Specialist tube bending company T+T Tubecraft is using a Unison all-electric CNC tube bending machine to accelerate production of precision tubular parts and eliminate material waste through right-first-time manufacturing.
Reputed for metal tube, pipe and section bending, Tubecraft serves a diverse customer base including pharmaceutical, petrochemical, aerospace and food processing industries. Tubecraft also has a particularly strong presence in the oil and gas sector, bending rigid small-bore hydraulic tubes for several subsea equipment manufacturers.
Tubecraft's pipe and tube bending services have been based on hydraulically-powered machines, although in recent years it has also invested in several hybrid hydraulic-electric machines. However, an increasing proportion of the company’s business requires very demanding shapes and smaller batch runs, which are not ideally suited to production on hydraulic tube benders. Many of the company's oil and gas projects fall into this category. For example, the tubular parts for subsea 'Christmas' trees, hydraulic flying leads and associated equipment are usually manufactured from expensive corrosion-resistant materials such as duplex, super duplex or 316L stainless steel, or more exotic alloys such as 6Mo, and invariably demand highly complex bends of exceptionally high accuracy.
Setting up a hydraulic tube bending machine to consistently produce parts of this complexity can be very time-consuming, taking Tubecraft’s specialists about 90 minutes to fit the tooling and configure a machine for bending a particular part. Given that more and more projects are generally produced in small batch sizes before the machine is retooled for the next part, the time overhead soon mounts up. For instance, Tubecraft on average performs eight complete tool changeovers a week for manufacturing subsea parts, representing as much as 12 hours of lost production time.
Aside from the time overhead, Tubecraft was also concerned about scrap material issues. On many bending contracts the tube material is supplied by customers, who often make no allowance for the waste incurred by trialling parts; with the material costs of even mid-range alloy tubing easily exceeding £200/metre, producing multiple trial parts for low volume, small batch size production runs was becoming uneconomic.
Tubecraft therefore sought to implement a right-first-time manufacturing strategy, based on a tube bending solution that combined ease of set-up and fast tool changeover with high accuracy and repeatability.
After assessing numerous tube bending machines over the years, including offerings from American, German, Swedish and Chinese manufacturers, Tubecraft concluded that UK-based Unison’s all-electric technology represented the optimal way forward. Another key factor behind the purchasing decision was Unison’s excellent reputation for support, which Tubecraft regards as vital for any business that is introducing new production technology.
The Unison tube bending machine, a 50mm Breeze all-electric model with a multi-stack tool head for fast, automated tool changeover, was installed at Tubecraft’s factory in Woking in January 2014. It is networked to the company’s CAD facilities and a coordinate measuring machine (CMM) that is used to verify bend accuracy and design conformity. The tube bender can be programmed manually or by importing CAD data using industry-standard IGES or STEP files, while data obtained by the CMM from the first manufactured part can be used, if necessary, to automatically adjust the bending machine ready for a production run.
Tubecraft’s Managing Director, Ross Turner said the all-electric architecture and automated software-controlled set-up offers major advantages over hydraulic machines including dramatically improved bending accuracy and repeatability, helping them achieve right-first-time manufacturing. Even for new projects, where measurements from the first manufactured part might be used to adjust bend parameters, the second part is usually perfect. Quick configuration of the electric bender is also a major benefit, taking only about 20 minutes, which is less than a quarter of the time it took with their hydraulic machines, resulting in at least nine hours a week of extra production time.
The multi-stack tool holding capability of the electric bending machine further helps to reduce the need for manual intervention, by allowing complex parts with multiple different bends to be made in one uninterrupted machine cycle. Although Tubecraft makes full use of Unison’s bar code scanning system to verify which tools are installed and configure the machine automatically, it does not yet use the quick-change tooling system and intends to implement some of the features over time.