月: 2023年7月

What Is a Torque Wrench?

A torque wrench is a wrench that allows you to check how much force (torque) you have tightened a bolt. Industrial products, including automobiles, have regulations on how much force is required to tighten bolts, and bolts must be tightened with the specified torque when assembling products.

When replacing automobile tires, it is often the case that the bolts are tightened with the appropriate force using the wrench that comes with the automobile.

Usage of Torque Wrenches

For mechanical products that use bolts to fasten parts, the amount of force (torque) required to tighten bolts is always considered at the time of design, and parts must always be tightened to the torque specified at the time of assembly.

If bolts are tightened with less torque than the specified torque, the bolts may loosen in the worst case, leading to product failure or a serious accident. If a bolt is tightened with more force than the specified torque, the bolt may break, which may also lead to a serious accident.

Principle of Torque Wrenches

Torque wrenches can be mechanical or digital, depending on the display of the measured value. The most typical mechanical type is the preset type. In the preset type, the torque value to be tightened is set before tightening a bolt, and when the bolt is actually tightened, a sound and response indicates that the bolt has been tightened with the set torque. After this sound is heard, the bolt cannot be tightened with any more torque.

A plate type torque wrench is also widely used for mechanical type. The preset type Torque Wrench measures the torque by compressing the spring, while the plate type Torque Wrench can measure the tightening torque by observing the amount of tilt of the metal rod (wrench itself) when the bolt is tightened. The plate type torque wrench is simple in structure and has few moving parts, so it can be used for a long time. However, since it is necessary to read the scale while tightening torque, the operator may not be able to read the measured value alone, depending on the angle of the bolt.

Digital type torque wrenches use a sensor to measure torque, but since the torque setting and measured value can be displayed on a digital display, they are more accurate than mechanical type wrenches.

How to Use a Torque Wrench

When using a pre-set type torque wrench, adjust the size and tightening force according to the size of the target bolt or nut in advance. When the pre-set torque value is reached, the wrench will vibrate to indicate the end position of the nut.

When a digital type is used, the screen displays the torque value that is currently being tightened. Therefore, fine adjustment of tightening can be made. As with the preset type, it is also possible to give a sound or light signal at the torque value you have set.

How to Choose a Torque Wrench

The following are things to keep in mind when selecting a torque wrench.

Torque Value

Torque wrenches have different ranges of measurable torque values depending on the product. If the torque wrench is used beyond the measurable torque value, it may cause damage or loss of accuracy. Conversely, using a torque value that is too small for the measurement range will also reduce measurement accuracy.

Applications

For tightening various nuts with different torque values, the adjustable pre-set type is recommended. On the other hand, a single-purpose Torque Wrench is recommended for tightening nuts with the same torque value over and over, such as tightening wheel nuts.

Required Accuracy

Torque wrench accuracy is higher with digital wrenches, some of which can achieve an accuracy of 1 Nm, so a digital type is recommended when high accuracy is required. However, digital type torque wrenches are more expensive than preset type torque wrenches, and there are disadvantages, such as the possibility of running out of battery power.

What Are Nitrile Rubber Gloves?

Nitrile rubber gloves are gloves made of nitrile rubber.

They are also called synthetic rubber gloves. They do not cause latex allergies and can be used by those who cannot use natural rubber gloves. Nitrile rubber gloves are used for detailed work because they fit the hand easily.

They are also more durable against organic solvents than natural rubber gloves, making them ideal for work that involves contact with oil. Nitrile rubber gloves also have excellent strength. On the other hand, they are not as stretchable, so there is a possibility of tearing when they are stretched.

Uses for Nitrile Rubber Gloves

Nitrile rubber gloves are used for cleaning, general medical work (limited to non-sterile work), oil work, painting, scientific experiments, and other detailed work. Because of their high resistance to organic solvents and glove strength, they are also used in manufacturing, plating, oil handling, and machine maintenance.

Nitrile rubber gloves are also used in the food industry because of their suitability for detailed work with the hands and the low risk of contamination of additives from the gloves, unlike PVC gloves.

Principle of Nitrile Rubber Gloves

Nitrile rubber gloves are made of nitrile rubber, a general-purpose rubber made from the copolymerization of acrylonitrile and 1,3-butadiene. Like natural rubber, it does not contain latex, so it can be used by people with latex allergies.

However, its disadvantage is that it loses flexibility at low temperatures, becomes hard, and is easily damaged. Working outdoors in cold temperatures for long periods of time or storing Nitrile rubber gloves at low temperatures is undesirable because it accelerates deterioration.

Nitrile rubber gloves are also resistant to common organic solvents, acids, and alkalis, but not to ketones such as acetone or ethers, such as tetrahydrofuran. Nitrile rubber gloves that come in contact with low-resistance organic solvents are prone to shredding and should be replaced immediately in the event of damage.

Other Information on Nitrile Rubber Gloves

1. Food Hygiene Laws

Nitrile rubber gloves do not contain phthalates as raw materials, and thus meet the standards for food, additives, etc. Phthalates are known to be toxic to the human body, including reproductive toxicity. Their use is restricted in some countries.

Nitrile rubber gloves are also available in many blue products. This is to make it easier to detect the presence of gloves in food when using nitrile rubber gloves for food preparation. 

2. Powder-Free Nitrile Rubber Gloves

Some glove products, such as nitrile rubber gloves, are coated with a powder to facilitate putting on and taking off. The powder is composed of magnesium hydrosilicate powder called talc or cornstarch (starch obtained from corn, etc.). Powder on skin can induce dermatitis and allergies in rare cases, which is why a shift to powder-free gloves is underway.

3. Delayed Onset Allergy to Nitrile Rubber

Nitrile rubber can cause allergic contact dermatitis, a delayed allergy. It tends to occur hours to days after contact, and symptoms include itchy eczema, erythema, edema, papules, dryness, cracking, and roughness of the hands. The causative agents are said to be vulcanization accelerators and anti-aging agents.

What Are Welding Glasses?

Welding glasses are a type of medical glasses designed to block light in the short wavelength band (500 nm or less) and allow other light to pass through. Since light with a wavelength of 500 nm or less is a cause of glare, effectively blocking such light with color filter lenses makes life more comfortable. Sunglasses are also available as glasses to reduce glare.

Welding glasses, but sunglasses are fashion-oriented and have insufficient light-shielding functions, such as making the wearer appear darker in dark places. Welding glasses, which provide appropriate contrast adjustment, are a different matter.

Uses of Welding Glasses

Welding glasses are used as medical glasses to reduce glare. In particular, they are used to support the comfort of patients suffering from cataracts, glaucoma, retinitis pigmentosa, and age-related macular degeneration. In addition to this, they can also be used by those who are prone to glare and difficulty seeing and by workers in the field where harmful light is generated.

There is a wide range of lens colors available, so it is necessary to select the most appropriate color lenses after confirming the actual feeling of use. Some colors may not be suitable for daytime or nighttime driving.

Principle of Welding Glasses

The following explains the principle behind welding glasses, which cut-off wavelengths of light of 500 nm or less. Light with a wavelength of 500 nm or less, including bluish-white light and ultraviolet light, has a high energy content and is easily scattered. The extremely easy scattering causes glare and glare that makes the outline of an object blurred and unclear. This phenomenon is called contrast reduction. Light-shielding lenses suppress this phenomenon by cutting off only the bluish-white light of 500 nm or less, thereby enhancing contrast.

Welding glasses cut wavelengths of 500 nm or less, but there are also lenses that cut wavelengths of 400 nm or less, each with different characteristics.

• Welding Glasses That Cut Wavelengths of 500nm or Less (CCP)

General welding glasses cut wavelengths of 500 nm or less. They are reasonably priced and can be used like sunglasses.

• Welding Glasses That Cut Wavelengths of 400nm or Less (CCP400)

CCP400 glasses allow moderate transmission of wavelengths in the 400-500 nm range, allowing for a more comfortable field of vision, while completely blocking light of 400 nm or less, thus maintaining glare reduction and improved contrast. A wide range of color variations are available, making them ideal for people who want to lead a more comfortable life.

Prices of Welding Glasses for Medical Use

The price of welding glasses for medical use varies depending on the purpose of use, such as single vision, double vision, bifocal, or polarized lenses. Based on the price of the lens for each purpose of use, the price is largely determined by the functionality added to the lens.

Welding glasses can be publicly subsidized as a prosthetic device.

The three necessary conditions are as follows:

• That photophobia is noted.
• No treatment is preferred over the use of welding glasses for the reduction of photophobia.
• The selection and prescription must be made by an ophthalmologist as stipulated in the administrative guidelines for the provision of prosthetic devices.

It should be noted that it is a prerequisite that Levels 6 to 1 of visual impairment are approved. The application must be made by a physical disability certificate holder.

An eligible person who meets these conditions receives a written request for judgment at the welfare office and submits a medical judgment form and an estimate for welding glasses. They will have these exchanged for a prosthetic device issuance ticket and submit it to the optician together with the prescription. After that, the applicant will receive the welding glasses made.

Welding Glasses for Nighttime Driving

The way light enters the eyes differs between nighttime and daytime. When driving at night, we experience a strong glare from the headlights of oncoming cars. Therefore, the required welding glasses must have lenses that suppress glare but do not interfere with nighttime driving.

To make this possible, colored lenses that enable nighttime driving have been developed. Welding glasses are available with brown, yellow, and green lenses, respectively.

The brown and yellow lenses can be used not only at night but also at all times by wearing spectacles with power lenses. Green lenses do not offer the same nighttime visibility as brown and yellow lenses, but can be expected to reduce flickering when using a computer.

The development of welding glasses using these colored lenses has enabled the development of glasses with visibility in the dark and light shielding properties that reduce the glare of light.

What Is an Induction Test Pencil?

An induction test pencil is a device that checks voltage. Unlike a tester, it cannot check the voltage value.

Induction test pencils can be used to check the voltage by simply placing them on the charging path to be investigated. Induction Test Pencils are available for low voltage, high voltage, alternating current, and both AC and AC-DC, so it is necessary to distinguish between these types. It is also necessary to know whether the charging circuit is AC or DC.

Induction Test Pencil Usage

Induction test pencils are used to check for no-voltage in the charging path.

In the case of low-voltage electrical work, it is used to verify that there is no voltage at the relevant terminal block immediately before any work is done. In the case of high-voltage, after opening the power supply with a circuit breaker or disconnecting device, the electric inspection is carried out at the lower charging section of the circuit.

Induction test pencils for both AC and DC are required to check for residual charge after the circuit breaker is opened.

Induction Test Pencil Principle

Induction test pencils these days are often equipped with a lamp that glows or emits a sound when a voltage is detected.

These mechanisms use an internal amplifier to amplify the minute electrical signals detected and emit a sound or light through a built-in battery. To detect an electric current, it is necessary to create an electric circuit, which is a closed loop, because electricity must flow. Induction test pencils detect the electricity in the charging section and create an electric circuit using the ground capacitance between the Induction Test Pencil and the detector (human).

Ground capacitance is the capacitor component between an object and the ground. In a DC circuit, once a capacitor is charged, it stops conducting electricity and becomes an insulator. For this reason, when conducting current detection in a DC circuit, voltage detection is no longer possible after a certain period.

In the case of AC circuits, however, the capacitor repeatedly charges and discharges, so it does not become an insulator and can continue to detect voltage.

What Is an Eye Bolt?

Eye (Denden) bolt, also called hinged bolt or lot bolt, refers to a bolt whose bolt head is shaped like a ring. It is said that they are called Denden bolts because they look like toy Denden drums.

Although they are similar in shape to eyebolts, Denden bolts have a smaller ring on the head and cannot be used for suspending like eyebolts.

Denden bolt materials include iron, stainless steel, S45C, SUS316L, SNB7, and titanium.

Uses of Denden (Eye) Bolts

Denden bolts, also known as hinge bolts or swing bolts, are used as adjusters. They are set horizontally and secured by inserting a rod or pin into the hole, with the threaded part swinging.

It can also be used for lifting objects, but this is not its intended use. Since it is not a bolt for lifting, it is not required to be strong even by the standard.

Incidentally, it cannot be used for hanging purposes. When you want to hang an object by hooking it in a hole, use an eyebolt.

Principle of Denden Bolt

Denden bolts are available in a variety of thread diameters and lengths, and are highly versatile bolts that can be used for suspending lightweight objects in addition to adjusters (although this use is not recommended).

Although steel ones are inexpensive and easy to obtain, stainless steel ones are superior in terms of strength. However, there are few situations where special strength is required for Denden bolts, and it can be said that the demand for stainless steel Denden bolts is increasing due to their superior corrosion resistance and hygiene.
The surface treatment includes common plating such as Uni-Chrome (bright chromate plating) and Trivalent White (trivalent chromium chromate plating).

Eye bolts, which have a similar shape, are used for the purpose of lifting heavy objects, so their load capacity must be checked as an important safety component. However, since Denden bolts are not used for lifting and suspending purposes, there is no such standard. Although Denden bolts can be used as a substitute for eyebolts in some situations, they are only used for lifting objects that are light enough, and are not recommended since they may break.

What Is an Anti-Vibration Mount?

Anti-vibration mounts are materials that absorb harmful vibrations generated during the operation of equipment and components and prevent them from being transmitted to the outside by supporting or sandwiching them between elastic materials such as rubber.

Vibrations generated by equipment and facilities can lead to sound damage to the equipment itself, and damage to surrounding parts, which can be reduced by using anti vibration mounts. In addition to equipment damage, anti-vibration mounts are used to improve user comfort by reducing vibration and shock.

Uses of Anti-Vibration Mounts

In building components, vibration isolator mounts are used to support various types of piping, outdoor units of air conditioners installed in buildings, elevators, and for floor vibration isolation.

In transportation equipment such as automobiles, they are used to mount engine suspensions, drive units, and other equipment to improve passenger comfort.

They are used as platforms for precision measuring and inspection instruments that do not tolerate vibration, such as high-magnification microscopes, surface roughness meters, and electronic balances for analysis.

They are also used in electronic equipment and home appliances to protect electronic circuit boards and components that are vulnerable to vibration.

Principle of Anti-Vibration Mounts

Anti-vibration mounts are inserted between a vibration source and an object subject to vibration. Elastic materials such as rubber, silicon, and urethane used in an anti vibration mount temporarily store the vibration energy generated by the equipment by deforming themselves, preventing the vibration from being transmitted directly to the object. To reduce the transmitted vibration, it is necessary to consider the natural frequency (number of vibrations per unit time) of the object.

Since an object will not vibrate significantly when shaken at a frequency far outside its natural frequency, the transmission of vibration can be reduced by separating the natural frequency, which is determined by the spring multiplier of the anti-vibration mount and the mass of the vibration source, from the object’s natural frequency.

The main purpose of anti-vibration mounts to reduce vibration is to avoid resonance by changing the natural frequency, which is determined by the mass of the object and the spring strength of the anti-vibration mount.

What Is a Bearing Roller?

Bearing rollers are either assembled with bearings and a hollow shaft or with bearings and a built-in bolt in the center.

Those assembled with a hollow shaft mainly insert the shaft in the center and use the bearing outer diameter as the guide section.

Those with a bolt built into the center section are mainly used by inserting the shaft into a tapped hole and using the bearing outer diameter as the guide section.

The guide part is used as a workpiece transfer guide or as a roller for transfer.

Similar parts include roller followers and cam followers that both use needle bearings in the bearing section.

Uses of Bearing Rollers

Hollow shaft rollers have a hollow shaft inserted into the bore of the bearing and can be fixed at any position on the shaft. Uses are as follows:

• Multiple bearing rollers on a single shaft and multiple parallel shafts of such rollers are used as rollers for workpiece conveyance.
• Two bearing rollers are placed on one shaft and used as tensioners by pressing a thin-film workpiece by the outer diameter surface of the bearing.

Those with built-in bolts have a structure that can be easily fixed by inserting bolts into the inner diameter portion of the hollow shaft and into the tapped holes. Uses are as follows:

• Use as a guide for workpiece conveyance by arranging several bearing rollers at equal intervals, like guardrails.
• Two bearing rollers are installed at an arbitrary distance in the same direction, and a thin film or belt is passed through the rectangle connecting the outer diameters of each roller to be used as a tensioner to hold the roller from the outside.

Principle of Bearing Rollers

For hollow shafts, a ring material with a hole in the center is inserted into the inner diameter of the bearing, and a retaining ring is assembled at the inserted end. The shoulder of the ring material and the retaining ring restrain the width of the bearing so that the bearing will not come loose from the ring material. The ring material can be tightened by bolts or by other means to reduce the inner diameter, allowing the bearing to be secured at any location on the shaft.

Because it uses bearings, it rotates smoothly even under high loads and at high speeds.

For those with a built-in bolt, the bolt is built into the inner diameter of the hollow shaft. Since the head of the bolt has a hexagonal hole or the like, it can be easily mounted in any desired location by machining a tapped hole in the part where you want to mount it.

In addition to the type in which the ring material is inserted into the inner diameter of the bearing, another type is available in which the ring material is press-fitted into the outer diameter of the bearing.

The outer diameter of the ring material can be made into a groove or a convex radius to create a tensioner or guide suitable for the shape of the workpiece.

What Is a Sealant?

A sealant is a paste material used to fill gaps in buildings to keep them waterproof and airtight.

Sealants are usually stored in tubes or cartridges and are applied by attaching the container to a special gun. Sealants can be either one-component (all components are pre-mixed) or two-component (the two components are mixed together at the time of use).

One-component systems can be moisture cured, dry cured, or non-hardened, while two-component systems are mixed reaction cured. Various polymers such as silicone and polyurethane are used as raw materials.

Uses of Sealants

Sealants are mainly used for repairing, maintaining confidentiality, and remodeling buildings. For example, silicone sealants are used in bathrooms and kitchens, and modified silicone sealants are used on exterior walls.

One way to prevent cracks in siding during remodeling is to fill the joints with a sealant in advance. Sealants are also used to secure printed circuit board components, seal connectors, and insulate electrical appliances.

Principle of Sealants

Sealants are composed of raw material polymers, additives for curing, and additives for adjusting various properties, such as viscosity. Various types of raw polymers are used, such as silicone, modified silicone, polyurethane, and acrylic, depending on the curing mechanism.

The characteristics of sealants vary depending on the raw material polymer. For example, polyurethane-based sealants are characterized by extremely high durability and elasticity after curing. Upon release from the tube, the sealant is a soft paste.

One-component products cure when exposed to moisture in the air (moisture cure type) or when dried (dry cure type), while two-component products cure when the two pastes (base and hardener) are mixed together. There are three stages in the curing process of sealants:

1. Surface Hardening

This is the state in which the sealant does not string when touched by hand. The surface of the sealant has not hardened completely.

2. Membrane Hardening

The surface has completely hardened. At this point, it is possible to paint over the sealant.

3. Complete Hardening

The inside of the sealant has hardened completely, and the strength of the sealant has been obtained.

Types of Sealants

The characteristics and installation methods of typical sealants (silicone, modified silicone, and urethane) are described below. When installing, the curing time must be observed, or the sealant may fail. Curing time differs depending on the type of sealant, so care should be taken.

1. Silicone Type

Most commonly used in general households around water. It has excellent heat and cold resistance and cost performance. The disadvantage is that it cannot be painted over.

After the silicone-based coating is applied, 0.5 mm of the surface hardens in about 1 hour. After about 8 hours, 2 mm of the film is cured, and after about 24 hours, 3 mm of the film is fully cured.

At the film-hardening stage, the caulking can be used around water. In other words, baths and kitchens can be used approximately 8 hours after caulking.

2. Modified Silicone Type

This is a sealant used outdoors. Unlike silicone type, it can be painted on top.

About 2 hours after casting, 0.5 mm of the surface hardens. After about 24 hours, 2 mm of the film is cured, and after about 72 hours, 3 mm of the film is fully cured.

Although it takes time to fully cure, once the surface is cured, there is no need to worry even if it gets wet. Also, it is safe to apply water-based paint after about 1 hour and oil-based paint after about 12 hours.

The reason why there is such a time difference between water-based and oil-based is that when oil-based is used, the silicone-based must cure at least 70%.

3. Urethane Type

Urethane is a sealant used outdoors. It has excellent adhesion and elasticity. Since it is weak against ultraviolet rays, it is used on the assumption that it will be painted when used outdoors.

0.5mm of the surface hardens in about 2 hours after it is cast out. About 3 days later, 2 mm of the film is cured, and about 7 days later, 3 mm of the film is fully cured.

This type requires even longer time than the modified silicone type. However, urethane sealants are used in large-scale construction sites such as mortar exterior walls and concrete caulking.

Other Information on Sealants

How to Store Excess Sealant

Ideally, all sealants should be used up in a single installation. However, there are cases when there is inevitably a surplus. If you have any excess sealant, first cut the tip of the sealant to the size of the installation area.

At this point, it is important to store the excess tip without discarding it. After the installation is finished, turn the stored tip upside down and insert it into the nozzle. At this time, insert the tip firmly to prevent air from entering and sealant from leaking through the gap. Finally, use tape to keep the nozzle in place, being careful of air and gaps.

Sealant hardens when exposed to air. Therefore, it is important to store the sealant properly so that it will not be unusable the next time it is installed.

What Is a Ball Screw?

A ball screw is a mechanical component consisting of a screw shaft with a helical groove (or peak), a screw nut, and a ball. 

It represents a mechanism for converting linear motion to rotational motion, or vice versa, and rotational motion to linear motion. The rolling motion of the ball screw between the threaded screw shaft (shaft) and the screw nut results in a highly efficient feed screw.

In this case, “screw” does not mean a screw for fastening parts, but a different way of using the threaded part.

Uses of Ball Screws

Ball screws are used in a variety of applications, including machine tools, semiconductor manufacturing machinery, and industrial robots.

For example, ball screws are used in numerically controlled machine tools called NC (numerically controlled machining) to configure the feed mechanism and obtain precision positioning accuracy. Ball screws have also long been used in steering gears that move the front wheels by the steering wheel of automobiles. Today, ball screws are also used in machines in various fields such as food equipment, medical equipment, and printing equipment, as well as for vehicles such as automobiles, trains, and airplanes.

Principle of Ball Screws

In a ball screw, a screw shaft (shaft) with screw-shaped grooves (or mountains) is called a ball screw, and when it is rotated, a ball engages the screw and the screw nut containing the ball moves left to right (or up and down). The screw nut is attached to the part or component to be moved to obtain the required motion.

A ball screw is a mechanical component that receives only an axial load and converts rotational motion into linear motion. The ball screw causes the required component to move linearly in the axial direction, and the axial load is applied to the screw shaft via the screw nut. Other loads (vertical loads, moment loads, etc.) must be supported by the guide rail.

Therefore, a linear motion mechanism that includes a ball screw consists of a ball screw + guide rail + power source (motor).

The ball screw uses tribology (friction control technology) in which a ball is placed between the screw shaft and the screw nut to allow it to roll lightly. Because the balls must circulate infinitely, a circulation component is essential in addition to the screw shaft, screw nut, and balls. Circulation methods include the following:

• Return tube type
• End deflector type
• End cap type
• Return plate type

Uses are divided according to size and precision, with small-diameter sizes mainly used in the precision field, and larger sizes mainly used in machine tools and conveying machinery.

What Is a Torsion Spring?

A torsion spring (torsion coil spring) is a spring that uses the repulsive force generated by the distortion caused mainly by the torsion moment.

Torsion springs are used by winding in a coil, but they may also be used by unwinding a coil.

Common everyday uses of torsion springs include clothespins.

Uses of Torsion Springs

Torsion springs are used in the following applications.

1. Opening and Closing Mechanisms of CD and DVD Drives in Personal Computers, Etc.

When the lid of a CD or DVD player is lightly pushed by hand, it is used in the mechanism that opens by recoil. Therefore, it can be opened and closed without turning on the power of the main unit.

Simply placing a spring eliminates the need for space for a motor.

2. Reclining Seats in Cars, Buses, Etc.

There is a mechanism to adjust the angle of the seat by pushing it with the back, and when the angle is returned to the original position, the force of the torsion spring is used to return the seat without pushing it by hand.

Principle of Torsion Springs

Torsion springs are the same coil spring, but there is a difference in the energy generated when the spring deflects.
A torsion spring is subjected to a torsion moment with the center of the coil as its axis.

In other words, compression coil springs and tension coil springs store torsion elastic energy in the material, while the torsion springs store bending elastic energy.

Therefore, torsion springs are used by exerting force in the rotational direction, while compression and tension coil springs exert force in the linear direction.

In designing a torsion spring, the number of coils, angle, inner diameter and length are determined.

The gap between the coils may or may not be tight, but when it is tight, resistance due to wear will cause torque variation.

A guide rod is placed on the inner diameter of the torsion spring, and the outer diameter must be selected so that the guide rod does not rub against the inner diameter of the coil (approximately 90%). (The outer diameter should be approximately 90% of the inner diameter.)

Torsion spring arms can be straight or bent, and are selected according to the environment in which they will be used.