月: 2023年7月

What Is a Durometer?

A durometer is a device used to measure the hardness of materials. It is used especially on non-metallic substances such as rubbers, plastics and elastomers.

Hardness is defined as “a measure of the degree of force exerted by an object on another object to resist it”. There is no uniform unit of hardness, since the force applied by another object varies depending on the purpose, such as bending, elongation, torsion, etc. T

Therefore, different durometers are used for different purposes and for different applications.

The following are typical test methods for hardness:

• Brinell
• Vickers
• Rockwell
• Knoop
• Shore
• UCI (Ultrasonic Contact Impedance)

Hardness between different test methods cannot be compared as is. By using a hardness conversion table, they can be compared relatively.

Uses of Durometers

1. Hardness Testing by Indentation

• Brinell Hardness Tester
  Measurement is made with a microscope or other optical device. It can handle higher loads (up to 3000 kg) than other measuring instruments and is suitable for large samples with rough surfaces.
• Vickers Hardness Tester
  This is measured by an optical device such as a microscope. In contrast to Brinell hardness measurement, in which the hardness value obtained varies depending on the test load even if the same indenter is used, Vickers hardness measurement is superior in that the influence of differences in test load is almost negligible. It can measure a wide range of samples, from soft to hard, and is used for clinical testing, especially in the field of dentistry.
• Rockwell Hardness Tester
  Unlike Brinell hardness testers and Vickers hardness testers, Rockwell hardness testers can measure quickly without optical equipment. Diamond conical indenters are mainly used, but steel or cemented carbide balls are used when measuring relatively soft samples such as soft steel, malleable cast iron, copper alloys, and aluminum alloys. They are mainly used to measure heat-treated steel materials.
• Knoop Hardness Tester
  Suitable for measuring light loads of a few grams, and used to measure cracks and coatings on ceramics and other materials.

2. Hardness Test by the Magnitude of Rebound of Hammers, Etc.

• Shore Hardness Tester
  This tester can measure without damaging samples and is easy to operate. No power supply is required, and since it is compact and portable, large structures such as rolling rolls and railroad rails can be tested on site.

3. Other Testing Methods

• UCI (Ultrasonic Contact Impedance) Hardness Tester
  The principle of UCI hardness measurement is based on Vickers hardness measurement. It has a smaller indentation mark than other test methods and can be used for thin and delicate parts. On the other hand, it is also used for large samples that are portable and cannot be moved.

Principle of Durometers

1. Principle of Brinell Hardness Measurement

A spherical indenter is pressed against a sample for 10~15 seconds, and the surface area S (mm2) is calculated from the test load F (N), indenter diameter D (mm), and dent diameter d (mm) to obtain the hardness.
Brinell Hardness (HBS) = 0.102 × (test load F/indentation surface area S)
 = (0.102 × 2F)/{πD(D-√(D2-d2)}

2. Principle of Vickers Hardness Measurement

A diamond pyramid indenter with a facing angle of 136° is pressed against the sample, and the surface area S (mm2) is calculated from the test load F (N) and the diagonal length d (mm) of the indentation to obtain the hardness.

Vickers hardness (HV) = test load F/indentation surface area S
 = 2Fsin68°/d2 = 1.854 F/d2

3. Principle of Rockwell Hardness Measurement

A diamond cone indenter with a 120° apex angle is pressed against the sample in the order of (ⅰ) to (ⅲ)

Hardness is measured from the difference in indentation depth between( ⅰ )and (ⅲ).
It is necessary to select a load at which the indentation depth is less than 1/10 of the sample thickness.

4. Principle of Knoop Hardness Measurement

A diamond square-weight indenter with diagonal angles of 172°30′ and 130° is pressed against the sample. The indentation is calculated from the surface area S (mm2) obtained from the test load F (N) and the long side diagonal d (mm) of the indentation.
The same testing machine is used as for Vickers hardness measurement.
Knoop hardness (HK) = 14229F/d2

5. Principle of Shore Hardness Measurement

A diamond hammer is dropped at right angles to the sample and the hardness is measured by the height of the rebound. The harder the sample, the higher the rebound.
Eutectoid carbon steel is used for hardness between 30 and 95 HS, and super eutectoid carbon steel for 100 HS.

6. Principle of UCI (Ultrasonic Contact Impedance) Hardness Measurement

A diamond indenter is pressed against a sample for approximately 0.5 seconds at a specified load. The resonance frequency that changes at this time is electronically read to measure the hardness.

Durometers for Metals

There are various types of durometers, some of which are suitable for certain materials and others for others. The following are examples of hardness durometers used for metals:

• Brinell hardness is mainly used to evaluate the average hardness of materials with inconsistent metallurgical structure, such as castings and forgings. It leaves relatively large measurement marks. It is also necessary to polish the measurement surface of the specimen prior to measurement.
• Rockwell Hardness is used to evaluate the surface hardness of heat-treated materials at the site of heat treatment of steel materials. This measurement method is suited for measuring relatively large materials and has little measurement error due to differences in the measurers. Various indenters are available according to the combination of reference load and test load.
• Vickers Hardness is used to evaluate hardness and coating hardness after surface hardener treatment, and to evaluate the cross section of welding materials and welding conditions. It also has the advantage that the same measuring element can be used regardless of the material of the specimen.
• Shore hardness is used to measure the hardness of metal materials after quenching, tempering and nitriding. Measurement of large materials is also possible.

Portable Durometer

Handheld hardness testers are available for measuring the hardness of sponges, rubbers, and plastics.

Portable hardness testers for metals are also available, although they are simpler than the simple tabletop durometers. The same indenter is used for the same type of measurement method, and multiple hardness units can be displayed by conversion.

What Is a Drill Grinder?

A drill grinder is a type of grinding tool that specializes in grinding drill tips.

There are two types of drill grinders: drill pointers, which grind the end face, and thinning machines, which grind the web.

One manually applies the drill to the grinding wheel when grinding and one automatically performs grinding when the drill is set. The fully-automatic grinding type can be operated even by unskilled operators because it literally sets the drill and automatically grinds everything.

Uses of Drill Grinders

Drill grinders are mainly used to regrind drills that have been used.

The tip of a typical drill is at 118 to 120 degrees, which when viewed from the side has less cutting resistance.

If the center of the tip’s thinning is off-center, the hole will not be drilled straight and in some cases the drill will break. Therefore, it is necessary to use a drill grinder to accurately grind the drill according to the type of thinning.

Recently, the number of 3-blade drills has been increasing, and there are CNC fully automatic tool grinders that can grind these.

Principle of Drill Grinders

Drill grinders are maintenance machines that use grinding wheels to grind and polish the cutting edges of used drills, thereby restoring the sharpness of the cutting edges and allowing the drills to be reused.

There are different types of drills, such as mountain drills, candle drills, one-letter drills, and chamfer drills. Most drill grinders that can grind according to those shapes are simple in construction, small, and portable, but some are fully automatic drill grinders, machines that can automatically grind a variety of drill shapes. The best grinder should be selected based on the drill shape and application.

Grinding wheels are selected according to the drill material. Tungsten carbide and titanium coated drills mainly use diamond grinding wheels, while HSS drills mainly use CBN grinding wheels.

NC tool grinders are also available with detailed settings for tip angle, thinning angle, compensation value, and grinding amount. These machines can grind end mills and other tools other than drills.

What Is a Limit Thread Gauge?

A limit thread gauge is used to check screw dimensions, and is available for both male and female threads. The inspection result is not a numerical value, but a pass/fail judgment based on whether the workpiece thread passes through the gauge or not.

Both for male and female threads, a set of two gauges is used to check both the upper and lower limits of the standard. The inspection points are the effective diameter (thickness of the thread) and outer diameter (diameter at the top of the thread) for male threads, and the effective diameter and inner diameter (diameter at the top of the thread) for female threads. Gauges to check the effective diameter look like screws and are used in combination with workpiece screws.

Inspection gauges are also used to check the wear limits of these gauges.

Uses of Limit Thread Gauges

Limit thread gauges are used by manufacturers and users to check bolts, nuts, and other threaded products.

If the manufactured threads and thumbscrews are within the allowable limit dimensions, interchangeability is ensured in the field of use, even if the manufacturer of each part differs. Conversely, if the screw threads do not fit, the screw threads cannot be assembled, or the tightening strength is insufficient, leading to part breakage.

Inspection gauges are also used to check whether the wear of limit thread gauges exceeds the wear limit. If the limit thread gauge is worn too much, the manufacturer’s and user’s results may differ. To avoid problems, it is important to control the amount of wear of limit thread gauges.

Principle of Limit Thread Gauges

Thread dimensions of limit thread gauges are made to the tolerances specified for each nominal size and grade.

The effective diameter of a thread is the diameter of the hypothetical cylindrical part where the width of the thread peaks and troughs are equal. The gauge used to check the effective diameter is manufactured so that it contacts only the flank (the sloping part of the screw thread that forms the crest and valley) of the workpiece screw, avoiding the top of the crest and the bottom of the valley, so that it is possible to determine if the effective diameter is within the standard.

The outside diameter of a screw is the diameter at the top of the screw thread. Plain ring gauges have a cylindrical inner diameter with no threads and are dimensioned to check the outer diameter of the male thread.

The inside diameter of a female thread is the diameter of the top of the thread. Plain plug gauges have a cylindrical outer diameter without threads and are sized to check the inside diameter of the female thread.

Since limit thread gauges are used by screwing them into the screw to be inspected, they are used in a manner that is prone to wear. Therefore, they are made of hard materials with excellent wear resistance. Gauges are made of bearing steel, alloy tool steel, cemented carbide, etc., depending on the gauge manufacturer. Some gauges are coated with TiN or DLC to improve wear resistance. The appropriate option is selected according to the frequency of inspection and cost.

What Is a Pinhole Inspection Unit?

A pinhole inspection unit is a machine that inspects packaging materials for pinholes. A pinhole is a hole the size of a needle in a packaging material, or a very small hole on a painted surface of an exterior wall after construction, as if an air bubble has collapsed.

The characteristics of pinholes are that they can be inspected in a nondestructive state, which facilitates re-inspection and pursuit of the cause of defects, and that they can be inspected even when bubbles are present in the product.

There are also pinhole inspection units that can even pinpoint the location of pinholes.

Uses of Pinhole Inspection Units

Pinhole inspection units are used in the manufacture of products that are familiar to us in our daily lives. For example, they are used in the manufacture of food products that contain a lot of liquid, such as jelly, pudding, milk cartons, sausages, etc.

In addition to food products, it is also used in the manufacturing process of household products such as detergent, toothpaste, and shampoo, as well as in the packaging of blood and infusion solutions used in the medical field and in the packaging of eye drops.

However, as will be discussed in more detail below, the principle may not be applicable to packaging materials with low insulation properties and low conductivity contents.

Principle of Pinhole Inspection Units

Pinhole inspection units are designed to determine the presence or absence of pinholes by occurrence or absence of electrical discharges when high voltage is generated in a circuit with electrodes placed at a certain distance from each other.

Normally, the air between two electrodes placed far apart is destroyed when the voltage of the high-voltage generator connected to both electrodes is gradually increased, resulting in a discharge phenomenon that causes the loss of electrical insulation. Plastics used for packaging materials generally have higher insulation properties than air and can withstand stronger voltages (dielectric breakdown voltage) than air can be destroyed, and no electrical discharge phenomenon occurs when a product without pinholes is passed between the electrodes. However, when a product with pinholes is passed through the electrodes, the insulation withstand voltage causes a discharge, which can be detected by the detector by sensing the change in electric current.

For products that are filled with gas to maintain quality, a type of inspection unit that checks for pinholes by detecting gas above a standard concentration is used.

Other Types of Pinhole Inspection Units

There are different types of pinhole inspection units, including discharge-type inspection, which inspects for the presence or absence of electrical discharge due to high voltage, each of which corresponds to the material and characteristics of the item to be inspected.

The main types of pinhole inspection include the following:

• Sheet pinhole inspection unit: Inspects pinholes in paper, film, and other sheet-like samples flowing on the line using a CCD camera (line camera).
• Ultrasonic inspection: Ultrasonic waves are generated when compressed air is injected into a container to be inspected and a pinhole is found. The ultrasonic tone is used to detect pinholes.
• Radiation transmission inspection: Used to inspect pinholes in welds of stainless steel, mild steel pipes, etc. X-rays are used to transmit through the inspected area, and an image is acquired by an X-ray receiver. The image is transmitted through the inspected area using X-rays, and the image is acquired by an X-ray receiver. The image is then processed by an image processor to detect pinholes.
• Airtightness inspection: There are two types of inspections: submersion inspection, which detects pinholes by checking whether bubbles appear on the surface of the water when the container to be inspected is filled with gas and submerged in a water tank, and foam inspection, which uses a foaming liquid that reacts to pinholes and causes bubbles to form.

Pinhole inspection units use cameras and image processing equipment, and automate the process of inserting gas. Pinhole inspection equipment can accurately perform inspections that are limited by visual checks.

Importance of Pinhole Inspection Units

Pinholes can be caused by small impacts on sheet materials such as paper and film, such as when they are caught on an overhang or by friction due to vibration during transportation. In welded metals, pinholes can also be caused by a decrease in gas solubility or gas entrapment.

If pinholes are left unattended, corrosion can start from the pinholes and lead to damage to the object. In the case of containers, the contents may leak out, or conversely, contaminants may enter the container from the outside and affect the contents.

Therefore, even the slightest pinhole must be detected, and pinhole inspection units play an important role.

What Is an Industrial Vacuum Cleaner?

An industrial vacuum cleaner is a vacuum cleaning machine, with a higher suction power than household machines. They are used in industrial settings where there is a need for powerful and efficient cleaning.

In appearance, it is a lid-shaped device with a hose connected to it. It is in close contact with a pail that serves as a collection container and performs its suction function by allowing compressed air to pass through it.

An industrial cleaner is easy to handle, compact, low-cost, and maintenance-free. They can operate independently without a compressed air supply line. However, on the downside they are much more expensive and require regular maintenance.

Uses of Industrial Vacuum Cleaners

Industrial vacuum cleaners can suction a wide range of materials, whether solid or liquid.

As for solids, the likes sand, metal chips, dust, wood chips, and resin pellets are suction targets. The system is used to collect chips in machining shops, sand and chips in foundries, and pellets in injection molding machines.

Liquids such as water, oil, and sludge can also be used for this purpose. The applications include oil change and sludge recovery from various machines, recovery of oil and muddy water in manholes and ditches, recovery and replacement of punching debris and hydraulic oil in presses, recovery of sludge in car washes, and recovery of sand and iron balls in shot blasting machines.

Principle of Industrial Vacuum Cleaners

The industrial vacuum cleaner can be used indoors or outdoors, wherever a supply of compressed air is available. First, compressed air is passed through the cleaner and then discharged from the ejector. This creates negative pressure inside the cleaner, including the pail, and the object is sucked in through the suction nozzle.

The cleaner and the pail are tightly sealed to ensure stable suction. Therefore, it is important that the rubber gasket connecting the two fit tightly into the groove of the rubber packing. Therefore, depending on the size of the collection container, an appropriate model should be selected.

The lineup of commercially available products ranges from those for tens of liters to those for open drums of 200 liters. The appropriate operating air pressure to be applied to the ejector is 5 to 6 kg/cm2. Pressure and vacuum have a proportional relationship. Therefore, if the pressure is too low, the ejector will not provide sufficient suction power. If the pressure is too high, the container may be crushed.

What Is a Helical Reducer?

A helical reducer is a device that reduces the rotational speed of a motor or other device by means of gears.

The teeth of normal gears are engraved parallel to the axial direction of the gear (called spur gears), whereas the teeth of helical gears are engraved at an angle to the direction of the gear’s rotational axis (called helical gears).

Compared to spur gears, helical gears have the advantage of improved gear meshing.

Uses of Helical Reducers

Compared to spur gear reducers, helical reducers are mainly used for final reduction gears in automobiles, because the gears in the reducer mesh more tightly with each other, resulting in higher torque and less noise.

In addition to automobiles, reduction gears are also used to drive screw propellers on ships and propellers on aircraft.

Reduction gears are also indispensable for conveyor belts, assembly robots, elevators, escalators, and other equipment used in factories.

Principle of Helical Reducers

The reason why helical reducers can achieve higher torque and power transmission than ordinary spur gear reducers is that the diagonal teeth improve the meshing ratio.

In addition, since the teeth of helical gears are engraved diagonally, several gear teeth mesh with each other at the same time.

This allows the gears to mesh more smoothly with each other, resulting in a more quieter operation.

Furthermore, helical gears have a higher surface pressure strength than normal spur gears, making them more durable gear reducers.

Although helical gears have many advantages, there are also some points that must be considered.

For example, helical gears generate a thrust force in the direction of the gear’s axis of rotation when the diagonal teeth mesh with each other.

If this thrust force is not taken into account, it can cause wear and rotation problems in gears and reduction gears.

There are several ways to solve this problem, but the most common is to install special bearings to avoid thrust forces.

In addition, the use of double helical gears, in which opposite helical gears are arranged at the same time, counteracts the thrust force on the gear mechanism.