Recognize and exploit optimization potential


The demands on EMS service providers are increasing continuously. This constantly drives efforts to optimize processes. Increasing quality of the products, higher process stability and saving of production time are decisive factors. A medium-sized electronics service provider has decided to use a process-accompanying overall solution which, in addition to the automation of optical inspections, helps to discover potentials for process optimization.

appeared in the EPP 11/2013

With extensive technology know-how ELOTEC Fischer Elektronik GmbH (ELOTEC for short) offers customized productions of electronic products. The medium-sized service provider produces electronic assemblies and complete devices for more than 80 industrial customers in its location in Furth im Wald. The ISO 9001: 2008 certified company attaches great importance to the high quality and reliability of the manufactured products and continuously works to improve the production processes.

Initial sample inspection - done quickly

For this reason, ELOTEC 2011 was looking for an effective support for the first sample inspection. With 10 to 15 real new starts per month, the full manual check of the first printed circuit board required a lot of time. Depending on the quantity of components, 3 to 4 hours had to be used for the manual inspection by means of a microscope, a printed assembly list and a placement plan. Meanwhile the line stopped. For small series with 10 to 15 boards, this waiting time was usually not worthwhile and the production continued parallel to the initial sample inspection. If a mistake was discovered, the series was often already produced and it had to be reworked consuming.

For process improvement, the main focus was therefore on accelerating the initial sample inspection. ELOTEC evaluated several systems and decided in August 2011 for EFA Inspection from the house of LEBERT Software Engineering (short LSE).

This semi-AOI solution automates manual inspection processes without the hassle of programming. Within minutes, an EFA program is set up, in which all information (eg assembly plan, coordinates, item number, component designation, values, etc.) is quickly and easily available to the operator. All information is displayed centrally to the inspector so that he can exactly check the component alignment, the values and the presence. EFA Inspection ensures that all components are viewed and evaluated.

Through the use of EFA Inspection, ELOTEC has been able to reduce the time required for initial sample testing from 3-4 hours to half an hour - including program setup. The line downtime during the inspection was thus reduced by 85%. As a result, the first sample inspection is now also profitable for small batches of 10 to 15 blanks. In addition to the quality assurance gained thereby times for reworking entire small series are almost completely eliminated.

Process reliability through random checks

After successfully improving the optical inspection of the initial samples, ELOTEC began optimizing the manual spot checks on the line. For process monitoring, EFA Inspection was used together with the EFA Picture recording station during the production of larger series. The main focus was on regularly monitoring the process quality of the current production and on detecting any faults occurring at an early stage. The faster deviations are detected, the faster it can be responded to. Here the Golden Board function of EFA Inspection is used. The image is automatically integrated into the program already created for the initial sample inspection and displayed alternately with a golden board. The guided inspection now displays the image in sections. Errors are instantly recognizable due to the movement in the image.

The use of EFA Inspection also saves valuable process time in this process step. In addition, process reliability was significantly increased and the effort for rework was noticeably reduced. Mr. Berzl, responsible for process control at ELOTEC, reports that the handling of EFA Inspection is intuitive and easy.

“We were also able to incorporate people into the operation who generally do not carry out an optical inspection. This means that each shift can easily monitor its own process steps, ”says Mr. Berzl.

Zero-error production in the THT area

The next step was to explore the use of EFA Inspection in the THT area. The conventional assembly is carried out manually at ELOTEC for batch sizes from 1 to 150 blanks. After assembly, the boards are checked visually. Due to fatigue in the manual production area there were always mistakes, which also caused complaints.

First tests with EFA Inspection showed that a stable image comparison between the Golden Board and the test object can also be established for THT placement. Thanks to the fiducial alignment in EFA Inspection, the images of the boards are positioned so stably against each other that only the component movement is visible. The camera-based recording solution can quickly take pictures of high-performance boards as well. The individually adjustable lighting ensures homogeneous illumination of the boards.

After the successful tests, each conventionally equipped board is now checked with EFA Inspection. The number of complaints could be drastically reduced.

"Complaints no longer exist," explains Mr. Berzl from ELOTEC.

As a nice side effect of the automatically generated documentation of the pictures of the circuit boards, even unjustified complaints can be safely averted.

Use beyond visual control

In the recent past, ELOTEC has turned to the special requirements of the assembly variants. For visualization, assembled and unpopulated components with different color markings are shown in the assembly plans. Up to now, these assembly plans have been created by a time-consuming, manual process. If changes had to be implemented, the marking process started anew. The visualization is now carried out with the work preparation of EFA Inspection. In addition to many other functions, this software extension offers the possibility of providing the components of the assembly plan with differently colored markings. In the process, these variant-based assembly plans are virtually a by-product, as the initial sample inspection with EFA Inspection is used anyway. Altered placement variants or subsequent adjustments can be entered with a few settings. EFA Inspection also provides a time-efficient and process-reliable solution in this field of application.

Originally purchased to support initial sample inspection, EFA Inspection has since become a production-ready tool. Not only manual inspection was purposefully automated. The information that EFA Inspection makes available for the individual production steps can be used to identify optimization potential. These can be used specifically to eliminate weak points in the process. Thus, ELOTEC has achieved additional manufacturing stability with feedback from EFA Inspection through training and changes in its processes. This directly increases the quality of the finished products and ultimately the competitiveness of the company.

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