Application Exploration: Verifying Opacity in Plastic Film

Tuesday, October 20, 2020

Protecting Critical Products from the Effects of Light

Packaging companies and many others understand the impact of lighting. These businesses use rolls of pre-made plastic film to package products. These films need to be of proper opacity to protect the goods inside from the damaging effects of light. If the film is too transparent, it could easily compromise the product inside, which could prove disastrous for products that need to be sanitary — such as food, personal care items, and many other products.

Verifying opacity in product packaging is critical, but often, this has to be done by taking several samples off of an existing production line to measure them in a lab. Not only does this cause delays in getting results, but it also means production can’t continue. Even worse, if the material has been produced prior to production and the test reveals that it doesn’t meet specifications, that material has to be scrapped.

The sheer number of challenges that verifying opacity presents to packaging companies and other manufacturers mean that an in-line solution is needed more than ever. To support companies in verifying opacity in their packaging (whether it’s bottles, tubes, molded plastic, HDPE, or some other type of transparent material), EMX Industries, Inc. offers the OPAX-1000 line of opacity sensors.

Recently, we assisted a major packaging company in determining if this sensor would support verifying opacity in its (their) specific application. With the goal of reducing spoilage and waste caused by light penetrating its (their) packaging (which in this case was a 3.66-mm-thick film containing calcium carbonate, polyethylene, and polypropylene), the company sent in some sample material to EMX for a free evaluation.

Reduce waste, downtime, and cost with the OPAX-1000. Submit your sample material to our application engineers for a complimentary evaluation.

How the OPAX-1000 Supported Verifying Opacity in This Application

The material provided was around 80” long, and while our OPAX sensor is not designed to scan across an entire surface, our engineers were able to conduct multiple tests by cutting four 10×8” sheets from the sample. From there, we tested each sample sheet at five different points along the right and left sides of the top and bottom as well as the middle point.

verifying opacity OPAXFor the purposes of differentiating good samples and bad samples in-line, our engineers concluded that the OPAX-1000 would indeed perform well. However, certain setup parameters had to be followed, such as maintaining a certain transmitter-to-receiver distance of 150 mm, maintaining a low sensor gain setting, and maintaining a low sensor light source setting. 

This is because the OPAX-1000 uses a separate light source. The sensor transmitter sends modulated light through the target material to a receiver, and the amount of light that passes through the material indicates opacity. This light transmission is measured on a scale of 00 (no light passed through) to 99 (most light passed through). Ensuring that the transmitter and receiver stay in alignment is critical to accurate readings; otherwise, the signal might give a false positive or inaccurate reading. 

Additionally, for this company, an aperture had to be fitted on the front of the sensor to reduce the amount of light being sent through the material as the light transmission is intense. Thanks to the sample evaluation results, the company was able to identify a benchmark to use when verifying opacity in its products. If readings should drop below a certain threshold, the discrete output (PNP/NPN) trips — allowing a production leader or QC specialist to address the situation. 

Why the OPAX-1000 Shines in Opacity Verification 

The OPAX-1000 was developed to be low-cost, high-speed, and accurate. Its modulated light source rapidly measures light transmission through a target material while ignoring the effects of ambient light. This is a simple and effective way to measure material thickness or opacity, as thinner and more translucent materials allow more light to pass through. The OPAX-1000 features a 0–5V analog output for real-time monitoring, and a discrete output with an adjustable threshold for those who wish to streamline their logic controller programming.

Using the OPAX-1000, pre-made plastic films can be monitored for quality and consistency, ensuring all products are in approved packaging. Sections that fail can be cut from the line. The OPAX uses a dual-digit display that offers real-time feedback, making set-up and calibration easy. A remote lock feature prevents unauthorized changes to the sensor settings. The sensor achieves a wide range of sensitivity by using a combination of gain adjustment, light source intensity settings, and interchangeable apertures that mount to the light source to control the amount of light being emitted.

Ideal for use in multiple packaging and materials manufacturing industries, the OPAX-1000 is a singular option for verifying opacity in high-speed environments. Accessory bracket hardware makes installation a breeze, and it can be installed over a conveyor system to inspect materials as they pass, ensuring complete inspection of all materials.

Contact us today for your complimentary sample evaluation, or connect with our sales team to learn more about the OPAX-1000.