Plastic is an ever-present part of our everyday lives and a key material in manufacturing. While it is present in a wide range of industrial and consumer products, there’s one notable place where we don’t want plastic – our food.
Being able to detect plastic before consumable products end up in the stream of commerce is essential for safety. X-rays have been a reliable technology for detecting materials like metal, bone, glass, and other foreign objects, including plastics. There are limitations, however, to what standard x-rays can detect.
With the reported instances of plastic contamination doubling in recent years, the situation requires more advanced measures to detect plastic material in an x-ray. This article outlines various methods to see plastics, including x-ray options.
How Plastic Contamination Occurs
Plastic contamination can come in a variety of forms, such as gaskets, o-rings, scraper blades, pens, safety glasses, bandages, and gloves. Commonly, plastic contamination occurs when a piece of manufacturing equipment breaks, though that is one of many possible scenarios.
Often, an activity as innocuous as cleaning can lead to an object or fragment getting introduced to a production line. The detection of a single piece of plastic by a consumer can result in recalling an entire batch of products.
The most common food products contaminated by plastic include chicken, dairy, bakery, and salad and vegetable products.
The Cost of Recalls
You might have heard of massive food recalls due to plastic contamination. Not only do these instances endanger the public, but they also cost a company thousands (or millions) of dollars. First, there’s the issue of pulling products off the shelf and issuing refunds to distributors, wholesalers, and retailers.
Even more expensive, however, can be the resulting blow to a company’s reputation. Once trust is lost and consumers lose confidence in a company’s ability to provide items that are safe to consume, sales can dwindle significantly. Further, it can take months or years to rebuild a company’s reputation and brand credibility after such an incident.
Detecting Plastic Contaminants
While visual inspections and manual sorting are the first line of defense for detecting plastic contaminants, there are limitations. The sheer volume of products and human error can allow all forms of contaminants to slip through the cracks.
Metal detectors, optical scanners, and x-ray machines are reliable options for metallic materials. However, because plastic has a relatively low density, it can often pass through x-ray detection. Solving this issue requires newer technologies, such as Material Discrimination x-ray, or MDX, for short.
Limitations on Standard X-Ray Systems
X-ray detection technology has advanced over the past several years, but conventional systems are limited. For example, most x-ray systems can only detect items with a higher density level than water, which is 1000 kg/m3. By contrast, stainless steel’s density is 7600 kg/m3, making it easily detectable.
From a practical standpoint, this means that some low-density materials can’t be detected using standard x-ray systems, including:
- Thin plastics
- Lightweight metals
- Wood fragments
- Human hair
The quality of an x-ray inspection system matters because some systems are able to detect materials that others cannot. Notably, TDI Packsys outperforms the competition by detecting plastic contaminants that other systems miss.
Benefits of Material Discrimination X-Ray (MDX) Technology
Where standard x-ray systems fall short, MDX technology can pick up the slack. Originally developed for use in security applications, MDX technology now provides food manufacturers and processors with unprecedented capabilities to detect plastic contaminants.
It works by simplifying x-ray imagery and identifying materials by atomic number rather than density. As a result, Material Discrimination x-rays can see foreign objects that were previously undetectable through conventional x-rays and other methods.
MDX can be used across a range of industries, including medical, industrial infrastructure, environmental monitoring, and more. In the consumable products industry, benefits include:
- Inspect large batches
- Detect foreign objects (including low-density plastics)
- Improve quality control
- Ensure consistent portion sizes
- Comply with regulations
- Reduce product waste
- Boost consumer confidence
- Trace contamination more efficiently through integration with data systems
Improving Detection of Low-Density Plastics
When x-raying food products, particularly meat, dairy, and items with small pieces (like shredded cheese and salad mixes), the x-ray image can appear “busy.” This makes plastic visualization and detection difficult.
Advanced x-ray systems can vastly improve the detectability of plastics. For example, triple beam architecture works by splitting the ray into three beams to eliminate blind spots. Other systems, like MDX, reclassify x-ray imaging using atomic numbers.
As the field continues to progress, software algorithms are also becoming smarter and can help recognize specific characteristics present in low-density plastics like polyethylene and LDPE (low-density polyethylene).
X-Ray Detectable Alternatives
To increase the odds of plastic detection, some specialty manufacturers known for producing common contaminants have turned to using materials that are more x-ray detectable than regular plastics.
These x-ray-detectable alternatives can include:
- Protective bandages
- Some protective gloves
- Metals, including tungsten
- Plastic additives that can be detected on an x-ray
- Items easily detectable by radiographic contrast
- Specialized markers
Best Practices for Plastic Detection
The goal is to detect and remove plastic contaminants before a product ever reaches a supermarket shelf. As the saying goes, an ounce of prevention is worth a pound of cure.
At TDI Packsys, we recommend the following best practices for plastic detection:
- Perform regular inspections and repairs of manufacturing equipment
- Implement x-ray inspections
- Calibrate metal detection systems to be sensitive to plastic contaminants
- Engage in optical sorting
- Train employees to understand the importance of plastic detection and reporting
- Develop a schedule that includes inspections of raw materials, packaging, and finished products
- Install screens or other sifting apparatus to filter plastics
- Use only food-grade plastics at every level of manufacturing and packaging
- Collaborate with suppliers on safety issues and hold them to a high level of quality and transparency
- Exercise proper hygiene at all levels of the organization
- Regularly audit procedures and identify areas for improvement
The Bottom Line
Keeping plastic contaminants out of products is imperative for any organization. It requires diligent procedures and the right equipment. TDI Packsys has a reputation for providing top-of-the-line inspection systems to keep your business operating safely and smoothly.