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Measurement of Dendrite Arm Spacing (DAS Measurement)

DAS測定について1

1. What is Dendrite Arm Spacing?

Dendrite arm spacing is a measurement method used to evaluate the microstructure of aluminum alloys.

A dendrite refers to a tree-like crystal structure that forms as metal solidifies.

This structure features a primary arm along the main axis and secondary arms that develop laterally, both observed in a branched pattern.

Measuring the distance between the centers of these arms provides an index of dendrite density and morphology.

This measurement is influenced by factors such as the metal’s solidification rate and cooling speed, as well as the distribution of crystalline precipitates.

Measuring dendrite arm spacing has become increasingly important in recent years as it reveals the quality and mechanical properties of castings.

2. Measurement Method of Dendrite Arm Spacing

1. Like typical metallographic observations, it involves preprocessing and can be performed using microscope images.

The main steps of preprocessing are:

1. Cutting
2. Embedding in resin
3. Polishing
4. Mirror finishing
5. Etching with chemicals
6. Rinsing with water
7. Drying with a dryer

→ For more information on preprocessing for metallographic observations, click here.

The preprocessing steps alone require significant effort and time.

Following the preprocessing steps mentioned above, dendrite arm spacing measurement is conducted using microscope or microscopy images.

There are two methods for measuring dendrite arm spacing:

– Secondary Arm Method
– Line Intercept Method

The Secondary Arm Method involves selecting sections where secondary arms are aligned and calculating the average spacing between them.

The Line Intercept Method is used for structures with low directional alignment, such as granular crystals, where it is difficult to select aligned secondary arms. This method involves drawing straight lines across dendrite arm boundaries and calculating the spacing based on the number of intercepts.

Manual measurement of these operations requires considerable effort and time.

Therefore, we will now introduce an efficient method for measuring dendrite arm spacing using the following software.

3. Efficient Method for Measuring Dendrite Arm Spacing Using Software

We introduce an efficient measurement method using the “Image Analysis Software WinROOF Material Option.”

This software can calculate measurement results using the “Secondary Branch Method” mentioned above.

Our microscope cameras are compatible with the “Image Analysis Software WinROOF Material Option,” allowing for measurements within live images.

(Of course, it is also possible to load multiple pre-captured images.)

⇒弊社の顕微鏡用カメラはコチラ

Step 1

Open the interface for dendrite arm spacing measurement and load the image.

It is common to perform this measurement across multiple fields of view (images).

DAS測定について2

Step 2

On the loaded image, use the mouse to set a “measurement line” (shown in the diagram below, within the yellow frame) at the area where you will measure the arm spacing.

Designate the boundaries of the secondary arms as intersections along the set measurement line.

DAS測定について3

Step 3

Click on the boundary between the measurement line and the secondary arms to add intersections. (Automatic detection feature for intersections available.)

DAS測定について4

Step 4

Once intersections are specified for one group of arms, repeat the process by setting measurement lines and specifying intersections for other groups of arms within the field of view.

Real-time measurement information is updated on the screen, allowing you to monitor current dendrite arm spacing values. Switch between images (fields of view) to ensure an adequate number of intersection points are specified.

DAS測定について5

DAS測定について6

Additional Information

Measurement results can also be exported to Excel for further analysis and documentation.

DAS測定について7

4. Conclusion

Specialized inspections like Dendrite Arm Spacing (DAS) measurement often require skilled personnel to conduct visual inspections over extended periods.

By introducing this software,

– Reduction in inspection time due to alleviated inspection burdens
– Standardization of inspections
– Improvement in the repeatability of inspections

These aspects significantly enhance efficiency. Moreover, the software enables smooth generation of evaluation reports, facilitating streamlined result reporting.

Graphite Spheroidization Ratio Measurement

黒鉛球状化率測定　

1. Graphite Spheroidization Ratio

Metal materials are used in various fields, and there are many types of metals. It is essential to select the appropriate material according to the application and purpose. One such metal material is cast iron.

金属材料の一つである鋳鉄。

Cast iron is a composite material in which graphite (a non-metal) is three-dimensionally dispersed within steel. The mechanical properties, such as tensile strength and elongation, as well as physical properties like thermal conductivity, vary depending on the shape of the graphite present. Notably, mechanical properties such as tensile strength and elongation require a graphite spheroidization ratio of at least 80% on average, as observed under a microscope at 100x magnification. Therefore, the graphite spheroidization ratio is a crucial evaluation criterion to ensure tensile strength and elongation.

鋳鉄とは

2. Methods of Analyzing Graphite Spheroidization Ratio

The procedure for analyzing the graphite spheroidization ratio involves the following steps:

1. Preprocessing step: Rough cutting for large samples
2. Preprocessing step: Embedding in resin
3. Preprocessing step: Cutting the sample
4. Preprocessing step: Coarse polishing of the cut surface
5. Preprocessing step: Fine polishing of the cut surface
6. Preprocessing step: Buff polishing for a mirror finish on the cut surface
7. Preprocessing step: Etching treatment with chemicals (burning the surface with chemicals)
8. Microscope observation
9. Classification, counting, and calculation

The preprocessing steps are numerous and time-consuming. For observation, a metallurgical microscope is used, and microscope observation is conducted at 100x magnification. Classification and numbering are performed using the roundness factor standardized by JIS industrial standards.

Using these methods, the area calculation and counting are performed to determine the graphite spheroidization ratio.

黒鉛球状化率を算出

The calculation of the graphite spheroidization ratio in the microstructure is performed as follows:

1. The magnification is set to 100x in principle, and the analysis is conducted over five fields of view to determine the average value.
2. Graphite and inclusions less than 2 mm (actual dimension 20 μm) are excluded from the analysis.
3. Comparison is made using a classification table.
4. The graphite spheroidization ratio is calculated as the percentage (%) of graphite particles with shapes V and VI relative to the total number of graphite particles.

This method is analog, requiring complex and time-consuming tasks. Including preprocessing steps, the process demands significant time and effort, is prone to human error, and makes evaluation challenging.

3. Improving the Efficiency of Graphite Spheroidization Ratio Analysis

We propose a method using graphite spheroidization software. This approach involves capturing clear images of spheroidized graphite under a microscope and analyzing them with software. The analysis adheres to the aforementioned calculation methods through image processing. Various shapes and sizes of spheroidized graphite can be identified in the images. Additionally, the software can automatically measure the area and count the graphite from these high-resolution images. Moreover, the software can export the static images and precise values in an Excel format, streamlining the entire process of report creation.

For more details on the graphite spheroidization ratio measurement software, please refer here.

Graphite Spheroidization Ratio Measurement Software (Nippon Steel Technology Co., Ltd.) KKS04

4. An Efficient Set for Analyzing Graphite Spheroidization Ratio

Recommended for those who need to analyze large cast iron samples, prefer portability, and want a simplified method for measuring the graphite spheroidization ratio!
● Set includes a compact, easy-to-use metallurgical microscope with a camera, and graphite spheroidization ratio measurement software.

Compact and Portable Metallurgical Microscope KKKI-STD6-130DN

● Easy observation of large cast iron samples
● Compact and portable design for convenient use

小型簡易金属顕微鏡

Graphite Spheroidization Ratio Measurement Software (Nippon Steel Technology Co., Ltd.)

Highly recommended for those who want a more comprehensive approach to measuring the graphite spheroidization ratio!

● Set includes a metallurgical microscope, a microscope camera, and graphite spheroidization ratio measurement software.

	Inverted Metallurgical Microscope (Ultra-High Magnification) GR-29J-C3J

	USB 3.0 Camera for Microscopes (5 Megapixels) HDCT-500DN3

	Graphite Spheroidization Ratio Measurement Software (Nippon Steel Technology Co., Ltd.)

5. Conclusion

Using software for measuring the graphite spheroidization ratio is highly efficient. We offer both convenient, simplified sets and comprehensive, advanced sets to meet your needs.

。

Observation of metal composition

When observing metal surfaces with a microscope, it is common to use a high-magnification microscope paired with coaxial illumination.

However, specifically for metal observation, there are microscopes specialized in this field known as metal microscopes, which are designed for this purpose. It is also possible to attach a camera to these microscopes for observation.

(The metal microscope has a large body size of 203x255x421 (H) mm.)


When observing metals using the high-magnification USB microscope NSH500CSU		When observing metals using the metal microscope GR3400J

	The high-magnification USB microscope NSH500CSU achieves magnification exceeding 1000x and features a 35mm long focal length.
	The metal microscope GR3400J, coupled with the microscope USB3.0 camera HDCT-501DN3, includes various filters, enabling a wide range of observations including metal structures.

The ultra-high magnification microscope and the metal microscope each offer slightly different views, even when using the same coaxial illumination. We will help you select the model that best meets your requirements. Please contact our technical support for assistance.

Preparation for Metal Structure Observation and Measurement

1. Prior preparation for observing and measuring metal structures

To observe metal structures under a microscope or a macroscope, prior preparation is necessary.
Generally, the following four types of preparatory methods are commonly used.”

①Sample sectioning

②Resin embedding (embedding)

③Polishing

④Etching process

2. Methods for each preparation step

① Sample sectioning

Large sample specimens are cut into smaller pieces using a cutting machine.

2. Methods for each preparation step

② Resin embedding

The cut sample specimens are solidified with resin.

The reasons and purposes for embedding in resin are as follows:

– Preservation of the edge shape of the sample specimen
– Maintenance of the shape to prevent deformation of the sample specimen
– Formation of a flat shape for easier observation

Various types of resin are available for curing, selected based on the material and characteristics of the sample specimen.

<Representative types of resin>

– Acrylic resin
– Bakelite resin
– Epoxy resin
– Melamine resin

Each resin has different properties and colors, and their curing methods vary as well. There are various types such as thermoplastic, thermosetting, natural curing, UV light curing, and two-component mixing curing.

The sample is placed in a cylindrical case and solidified with resin. For heat curing, a heating embedding device is used, while for UV curing, UV light is irradiated.

Some observations may omit this step depending on the subject.

③ Polishing and mirror finishing

The surface of the metal sample specimen is polished.
Generally, a polishing machine is used.
There are manual and automatic types of polishing machines, with the former being suitable for experts and the latter for beginners.
Manual types tend to create uneven polishing due to variations in the pressure applied by hand to hold the sample, making them suitable for experts.
Automatic types, on the other hand, fix the sample specimen on a fixture and automatically polish it, resulting in more consistent polishing and making them suitable for beginners.

Using waterproof sandpaper, the sample specimen is polished from coarse to fine using a wet method (sprinkling water).

In precision polishing, cloth or buff polishing is used along with diamond slurry or alumina powder to achieve a mirror finish. Therefore, it’s necessary to change the grit of the waterproof sandpaper several times.

Polishing machines come in single-layer and two-layer types, with the latter being more expensive but more convenient.

④ Etching process (surface corrosion)

The polished surface of the sample specimen is immersed in etchant (corrosive liquid) suitable for its material and properties. Etching is performed for a specific time based on the concentration of the etchant and the material and properties of the sample specimen.

For example, in the case of graphitization, a 3% nitric acid alcohol solution (Nital solution) is used.

After etching, rinse the sample with water to remove the etchant, then clean with ethyl alcohol or similar solvent, and finally dry using a dryer or similar method.


Graphitization rate before etching		Graphitization rate after etching

3. Microscopic Observation of Metal Structures

After undergoing the aforementioned preparation processes, metal structures can finally be observed. The polished surface of properly pre-treated sample specimens is observed under a microscope. By enlarging the structure and adjusting the focus, metal structures are examined.

At our company, we offer “metal microscopes,” “USB cameras for microscopes,” and packages combining metal microscopes with cameras.

For product details, please refer to the following.

Analysis of metallographic grain size

1. Crystalline Grain Size

There are various types of metals, and it is necessary to select appropriate metal materials based on their intended use and purpose. For instance, the metal materials used in automotive engine parts differ from those used in general metal parts. This is because different metals exhibit significantly varied mechanical properties (such as resistance to tensile, compressive, and shear forces).

To evaluate these mechanical properties of metal materials, it is essential to observe the crystalline structure of metals.

Metal structures consist of polycrystalline structures composed of crystalline grains. There are regions between these grains where the arrangement is disordered, and these boundaries are known as grain boundaries. The size of these crystalline grains (grain size) is a crucial factor that determines the mechanical properties of such metal materials.

Generally, crystalline grain size refers to the “size of the grains” in materials like metals.

Furthermore, metal structures change with heat treatment, not just based on the type of metal material like aluminum, iron, or alloys. Even within the same type of metal or alloy, heat treatment arranges the crystalline grains into specific patterns, forming grain boundaries different from those before heat treatment. Therefore, heat treatment alters the crystalline grain size, thereby changing the mechanical properties and characteristics of metals.

Consequently, the analysis of grain size is a critical inspection for ensuring the quality of metal products.

　・Austenitic Crystal Grains

Face-Centered Cubic (FCC) crystal grains containing annealing twins

　・Ferrite Crystal Grains

Body-Centered Cubic (BCC) crystal grains without annealing twins

２．Methods for analyzing crystal grain size

1. Visual Comparison between Standard Chart and Metallographic Microscope

The metal surface is prepared by polishing, followed by observation under a metallographic microscope. The grain size is estimated by visually comparing the enlarged metal structure observed through the microscope with the “Austenite Crystal Grain Size Standard Chart for Steel (×100) JIS G 0551.”

　金属顕微鏡の詳細はこちら

However, it is cumbersome as it requires temporarily looking away from the metallographic microscope.

②Integration of Eyepiece Micrometer into Metallographic Microscope for Simultaneous Observation and Comparison (Comparison Method)　

Insert an eyepiece micrometer (reticle) with grain size patterns printed on it into the eyepiece of the metallographic microscope. This allows for simultaneous visual comparison between the enlarged sample and the grain size standard pattern. By observing them concurrently without needing to look away from the metallographic microscope, the grain size can be estimated comfortably.

Shibuya Optical Co., Ltd.’s R1901 Particle Size Scale

3. Incorporating an eyepiece micrometer into a metal microscope for simultaneous observation and comparative measurement (counting / planimetric method, intercept method).

Insert the eyepiece micrometer (reticle) with the pattern printed as shown below into the eyepiece of the metal microscope. Determine the average line segment length per crystal grain crossing through enlarged samples and their patterns, calculating the grain size in accordance with JIS G0551/ASTM E112 standards.

Shibuya Optical Co., Ltd.’s R2010-24 Steel – Grain Size Testing Scale (Sectioning Method)

④ Using a camera to perform particle size measurement with software (comparative method, counting / planimetric method, intercept method)

Furthermore, attaching a microscope camera to the metal microscope and performing automatic measurements using the following measurement software.

This method enables automated measurements, significantly enhancing efficiency.

For details on the USB3.0 camera for microscopes (5MP), click here.

For details on the particle analysis software G-S Measure (manufactured by Nippon Steel Technology Co., Ltd.), click here.

◆ Particle Analysis Software G-S Measure for Grain Size Measurement

【Compliance with JIS and ASTM Standards!】

This tool evaluates grain size based on the following standards:
– JIS Standard (JIS G 0551:2005)
– ASTM Standards (ASTM E 112-96, ASTM E 1382-97)

【Up to 12 Different Grain Size Measurements Possible!】

– Evaluation methods allow simultaneous measurement of up to 12 patterns using combinations of cutting patterns, enabling calculation of grain size numbers.

【Choose from 5 Cutting Patterns!】

– In the sectioning method, you can select from 5 cutting patterns and adjust intervals and line lengths.

【Convenient for Report Generation! Excel Output】

– Measurement results for grain size can be exported to Excel (CSV format), facilitating report creation.

粒子解析ソフトウェア　G-S Measure　結晶粒度測定

＜Measurement Display Example＞ ASTM (Intersection Sectioning Method, Slice Length Comparison Method)

After measurement, the display highlights grain boundaries in blue where they intersect with the cutting pattern.
* The image example measures within a microscope magnification of 100x and a range of 1000×1000 dots.

3．まとめ　

結晶粒度解析の頻度が少ないのであれば接眼マイクロメーターを使用する方法が　

費用を抑えられます。　

頻度が多いのであれば初期コストがかかりますが顕微鏡カメラを使ってソフトで　

自動測定する方法が自動化・省力化できて、オススメです。　

ソフトにはさらにこんな便利な機能もあります。　

Regarding the illumination of the borescope

Borescopes typically utilize coaxial illumination, such as the following.

However, for highly reflective objects, using a ring light designed for borescopes is also an option.
(Conditions such as “diameter greater than 10mm” or “shallow depth” may apply.)
This involves replacing the coaxial illumination with a dedicated ring light.

However, since direct connection to the borescope’s rod section is not possible, it is necessary to fabricate a fixture.
(The rod section of the borescope contains lenses and is sensitive to external forces.)

Its lightweight nature allows for observation even with a simple chuck fixture.	The fixed holes of the ring light can also be used for secure fixation.


■Key Observational Points
There is not much difference with direct-view borescopes.

<Coaxial Illumination>	<Ring Illumination>


In oblique or side-viewing borescopes, there is an effect to prevent halation.

<Coaxial Illumination>	<Ring Illumination>

Precautions when using a borescope for distant viewing

To use a borescope and precautions when viewing at a distance,
The borescope is configured with a wide field of view.
Consequently, there is some desire to use the borescope to view wide areas.
Visibility is not impossible, but the image quality tends to degrade compared to standard lenses.
For reference, I have captured the visibility of an A3 catalog 2 meters away using both a borescope and a standard lens.

ボアスコープφ4ｍｍ　画角100度

A fixed-focus lens with a 5mm focal length and a horizontal viewing angle of 56 degrees

Displaying magnified images using an industrial rigid endoscope (borescope).

When combining a borescope (industrial rigid endoscope) with a camera, inserting a macro ring allows for magnifying the image.

However, inserting the macro ring shortens the focal length. While you can adjust to some extent with adapter lenses, there are limitations. Additionally, magnifying the image can result in decreased brightness, necessitating a sufficiently bright light source.

I tested the effect of the macro ring with a focal length of 5mm.
(Photographed graph paper with 1mm pitch.)

– Without macro ring

5mm macro ring

10mm macro ring

・

15mm macro ring

Observation Using a Cone Mirror

First, use the borescope to view the front horizontal line.

In this state, placing a cylindrical object like the one in the photo below does not allow the wall surface to be visible.

Place a cone mirror and then position the cylindrical object as described above.

It enables 360-degree (omnidirectional) capture as depicted in the lower photograph. However, the central area is significantly scaled down, limiting effective use to the outer periphery.。

コーンミラーについて5

■Field of View

Cone Lens Method		Fish-eye Field of View

The wall surface is visible		The front is seen broadly, with some of the wall surface visible as well.

The borescope used for this observation is available at our company.

Please see the product page for details.

Example of an Internal Wall Observation Microscope

I have observed various specimens using the Internal Wall Observation Microscope.

・PHL200BAでの観察事例①：φ８ｍｍ穴内のクロス穴バリ観察

・PHL200BAでの観察事例②：φ18ｍｍパイプ穴内壁キズ検査

・PHL200BAでの観察事例③：φ30ｍｍ穴内壁段違い+クロス穴検査

・PHL200BAでの観察事例④：φ45ｍｍ穴内壁クロス穴検査

・さらに深穴を観察したい場合は…。

Observation Case ① with PHL200BA

Observation of Cross-Hole Burr in a φ8mm Hole

It’s a drill hole in an aluminum plate.

I observed the cross-hole inside.

With the adoption of ultra-small diameter LED ring illumination, light penetrates the hole effectively, ensuring clear visibility. The depth of this hole is approximately 20mm, achieving full circumference focus in one go, allowing clear observation of cross-hole burrs as well.

穴内壁観察マイクロスコープの実例2

Observation Case ② with PHL200BA

Scratch Inspection of Inner Wall of φ18mm Pipe

I conducted a scratch inspection on the inner wall of our company’s extension pole (inner diameter φ18mm).

< (Reference) Inspection Image from Zoom Lens Type Digital Microscope >

Light does not enter the hole, and the inner walls of the hole are completely invisible. Thus, inspection cannot be conducted.

■ Inspection Image with PHL200BA

By utilizing ultra-small diameter LED ring illumination, light effectively enters the hole, allowing for clear visibility. The microscope achieves full circumference focus in one go up to approximately 0-30mm depth, enabling the observation of scratches even at 25mm depth.

穴内壁観察マイクロスコープの実例5

Observation Case ③ with PHL200BA

Observing φ30mm Hole with Staggered Cross-Holes in Inner Wall

I have observed the angled hole in our company’s microscope (inner diameter φ30mm, with staggered cross-holes inside).

< (Reference) Inspection Image from Zoom Lens Type Digital Microscope >

Light enters the hole, but the inner walls of the hole are completely invisible. Inspection cannot be conducted under these conditions.

■ Inspection Image with PHL200BA

By utilizing ultra-small diameter LED ring illumination, light effectively enters the hole, enabling clear visibility. The microscope achieves full circumference focus in one go up to approximately 0-50mm depth, allowing observation of step differences and cross-holes. During this inspection, machining debris was observed around the cross-holes.

穴内壁観察マイクロスコープの実例8

Observation Case ④ with PHL200BA

Observation of Cross-Holes in φ45mm Hole Wall

I observed the inner diameter φ45mm hole in aluminum casting near the engine area.

< (Reference) Inspection Image from Zoom Lens Type Digital Microscope >

Light enters the hole, but the inner walls of the hole are completely invisible. Inspection cannot be conducted under these conditions.

■ Inspection Image with PHL200BA

With the adoption of ultra-small diameter LED ring illumination, light effectively enters the hole, providing clear visibility. The microscope achieves full circumference focus in one go up to approximately 0-50mm depth, allowing observation of cross-holes as well. The area around the cross-holes is also clearly visible.

穴内壁観察マイクロスコープの実例11

For more details on the “Internal Wall Observation Microscope” used in the above observation, please click here to view the product information.

穴内壁観察用マイクロスコープ

（φ8mm～φ50mm）

PHL200BA

392,000円(税抜)

If you need to observe deeper holes, …

For Case ②:

■ Inspection Image with PHLH200BA

By using a narrow 30° LED ring illumination, the hole inspection lens can be inserted slightly into the hole, enabling observation. The microscope achieves full circumference focus up to approximately 100mm depth in one go, allowing for observation.

穴内壁観察マイクロスコープの実例12

For Observation Case ②

■ Inspection Image with PHLH200BA

By using the small diameter 30° LED ring illumination, the internal wall observation lens can be inserted slightly into the hole. It achieves full circumference focus up to approximately 100mm depth in one go, allowing observation.

穴内壁観察マイクロスコープの実例13

Observation Case ④

■ Inspection Image with PHLH200BA

By using the small diameter 30° LED ring illumination, the internal wall observation lens can be inserted slightly into the hole. It achieves full circumference focus in one go up to approximately 100mm depth, enabling observation.

穴内壁観察マイクロスコープの実例11

What is an Internal Wall Observation Microscope using a Hole Inspection Lens?

The microscope designed for observing internal surfaces, such as hole walls and rail interiors, allows for a 360° view in a single shot. Here are its key features:

1． Features of the Hole Wall Inspection Microscope

Feature 1: Utilization of a 178° Field of View Hole Inspection Lens

When observing inside holes, it’s common to use a borescope. Borescopes typically offer a standard field of view around 60°, and up to about 100° for wide-angle types. In contrast, the hole inspection microscope utilizes a hole-in inspection lens with a field of view of 178°.

(Understanding that the hole inspection lens will be discussed in the next section.)

Feature 2: Utilizes ultra-small diameter LED ring illumination tailored to accommodate hole diameters

Ideal for hole diameters ranging from φ8 to φ50mm, featuring ultra-fine LED ring illumination.

Optimal for hole diameters ranging from φ50 to 100mm and depths up to 100mm, featuring ultra-fine LED ring illumination.

2．What is a Hole Inspection Lens?

Point 1. Viewing angle: 178° wide-angle lens

The viewing angle is a whopping 178°.
As shown below, the field of view expands at almost horizontal angles.

ボアスコープと穴内壁観察マイクロスコープの比較

Point 2. 360° entire circumference observation possible

The fisheye effect allows you to observe a wide range of interior walls in one shot.

穴内壁観察マイクロスコープを上からみたイメージ

Point 3: High Depth of Field

The hole diameter ranges from φ8mm to φ50mm, with a depth approximately equal to the diameter (e.g., about 50mm deep for a φ50mm hole) being the limit.

We employ lenses inherently possessing a deep depth of field. Additionally, adjustment of the depth of field is feasible with an integrated aperture mechanism.

穴内壁観察マイクロスコープの被写界深度イメージ

When compared to images captured with fixed-focus lenses, the greater depth of field becomes evident.

固定焦点レンズと穴内壁観察マイクロスコープの画像比較

Point 4: Observation of Inner Hole Walls Without Inserting Lens into Every Hole

The Hole Inspection Lens offers a wide field of view at 178°, eliminating the need for insertion into each hole. Even at the entrance or with minimal insertion, the risk of damaging the object is significantly reduced.

内壁観察マイクロスコープ使用時のイメージ

3. Summary of the Internal Wall Observation Microscope

The internal wall observation microscope maximizes the features of the “Hole Inspection Lens” and “Ultra-Small Diameter LED Ring,” enabling a comprehensive 360° inspection of the inner walls of holes in a single operation.

Point 4: Observation Images from the Internal Wall Observation Microscope

● Observing the Inner Wall of a φ30mm Flange

穴内壁観察マイクロスコープでフランジ内壁を観察している様子

固定焦点レンズと穴内壁観察マイクロスコープの画像比較

Observation Range: Narrow

Depth of Field (distance in focus at once): Shallow

Observation Range: Wide

Depth of Field (distance in focus at once): Deep

●Observing the Inner Walls of a C-shaped Rail

レールを穴内壁観察マイクロスコープで観察

固定焦点レンズと穴内壁観察マイクロスコープの画像比較

Observation Range: Limited

Depth of Field (distance in focus at once): Shallow

Observation Range: Wide

Depth of Field (distance in focus at once): Deep

● Observing Engine Surrounding Components

I observed the inside of a φ45mm diameter hole.

< (Reference) Inspection Image of a Zoom Lens Type Digital Microscope >

Light enters the hole, but the inner walls of the hole are completely invisible. Thus, inspection cannot be conducted.

< (Reference) Inspection Image with Borescope Camera >

Light enters the hole, and the view is clear towards the distal end (0° direction), but the depth at which the inner walls of the hole are visible is shallow. To improve this, it’s necessary to adjust the insertion depth of the borescope from front to back.

Inspection Image with the Internal Wall Observation Microscope (PHL200BA)

Thanks to the adoption of ultra-small diameter LED ring illumination, light enters the hole effectively, allowing for clear visibility. The depth range of approximately 0 to 50 mm is in focus all around in a single operation, enabling clear observation of cross holes as well. The area around the cross holes is also observed thoroughly.

穴内壁観察マイクロスコープの実例11

A method for observing the inner wall of cylindrical holes (approximately φ45~100mm)

The “Hole Inspection Lens PHL178” allows for 360° observation of the inner wall surface. Due to its compact size, the lens can be inserted into and used for inspection of holes with a diameter of φ45mm or greater.

Hole Inspection Lens PHL178

A black rubber sheet was attached to a cylindrical PVC pipe with a diameter of approximately φ100mm, and the inner wall was observed.

(Equipment used: Inner Wall Inspection Microscope PHL200BA)

▼camera setup 円筒穴内壁を観察する方法03

円筒穴内壁を観察する方法04

Since black rubber tends to absorb light, the image can easily become dark. However, by adjusting the lighting and camera settings, it was possible to observe with sufficient brightness.

Even if the light is insufficient, it can be brightened by modifying the illumination. We experimented by attaching commercially available LED tape lights to the side of the lens.

By using the Matsuden Corporation CS/EG series cameras, which are compact, the entire camera can be inserted into the interior, allowing for 360° observation of the inner wall.

The camera can be inserted into a cylinder with an internal diameter of φ45mm, enabling observation of the inner walls.

By manufacturing a jig for inserting the camera, it is possible to observe the inner walls of deep holes.

Methods for Inspecting Internal Wall Surfaces

What is internal wall inspection?

Generally, when referring to internal wall inspection, one might envision a setup using a side-view borescope. While side-view borescopes provide a clear view of internal walls, the observable area is limited. Consequently, the process involves rotating the side-view borescope to achieve a comprehensive, 360-degree inspection.

Lenses Effective for Internal Wall Inspection

In addition to borescopes, there are other lenses effective for internal wall inspection, known as hole inspection lenses. These lenses capture a 360° field of view, allowing for comprehensive observation of the internal wall from outside the hole. Note that their use is limited to specific hole sizes and may not be applicable for all holes. Their ability to enhance work efficiency makes them a valuable consideration where applicable.

Hole Inspection Lenses

PHL178

210,000円

Shodensha ‘s internal wall and hole inspection microscopes can be found here.

When utilizing an oblique or side-viewing borescope, methods to minimize reflections include…

When using oblique or side-viewing borescopes to inspect objects with uneven surfaces or glossy finishes, halation can often become pronounced.

(standard coaxial illumination)

Using ring lighting designed for borescopes (indirect light) facilitates easier observation.

(optional ring lighting for borescopes)

The effectiveness of external illumination varies depending on the depth and diameter of the hole. It is feasible for holes up to approximately 10 mm in diameter.

Details about the tip of the endoscope (X2000)

The specifications indicate a 130° field of view, but the actual performance is as shown in the photograph below.

High-performance articulated endoscope <X2000 series>

Inspection of the inner walls of small-diameter holes

Observations of the wall surfaces of small-diameter holes that are inaccessible to a borescope must be conducted from outside the hole.

Consequently, observations can only be performed to a depth approximately equal to the diameter of the hole itself.

We attempted observations of a wall surface with a diameter of 2 mm and a depth of 2 mm using three different methods.

(1) Oblique-viewing microscope for hole observation

The object is observed at a 45-degree angle.

By rotating the object, the entire circumference can be examined.

Observation is feasible if the diameter and depth of the hole are identical.

(2) Inspection hole lens

This is a lens specifically designed for internal wall verification using a fisheye lens.

It is suitable for observing the inner walls of holes with diameters of 10 mm or larger.

It is not appropriate for smaller diameters.

For reference, it was tested with a 2 mm diameter hole.

(3) Wide-angle borescope

Utilizes a borescope with a diameter of 2.7 mm and a variable magnification camera adapter lens.

Typically employed by inserting it into a hole,

the wide-angle design permits a certain degree of observation even from the outside.

The camera cover for the borescope

Disposable covers for borescopes are available for medical purposes. They serve to protect the camera in adverse environmental conditions.

Camera lý tưởng cho borescope

Borescope là một sản phẩm thường được sử dụng để quan sát bên trong các sản phẩm gia công kim loại.
Tình trạng gia công kim loại, bề mặt R, và sự lệch tâm có thể dẫn đến sự khác biệt lớn về ánh sáng và bóng tối.
Trong trường hợp đó, việc sử dụng máy ảnh có dải động rộng (Wide Range) có thể làm cho việc quan sát trở nên dễ dàng hơn.
Chúng tôi đã so sánh giữa camera video đa dụng của chúng tôi (GR-i700) và camera HD có độ nhạy cao và dải động rộng được sử dụng cho boa-scope (BA200HD).


Camera video truyền thống	Camera siêu nhạy cảm và có phạm vi rộng Camera siêu nét

– Quan sát một phần của động cơ nhỏ (cấu trúc với phần trục tròn có phần vặn ốc ở phía sâu bên trong).

– Quan sát phần trục tròn và phần vặn ốc bằng borescope loại trực tiếp.


Camera video truyền thống	Máy ảnh có độ nhạy cao và dải động rộng

Khi có các vùng R và lồi lõm trên bề mặt kim loại, khu vực halo và khu vực đen sẽ tăng lên.
Việc sử dụng camera có dải động rộng sẽ mở rộng phạm vi quan sát.
Như được mô tả trong hình trên, phạm vi quan sát của phần vặn ốc ở phía sâu, mà trước đây khó quan sát với camera video truyền thống, đã được mở rộng.

The optimal camera for a borescope

The borescope is a product often used to inspect the interior of metal machined products. There are instances where the contrast between light and dark may become pronounced due to the metal’s machining state, R-value, and surface irregularities. In such cases, employing a wide dynamic range camera may enhance visibility. We compared our general-purpose video camera (GR-i700) with the high-sensitivity, wide dynamic range high-definition camera (BA200HD) adopted for borescope applications.


The conventional video camera	High-sensitivity, wide dynamic range high-definition camera

● Observation of a component of a small engine (structure with a threaded portion deep within the cylindrical section)

●Observation of the cylindrical section and threaded portion using a direct-view type borescope


The conventional video camera	High-sensitivity, wide dynamic range camera

When there are irregularities such as R-values or surface imperfections in the metal parts, there tends to be an increase in halation areas and darkened regions. Utilizing a wide dynamic range camera broadens the observable range. As illustrated above, the range of observation for the threaded portion deep inside, which was difficult to observe with conventional video cameras, has expanded.

Highly durable endoscope with superior environmental resistance.

There may be occasions where a “highly environmentally resistant” borescope is requested. Our borescope is a general-purpose product, capable of:
– Operating under atmospheric pressure
– Operating within a temperature range of -5℃ to 36℃ in the insertion section, and 15℃ to 70℃ in other sections.

The borescopes from Karl Storz Endoscopy Japan Co., Ltd. are renowned for their exceptional environmental durability. They can withstand temperatures up to 150℃ and exhibit resistance to oils and solvents.

It is designed to be rugged and capable of withstanding harsh industrial applications.

Moreover, there are specialized variants available.

There seems to be a borescope available for observing conveyor mechanisms within vacuum systems and discharge phenomena in film deposition processes from a closer proximity using an endoscope. Additionally, it is capable of capturing both still images and videos.

Ultra-high magnification, high-resolution USB microscope with measurement software　USH500CSU-L1-MFSV

Ultra-high magnification, high-resolution USB microscope with software that enables a wide range of measurements

●In addition to image linking, software with a variety of measurement and focus stacking functions is included as standard.

●Ultra-high magnification, up to 800 times maximum

● Chromatic aberration reduced to the utmost

● Sharper edges

● Japan’s top level zoom ratio of 12

● 1/4 the price of conventional high-end machines

● Coaxial lighting type

※ If you want to observe diffuse reflecting objects (paper, wood, sandblasted resin, etc.), you can also change to ring lighting.

Ultra-high magnification, high-resolution USB microscope with measurement software　USH500CSU-H1-MFSV

Ultra-high magnification, high-resolution USB microscope with software that enables a wide range of measurements

●In addition to image linking, software with a variety of measurement and focus stacking functions is included as standard.

●Ultra-high magnification of up to 2700x!

●Minimize chromatic aberration

●Sharper edges

●Japan’s top zoom ratio of 12

●Uses a global shutter to prevent screen shaking at ultra-high magnification

●1/4 the price of conventional high-end cameras

Ultra-high magnification USB microscope with measurement software NSH500CSU-MFSV

A low-cost, ultra-high magnification microscope with software that enables a wide range of measurements!

●In addition to image linking, software with a variety of measurement and focus stacking functions is included as standard.

●Ideal for observing highly reflective flat surfaces (polished metal, plating, silicon wafers, fiber end faces, etc.)! Coaxial lighting type
*Not suitable for observing uneven surfaces or diffusely reflecting objects.

●Uses a global shutter to prevent screen shaking at ultra-high magnification ranges

●Software can be developed according to customer needs

●Objective lenses can be replaced. (Optional)

Borescope　φ4.0mm　300mm BAL-0430(0°)

●It allows non-destructive visual inspection of the inside of narrow parts that cannot be directly reached by the human eye.

●Compatible with various lighting such as M10 P=0.5 and M8 P=0.5.

Borescope　φ4.0mm　300mm BAL-3430(30°)

●It allows non-destructive visual inspection of the inside of narrow parts that cannot be directly reached by the human eye.

●Compatible with various lighting such as M10 P=0.5 and M8 P=0.5.

Borescope　φ4.0mm　300mm BAL-7430(70°)

●It allows non-destructive visual inspection of the inside of narrow parts that cannot be directly reached by the human eye.

●Compatible with various lighting such as M10 P=0.5 and M8 P=0.5.

Borescope　φ4.0mm　300mm BAL-9430 (90°)

It allows non-destructive visual inspection of the inside of narrow parts that cannot be reached by the human eye.
Compatible with various lighting such as M10 P=0.5 and M8 P=0.5.

Specifications regarding the explosion-proof features of the borescope.

The explosion-proof specifications entail special technical measures to prevent becoming an ignition source for combustible materials.

Unlike endoscopes with cameras integrated into their tips, borescopes consist solely of lenses and fibers, devoid of any electrical components. (The borescope itself does not serve as an ignition source.)

Certainly, in environments where explosion-proofing is required, dedicated equipment is necessary for light sources and cameras. For instance, specialized explosion-proof C-mount cameras, such as those below, are available for sale.

。

Borescope illumination port

In many borescopes, adapters are often included to accommodate various manufacturers’ illuminations. Our borescope also comes with an adapter, capable of accommodating three types.

The following is an excerpt from the catalog of Karl Storz. Similarly, it is divided into three sections.

Removing two conversion rings will result in an ACMI light guide connection.

What is ACMI light gide connection?

Comparison of brightness for borescope cameras.

When observing the inside of the extension kit using a φ4mm bore, the brightness of each camera was compared.

■ 1/2-inch HD camera

Brightness set to the maximum of “100”.
HDR set to “1”.

A 3W illumination was employed, adjusted to the maximum illuminance.

* Despite having a low reflectance and a wide diameter of φ18, in the above combination, there is insufficient brightness.

■ 1/3-inch HD camera

Brightness set to the maximum of “100”.
HDR set to “1”.

A 3W illumination was employed, adjusted to the maximum illuminance.

* Captured for comparison. The brightness of a camera unsuitable for use as a borescope camera.

■ DN3V-200

Brightness set to maximum only for Fine, Rough set to Min.
Gain set to “1”.

A 3W illumination was employed, adjusted to the maximum illuminance.

* Brighter than the 1/2-inch HD camera, maintaining this brightness with Gain set to “1” and Rough set to Min. DN3V-200 ensures sufficient display speed, with a sensor size of 1/1.8 inches and high sensitivity, making it suitable for borescope applications.

Methods for outputting the imagery from industrial endoscopes to a separate monitor or PC.

The endoscopic series of cameras for borescopes typically involve visual confirmation of the imagery on the main monitor. However, as the main unit outputs video signals (AV terminals), if a monitor with a 4:3 aspect ratio and video terminals is available, one can connect via a video cable to view the imagery on an external monitor.

During this process, visual confirmation of the imagery on the main unit’s monitor becomes unavailable. If one wishes to connect to a PC, converting this AV output to USB signals via a converter like the one described below enables input.

Industrial endoscopes are showcased on the Shodensha product website.

High-sensitivity high-definition camera for borescope use

What cameras are necessary for a borescope?

Attaching a camera to a borescope results in diminished brightness. Consequently, cameras with high sensitivity or intense illumination are requisite. While our BA200HD model offers both affordability and high sensitivity, certain conditions of the object or the type of borescope may still result in insufficient brightness even with this model. While using intense illumination is an option, it can be costly.

Recommended feature: “Auto Exposure Master”

Here, we introduce our sophisticated high-definition camera. It combines advanced functionality with high sensitivity, rendering it highly effective in dim conditions, especially when coupled with the “Auto Exposure Master” feature. One drawback is the smaller camera sensor size, at 1/2.8 inches, resulting in a slightly narrower area captured in the imagery. However, this model performs well with borescopes with diameters below φ2.7.

High-sensitivity high-definition camera for borescope use.

What cameras are necessary for a borescope?

Recommended feature: “Auto Exposure Master”

The relationship between the borescope and the connected camera’s sensor size in inches.

The sensor size of the camera connected to the borescope affects the extent of blurring. Conversely, it approaches the image seen directly by the eye.

The focal length (f-value) of the adapter lens also varies.

Confirmation was conducted using a φ4mm 0° borescope.

■ When using an 18mm focal length adapter lens:

(1) With a camera featuring a 1/1.8-inch imaging sensor:

(2) With a camera featuring a 1/2.5-inch imaging sensor:

■ When using a 35mm focal length adapter lens:

(1) With a camera featuring a 1/1.8-inch imaging sensor:

(2) With a camera featuring a 1/2.5-inch imaging sensor:

Field of view on monitor when borescope and camera are connected

The field of view when a camera is connected to a borescope and observed on a monitor changes depending on various factors.

This time, we compared the following three points.

　(1) Borescope diameter (φ4mm and φ2.7mm)
(2) Number of camera inches (1/2 inch and 1/3 inch)
(3) f number of connected lens (mm) (35mm and 27mm)

(1) Comparison of borescope diameter between φ4mm and φ2.7mm
(Fixed camera size to 1/3 inch and lens to 35mm)

■φ4mm		■φ2.7mm

As mentioned above, increasing the diameter of the borescope will increase the field of view on the monitor.

(2) Compare camera inches between 1/3 inch and 1/2 inch

(Borescope φ4mm, lens fixed at 35mm)

■1/3inch		■1/2inch

As mentioned above, reducing the camera sensor size will increase the field of view on the monitor.

(3) Comparison of connected lenses between 35mm and 27mm

(Borescope φ4mm, camera fixed at 1/3 inch)

■35mm		■27mm

As mentioned above, increasing the focal length of the connecting lens will widen the field of view on the monitor.

In addition, our connection lens BA-A1835 allows you to adjust the field of view, so you can further widen the field of view on your monitor.

■■Full-field observation (using 1/2 inch camera)		■During magnified observation (using 1/2 inch camera)

By reducing the camera’s sensor size, it can be expanded to almost cover the entire monitor.

(When using 1/3 inch camera and magnifying observation)

BA-A1835可変倍率カメラアダプタレンズ03

For product details of the camera adapter, please see the product page below.

How to fix a borescope

ボアスコープの固定方法

Basically, it fixes the handy light part and camera part.

ボアスコープの固定方法

How to observe the inside of a hole

The feasibility of observing the interior of a hole using surface-emitting coaxial illumination depends on the diameter of the hole; larger diameters facilitate more effective observation.


The subject is the hole in a cylindrical metal object.	I utilized surface-emitting coaxial illumination to observe the interior of the hole
	– The coaxial illumination allowed light to penetrate deep into the hole, enabling clear observation of any imperfections or scratches within its depths.
	Surface-emitting coaxial illumination

– Endoscopes and borescopes are also effective methods for observing the interiors of holes.

	– High-function industrial endoscope with a 3.5-inch monitor MIGS300-V551 – Cable lengths of 1 meter and 2 meters are available for selection.
	– Flexible, user-friendly cable with a diameter of 5.5mm. The tip features a slim 4.0mm diameter type. MIGS300-401 (available in 1m and 2m lengths).
	– Borescope BAL-0418L (0°) – Available in 0° (direct view), 30° (side view), 70° (side view), and 90° (side view) types. – The outer diameter of the tube is 4mm.
	– Ultra-slim industrial endoscope – Equipped with a 0.7mm ultra-slim probe, enabling the inspection of precision-engineered components.

For more details about the product, please feel free to contact our technical support. We also accept requests for testing.

Method for Observing the Inner Diameter Surface of a Cylindrical Object at Once

– When capturing images of the inner sidewalls of cylindrical objects, utilizing a wide-angle borescope proves effective.

Wide-Angle Borescope
ME.40175.00100

– Compared to a standard borescope, a wide-angle borescope offers a broader field of view, allowing for a more extensive visual inspection in one glance.

If the subject has a glossy appearance, it can be observed using our 3W coaxial illumination. However, if the object lacks gloss, the 3W coaxial illumination may not provide sufficient light intensity.

In such cases, the use of a higher-power coaxial illumination system is recommended.

ハイパワーの同軸照明

“High-power coaxial illumination”

We observed the inner side of a 20mm diameter object using a wide-angle borescope

“Video: Observing the inner side of a cylindrical object with a wide-angle borescope (using borescope LED illumination)”

“Video: Observing the inner side of a cylindrical object with a wide-angle borescope (using high-power coaxial illumination)”

However, with a wide-angle borescope, it can be challenging to illuminate and observe objects larger than 25mm in diameter.

For such objects, there is a specialized lens known as a 360° internal inspection lens. Using this lens, we observed the inner side of a 50mm diameter glossy object.

The object is a 50mm diameter cylindrical inner side.

“Video: Observing a 50mm diameter object with a 360° internal inspection lens”

This lens allows for the observation of the interior surfaces without inserting the lens into the object, unlike a borescope.

Specifications of the lens used

Model	Optical System Specifications
	Compatible Camera	Minimum Field of View (Diameter × Height)	Maximum Field of View (Diameter × Height)	Hole Diameter	Visible Object Height (High Resolution)	Visible Object Height (VGA	Working Distance (WD)	Wavelength Range	F-Number
	(inch)	(mm)	(mm)	(mm)	(mm)	(mm)	(mm)	(nm)
PCHI012	1/2	10×10	120×190	10〜120	6〜120	10〜190	5〜62	450〜650	5.8

Please note that the actual field of view in the height direction varies depending on the pixel size of the camera used (high resolution or VGA).

＜Camera Used＞

USB 3.0 Camera (10 Megapixels, Color)

Please feel free to contact us for product details

When performing close-up photography with a borescope

When connecting a camera to a borescope for observation, there may be instances where achieving focus at close range (with a focal distance of approximately 2-4mm) proves challenging due to certain conditions.

For example, when a conversion lens is directly attached as demonstrated below, it may not be possible to perform close-up photography.

ボアスコープの接写方法01

In such cases, inserting a close-up ring between the lens and the camera can enable close-up photography.

ボアスコープの接写方法02

ボアスコープの接写方法03

The minimum focusing distance was verified using the aforementioned combination.
* Employing a 4mm diameter, 0° angle borescope.

In the absence of a close-up ring (approximately 4mm)		Adding a close-up ring (approximately 1.5mm)

The close-up rings introduced herein are available through our company.

Please view the product details at the link below.

Concerning the Focal Length When Utilizing a Side-Viewing Borescope.

– When using a side-viewing (90°) borescope, attention must be given to the focal length.

Utilizing a side-viewing configuration inevitably results in a shorter distance to the wall surfaces (indicated by the red arrow).

– Upon magnifying the tip of the side-viewing borescope, it appears as follows.

Compared to the direct-viewing type, the side-viewing type has a shorter actual focal distance (indicated by the blue arrow) due to the distance represented by the red arrow.

In practice, a 4mm diameter side-viewing borescope was employed to observe the sidewalls of holes with diameters of 4.5mm, 6mm, and 7mm.

Even when utilizing the focal adjustment feature of the side lens with a diameter of φ4.5mm, the focal point remains entirely unaligned.

ボアスコープ（側視）で直径4.5ｍｍの穴を観察

■The focal point barely aligns on the side with a φ6.0mm aperture.

However, discrepancies in product manufacturing may result in misalignment.

ボアスコープ（側視）で直径6.0ｍｍの穴を観察

■On the side with a φ7mm aperture…

There is ample room for adjustment in the lens’s focal adjustment capability. Even accounting for variations in product quality, the distance remains sufficiently usable.

ボアスコープ（側視）で直径7.0ｍｍの穴を観察

Observation of the side with aperture diameters smaller than φ6mm is made feasible through the utilization of a macro lens attachment ring.

接写リング取り付けイメージ

I observed the side with a φ4.5mm aperture diameter by inserting a 5mm macro lens attachment ring.

■Observation of the side with a φ4.5mm aperture diameter (with the addition of a 5mm macro lens attachment ring)

Even at φ4.5mm (with a distance to the wall of 0.25mm), the focal point aligns.

(The presence of a distance between the lens and the mirror within the borescope allows for focal alignment even at 0.25mm.)

ボアスコープ（側視）で直径4.5ｍｍの穴を観察（接写リング使用）

■Observation of the side with a φ6mm aperture diameter (with the addition of a 5mm macro lens attachment ring)

There is still room for further adjustment.

ボアスコープ（側視）で直径6.0ｍｍの穴を観察（接写リング使用）

When observing the side with a φ4.5mm aperture diameter using direct (0°) wide-angle viewing, the macro lens attachment ring is unnecessary. (Adjustment is possible within standard specifications.)

■Observation of the side with a φ4.5mm aperture diameter (wide-angle, direct viewing)

ボアスコープ（直視　ワイドアングル）で直径4.5ｍｍの穴を観察

The appearance when observed with the standard type of direct viewing is as follows for reference.

ボアスコープ（直視）で直径4.5ｍｍの穴を観察

Please refer to the following for detailed product information on the “φ4mm side-view borescope” and the “5mm macro lens attachment ring” being used this time.