Garment Conveyor

Overview

The garment conveyor is an automated overhead transport system for clothing in commercial laundries, dry cleaners, and finishing plants. Unlike flatwork conveyors that transport loose fabric, the garment conveyor hangs individual items (shirts, trousers, dresses) on articulated slots, then routes them through a continuous loop circuit to specified stations for inspection, pressing, packaging, or delivery.

The system consists of a welded roller chain suspended on steel track rails, with integrated aluminum slot hangers spaced 0.5 m apart. Garments are manually hung on a hanger at the loading station, where a barcode reader scans the tag and communicates a destination to the PLC. As the hanger circulates through the loop, the controller monitors its position via an position encoder and triggers the appropriate pneumatic diverter arm when the hanger reaches the target station, deflecting the garment onto a drop-off chute.

A typical system loops through 3–5 stations (pressing, tagging, bagging, pickup) over 2–5 minutes circulation time, allowing a single operator to manage 50–100 garments in flight simultaneously.

How It Works

Garments arrive on hangers from the water-extraction stage or from a batch washer. An operator places each garment on a slot hanger at the loading station and closes the safety clip to secure it.

A barcode label or RFID tag on the garment indicates its destination: "Press 1" for dress shirts, "Quality Check" for delicates, "Bag & Tag" for regular orders, or "Hold" for customer pickup. The operator scans the tag with the barcode reader, which sends the destination code to the industrial PLC.

The 5.5 kW motor continuously drives the chain loop at 0.54 m/s (one hanger every 0.5 m moves past a fixed point in 0.93 seconds). The position encoder on the motor gearbox output counts hanger positions, allowing the PLC to track where each loaded hanger is in the loop.

The hanger circulates through the rail system, which forms a closed loop: horizontal track from loading station → pressing area → quality check → bagging station → return path → loading station. The loop is typically 40–60 meters long, taking 120–180 seconds for a hanger to complete one circuit.

As the loaded hanger approaches Station 1 (Pressing), the proximity sensor at that station detects the hanger's presence and signals the PLC. The PLC checks its memory: if this hanger's barcode destination matches "Press 1," it energizes the pneumatic cylinder, which extends the diverter arm blade. The blade pivots upward beneath the hanger slot, gently lifting the garment off the chain and deflecting it onto a chute that feeds it to a pressing machine.

Once the garment is diverted, the now-empty hanger continues on the loop and is available for reload at the loading station.

If the barcode destination is "Press 2" instead, the PLC does NOT energize the diverter at Station 1; the hanger passes through under the inactive arm blade and continues circulating. When it reaches Station 2 (Press 2) some minutes later, the PLC again confirms the destination, energizes that station's diverter cylinder, and ejects the garment.

This selective routing without mechanical mode-changing is the key advantage: operators select destinations with a button click or barcode scan; the PLC automatically routes each garment to its correct station. A single loop can serve 8 divert stations simultaneously.

Hanger and Chain Design

The chain is heavy-duty roller chain (1.5-inch pitch, welded links) rated 5 kN working load. At the hanger connection points, the chain is welded to cast aluminum hanger frames, which are 0.15 m wide with two articulated grip jaws that can be pneumatically adjusted to grip garments of different widths (0.1–0.2 m).

Each hanger slot can support 1–3 kg of hanging garment. The slot is equipped with a spherical roller bearing that allows the hanger to articulate (rotate ±60°) when diverted, ensuring the garment is gently dropped rather than snapped off. The spring-loaded safety clip prevents the garment from accidentally falling off during normal circulation.

The grip jaws are passive (gravity-operated) in the basic version; operators manually adjust the opening to accommodate garment width. In advanced versions, a solenoid valve can pneumatically open the jaws during loading and close them during transport, providing extra security for delicate items.

The chain loop is kept under constant tension by a hydraulic or spring tensioner, which applies approximately 2 kN load to the chain. This tension ensures smooth entry into sprockets and prevents sagging. The drive sprocket (72 teeth) is keyed to the motor gearbox output shaft.

Rail System and Routing

The rail system comprises horizontal rails on which the chain glides, curved rail sections for 90° turns, and optional vertical sections if the loop rises to a second floor or descends to a basement level.

Rails are steel angle-iron or box-tube welded to support brackets every 0.5 m. The brackets are bolted to building beams or floor structures. A typical single-level loop requires 40–50 brackets; a multi-level loop requires additional vertical posts and bracing.

The curved rail sections are precision-bent to a 1.5 m radius, allowing the chain to negotiate 90° turns without excessive stress. At each curve, the outer rail is slightly elevated (2–3 degrees) to reduce lateral forces on the chain and ensure smooth hanger articulation.

In multi-level systems, vertical rail sections allow the loop to rise or descend. The motor drive must overcome the additional potential energy: for a loop rising 3 m vertically with 50 hangers each holding 2 kg garments, the total lifting load is approximately 3000 N, requiring additional motor power. This is typically accommodated by using a 7.5 kW motor instead of 5.5 kW for multi-level systems.

Control and Diverter Logic

The PLC is programmed with a lookup table: Barcode "001" = Station 1, Barcode "002" = Station 2, etc. When the barcode scanner reads a tag, it sends the code via Ethernet to the PLC, which stores it along with the current hanger position.

The chain position encoder generates one pulse per hanger position (typically one pulse every 0.5 m). The PLC counts these pulses to determine hanger position throughout the loop. When a hanger arrives at a divert station, the proximity sensor confirms presence, and the PLC checks its lookup table.

If the hanger destination matches the station, the PLC energizes the solenoid valve for that station, which supplies 6 bar air to the diverter cylinder. The cylinder extends, rotating the diverter arm upward in approximately 1 second. The hanger is gently lifted and the garment tips onto a chute below. The cylinder retracts as the hanger passes, returning the arm to standby position.

If the destination does NOT match, the solenoid valve remains de-energized, the diverter arm stays down, and the hanger passes through harmlessly, continuing circulation.

This event-driven logic allows complex routing: a single loop can serve 8 divert stations, each handling different garment types or customer orders. Garments are sorted and routed automatically based on barcode content, eliminating manual sorting.

Pneumatic System

The solenoid valve manifold distributes air to up to 8 diverter cylinders. Air is supplied at 6 bar from a shop compressor. The PLC energizes the appropriate solenoid channel when a hanger is detected at that station, triggering a quick air pulse that extends the cylinder and retracts automatically once the garment clears.

Each diverter cycle consumes approximately 0.01 m³ of air (0.6 liters at 6 bar). With 300 garments per hour (50 garments on the loop, 6-minute cycle time), divert events occur at an average rate of 5 per minute, consuming 0.05 m³/min on average, well within a typical shop compressor capacity.

Maintenance and Safety

The chain is inspected every 2 weeks for wear; typical chain life is 10,000–20,000 operating hours. The hanger pivot bearings are sealed and require no lubrication. The sprockets are inspected annually for tooth wear.

The rail system is cleaned monthly to remove lint and dust. The motor and gearbox follow standard industrial maintenance (oil change every 2000 hours).

Safety interlocks prevent motor start if the structural frame door is open (preventing operator contact with rotating chain). E-stop buttons are positioned at all operator stations; activating e-stop de-energizes the motor contactor and vents all pneumatic lines within 1 second, halting the chain and retracting all diverter arms.

Guard rails and covers surround the rail system to prevent operator contact with moving chain and hangers. Garments cannot be ejected if a hanger passes through a divert station without an active divert signal (fail-safe design).

Typical Installation and Capacity

A standard installation in a medium-sized laundry (200 kg/day garments) uses a 40 m single-level loop with 4 divert stations (Pressing, QC, Bagging, Hold). The loop accommodates approximately 80 hangers, each carrying 2 kg garments, totaling 160 kg in flight. Circulation time is 2–3 minutes per lap, providing continuous flow.

Energy consumption is approximately 4 kW continuous (motor + pneumatics). Throughput depends on processing time at each station: if pressing takes 1 minute per garment, the system processes 40–50 garments/hour at the pressing station, scaling proportionally for other stations.

The system is particularly valuable in dry cleaning operations where precise garment tracking, barcode-based routing, and multi-station integration are critical for managing orders and customer satisfaction.