Efficient optical inspection from batch size 1 with EFA Inspection®
The use of automatic inspection systems is dependent on the economic considerations, whether the time saved by the automatic inspection is in reasonable proportion to the effort required for programming. Visual inspections such as first-sample or small series inspections usually do not fulfill this requirement. Here smart concepts such as Augmented Reality Inspection (ARI) have to be used, which involve the operator with his experience and flexibility to a much greater extent than before - in line with Industry 4.0.
appeared as title story in the Productronic 11/2014
Industry 4.0, the fourth industrial revolution, is the omnipresent topic in the media and one of the Federal Government's future projects. For the area of industrial production, the strong individualization of the products up to lot size 1 under the conditions of a highly flexible production is decisive. The following key statement can be found in the "Implementation Recommendations for the Future Project Industry 4.0" of the final report of the Working Group Industry 4.0:
"At the heart of Industry 4.0 is the human being (...), who is expanding his capabilities through technical support, becoming a 'creative creator' in the Smart Factory, and a mere operator and controller. '
Man moves into the center of the 4th Industrial Revolution - not the machines. Although machines are fast, precise and powerful, today they are often static. Humans, on the other hand, are very flexible and can master an abundance of tasks in a very short time.
Balancing the feasible and the economically sensible
Therefore, in the past, especially those processes have been automated that perform repetitive, similar tasks and only need those human skills that can be easily replaced by machine. More complex human skills, such as For example, quickly grasping new or unexpected situations, or learning something new, are based primarily on human experience. This is part of his life experience and is significantly influenced by the visual and acoustic perception of his environment.
By contrast, the mechanical, visual acquisition of a single image requires a large number of parameters, often for many small image sections, which, moreover, still have to be packed into narrow parameter limits. And even then only a few previously intensively learned objects can be recognized. Therefore, the machine image acquisition is always associated with a not inconsiderable parametrization effort at the same time tight tolerance limits.
As a result, such processes can only be optimized with a reasonable balance between the technically feasible and the economically reasonable.
Small lot sizes are not fully automated economically
Optical inspections for small batch sizes, such as first sample inspections, are a good example of this. In many companies, two people work hand in hand for several hours. A person searches the component to be inspected on the printed circuit board while the other person holds all the necessary information for an informed decision in the production documents. The constant change of focus between the schematic drawing and the printed circuit board quickly leads to fatigue and a "blindness" to the details. In addition, finding the right components on the printed circuit board and the necessary information in the production documents for the correct evaluation of a component requires valuable process time. During a first sample inspection in particular, the finished-equipped production line sometimes waits several hours until the result of the inspection is available.
Such visual inspections are real candidates for a more automated process! However, completely automatic optical inspections are not expedient here because their parameterization effort for the visual recognition of the printed circuit board is usually economically unreasonable with such small quantities. In addition, newly created parameterizations are rarely so perfect that the desired inspection at the beginning could actually run without human auditors. As a rule, many real errors are necessary in order to reduce the pseudo error rate of an AOI to an economically justifiable measure by constant post-parameterization.
Therefore, initial sample inspections, small series inspections as well as set-up and random checks can not be fully automated for economic reasons!
ARI - all information at a glance
For several years, the company LEBERT Software Engineering has been developing the inspection system EFA Inspection, which from the beginning focuses on the experience and the flexibility of the user. The process of searching for and finding the right information is done by the inspection system, while the human being can concentrate on his core competency of evaluating.
In order for the time advantage of partial automation to be fully developed, the programming process must be quick and easy without great loss of time. In EFA Inspection, the manufacturing data can be integrated with minimal effort. The assignment between the placement data and the schematic drawing learns the software in a short setup process. Since up to three lists can be combined with each other, all information relevant to the examination is available on a component-by-component basis.
The operator gains an information-enriched reality within minutes - an augmented reality.
In the representation of the inspection system, the assembly plan can be faded in on the inclusion of the board to be tested. Information such as colored markings for the placement variant or polarity markings can now be compared at a glance with the mounting of the board.
In addition, a balloon with the test-relevant information is displayed on the current component. Again, the operator sees directly in the image on a focal plane all the information that he needs for the inspection decision. Due to the guided procedure of the inspection no component can be forgotten or overlooked. Thus, EFA Inspection ensures a thorough inspection by the operator. After the complete test, a test report can be generated or a statistical evaluation can be made.
EFA Inspection® allows time savings of up to 85%
The requirements for such a semi-automated inspection system are high. It must be highly flexible to adapt to the operating requirements and preferences of the user. Only then will the system be used by the users.
In addition, different test tasks must be covered. EFA Inspection fulfills this flexibility through the diverse selection of display options and inspection sequences. For example, all components of the same part number can be displayed together and evaluated together. The image sections of the components are rotated back to zero degrees according to the stored angle of rotation. Simplified, this means for the examiner that all components of the same item number must be aligned identically in the illustration. The comparison with the data and the assembly plan is made with a component of each article number (see Figure 1).
Thanks to the close cooperation between man and machine, significant time savings are achieved for this process. Initial sample checks can thus be demonstrably reduced by up to 85% compared to the purely manual procedure. This time saving can be used directly to increase productivity.
EFA Picture Touch Inline - adaptable to existing handling systems
The basis for ARI is the highest possible quality of the board to be tested. For this purpose, LEBERT Software Engineering offers the camera-based product family EFA Picture. These devices can be set up via profiles for different board sizes, component heights and lighting concepts. It can record up to 100 million pixels are generated.
The newly developed inline attachment "EFA Picture Touch Inline" can even be integrated on handling systems of existing lines (see Figure 2). The intended position of the device for the inspection of initial samples and samples is in front of the brazing furnace. Blanks can be checked before the soldering process, without removing them from the line. Even a correction of assembly errors is thus possible without great effort (see Figure 3).
The use of the inline device is recommended for lines that are frequently retrofitted or that require regular random checks.
Man at the center of software development
People are moving into the center of the 4th Industrial Revolution and, of course, into the center of software development. In the future, this development will have to be increasingly geared to the wishes of the customer and the experiences of future users.
The software company LEBERT Software Engineering has been implementing this for years with a unique concept. The continuous development of the software is the result of close cooperation with the users. Thus, ideas and requirements of the customers regularly find their way into the software. The result is a practical application "of customers for customers". It is always important to combine the strengths of machine and person. Because the close cooperation leads to optimizations and time savings in processes that do not seem automatable at first glance.
As a result of this collaboration, the initial EFA Inspection application has grown into the EFA SmartSuite application suite over the last few years, which can sustainably support the entire manufacturing process of an EMS service provider from the quotation phase, through pre-production to production (see Figure 4).