Tube manipulation specialist embraces all-electric technology

According to Toolspec Manufacturing's Operations Director, Howard Dean: "Moving from hydraulic to all-electric tube bending technology is like coming in from the Dark Ages! The complex art of precision tube bending, known only to highly skilled operatives, is replaced by a system that is easy to understand and use. We took delivery of two Unison machines less than 8 months ago and by integrating them with our CAD and CMM (coordinate measuring machine) facilities we have implemented a much more efficient and flexible manufacturing system. We are now able to produce prototype parts in a fraction of the time that it took with our old hydraulic tube benders, with significantly reduced labour costs and much less scrap material."

Founded in 1961 as a tool-making company, Toolspec Manufacturing has grown to become a leading supplier of specialist parts that involve precision manipulation and welding during their manufacture. The company has developed particular expertise in the production of complex welded sub-assemblies manufactured from hollow section and tubular materials for the automotive, agricultural and construction machinery sectors. Its customers include several blue-chip companies serving world markets in luxury cars and construction machinery. Typical products include under-chassis cross-body braces for cars, complex door assemblies, fender stays, safety cages, cab and window grab handles for heavy-duty vehicles such as tractors and earth-moving equipment, together with hydraulic brake pipes and coolant pipes for a variety of vehicle types. Toolspec is a medium volume manufacturer, typically producing around 16,000 product assemblies a week for the automotive, agricultural and off-highway vehicle markets.

Continual investment in people and equipment has meant that over time, Toolspec has built up a large and diverse base of production automation, supported by skilled resources. This includes three ring rolling machines, four end-forming machines, seven power presses and 16 robotic welding cells. The company also has a considerable number of tube benders, including 14 hydraulically powered CNC machines that offer tube manipulation ranging from 4mm through to 120mm. Until recently, Toolspec favoured hydraulic tube benders, partly for historical reasons and partly because its workforce is highly skilled in the use of this technology.

Scrap material costs

However, one of the disadvantages of hydraulic tube bending machines is that they can be difficult and time-consuming to set up. It was typically taking Toolspec's tube bending specialists over an hour to get a machine ready for producing a complex part, which then demanded multiple trial runs and readjustments before a part could be produced that met specification. The scrap material costs of this approach were also significant. The problem was compounded by the fact that process variables such as hydraulic fluid temperature and pressure can vary during a work shift, making it challenging to maintain bend consistency throughout a production run.

In the light of these issues, Toolspec investigated alternative types of tube bending technology. It quickly formed the impression that all-electric technology represented the best way forward and that Unison machines stood out from the competition as being the most efficient, reliable and easiest to operate. As part of the review, Toolspec's Bending Supervisor visited Unison's UK factory and - despite having over 30 years' experience of hydraulic tube benders - was immediately convinced of the superiority of all-electric machines. Toolspec subsequently ordered two machines from Unison, to replace two early generation hydraulic benders.

The new Unison all-electric tube benders were installed at Toolspec's manufacturing facility in Luton, UK in May 2014. Both machines are 50mm Breeze models, equipped with multi-stack tool heads designed for fast, easy tool changeover. They are also both fitted with Unison's laser-controlled springback correction system. This accurately measures bend angles as they are produced and automatically applies any necessary correction to compensate for the tendency of tubes to spring back slightly after being bent.

Both of the Unison tube bending machines are networked to Toolspec's CAD facilities and to a ROMER portable coordinate measuring machine (CMM) that is used to ensure consistent production quality. The bending machines can either be programmed manually, or by importing data from CAD models that are created by Toolspec or supplied by the customer. Data obtained by the CMM from the first manufactured part is used, if necessary, to correct any errors and to automatically adjust the bending machine so that the second and all subsequent parts are manufactured correctly.

The advantage of this "closed-loop' manufacturing strategy is that it shortens the "time to first good part' considerably, by capitalising on the automated software-controlled set-up of Unison's all-electric machines.

Until a few months ago, it could take Toolspec several weeks to get to the stage where it was producing new products in volume to the customers specifications, especially if the part involved multiple complex bends prior to welding. After bending a prototype and obtaining customer feedback, the company would implement any necessary design changes, create new bending data and manually reprogram the bending machine to produce a new trial part. This often needed to be done quite a few times before it had a useable prototype, resulting in high development costs.

Minimal set-up time

As Howard Dean points out: "On the Unison machines, set-up time for a new part is minimal, and tool changeover only takes us about 10 minutes compared to hours with our hydraulic tube benders. Now, the first part is useable and the second part is totally correct to drawing, to the point where we can immediately enter full production. This saves an enormous amount of time and has also enabled us to reduce our scrap material costs per month. The combination of automated setup and tool changeover on Unison machines means that they do not demand operators with specialist tube bending skills, which helps to reduce labour costs and makes it much easier to expand production capacity. On top of this, Unison's customer support and engineering backup are excellent and I look forward to the time when we can install more of their machines."

Toolspec is now able to produce prototype parts to customer specification within about 30 minutes - and to handle volume production of parts with tolerances as tight as 1mm, demanding bends that are accurate to within 0.25 of a degree. One immediate result of this capability is that the company has secured a major new contract worth some 500,000 per year from one of its customers in the Europe - a prestigious agricultural vehicle manufacturer - for tractor rear window grab handles. In the first instance, Toolspec used Unison's Opt2Sim 3D simulation software to demonstrate its new tube bending capability to the customer. It recently delivered the first parts under this contract, all of which passed quality inspection and verification first time.

To learn more about all-electric CNC tube bending machines from Unison go to www.unisonltd.com.