WCA September 2012

Cable Print Verification system

By Craig Girdwood, Taymer International Inc, and Brian Franklin, Commscope

The system will be able to analyse print legends done by any type of printing method such as hot foil, inkjet, emboss, indent, laser, and gravure printing. Maintenance on the unit involves a quick wipe when the unit is dusty. The lifetime of the lights can be over 50,000 hours of usage, and they are the only consumable part in the whole system. 2 Various Print Detection Technique Limitation 2.1 Inline Visual Inspection Using Stroboscope This type of inspection involves using a stroboscope inline. A stroboscope flashes light at the proper period to make the print legend appear to be slow moving or stationary. This gives some time for the operator to verify the existence or quality of the print. However, one limitation is that there is not enough time to carefully verify lengthy print legends until the next print shows up. As well, the flashing light strobes can be a nuisance to the operator. 2.2 Offline Viewing Through Magnifying Lens One technique to detect print defects is having the operators look through a magnifier. Although the operator can see the print defects and categorise them accordingly, there are a lot of limitations. The operator can only read the print up to a certain speed.

Abstract The use of the Print Verification (PV) system in detecting print defects greatly improves quality assurance of wire and cable. Defects on the jacket are continuously detected by a machine vision system at production line speed. Images of the defects are processed and saved. This technology improves the print quality of the cable produced and by greatly reducing defective products from reaching the customer. 1 Introduction Print defects are generally the biggest single source of defects in power cable and fibre optic cable manufacturing facilities. Wrong messages, print smudging and faded prints are print defects that should not be on good quality products. The defects are not only cosmetic problems, but the wrong message can lead to misuse of the cable when it reaches the end-user. By being able to detect the defects, corrective actions can be taken at the production level and defective pieces can be reprinted or discarded. The PV system uses machine vision technology to analyse, isolate, and identify print defects. The system runs inline and saves the all defect image data including length and defect size in a database. The camera is generally positioned close to the printer to simplify print legend identification and print location. Images of the print legend are created and processed through high-speed image processing algorithms and character verification techniques. Any illegible or incorrect print legends are detected by the software, alerting the operator to take corrective action. The images are stored together with length information providing further analysis or report generation. The alert provides operators with instant feedback on current printing conditions resulting in not only corrective actions, but more importantly allows the operator to identify and reduce the root causes of the print defect. This reduces the print defects before they actually happen; improving print quality, reducing rework cost, wasted consumables, and defective products. The PV system can also easily integrate to your lines and works well for all types of printed cables (twisted pair, jacketed, bare wires, and convoluted profiles).

❍ ❍ Figure 1 : Taymer Print View System

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