Automatic optical inspection guide - about (AOI) machine, what do you want to know
Instructions for automatic optical inspection (AOI) equipment
1. What is optical detection?
Before
we introduce automatic optical inspection (AOI) equipment in detail,
let's understand the role of optical inspection in industry.
In the
manufacturing process of optical components, optical detection can be
used to ensure the optical characteristics and quality of the produced
components. For example, defects such as scratches and pits on the
surface of optical components can be found by optical detection, and
then these defects are graded according to different standards. Finally,
the component is judged to be qualified by summarizing and analyzing
all the grading results of defects. Therefore, generally in the final
stage of optical components production process, optical detection will
be used to ensure the final product quality to meet the required
standards.
Instructions for automatic optical inspection (AOI) equipment
1. What is optical detection?
Before
we introduce automatic optical inspection (AOI) equipment in detail,
let's understand the role of optical inspection in industry.
In the
manufacturing process of optical components, optical detection can be
used to ensure the optical characteristics and quality of the produced
components. For example, defects such as scratches and pits on the
surface of optical components can be found by optical detection, and
then these defects are graded according to different standards. Finally,
the component is judged to be qualified by summarizing and analyzing
all the grading results of defects. Therefore, generally in the final
stage of optical components production process, optical detection will
be used to ensure the final product quality to meet the required
standards.
2. What is automatic optical inspection?
Automatic
optical inspection (AOI) equipment is a kind of inspection equipment
based on machine vision technology. It is generally used in the
production process of optical components to verify the quality of
optical components. The optical element to be tested may have different
geometric or material characteristics, it may be planar (window piece,
mirror piece, etc.) or curved surface, it may have a coating on the
surface, or it may be made of special materials.
Automatic optical inspection equipment obtains images by optical imaging, and processes and analyzes them to find out the potential problems that may lead to the products not meeting the standard specifications, such as the size deviation or surface defects (pitting, scratch, edge chipping, bubbles, stains, impurities, etc.). Compared with the manual detection method, it is more efficient and accurate, so as to better guarantee the reliability of the final product quality.
With the increasing complexity and shrinking size of optical components in production and application, manual detection methods have gradually been unable to meet the demand, so automatic optical inspection (AOI) will play an increasingly important role in the quality control of optical components.
3. The working principle of AOI
The three core components of AOI equipment are lighting, imaging system and processing analysis software.
3.1 lighting
In
the detection process, by using a high-intensity light source to
irradiate the optical element to be detected, the surface defects of the
element can be distinguished from the background, and different types
of light sources will highlight different types of defects.
Automatic
optical inspection (AOI) equipment is a kind of inspection equipment
based on machine vision technology. It is generally used in the
production process of optical components to verify the quality of
optical components. The optical element to be tested may have different
geometric or material characteristics, it may be planar (window piece,
mirror piece, etc.) or curved surface, it may have a coating on the
surface, or it may be made of special materials.
Automatic optical inspection equipment obtains images by optical imaging, and processes and analyzes them to find out the potential problems that may lead to the products not meeting the standard specifications, such as the size deviation or surface defects (pitting, scratch, edge chipping, bubbles, stains, impurities, etc.). Compared with the manual detection method, it is more efficient and accurate, so as to better guarantee the reliability of the final product quality.
With the increasing complexity and shrinking size of optical components in production and application, manual detection methods have gradually been unable to meet the demand, so automatic optical inspection (AOI) will play an increasingly important role in the quality control of optical components.
Automatic optical inspection (AOI) equipment is a kind of inspection equipment based on machine vision technology. It is generally used in the production process of optical components to verify the quality of optical components. The optical element to be tested may have different geometric or material characteristics, it may be planar (window piece, mirror piece, etc.) or curved surface, it may have a coating on the surface, or it may be made of special materials.
Automatic
optical inspection equipment obtains images by optical imaging, and
processes and analyzes them to find out the potential problems that may
lead to the products not meeting the standard specifications, such as
the size deviation or surface defects (pitting, scratch, edge chipping,
bubbles, stains, impurities, etc.). Compared with the manual detection
method, it is more efficient and accurate, so as to better guarantee the
reliability of the final product quality.
With the increasing complexity and shrinking size of optical components in production and application, manual detection methods have gradually been unable to meet the demand, so automatic optical inspection (AOI) will play an increasingly important role in the quality control of optical components.
Compared with other types of light sources, LED light source can provide more stable lighting, and although its output light intensity will decrease with time, it can be compensated by increasing the input current of the light source. In addition, the output light intensity of LED light source can be easily controlled by digital programming.
Therefore, LED light source, especially coaxial LED point light source and ring LED light source, is more suitable for machine vision and other applications requiring uniform lighting than fluorescent light source and incandescent light source.
In optical detection, besides the type of light source, the installation position and spatial topology of light source are also important. In order to make all defect areas have better contrast after imaging, it is necessary to ensure that all areas in the imaging field of view are effectively illuminated, which needs to be adjusted for different application scenarios.
3.2 imaging system
The main function of the imaging system is to obtain the image of the optical element to be detected and send it to the processing program in the AOI equipment for processing and analysis. Usually, AOI devices contain one or more high-definition cameras, and some types of devices can control their moving position in the device through software instructions.
According to the different requirements of application scenarios, different types of AOI devices contain different cameras, from low resolution XGA units to high-resolution video cameras, from monochrome cameras to color cameras. Generally, the new type of camera has higher frame rate, so it will produce more data, which has higher requirements for processing software and hardware.
Resolution and field of view (FOV) are two key parameters of AOI imaging system. The resolution determines the size of the smallest detail that can be captured and resolved by the device, which has a great influence on the detection accuracy and speed of AOI devices. The field of view represents the size of the physical space corresponding to the image. The larger the field of view, the larger the physical area corresponding to a single image, and the larger the size of the components that can be imaged at one time. However, it also means that capturing a single image requires more pixels and more time, that is, the lower the frame rate. On the contrary, the camera with smaller field of view can be imaged at one time The smaller the component size of the image, the higher the frame rate.
3.3 processing and analysis software
·Use the "gold standard". The relevant characteristics of the product can be obtained by scanning and testing the standard qualified product, and the product can be filed and stored for use in the later actual testing. In order to obtain reliable statistical data of product characteristics, it is necessary to test several "gold standard" products in practice.
·Software import. The description information of the product to be tested is obtained by direct software import, and it is filed and stored.
4. Comparison between AOI equipment and traditional manual detection method
4.1 efficiency
Restricted
by physiological conditions, manual detection staff need to rest from
time to time in the process of inspection. Moreover, each employee can
only check one product at a time, which will reduce the efficiency of
the whole process. With the increasing market demand for production,
product size is getting smaller and smaller, in many cases, manual
detection is no longer a feasible option.
Compared with manual,
automatic equipment can detect multiple products at one time, that is
batch detection. They can work 24 hours without interruption, and can
also be remotely controlled and monitored, which greatly improves the
efficiency and helps manufacturers meet production needs. Of course,
automation equipment will appear different types of aging phenomenon
after long-term use, which needs regular maintenance, and if the
equipment suddenly fails, it will lead to the stagnation of the
production line.
4.2 consistency
In the process of manual
detection, staff can not keep the consistency of detection results for a
long time due to fatigue and other reasons. Research shows that the
human can not maintain a stable performance for a long time, and the
probability of error will be greatly improved after 15 minutes of
continuous work, and with the increase of work complexity and daily
working hours, the number of errors will be greatly improved. In
addition, due to the subjective influence of the staff, there must be
inconsistency between the test results of different staff.
Compared
with manual, automatic testing equipment has high stability, they can
keep the same objective testing standards for all products, so as to
maintain the consistency of test results.
Manual
inspection usually requires more than one testing staff at the same
time, so it will produce a high labor cost. The research report shows
that one automatic detection equipment and one equipment operator can
replace five manual detection personnel, which can save a lot of labor
costs in the long run. Moreover, if more production lines are needed,
more money and manpower will be saved by using automatic equipment
instead of manual detection.
Compared with manual detection,
automation equipment needs to invest more money in equipment procurement
and operator training at the initial stage, and there will be extra
expenses such as maintenance, repair and update in the process of
equipment use.
4.4 test report
Manual inspection reports are
mostly manually recorded, so it is easy to make mistakes, and a large
number of manually recorded reports are difficult to manage, which makes
it difficult to use them for production process analysis.
Different
from manual operation, at each stage of the production process,
automatic detection equipment will generate printable reports according
to the required file format, so as to analyze errors and ensure and
improve product quality. This can prevent customer complaints and
returns, so as to improve customer trust and satisfaction.
5. Optinspec series - AMF vs. AOF vs. MOF
At
present, Edinburgh (Nanjing) photoelectric equipment Co., Ltd. has
optinspec series of different types of surface defect detectors
Automatic micro surface defect detector (AMF)
Automatic plane surface defect detector (AOF)
Manual plane surface defect detector (MOF)
It
can be seen from the name of the machine that AMF and AOF are automatic
detection devices, while MOF is manual equipment that needs manual
operation. These all-round surface quality testing equipment can carry
out quality assurance and quality control inspection for optical
elements of different materials, such as plane, curved surface and
coating.
Aof and MOF machines are used to check the plane optical
diameter up to 25.4 mm, while AMF system can be used to check the plane
micro optical diameter up to 12 mm.
The equipment adopts American
military standard (mil-prf-13830b), which can effectively detect
scratches and pitting on the surface of products, and can automatically
judge and classify the grades of scratches and pitting. The design
conforms to the human engineering, reduces the staff operation fatigue
feeling. The software interface is easy to operate, which is convenient
for employees to learn and operate. Automatically generate test reports.
Optinspec-amf103
is a kind of equipment for measuring the size of lens and other
precision parts, which is suitable for the size detection of products
under 12mm. It can measure the length, angle, radius, area, true
roundness and other related geometric dimensions.
In
a word, in this paper, we introduce the basic information of AOI
equipment, the advantages and disadvantages of artificial optics and
automatic optical detection, and the differences between various AOI
equipment we provide.
There is no doubt that due to the rapid
development of technology, the efficiency has been improved and the
operation cost has been reduced. Machines are replacing the work of
human beings. However, in some links of the optical detection process,
such as operation and ensuring good maintenance of equipment, manpower
is still needed.
With the invention of this technology, equipment
operators can acquire new skills to improve the company's productivity
in other areas.