Unison has commissioned one of the highest-specification tube bending machines it has ever built, at UBER Precision Manufacturing — a start-up contract manufacturer based in Lynchburg, Virginia. The machine's electronically-actuated bending axes are controlled by a laser measurement system to ensure that tubing is bent without scrap — overcoming the common problem caused by variances in the 'spring back' characteristics of materials. The new machine is already repeatedly bending tubular parts to accuracies of a tenth of a degree or better, and in very small batches. In contrast, traditional tubular parts manufacturing almost inevitably generates wastage, which is beginning to impact heavily following recent surges in metal costs.

At a time when much of the country's traditional manufacturing base is migrating to lower-wage economies, UBER sees an opportunity for US-based supply. The new machine is a key element of its competitive strategy, which provides a highly automated design-to-manufacture methodology that minimizes time to market.

"Dealing with overseas sub-contractors is not always as beneficial as it's made out to be," says Jeff Boggess, Director of R&D at UBER. "There can be many issues to overcome when bringing products to market, introducing delays, quality issues and cost increases. We take the time on the front end of a project to closely define job requirements, verify designs before production, and run test parts to compare back to the original design. With proper planning, and good communications, you can do the job right first time."

The Unison tube bender is a multi-stack machine capable of bending tubing diameters up to four inches (100 mm). UBER's other machinery investments include two advanced 4 kW laser cutting machines with 3D capability, one dedicated to tubing. The company has also invested extensively in software infrastructure. It can accept design files produced by virtually any CAD software. Verification tools are used help avoid problems before parts actually enter production, including collision detection algorithms for the automated production machinery. And ERP software is employed to streamline processes.

"Flexibility of production was a critical goal for UBER. It had to be able to manufacture perfect products even in batch sizes down to one or two," adds Alan Pickering of Unison. "Speed of tool changeovers and reconfiguration, and accuracy and repeatability were critical characteristics, which we handled by providing a large multi-stack system that can accommodate tools for perhaps three different jobs, plus the laser control system — a unique product that effectively assures no-scrap bending. And today, if you're dealing with exotic alloys, this can save thousands upon thousands of pounds."

Unison's laser measurement module overcomes the common problem of variances in the spring back characteristics of materials from different metal production batches with minor differences in grain and temper. The new module is targeted at manufacturers of precision and high-value tubular parts.

The non-contact optical measurement system measures bend angles by monitoring changes in the reflection distance of two laser beams. In operation it takes a reference measurement from the straight edge of the tubing. Then, after the bend is made, the system automatically commands the clamping die to move away — allowing the material to spring to its natural position — and takes a second measurement from which the actual bend angle is calculated. Any difference to the programmed bend is displayed, along with a simple selection button that commands the machine to automatically re-grip the tube and apply an additional force to achieve the required angle. The system automatically calculates the required adjustment, taking into account the actual spring back characteristics of the tubing material from the first bend. It ensures that angles can be fabricated first time to very high accuracies.

Unison originally developed the measurement system to support a defense equipment contractor that produces precision tubular parts in single or very small batches just-in-time, and often from exotic alloys, supporting ship production.