direct contact with the skin.

Be careful to be safe and keep your caulking gun clean.

What Is a Grease Gun?

A grease gun is a tool used to lubricate bearings that support parts involved in the rotation and reciprocating motion of equipment with grease.

Grease is used to smooth rotation and reduce friction and is a semi-solid mixture of liquid lubricant and a thickening agent.

Certain cartridge types load easily with greases, such as flexible types with a bendable nozzle, manual types, rechargeable types, and air types used in connection with air equipment.

Uses of Grease Guns

Grease guns are used for machine maintenance and greasing in various fields such as machinery, construction, heavy equipment, agriculture, and production plants.

Examples of use are as follows

• Greasing of construction machinery
• Removing working oil and other oils from old machinery
• Greasing of tractors and other agricultural machinery
• Automobile maintenance and motorcycle greasing
• Grease replenishment maintenance of turret punch presses
• Grease up power gates and air jacks
• Maintenance of forklifts and other heavy machinery for greasing
• Grease-up of hub bearings of boat trailers
• Grease replenishment of food production machinery
• Greening piece of motor/actuator of solar system tracker

Principle of Grease Guns

Grease guns are available in two types according to the grease setting method: cartridge type and manually filled into a cylinder, and grease capacities vary from 80g to 500g. The cartridge type is often used because it keeps hands clean when replacing grease and can be refilled easily, but its disadvantage is that there are few types, and they are expensive.

When you insert the tip of the nozzle of a grease gun or attach it to the grease inlet (grease nipple) of a machine that is blocked by a steel ball, push the pistol lever of the grease gun, oil enters the machine by pumping action.

Use a straight metal nozzle when the inlet port is close to the machine. Use a flexible hose nozzle when the distance or angle is significant so lubricant can be applied regardless of the machine’s inclination.

After completing the work, remove the grease gun by tilting the tip and releasing the internal pressure.

Use the manual type when injecting a small amount of grease into a narrow space and the air type when injecting a large amount at high pressure into a large machine. The rechargeable type is convenient for injecting grease quickly into places with no power supply.

What Is a Temperature/Humidity Chamber?

A temperature/humidity chamber is a device or system used to maintain a constant temperature and humidity.

These chambers are essential for testing product durability and reliability across various industrial sectors. They primarily simulate extreme climatic conditions to evaluate a product’s longevity under typical usage scenarios.

Uses of Temperature/Humidity Chamber

Temperature/humidity chambers serve various purposes. Below are some common applications.

1. Laboratories and Research Facilities

Controlled temperature and humidity conditions are crucial for scientific research and experiments. These chambers are widely utilized in biology and chemistry labs to ensure precise environmental settings.

2. Manufacturing

Some manufacturing processes of products and materials demand consistent temperature and humidity levels. These chambers are employed in sectors like food processing, pharmaceuticals, and electronics manufacturing.

They are also beneficial during development, quality assurance, and production. They are particularly used for testing quality degradation in raw materials, food products, and, in the automotive industry, for component testing.

3. Warehouses and Storage Facilities

Controlling temperature and humidity is crucial for storing certain items. These chambers help preserve the quality of products, preventing spoilage and degradation. They are used for storing food, and wine, and protecting museum exhibits.

4. Medical Facilities

Hospitals and medical facilities often need stable temperature and humidity conditions. These chambers are critical for maintaining cleanliness and safety, such as in operating rooms and for infection control. They are also used for culturing plants and microorganisms.

Principle of Temperature/Humidity Chamber

Temperature/humidity chambers comprise temperature control, dehumidification, internal circulation, and control devices. The temperature/humidity controller inputs settings, while sensors detect and adjust environmental changes.

Refrigeration units and heaters finely control temperature and humidity, humidifying or dehumidifying as required. To maintain uniform conditions, a sirocco fan or other air circulation devices ensure a stable environment.

Various control devices are available, including those with multilingual displays and LAN connectivity for internal monitoring and test control. They can send email alerts during abnormalities and offer remote monitoring capabilities.

Types of Temperature/Humidity Chamber

Temperature/humidity chambers offer temperature control from -20 °C to 180 °C, humidity control from 5 to 98% rh, and capacities from 120 to 1,000 L. They come in various models, allowing selection based on temperature, humidity range, and capacity.

1. Steam Temperature/Humidity Chamber

Steam temperature/humidity chambers, a common humidifier type, heat water to generate steam, which is then dispersed into the air to raise humidity. Fans or blowers aid in distribution.

They typically include a heating element and a water tank. The heater warms the water, turning it into steam, efficiently generating vapor. This direct heating allows for a rapid increase in humidity.

Some models have safety features that automatically shut off if they run out of water or overheat, enhancing user safety.

2. Drying Temperature/Humidity Chamber

To reduce humidity, these chambers use refrigeration cycles or dehumidifiers. The cooling cycle cools the air, condensing moisture, which is then removed, releasing dry air.

Dehumidifiers absorb moisture to lower humidity. They need periodic removal or regeneration to maintain efficiency.

Unlike standard chambers, dry temperature/humidity chambers may lack a humidification feature to increase humidity.