87% Reduction of Defects using a Vision-Based Assembly Assistance System

Develop an inspection system to identify defects associated with manual assembly and improve assembly processes.

Each of the 200 variants requires a dedicated manufacturing fixture. The inspection system has to be able to reliably identify all fixtures and component groups and provide the flexibility to adapt the system for any new or modified variants.

At the Kautex plant based in South Wales, around 200 different variants are manufactured with some 12,000,000 tubing assemblies produced each year. They comprise numerous components, including the tubing, nozzle, clips, coloured tapes, foam pads, t-pieces etc. which are constructed completely by hand. The operators assemble the product from printed assembly documentation. On completion, the assembly is visually inspected. 

Each assembly variant requires a dedicated manufacturing fixture which can be used on any of 80 assembly workbenches. The inspection system had to reliably identify both the fixtures and the components used and provide the flexibility to adapt the system for any new or modified variants.

STEMMER IMAGING and Envisage Systems developed an intelligent, vision-based assistance system that is fully integrated into the manual assembly process providing a number of additional benefits on top of simply monitoring the components’ quality: 

• 100% quality control 
• 87% reduction in the total number of defects
• 100% traceability of every single assembly  
• 70% reduction in the amount of paperwork being printed 
• Flexibility to adapt the system for any new or modified variants
• Automated component and operator verification 

The sophisticated vision solution was developed by STEMMER IMAGING in conjunction with systems integrator Envisage Systems Ltd. A touch screen and a flexible vision system were installed at each workstation, using standard Teledyne DALSA Sherlock measurement and inspection tools to check for the presence of the correct coloured tape in the correct position and to take measurements on foam parts, clips, etc. Envisage designed a bespoke operator interface for the software. STEMMER IMAGING supplied all of the imaging components used as well as providing software training for the Kautex team. 

High-performance cameras

A 5 Mpixel Genie Nano GigE Vision colour camera from Teledyne DALSA equipped with a 1” format, 12 mm focal length lens is mounted above a workbench.

Flexible illumination

Barlights from Smart Vision Lights provide perfect illumination of the 1.3 metre field of view, overcoming any effects from ambient light coming through skylights in the assembly area.

Scalable image evaluation

A Teledyne DALSA GEVA-300 compact vision processor, running Sherlock machine vision software provides local image evaluation before images are transferred to the central server via Ethernet. It can also accommodate additional cameras for upward scalability.

Unlike visual inspections previously carried out, the assembly processes can be reliably checked with the help of machine vision, resulting in 100% reduction in all targeted defects and on top almost 90% reduction of assembly-related defects.  

All production data, including instructions, diagrams, pictures etc., are centrally stored in the database and are displayed on the touch screen after scanning the barcode. The amount of printed documents that have to be available to the operators could thus be reduced by 70 %.

The operator logs in via a touch screen using their unique ID. The system checks whether the operator has the required assembly training based on the assembly part number and the operator ID in the database and displays the number of parts to be assembled. 

All assembly steps are recorded. Once assembly is complete, the operator initiates inspection with the system generating an image of the inspected part. All images and recorded actions are stored on the central server providing a full audit trail for every single part. 

By scanning the barcode on the production parts, the vision inspection file is loaded, and the vision system checks whether the correct part is used for this application. A unique identifier (UID) prevents the same batch from being reassembled if a label is accidentally scanned twice.

Through careful selection of the components used, the system can be quickly and easily adapted to new product variants. It can readily accommodate an additional camera if larger assemblies are introduced and any inspection can be set up using the sophisticated range of measurement tools available.

Intelligent cobots using 3D vision

Collaboration between humans and robots without safety fences is constantly growing. With intelligent 3D vision systems from LMI Technologies, the experts at STEMMER IMAGING enable the collaborative robots from Universal Robots to perform demanding pick-and-place tasks. They can grip objects and move them to a target point without any unwanted collisions – together with their human colleagues.