In many plastics injection moulding processing plants, resin dryers are a standard piece of equipment uses to remove moisture in hygroscopic polymer such as PC, ABS and PBT. These polymer exhibits some level of polarity in the functional group and therefore can absorb a certain amount of moisture from the atmosphere even in tightly sealed bag However many treated drying processes solely to bring moisture content to below supplier`s recommended moisture percentage or PPM. What some molders did not realised was varying moisture content even within its limit can cause poor moulded component quality. In certain material, moisture creates process sensitive and needed to be control with suitable technology in order to maintain the correct level of moisture and process robustness. In recent study of PBT material, moisture directly correlates with cyclic variation in moulding process output. Drying 3 – 4 hours to reduce the moisture content below 0.02% is not suffiecient, we also found between 0.02% and 0.01% of moisture caused significant variation in moulding process.

Therefore, in some jobs, it is important to have tighter control and proper moisture monitoring solution as have been highlighted by many experts. Conventionally moulder monitors actual moisture content daily in the plant and it can be tedious task for technician to test all samples. It can take up to 20 minutes per sample and become ineffective for manpower if there are too many samples to be tested in routine quality check. Currently online moisture monitoring solution offers by the supplier. As of today, although it is not fully robust, the technology is improving as suppliers use few detection principles for reading online moisture content accurately. Soon enough, there will be a robust solution for online moisture monitoring offered in the market. Alternatively, near-infrared (NIR) measurement devices are increasingly used by moulder for faster measurement. These devices have become more portable, cost-effective and easier to use. NIR spectroscopy can now provide immediate, real-time laboratory quality readings via a non-contact measurement method that can deliver moisture, composition analysis, and even full-spectrum composition readings for a fraction of the cost of conventional methods. Changing from current gravimetric methods to NIR analysis can slash testing costs by up to 90% due to the dramatic reduction in both ‘people time’ and the elimination of chemical reagents, scrap from testing, and ‘people error’ that creates the need to repeat the tests. Real-time NIR measurement is possible for continuous monitoring and optimization of polymer processes. It provides more timely quality assurance data than a team of QA people using traditional testing methods, and 100% of the product can be inspected.  Instant testing enables superior quality control and immediate troubleshooting if a process starts to drift out of the target range.  The results can improve batch consistency and yield, while helping to eliminate batch failure and reduce material waste.   In principle, NIR spectroscopy bounces beams of light off a solid or liquid and measures how much light is absorbed in certain wavelengths—about 700 to 2500 nanometers.  This produces an “optical fingerprint” of the sample’s chemical composition, with the device calculating the desired measurements after it has initially been calibrated to a lab or production standard. The equipment can be handheld, desktop, online or inline, and is versatile enough to work inside mixers, blenders, extruders, or pneumatic and vacuum transfer lines, as well as pipe-flow applications when utilizing fiber-optic accessories. They are instant, non-destructive and they may even be non-contact. Often, NIR moisture meters are used to inspect incoming raw materials.  However, the meters can also be used anywhere in the production process where achieving a specific moisture content is important. These devices typically use only a couple of wavelengths for moisture measurement. An example of a polymer manufacturer that uses a NIR moisture meter to produce pellets for a medical-device company. They creates products that are inserted into the body. For this application, the polymer manufacturer needs to have extremely low moisture in the pellets before they are injection molded. If the moisture level rises above a certain amount, the molding process does not work well, which increases the part failure risk. Management should aim to simplify the process and help the team to make daily work effective. Changing from conventional method of drying detection surely improves the consistency in injection moulding process.