In the modern world of Science
and Technology we the human society always try to use the modern equipment and
tools for better usability.
In the field of Quality Assurance
and Quality control, we have also such types of equipment for surface
inspections in sheet metal.
Now a day’s many types of surface
inspection systems are being used in different industries. However, here we
will discuss about the technology used in the surface inspection systems.
There are basically two types of
technology used for inspection the surface they are line scan Technology and
Area Scan Technology. Here we will differentiate between both the technology
and you will also find the best suitable technology for your application.
There are hundreds of surface inspection systems providing company available in the world.Out of which two to three companies are the best in service and quality.They are the ISRA Vision Parsytec and Ametek Surface Vision.
ISRA Vision Parsytec is a company based on Germany and Ametek is based on US Company. All two companies works in different technology which i will describe in below. After the reading this article you will find the best system for you at the end. Perhaps the most critical decision is weather to use Line scan camera or Area Scan Camera.
Line Scan camera build images in a single pixel raw at a time using a sensor which passes in a liner motion over an Object or a object passes under the sensor. This makes it ideal for high-speed continuous applications such as document scanning, print inspection, web inspection of paper, aluminum, steel or glass, and in detailed inspections requiring measurements be done in microns. Line-scan can also inspect round bodies without perspective distortion.”
Because line-scan cameras use a single row of pixels, they can build continuous images not limited to a specific vertical resolution, allowing for much higher resolutions than area-scan cameras in both 2D and 3D.
Additional benefits of line-scan systems include their more compact footprints that allow them to fit more easily into tight spaces, for instance, when a camera must peek through rollers on a conveyor to view the bottom of a part. Also, line-scan cameras create smear-free images of fast moving objects without requiring strobing or the redundant processing of frame overlaps. Despite these advantages, integrators regularly harbor reservations about deploying line-scan cameras because of perceived system complexities or higher cost. In reality, a single line-scan camera will often do the job of several area-scan cameras, minimizing setup and overall system cost. And while coordination and acquisition timing are critical, line-scan cameras require only simple illumination.
F&Q
1. What is
Line Scan Camera?
Ans:- Continuous gray scale image line by
line, providing the complete defect on the strip. Using linescan cameras
and collimated light, all areas of the defect are uniformly illuminated.It Scan line by line along the width.For Exsample:-In Ametek at JSW it has 80000Scan/Sec
2. What is
Area Scan Camera?
Ans:- Single images per camera -
many boundaries are created due to row of cameras. Defect has different
Appearance in different parts of same image due to inhomogeneous conditions. It takes a single image per camera and later on it combines to form a full with image.
3. What is
Bright Field in camera?
Ans:- In Bright Field Camera Defect image showing Dark against Bright Background.
4. What is
Dark Field in Camera?
Ans:- In Dark Field Camera Defect image showing Bight against Dark Background.
5. Which
Field is better for Glossy surface?
Ans:-It is better to have both the Bright field as well as Dark field camera. As some of the small defects are not visible in bright field.
6. Which
Field is better for Dull Surface?
Ans:- It is
better to have the Bright field camera to detect the defects.
7. Which type of light sources is better for the SIS in bright Filed?
Ans:- More the wavelength more the light distance
travel. Wavelength of the light is inversely proportional to the frequency.
More the wavelength less is the frequency and less the wavelength more is the
frequency. In case of white light it is the mixture of the all the light
wavelength ranging from 400nm to 700nm.
In case of the Infrared, light wavelength is ranging
from 700nm to 1000nm.Thats why it is not visible to naked eye.
8. What is Camera Resolution?
Ans:- Camera resolution is the ability of the imaging
device to resolve two points that are closer together, Higher the Resolution
smaller the details. In SIS 250micrometer,500micrometer is the Pixel Size &
4K,2K is the number of Pixel on sesor.In 2K- 2048 × 1080,4K- 3,840 horizontal pixels and 2,160 vertical & In
8K- 7680
× 4320
9. What is the Minimum detectable Defects size?
Ans:-
Generally it requires few number of pixel to detect a defects. So that the size
of the defects to be equal to the size of the Pixel minimum required.
Example-Suppose
it takes 04 Pixel to detect a defects then the minimum size of the defects to
be detected is 2*2 Pixel
01 Pixel
size-250micrometer
=(2*250)*(2*250)micron
=500*500micron
=0.5*0.5mm=0.25mm²
10. What is the minimum guaranteed detection size?
Ans:-Minimum
guaranteed detection size is the minimum size of the defect which can be
detectable with more than 90% of guarantee.
11. What is
the basic difference between Detection and classification?
Ans:-Detection
is related to the defect, which can be detected in system, and Classification
is the term, which is related to the actual naming of the defects, which is
detected by the system.
12. How much pixel required for the classification?
Ans:-Always
for classification, it takes more pixel than the pixel required for detection.
13. What
does it mean by System Availability?
Ans:-System Availability
is the term means system available for the user for use.
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