A vision-based inspection system designed by AMH Material Handling and developed and installed by Bytronic has brought significant benefits to the garment conveyors of a major international clothing retailer.
AMH Material Handling specializes in the design, installation and integration of automated conveyor and sortation systems for some of the UK's largest retailers. Since launching in 2015, the company has rapidly grown to become the 'go-to' provider of profitable e-commerce and warehouse automation solutions.
The engineering team approached Bytronic as the company has particular expertise in garment on hanger (GOH) conveyor lines, and AMH wanted to develop a partnership that would help create a new specialist solution for the leading off-price fashion retailer.
The challenge was to create an automated, “vision-based” inspection system for the fashion retailer's GOH conveyors. These conveyors transport up to 140 hanging garments per minute, but to function effectively the solution needed to capture and process data within milliseconds.
Developed by AMH Material Handling, GOH conveyors handle millions of garments each year. Overhead GOH conveyors can be designed to transport either single units for sorting or ratio packs and batches for transport and storage.
When GOH conveyors are used to transport ratio packs or batches of hanging garments, they must be separated into single units for accurate sorting. The high speed separation process often results in hangers being accidentally double stacked, which is often missed with older item detection technology.
Over time, double hangers can cause inventory control issues as the inventory information for shipped items is inaccurate when compared to the inventory received at the final destination. For large retailers, this can be a big problem. To solve this problem, they placed dedicated operators on the line to find the double hanger problem, which was a costly and labor-intensive solution.
When AMH began developing a custom automation solution in 2015, they approached manufacturer Cognex and its partner network to provide their machine vision expertise. Bytronic, one of Cognex’s only Platinum Partners in the UK, was recommended to develop and install the vision solution.
The result was AMH's vision detection system, which identifies double hangers as they pass through automated single-unit sortation lines – a solution that helps prevent inventory loss without the need for manual checks.
The system combines mechanical and electrical equipment from AMH supported by programmable logic controllers (PLCs), Cognex cameras, and Bytronic lighting and vision software programming. The line can count each carrier, identify its unique number, track its location, ensure it is safe and unbroken, identify double hangers and accept or reject the carrier accordingly.
Bytronic installed and programmed camera software that captures images of each carrier when triggered by the line. The cameras detect several key characteristics including the condition of the carrier and its individual parts, and ensure that maintenance and servicing is carried out as necessary to extend the life of the system.
Images are captured, the data is processed, and an “accept” or “reject” message is sent back to the control system – all within milliseconds. If a duplicate hanger or damaged carrier is detected, the “reject” message activates a reject diversion and the item is sent to a separate defect lane for further inspection.
Managed by AMH, the project was realised through a partnership, with data captured by Bytronic's cameras and lighting system processed by PLC control and software solutions provided by AMH. All Factory Acceptance Tests (FAT) can be carried out off-site, so the inspection system was calibrated and tested offline prior to installation.
Once operational, cost savings were immediate. The upgrade significantly reduced operator costs, achieving a payback period of less than one year. This allowed “inspection” operators who previously worked 24/7 shifts to be allocated elsewhere. Additionally, the new overhead system improved both inventory accuracy and the stock distributed to stores nationwide, leading to reduced inventory loss.
While the primary focus of the project was double hanger detection, it also delivered the added benefit of identifying potential maintenance issues. With the solution, statistics on carrier damage are now identified and stored, enabling maintenance engineers to repair and update the system. Removing double or damaged hangers from service also reduces the risk of hanger tangling and unnecessary downtime due to recurring damage.
Barry Pemberton, solutions director at AMH Material Handling, said: “We engaged Bytronic to deliver this AMH Material Handling-led solution for one of our largest customers. The two companies worked closely together to identify what data the system needed to generate and how it should be presented. From our discussions with Cognex, we recognised that the success of this project depended on the installation of lighting and vision software, so we selected Bytronic.”
