Pet Food Foreign Material Control: Metal Detector vs X-Ray After Fromm Recall

# Pet Food Foreign Material Control: Metal Detector vs X-Ray

Fromm Family Foods voluntarily recalled 300 cases of Bonnihill Farms BeefiBowls gently cooked frozen dog food after consumer complaints about plastic contamination. Such recalls are not rare — from desiccant fragments in freeze-dried treats to metal shavings and plastic bits, **foreign material control is one of the most underrated yet most liability-prone parts of co-packing.**

Where Foreign Material Enters

| Source | Typical foreign material | High-risk step |

|---|---|---|

| Incoming ingredients | Metal shavings, bone chips, plastic wrap, grit | Receiving, thawing |

| Equipment wear | Stainless steel chips, seal rubber, bearing debris | Grinding, mixing, extrusion |

| Packaging | Film fragments, desiccant beads, label paper | Packaging, sealing |

| Personnel | Hair, buttons, pens, glove fragments | All steps |

| Pests | Insects, rodent hair | Storage, workshop |

Fromm's plastic likely came from packaging film or a worn plastic part — something visual inspection cannot catch.

Metal Detector, X-Ray, Magnet, Sieve: What Each Does

1. Metal Detector: First Line

Detects ferrous, non-ferrous (copper/aluminum) and stainless steel. Installed after packaging, before case packing. Key sensitivity:

• Dry powder/kibble: Fe ≤1.5mm, Non-Fe ≤2.0mm, SUS ≤2.5mm;
• Wet/frozen product (higher moisture interferes): relax one grade or use X-ray.

**Metal detectors are blind to plastic, stone, bone and glass.**

2. X-Ray Inspection: Second, Expensive Line

X-ray sees through packaging and finds:

• Metal (iron, copper, stainless, lead);
• Stone, glass, hard plastic, calcified bone fragments;
• Missing weight, packaging defects, mix-ups.

Premium brands and export lines now require **metal detector + X-ray dual inspection.** Imported X-ray units cost $40k-$110k; domestic units $20k-$45k.

3. Magnetic Separator: Stage It At Ingredient Intake

High-gauss magnetic rods (10,000-15,000 gauss) at ingredient intake and mill exit catch ferrous contamination early. Cheapest, highest-ROI control.

4. Sieve: Powder and Granule Lines

Vibratory sieves after grinding/mixing catch lumps and large particles. **Inspect mesh regularly — a torn sieve becomes a new contamination source.**

A Co-Packer's Foreign Material System

1. **Ingredient receiving**: each lot passes metal detector + magnet; records retained;

2. **In-process controls**: sieve/magnet after milling, mixing and extrusion;

3. **Post-pack metal detector**: every bag, with automatic reject;

4. **Export-line X-ray**: every bag on premium/export lines;

5. **Monthly challenge tests**: use test wands (Fe/SUS/non-Fe/plastic card) to verify sensitivity;

6. **Complaint traceability**: pull production records, equipment calibration logs and retention within 2 hours.

Factory Audit Checklist

• What brand/model are the metal detector and X-ray? When were they calibrated?
• How often are challenge tests run? Are records available?
• Is the reject bin locked? (Prevents rejected units from being returned to the line.)
• Is there a brittle plastic program? Are all plastic parts numbered and inspected?
• What is the foreign material complaint SOP? When was the last complaint and how was it handled?

Cost Reference

| Equipment | Cost (RMB) | Use case |

|---|---|---|

| Pipeline magnet | 5k-20k | Ingredient intake |

| Vibratory sieve | 10k-30k | Powder/granule |

| Online metal detector | 50k-150k | Post-pack, mandatory |

| Imported X-ray | 300k-800k | Premium/export |

| Domestic X-ray | 150k-300k | Mid-tier |

Bottom Line

Fromm's recall is not about "Fromm being careless" — it shows that even a century-old US family brand can ship plastic. For Chinese co-packers, foreign material control is not "having a metal detector" — it is a layered system from intake to shipment.

If you need an export-line co-packer with metal detector + X-ray dual inspection and monthly challenge-test records, **Mixiaoqi pet food OEM/ODM** in Guangzhou runs post-pack metal detection on every line and X-ray on export SKUs. Bring your audit checklist.

---

FAQ

**Q: Metal detector vs X-ray — what is the difference?**

A: Metal detectors only sense metal; X-ray finds stone, glass, hard plastic and metal. Premium export lines use both.

**Q: Why can't metal detectors catch plastic?**

A: Plastic is neither conductive nor magnetic. X-ray or a brittle-plastic program is required.

**Q: How much should a co-packer spend on foreign material control?**

A: Basic line (magnet + sieve + metal detector) ~100k-200k RMB; export line adding X-ray ~500k-1M RMB.