As a result of receiving new, ongoing business from a manufacturer of flow meters used in the oil, gas and food industries worldwide, Leicester subcontractor, Nisan Engineering, has invested in an Akari 4-axis, horizontal machining centre (HMC). Supplied by Whitehouse Machine Tools, the machine is built by Averex Automation in Taiwan and is the first of its type to be installed in the UK.
The flow meter contract involves the manufacture of a family of 10 cylindrical components which at first glance look as though they should be made on a twin-spindle lathe with live tooling. On closer inspection, it is evident that two operations on a twin-pallet HMC with a rotary table to provide a fourth CNC axis is the most efficient and cost-effective way to machine the steel parts. Mukesh Prajapati, managing director of Nisan Engineering, said, “Whitehouse Machine Tools is one of our first ports of call when we need to invest in new plant. “We have dealt with them for over 20 years and have found that they always provide reliable applications engineering to get us started, as well as good service backup.
“The Akari we bought from them in January this year (2013), which has a working volume of nominally two-thirds of a metre cube, is a competitively priced, 40-taper machine ideal for producing the new meter components economically. “Nevertheless, it is a top quality machine that we believe is robust enough to hold tolerances measured in tens of microns for a decade and more.”
When Nisan Engineering took over the flow meter component contract from another Leicester subcontractor, Mr Prajapati consulted with the customer to re-engineer the manufacturing process. The exercise has simplified production and reduced the previous 12-week lead-time by around 50 per cent.
A number of changes were made to the component design. For instance, a flat was resized to allow a standard milling cutter to produce the feature in one pass, as a stepover was not allowed by the customer. This avoids the cost and delay associated with sourcing a special size of tool. The sides of the milled flat were also changed from vertical to 45 degrees, eliminating the need to deburr the edges.
Another example of re-engineering was the introduction during op 1 of chamfers at both ends of the bore, which runs right through the component, facilitating accurate clamping for op 2. OSG and Seco were involved at an early stage to advise on optimal tooling for various operations. One innovation was the adoption of a roll forming tool in a synchronised tapping head to produce M3 threads, rather than using a conventional holder and tap, which was found to break regularly. At the time of interview, over 400 holes had been roll-tapped without the first tool breaking.
The turnkey solution provided by Whitehouse Machine Tools also included Renishaw probing for setting workpiece datums, design and fitting of an uprated pump to increase coolant flow, and one of the supplier’s applications engineer on the Leicester site for two weeks to set up the process.
The result of all these measures was to reduce to 15-off the economical batch for each of the 10 components. Between 30 and 50 of each type are currently delivered monthly to the customer, without the expense of having to hold consignment stocks. Whereas previously each component was machined from carbon steel hollow bar, it is now made from less expensive solid EN8 stock that has been turned to size.
As a result, the previous turning, boring and prismatic machining operations, which required three setups plus separate deburring, have been condensed to two clampings on the two Akari pallets, parts coming off complete in a total cycle time of 25 minutes.
Interestingly, Nisan Engineering made 30 of one of the components conventionally last December, before the new HMC was installed, to meet an urgent demand from the customer during the changeover period. The batch took four weeks to complete, whereas an identical run on the Akari in early February took just two days.
The flow meter cylinders are machined from solid round billets measuring from 74.5 to 145 mm diameter and 270 to 557 mm long. A bore of between 34 and 65 mm diameter is machined during op 1, after which the part is held in a special fixture made by Saluki, Leicester. It is capable of accommodating all of the component variants for op 2, which involves drilling, tapping and milling. Bores have to be accurate to 37 microns total and other dimensions to between ± 0.1 and ± 0.2 mm, while the faces of the component are tied up to the bore to within 50 microns concentricity and parallelism. All of these tolerances are easily held on the Akari.
The project has been so successful that Nisan Engineering has already started manufacturing a second component for the customer, this time on a twin-spindle turning cell with automation. All of the work is being carried out alongside the subcontractor’s other contracts spanning many different sectors including medical, autosport, rail, marine and yellow goods.
In conclusion, Mr Prajapati said, “We are pleased to be the first user in the UK of the Akari HS-450i. It is also the first horizontal-spindle machining centre that we have bought, which adds to the capabilities and scope of Nisan Engineering. “The machine was installed and commissioned by Whitehouse Machine Tools in a short time frame so that we could urgently pick up flow meter component production during the changeover period.
“Although the Akari is manufactured in Taiwan, which keeps the price down, it is of high quality construction with, for example, hand scraped surfaces for mounting both the Tsubaki ballscrews and THK heavy duty roller guideways. “We also like the Fanuc control with nano interpolation, BIG Plus spindle and other top-end features as used by many leading Japanese machine tool builders.”
It is noteworthy that the Akari HS450i includes a novel design feature whereby it can be retrospectively expanded, quickly and affordably, from two to six pallets and from 80 through 120 to 220 tools, allowing the manufacturing facility to grow with a user’s business.
