Advances in surface inspection lower costs

A discussion with Mark Shelton Shelton Vision Systems

VSD: Please give some background information on your company. How are you using machine-vision components and systems?

Shelton: Shelton Vision Systems was founded in 1995 as a subsidiary of Shelton Machines by cofounders John Ryder and Mark Shelton. We develop surface-inspection systems using off-the-shelf machine-vision components to operate on a PC platform that can take advantage of specialized vision-system-component-supplier development. We recruited image-processing engineers with a broad range of skills to tackle demanding applications at a level that established systems were not able to cope with, such as inspection of high value textiles and laser guiding over a deformable edge of stretch lace. The machine-building experience of the parent company recently combined with our vision-system expertise to produce an integrated stand-alone, large-batch, high-speed inspection machine for automotive interior fabrics.

We see an important part of our role as providing risk reduction for our customers when adopting, what is essentially, disruptive technology-that is technology that allows them to significantly change the way they do business. Our support continues once the system is installed to ensure all the objectives and benefits established during the initial consultancy phase are fully achieved.

VSD: How do you approach a new customer and their application? Do you work with OEMs or other system integrators?

Shelton: Much of our business comes from referral either within a group of companies or to associated companies and is mainly end-user oriented, although more interest is now coming from the OEM sector as the use of automatic inspection becomes more accepted.

For new applications we have a multistage process; to begin with we work to understand the potential customer's business and develop with them the areas where benefit can be gained and point out opportunities for change and potential risk. We then obtain a representative set of product and defect samples to evaluate either by experience or on our in-house test rigs. This quickly allows us to establish the technical requirement of the application solution.

Our systems are built around components from leading suppliers with whom we have built up a close relationship such as DALSA (Waterloo, ON, Canada) for cameras, frame gabbers, and its versatile WiT programming platform.

VSD: What technologies and components do you sell or use in these applications?

Shelton: We use DALSA Camera Link linescan cameras and frame grabbers, PCs with Intel Core-2 processors, Gigabit Ethernet networks, and fiberoptic and high frequency fluorescent lighting

Shelton’s on-line WebSPECTOR inspection system can image textile production at 90 m/minute. Eight DALSA linescan cameras are used to image three separate camera planes simultaneously.

VSD: In which areas do you see the most growth? What are users demanding from you in the design of new systems?

Shelton: We see a requirement for systems that offer flexibility and that are able to ‘grow’ with the user's business development, for example, to enable future upgrades to provide speed increases of 50% to 100% for less than 10% of the initial system cost.

Additionally, systems are needed that are developed to operate with minimal supervision and operator input where simple validation processes can be implemented to provide an audit trail of the performance level. It is important that a system provide a complete solution to incorporate the needs of all stakeholders within an organization, including sales and marketing, production/process improvement, and IT, as well as the quality department.

By incorporating these requirements at an affordable price, we see the potential to broaden the uptake of advanced technology into areas of industry traditionally attracted to low-labor-cost operating environments but where consistently high quality is still necessary.

VSD: How is each OEM component more or less important for the applications that you serve?

Shelton: Camera sensitivity and lighting are very important. To achieve high inspection speeds at high resolution (>200 m/min, 0.5-mm resolution), we need cameras that can capture a high-contrast image with a very short exposure time. A few years ago, CPU performance limited the speed that we could inspect, but with the latest CPUs this is no longer an issue.

VSD: What could vision-equipment manufacturers do to make your implementation jobs easier?

Shelton: Our systems are much easier to design and build since the introduction of the Camera Link standard. The GigE Vision standard is an exciting new development that we hope will continue to evolve and offer a broader range of cameras with even higher performance.

Lighting for web applications is still challenging. LED lightlines are improving but they still do not produce the broad-spectrum high output white light that we need. VHO aperture fluorescent lamps are old technology but they remain unbeatable for high lumens per meter output, long life, reliability, and low cost.

VSD: What kinds of new applications do you expect to emerge, and where do you expect to see the most growth?

Shelton: Many industries produce low-cost products in the form of continuous flat sheet but they have not implemented vision systems mainly because their initial investment is high and labor costs for manual inspection are low. We have to work hard to lower the cost of our systems to make machine vision affordable for all.

VSD: How will OEM components targeted toward machine-vision applications have to change to meet future needs?

Shelton: GigE linescan cameras are a way forward for lower-cost systems as frame grabbers are not needed, but their performance needs to improve before they can be used for multiple-camera, high-speed, high-resolution applications. LED lighting continues to improve, and we hope that in the near future we will no longer rely on mercury-dosed fluorescent tubes or short-life halogen lamps.

Mark Shelton is managing director of Shelton Vision Systems (Kibworth, UK; www.sheltonvision.co.uk) and has created a development team over the last 10 years to provide surface-inspection systems for high-level applications. He coordinates efforts and strategic direction with customer, industry, and university research groups. Editor in chief Conard Holton spoke with him about trends in inspection systems.