A client recently asked us if we could 100% guarantee that our magnets would pick up every metal fragment in their processing lines. Rather than over-promise and lead the client down a false path of security, we think it is critical to educate on why 100% magnetic separation can never be realistically promised.
This is because the effectiveness of magnets can vary beyond our control. These factors may include partial demagnetization over time, variation in flow, or variations in additives and moisture contents in materials processing. Other variables can be space restrictions, budget limitations, and the degree of magnetic susceptibility of the magnetic contamination. These factors affect the degree to which a protective installation can be ideal and for how long the ongoing degree of separation efficiency is maintained.
It would be ideal if 100% magnetic separation could be guaranteed but, although aimed for, unfortunately, there are several reasons why this is practically not feasible.
Let's unpack this a bit:
1. We don't have control of install environments and applications.
We work very closely with our clients and take into account even the smallest details prior to recommending our solutions. This ensures that the magnets we supply are tailored to each specific install location and product application.
But not all applications are the same. As it often happens in food manufacturing plants, production lines change, plants may relocate, and magnets (along with other equipment) are shifted around. What may have been the most effective solution for one location may not be ideal for another.
For each application, we carefully consider several factors including ingredients processed, tonnage rate, product flow, product stream coverage, and install location. Although our magnets are versatile and suit many and varied applications, it may be that a major change in one of these factors could negatively impact the separation capabilities of a magnet.
2. Magnets can lose their strength and this impacts their ability to attract and retain fragments.
Our magnets are certified to +11,000 gauss strength and designed to cover 80% of the product stream - this is ideal for food manufacturers and is in accord with current standards.
Although extensive measures are taken by our manufacturing and quality assurance teams to reduce the risk of demagnetization, this can never be ruled out.
If magnets are badly damaged, exposed to excessive thermal shock or resonant vibration, or altered in any way (e.g. welding/cutting - not recommended for safety reasons), there is a risk that magnet elements experience a rapid drop in strength. As mentioned, this will negatively impact their effectiveness in separating weakly magnetic fragments from the product stream.
3. Foreign metal fragments can be of varying materials and this means their degree of magnetic susceptibility differs.
The term 'metal fragments' covers a wide array of foreign materials that can be found in food processing lines. These can include:
- Work-hardened stainless-steel
- Nuts & bolts
- Metal tools
- Magnetic stone
'Magnetic susceptibility' is a term we use to describe the level at which a metal fragment is prone to attraction to a magnet.
Due to the variables in the magnetic susceptibility of metal fragments (e.g. extent of work-hardening, material composition, size of fragments, etc), it is clear that magnets should not be the sole final metal fragment control in food processing plants.
When selecting magnetic separation devices for final applications, it is crucial that proven magnetic separation principles are applied to maximize the separation efficiency of the magnets. Having the above knowledge will help to ensure that measures are taken to reduce risks and, at the same time, make the most responsible decisions based on practicality and risk reduction.
It is strongly recommended for responsible companies to obtain HACCP-certified validation of their installed magnets annually to ensure early detection and rectification prior to a major incident.
For questions regarding the effectiveness of your magnets or for new project inquiries, please contact our team here.