Vision systems perform a wide variety of tasks in manufacturing, including inspection, monitoring and control functions. They can also be used in safety systems to help prevent injury to machine operators if, for example, they inadvertently obstruct the operation of a press brake or stamping machine ram/punch and die.
In principal the problem of inspecting a component might seem straightforward — illuminate the component, examine it using an image capturing device such as a digital camera, cross reference the captured data with a digital template and use the result to determine whether or not to accept or reject it.
But designing a system is far more complex. For example, system integrators must determine exactly what needs to be inspected. This requires consultation with all parties involved, the nature of the production line, what type of light source to use so that the system can ‘see’ properly, the camera type/output format used and how many cameras are needed. A 3D object shape can only be seen in two dimensions with a single camera.
The integrators must also consider the lenses used. The field of view must be large enough to accommodate the biggest objects, but this may mean that the smallest examples may not be seen very easily. Finally, the integrators must determine what is in place to present the component to the vision system. This can be a simple conveyor-and-guide system or a complete five-axis robot.
Automated vision systems are often involved in very complex processes. For example, one medical component manufacturer is using a laser-based material removal cell featuring Cognex In-Sight vision. The system, designed by Invotec, was created to de-gate and remove flash from an injection-moulded, synthetic rubber part.
The In-Sight 5403 camera communicates with the motion control system to dictate the path of the laser-cutter. It is triggered by a programmable logic controller (PLC) to set up the calibration target, move a power meter and inspect the part. The cycle time of the entire system is about eight seconds.
Systems such as these must be easy to use and acceptable to the workforce. This requires careful attention to a wide variety of factors, including the user interface. They must also be able to keep up with production and perform all the necessary function with a minimum of human intervention.
Italian automotive manufacturer Cabi, for example, cannot take any chances when it comes to part safety and quality control for the production of engines. So complete traceability of each part is essential.
Cabi chose marking specialist Technifor to ensure this traceability using direct part marking (DPM) on the surface of each product.
The company also specified Cognex Checker and In-Sight vision systems to eliminate the risk of errors in the production process as well as to read and inspect the directly marked codes at each point of production.
The company’s production site has several different work areas, each dedicated to a different client. Each component handled within the specified work area has a specific graphical symbol identifying the client, thus ensuring the production process is error-proofed from the onset of production. In addition to client identification, a 2D code ensures traceability of every individual component.
This two-tier identification is initially performed by Checker, for symbol detection, and then by In-Sight for code verification and reading.
The Checker vision sensor detects the presence of each symbol before the part is marked with the 2D code using a Technifor laser marking system. Each inspection is recorded so that at each control point an accurate trace is kept on the part.
These details are automatically entered into a database which is integrated into the client’s operations details.
By investing in this system, Cabi can assure its clients that the entire production process is controlled, inspected and recorded from start to finish. It can also prove that each piece is completely traceable and has been correctly inspected.
For manufacturers dealing with high-volume applications such as medical device manufacture and processing, throughput is a main concern.
For that, Industrial Vision Systems has released a range of high-speed, ultra-compact digital monochrome cameras with image capture rates of 90 frames/sec.
All of this is combined with 800Mbit/sec communications. These cameras provide ‘plug-and-play’ integration with the company’s NeuroCheck software.
The new NCF range of cameras is claimed to be 30 per cent faster than previous units — even with two megapixel image sizes — offering increased throughput with no loss of fault resolution.
Typical applications include high-speed character recognition, precision gauging and measurement of products and checking completeness of assembly groups. Each of the five models in the NCF range includes FireWire-compliant interfacing for communications and power, allowing ‘out of the box’ system integration.
Other companies such as Firstsight Vision, based in Surrey, believe manufacturers are also looking for vision systems that can demonstrate ruggedness as well as all the other features.
The company’s new IPD VA61 compact vision system contains all the processing power in a rugged enclosure, instead of the camera head, and so can be readily integrated into a factory environment.
The VA61 supports two dedicated Gigabit Ethernet (GigE) camera ports in addition to one GigE compliant network port for a range of monochrome and colour GigE cameras.
The use of GigE vision makes it possible to have long Ethernet cable lengths between the controller and the inspection point. Using an Ethernet hub, a large number of cameras can be connected to the two VA61 camera ports. Multiple camera inputs will allow the inspection of different views of the same part, or even different parts simultaneously. This integrated functionality provides a cost-effective and less complex solution than comparable smart camera implementations.
Overall, vision systems have a huge potential in all manufacturing and processing environments.
But to ensure that the best solution is acquired, customers need to consider what they want to achieve and what can be done to aid the undoubtedly complex installation.
Whether used for monitoring and control; or complete component traceability, vision systems have great potential in all manufacturing and processing environments. Martin Oakham explains what’s on offer.