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 Why dedicated systems are required for the inspection of corrugated board? Why not general-purpose ones?
Here we take "Image Processing System" for example that has become established as the mainstream inspection device.
As it well known, Image Processing System is used for various inspections and controls like inspections of print and die cutting misalignment, joint gap intervals, additional processing like tear tape and liner cut as well as tracking control of each part.
Realization cost of the system varies according to its configuration, numbers of used image processing unit and installation requirements.
Moreover, it varies a lot depending on whether establishing a dedicated system to suit the certain line and intended use or working out by using existing devices supplied by sensor makers within their functions.
Difference between a dedicated system and a system using the existing devices is the following, not to mention the price.
● Dedicated system：
= System is established based on the purpose and the inspection environment, which are the leading parts.
● System using existing devices (general-purpose devices):
= System is established based on the purchased general-purpose devices, which are the leading parts.
It is completely different depending on what is the base for system establishment.
It seems similar to the difference between the concept of values in mass production era that is supplier based and the one in current days that is consumer based.
Of course there are various advantages to use the existing general-purpose devices.
We have no intention to deny it. Instead, we admit the benefit to enjoy a lot of know-how at a reasonable price.
However, what we have to inspect is "corrugated board".
Only because of it, useful functions of general-purpose devices are sometimes constrained or the system does not work properly despite the fact it is theoretically possible.
Why does it happen? Now we would to describe the possible factors learned through our experiences.
■ Wide variety of products
In case of general industries, one or several orders at the most are produced at one production line per day. While in the corrugated board plants, dozens of different orders are produced per day; sometimes it is 50 or 60.
It is remarkable in the converting processes. Down time for changing dies is far longer than running time. it is a very special category of industry.
Due to this fact, it is practically impossible to modify the settings of inspection devices for adjustment at each order change.
■ Small lot
Producing wide variety of orders per day means that each one is a small lot.
In some cases, nearly 10 minutes are spent to change the die for the production of one hundred sheets.
■ High-speed production
Production speed is quite high. It is approx. 200m/min. for conventional machineries and 400m/min. for state-of-art machineries. (It varies from line to line). In this severe production environment, common requirement of customers (corrugated board companies) is a complete inspection of whole kinds and numbers of sheets. In order to meet this requirement, processing speed of the inspection devices has to be increased.
■ Quality
Color of inspection object varies according to paper quality. In addition, there is a surface irregularity caused by uneven paper pressing. To be exact, therefore, pattern (image) of inspection object varies every time.
In other words, the background of inspection object varies every time so that it is difficult to carry out the inspections under the same conditions.
■ Warp
As it well known, corrugated board has a property of being easily warped from its structure. When a warped sheet is inspected, factors of instability are born, such as variation in the gap between camera and the sheet or in the color component of the image when the sheet goes through the detecting area.
■ Color
Even if exactly same color ink is used, color development varies depending on the background of image that is color of the containerboard (linerboard). Colors look same to human eyes are sometimes considered different in tone at image processing according to viscosity and amount of pigment.
■ Flute
In general, three kinds of flutes; A, B and AB are used for corrugated shipping container. Difference in board caliper according to flute leads to variation in detecting distance. Furthermore, shape and frequency of warp varies according to flute.
■ Plant environment
Only some corrugated board plants are closed type equipped with air conditioning units but most of the plants are not. In many plants, internal illuminance level varies between daytime and nighttime. Spot illuminance level also differs depend on the place of the plant. Besides, some places get strong afternoon sunshine in early evening. It means it is difficult to get stable luminance, which is a basic condition for image processing system.
Another problems are accumulated paper dust generated through corrugated board production and wastes of die cut flying off from each part of machinery in the processing line.
■ Conditions of use
Operator of the machine is not always the same person who gets used to it. Therefore, operator friendly devices are desired. No operation required is most favorable to customers.
As described above, there are highly diverse conditions to be reflected to the inspection of corrugated boards.
We heard that some plants had troubles by adopting ready made devices. Despite that it was not due to the failure of the device, it was evaluated as not practically usable because of too frequent error alarm.
As you may know already, corrugated board inspection is quite demanding and has to meet considerable conditions.
Inspection device is evaluated as usable once it satisfied those conditions.
Please find our product lineup in (the page of) "Products".
When you find a suitable or close system you desire in our product lineup, please consider it is a fundamental system. It is not a whole system we would like to offer you.
In some cases, specification matching is required to the inspection environment of your plant.
Based on this matching, reflection or addition of conditions to our offering system is possible on your request.
After those procedures, we provide our quotation.
We strongly recommend the inspection systems exclusively developed for corrugated board that matches to the production environment. It also has to be operator friendly and has long service life.
We recommend you to provide the manufacturer necessary information like inspection environment, features of inspection object as well as your requests for usability and stability in advance.
Then when you are satisfied with their offer, please invest in it.
Image Processing System being used for our inspection system is a combination of our uniquely developed applications and the hardware supplied by vendors under OEM agreement.
Therefore, modification of the specifications and addition of functions can be done relatively easily. In other words, development after the installation is available.
cannot make good inspection without good maintenance. Inspection devices only works well when all the sensors fixed in its each part function well.
Recognition of the condition, regular check and replacement of wear parts as well as motion check with waste sample are essential. |
Slow but steady win the race.
If you take what you would like to do now or measures you have to do urgently without serious consideration, you tend to develop a system by yourself using existing cheep devices or ask to local suppliers to develop it with small budget.
Let us point out it is very risky. We know many failed cases as a result of the above.
In fact, we had many experiences to receive inquiries for system establishment from the companies who gave it up after spending a lot of time and expenses.
Although there were various causes for the failure, we think fundamental cause was the result of "forgetting the fact that the inspection object is corrugated board".
This is certainly the reason why dedicated devices are required for the inspection of corrugated board.
Please contact us before choosing an easy way.
We will offer you the way to realize your plan at a reasonable price, and of course offer you the best system within your budget.
It looks expensive at a glance but it is sometimes the cheapest way. |
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Study of Image processing System