Panels & Furniture Asia Sep/Oct 2020

September / October 2020, Issue 5 | Panels & Furniture Asia 32 | PANEL MANUFACTURING Figure 1. EcoScan FBD using high-performance linear array scanning technology time covering <3mmof themat, depending on speed. For reliable FBD, a certain pixel coverage of the scanned object is required for good contrast in the X-ray image. A high-detection resolution is also attributed to optimised X-ray energy and sensitivity of the sensor elements in the linear array. The FBD operates with high X-ray power to obtain a sufficiently high radiation intensity on the imaging sensors. This is because of the large distance between the radiation source and detector line, the extent of the fan beam to cover the complete mat width and the short sample time (comparable to bright light for a short camera exposure time). Customers have individual possibilities to adjust the detection settings depending on the application, with three typical foreign body types: metal, high density (eg, resin lumps) and quality (eg, small metal detection in oriental strand boards or rubber particle visualisation and counting in MDF). An optional marking unit with heat-resistant ink for marking individual detections on the mat surface enables downgrading of the panel downstream from the hot press. In contrast to FBD, area weight measurement of panels with thicknesses ranging from1.5 mm to 40mm requires a differently designed X-ray system. EcoScan’s high-precision area weight gauge utilises unique double-traversing and self-adjusting flying measuring heads (FLY), which employ MultiEnergy Technology – finely graduated X-ray energies consistently yielding a high measuring resolution of ± 0.5 % over a wide area-weight range, and accurate absolute values. An enhanced detector with short sample time enables fast traversing of the measuring heads. For example, the two synchronised traverses allows a cross-scan of an 8 ft mat every 2.5 seconds. However, lower X-ray energies are automatically adapted to the measured area weight, such that the relative measuring sensitivity is equivalently high along the relevant range (green plot in Figure 2). This yields maximum relative signal differences (X-ray measuring contrast) with small area weight variations between the measuring positions. The X-ray energy level of the EcoScan FBD (blue plot in Figure 2) would be too high, with considerably decreased sensitivity, for area weight measurement in the relevant range. This is because its parameters are optimised for high radiation intensity and proper imaging contrast for FBD. The EcoScan FLY’s “little brother” – MASS-SCAN XME (Figure 3) – is a single-head traversing area weight gauge with ± 0.6% to 0.8 %measuring resolution. It is commonly applied in particleboard- forming lines with up to three connected units covering the panel layers. However, it is also appropriate for applications in regular MDF lines withmainly >7mmpanel thicknesses. Moisture content measurement using infraredmoisture analyser MT-SCAN completes the forming line measuring equipment at several relevant positions. Downstreamof the hot press, thickness gauge and blow detection systems are essential devices for final panel quality and process performance monitoring (Figure 5). Because panel producers are faced with decreasing panel thickness tolerances, they need an inline measuring instrument with almost calliper-like accuracy. Figure 2. EcoScan FLY high-precision area weight measurement using self-adjusting flying measuring heads