SUBCONTRACTOR ORDERS SECOND AUTOMATED CELL FOR MACHINING PRISMATIC COMPONENTS

Having installed a Japanese-built Brother production cell at the end of 2019, comprising two 5-axis Speedio M140X2 mill-turn centres served by a Feedio vision-based robotic unit for component handling, Worthing subcontractor Roscomac has ordered a second identical cell. Due to be delivered in April 2021 by Brother’s sole UK agent Whitehouse Machine Tools, the latest acquisition is symptomatic of a fundamental change in the way Roscomac’s owner Joe Martello views automated manufacture.

He said, “About 20 years ago we installed a large flexible manufacturing system consisting of six 3-axis, 40-taper, half-metre-cube machining centres linked by a three-level storage and retrieval system for 104 machine pallets.

“Having served us well, it is being decommissioned in February 2021. Part of the space it frees up will be used for relocating the first Brother cell and the second will be placed alongside it, all in a relatively small footprint.

“Since 2018 our company has undergone a major shift towards 5-axis machining. We have spent the majority of a £4 million investment in that period on multi-pallet pool systems with large tool magazines.

“They machine parts in fewer operations while achieving a high level of automation, without the complexity of an FMS based on 3-axis capacity. Had we not gone down the 5-axis route we would be dead in the water by now.

“With the two Brother systems, we have gone a step further by installing our first 30-taper 5-axis capacity for automated, ultra-fast machining of aluminium components in fewer set-ups and hence to superior quality.”

He explained that while the FMS was an efficient production facility, the 3-axis CNC technology often required several parts at a time to be clamped multiple times in expensive staged fixtures for completion of several separate machining operations. The system’s utilisation dropped because the type of work coming through the door was changing; it was becoming lower volume and more complex. Production was more difficult to control and the increasing number of set-ups raised the labour cost content of component production, as operators were frequently at the load / unload stations.

The timing of the arrival of the first Brother cell, a matter of months before the start of the Covid-19 pandemic, could not have been more fortuitous. Nearly a quarter of Roscomac’s turnover normally comes from the medical industry but in 2020 that proportion doubled, leading to an increase in annual turnover of £2 million despite the virtual disappearance of aerospace work, which historically has accounted for one-tenth of Roscomac’s throughput.

For many years the subcontractor had been machining four different components for hospital syringe pumps from aluminium castings and extrusion. They used to be machined at a rate of 4,000 per month per part number on 40-taper machines in the FMS, but were ideal candidates for transfer to the first Brother cell. It was therefore supplied with a turnover station so that one Speedio can carry out Op 10 while the other completes Op 20 after the component has been rotated, all fully automatically.

These nimble, 30-taper, 5-axis machines could produce the parts much more cost effectively in two operations, 24/7, without operator intervention apart from placing raw material onto the input conveyor and unloading finished parts from the output conveyor. In contrast, unattended and lights-out running was impossible on the FMS due to the constant loading and unloading, so in practice the system was only capable of one-quarter of the output of these components compared with the Brother cell.

Within one month of the start of the pandemic, the customer quadrupled the order quantity to 16,000 per month per part. Mr Martello advised that it would not have been feasible to achieve even half that amount using the other plant in the factory, which would have meant turning away business. As it was, the Brother cell was able to cope. It started paying for itself and making a profit from the first day it was installed, as the operator only needs to load and unload the conveyors and keep an eye on production, so is free to run other machines.

By the middle of 2020, due to the success of the cell, the decision was taken to transfer all the remaining work from the FMS and plan for its removal. As the Brother cell was working flat out, this work was initially put onto 40-taper machining centres, but to add more high-speed capacity, a third Speedio M140X2 was hired from Whitehouse Machine Tools and operated as a manually-loaded machine.

Mr Martello continued, “It really focused the mind, seeing the operator having to attend the machine virtually continuously during the relatively short Op 10 and Op 20 cycles. So we decided to purchase a second fully automated Brother cell, exactly like the first.

“Whitehouse supply them as turnkey installations with time studies, programs, fixtures and tooling. We have the skills to do this in-house, but we are very busy at the moment with the surging medical work.

“In any case, we find that we learn a lot from Whitehouse each time they prepare and supply a fully functioning production cell, so we get the benefit of knowledge transfer along with their experience of the best way to produce parts most efficiently.”

The cell configuration

The Speedio M140X2 has a machining volume of 200 x 440 x 305 mm and incorporates a 2,000 rpm turning table, which is not used for machining the current range of prismatic medical parts. However, together with the +120 to -30 degree swivel of the trunnion carrying the table, the two extra rotary CNC axes are invaluable for automatically positioning components in-cycle for predominantly 3-axis machining, although there is some 4- and 5-axis simultaneous metalcutting within some of the cycles.

The machine’s extremely high productivity comes in part from simultaneous movement in the X, Y, Z, A and C axes plus tool change when the machine is not cutting. Tool change time from the 22-position magazine is 0.9 second, giving 1.4 seconds chip-to-chip, and spindle start / stop is completed in 0.2 second. Cutting feed rate is up to 30 m/min, with 50 m/min rapids.

The Feedio robotic component handling system option exploits this speed to the maximum by delivering parts to the spindle faster than an operator is able to and without interruption. The plug-and-play automation unit, which communicates with the machining centre via a Profibus interface, is supplied with a 6-axis ABB robot and the manufacturer’s smart teach pendant incorporating a customised Speedio page.

A camera vision system and built-in PC allows the robot to detect where on the upper input conveyor the raw material has been placed. After machining, components are returned to an output conveyor positioned below the first. Accessibility to the machining area of both Speedios from the front is maintained by positioning the automation unit between the machines.

Conclusion

Mr Martello regards the Brother cell, based on very fast 30-taper machines, as being the ideal solution for machining aluminium components, in this case for medical applications. The 5-axis capability and turnover station enables the mainly 3+2 machining operations to be carried out in two operations without manual handling. Some fully interpolative 5-axis sequences are also completed. Jobs requiring straightforward 3-axis prismatic cycles without any need for the rotary axes will in future be put onto the cell, if expedient, simply to take advantage of the automation.

Other contracts where the in-cycle turning capability of the M140X2s can be utilised will be obvious choices for the Brother cell. Those within the Speedios’ capacity involving tougher material like steel will also be confidently allocated to the cells due to the build quality of the machines. Only if work involves continual machining of superalloys like Inconel would alternative plant be chosen.

Mr Martello concluded, “This was new technology for Roscomac and we leant on Whitehouse quite heavily in the early days. We have received very good support from this supplier throughout, with their engineers even on-site at weekends occasionally, which was especially important in view of the urgency of the Covid-related work.

“As the very large volumes associated with the pandemic subside, there will still be a lot of medical work around due to the backlog of elective surgical procedures. When it does return to its normal level, we have a lot of contracts in other industry sectors that can be transferred to the Speedio / Feedio cells to be fulfilled more economically.”