Gravity-Fall vs Inline Conveyor Metal Detector: Where Should It Go?

Metal contamination control isn't a single decision — it's a decision about where in the line to catch it. ENZAC supplies metal detectors in two configurations built for different points in the process: gravity-fall, installed in the bulk material stream before packaging, and inline conveyor, installed on the takeaway conveyor after bags or packages are sealed. Most lines that need reliable contamination control end up specifying one, the other, or both — and knowing which does what changes how the rest of the line gets designed around it.

Gravity-Fall: Catching Contamination in the Bulk Stream

A gravity-fall metal detector sits inline in the bulk conveying stream — typically above the bagging hopper or below a silo outlet — where material falls freely through the detector's aperture. It detects ferrous, non-ferrous, and stainless steel contamination in unpackaged bulk material, before that material ever reaches a bag or box.

This is the right point to catch contamination when the goal is protecting downstream equipment (a screw conveyor, a bagging station's feed mechanism) from damage caused by tramp metal, or when contamination needs to be removed before it's committed to a sealed package at all. It's standard practice in fertilizer, oleochemical, food ingredient, chemical, and plastics processing — anywhere raw or intermediate bulk material moves through the line before final packaging.

Inline Conveyor: Catching Contamination in the Finished Package

An inline conveyor metal detector is installed on the takeaway conveyor after bag or package sealing, inspecting the finished product at full production speed. ENZAC's premium-class detectors run 30% better sensitivity than entry-level tuned detectors, with three user-selectable operating frequencies and auto-reject that triggers a pneumatic pusher, air-blast, or divert conveyor on detection — no operator action required.

This is the right point when the concern is what ends up in the customer's hands, not just what's in the bulk stream — because contamination can also be introduced during the packaging process itself (a staple, a piece of equipment wear debris, packaging line hardware). It's the standard checkpoint for food, pharmaceutical, and any product going to a customer where a contamination incident carries recall or liability risk.

The Decision Framework

In practice, many lines specify both — gravity-fall to protect equipment and catch bulk contamination early, inline conveyor as the final checkpoint before the product leaves the plant. Neither configuration substitutes for the other; they're solving different problems at different points in the same line.

When You Need More Than Metal

Both configurations detect ferrous, non-ferrous, and stainless steel — but neither catches glass, stone, bone, or dense plastic. If your product or export market requires detecting those contaminant types, or if packaging (foil, metalised film) blocks reliable metal detection, that's a signal to look at X-ray inspection instead of, or in addition to, a metal detector.

Speccing This for a Client Project

Where to place metal detection, and whether one or both configurations are needed, depends on the process flow, the contamination risk profile, and the regulatory requirements of the target market. Review the base Metal Detector specification and bring ENZAC your line layout and product data so we can recommend the right placement.