TeraMetrix Uses Online Terahertz Measurements to Improve Bottle Manufacturing
瓶子或容器的最关键特性之一是壁厚。bob综合平台无论是单层还是多层结构，容器的性能和质量都非常取决于层厚度值。bob综合平台
Terametrix.T射线5000太赫兹控制单元（TCU）和在线EPG传感器头have demonstrated the ability to measure the thickness of both single layer and all the individual layers in a multi-layer sample. The measurements are collected very quickly (1000/second) and repeatably (< ±0.5 µm or better (±2σ) resulting in Cpk values typically > 7). Thus, showing one more application for which the terahertz sensors can be used for industrial process control, quality control, and non-destructive testing.
A three-layer bottle, conveyed past the sensor at a rate of forty (40) feet/min, was measured on a blow molding production line to demonstrate thickness measurement and other detection capabilities.
On-line measurements can occur before the bottle / container is manufactured (on preform or parison) or after the unit has been molded. Measurements after the unit is manufactured are critical for Quality Control.
由于THz在简单的非接触反射配置中操作，因此设置传感器以进行在线测量是直接的。在这种情况下，传感器设置在生产区域以外的支架上，以使成品瓶的测量传达过检查点。最大检验率为每分钟300瓶。bob综合平台收集瓶子上单个高度的厚度结果。
The bottle being manufactured has three major layers (up to six or seven layers total):
- Outer polymer (virgin/regrind) plus adhesive “tie” layer
- EVOH barrier layer
- 粘合剂加内聚合物（原始/再生）层
Over the 3+ hour trial period, the stationary THz sensor was able to collect > 30,000 measurements on production bottles.
The THz online measurements recorded the thickness variations within in each layer.
Outer = 11.9 ± 2.2 mils
EVOH = 1.5±1.1密耳
内部= 37.9±5.9密耳
The level of variation in the results were reinforced with two other sets of data:
- B扫描
- 工厂离线QC检查
A B-Scan is an image of a cross section image of the bottle wall along a scan line. For this example, the scan line is the circumference around the bottle at the height of the online THz measurements. The image demonstrates variations in layer thickness within a single bottle.
图像中线的灰度和强度对应于沿扫描线中波形中的反射峰的极性和幅度。B扫描的Y轴是波形特征的时间，其对应于深度进入瓶壁。
从图像中，可以看到瓶壁层的横截面。
In addition to thickness variation, additional features such as potential gaps in the center layer can be seen.
The other set of information confirming the online THz measurements are the standard factory destructive QC checks. Four (4) QC samples were collected during the trial, and four additional samples after the THz trial was complete (thus 8 measurements all together). The thickness of all the layers in the sample were measured. Adding these results to the THz data plots confirm that the on-line THz measurements fit within the at-line QC measurement results.
A discrepancy was noted for the lower limit of the Outer Poly layer results. During this limited-time online testing trial, the measurement of the Outer Layer was (incorrectly) assigned a lower limit of 10 mils. With a simple setting adjustment, THz measurements can range down to 1 mil or less. Doing that in this case, would have allowed the THz on-line measurements for the Outer Poly layer to agree with the QC measurement range as it does for the other two layers.
The higher density of THz results, versus the current standard QC checks, better defines the current manufacturing conditions. The results identify periods of product changeover, out of specification operation, defects within layers, and the product variation during routine production.
For functional layers, such as the EVOH Barrier layer in these bottles, it is crucial to ensure the layer is present and has the proper thickness value. Such on-line monitoring easily provides layer thickness, and other layer information, thus helping ensure high product quality.