Sliding head CNC cuts cycle times by 60%
March 10th 2009
Peerless Precision Engineering is using a platen style tooling arrangement on a Citizen L20 CNC automatic sliding-head lathe, which offers flexibility when compared to a fixed-head machine.
Nigel Bargery and Pamela Oakley set up the subcontract precision machining business Peerless Precision Engineering (PPE) 11 years ago.
With a secondhand lathe and a few drill spindles to satisfy the beginnings of what would become a steadily growing order book.
His business partner and financial director Mrs Oakley would rebar the lathe, check parts and input any offsets.
She would also operate the drill spindles for second operation work, remove burrs, pack up work for despatch and attend to all the paperwork.
For three years this working regime was rewarded as they progressively established the business.
In April 2008, the company moved into a 6,000ft2 machine shop adjacent to the original factory in Goathurst near Bridgwater, Somerset.
PPE now employs a further seven people and has nine of the latest turn-mill centres including four Citizen CNC sliding head lathes.
Bargery still looks back fondly to those tough, early days having been persuaded by Mrs Oakley to use up his previous 30 years of subcontract machining and business skills to set up PPE.
As the company grew, investment strategy followed that of a genuine ‘turning specialist’ and an early favouritism for fixed-head lathes.
However, many of the parts produced were under 20mm diameter and quite often it was felt there had to be a better way of machining by combining second operation turning and drilling cycles.
Frequently, parts would be turned then either one of them would be loading drill jigs, spending hours in front of pillar drills and then moving over to the bench to remove the burrs they had created.
Then a contract for a batch of 2,500 parts brought forward the day for decisive thinking.
The solution was a fixed-head lathe with subspindle and driven tools that decimated both the manufacturing lead time and machining time.
Then, in 2001, Bargery came across sliding head technology that led to an investigation of the machines and their suppliers, and an evaluation of the level of technical complexity and promises of support.
As a result, all the boxes were ticked by NC Engineering of Watford, now Citizen Machinery UK, that led to the installation of a Citizen L20.
Bargery said: ‘With the Citizen’s faster and shorter axis movements and overlapping, we are able to take 60 per cent out of the cycle time of the fixed-head lathe method.’ He commented further how high standards of quality, and consistency of size and finish has never drawn any concern leading to PPE becoming a dedicated Citizen user for up to 20mm components in materials such as mild steel, 606-M36T, 303 stainless and silver steel.
This is confirmed by today’s installations of two Citizen L20s, a C16 and K16, the latter installed in 2007, and all are working round-the-clock.
‘The reason for continuous Citizen purchases is that Citizen Machinery has been true to its word with support,’ said Bargery.
‘As an extension to normal machine training, Citizen sent applications specialist Phil Francis to help enhance the single cycle “one-hit” methods and set ups.’ To date the Citizens have produced some 130 different parts up to 75mm long, mostly covered by repeat orders and almost all cycle times vary between 20 seconds to two minutes.
‘Tolerances have never been a problem, even when holding 10 microns size on batches of silver steel components that are run continuously through night and day,’ added Bargery.
Most general tolerances present no challenge between + 0.1mm and + 0.05mm with surface finishes typically 1.6 micron CLA.
However, Bargery will always ‘throttle-back’ speeds and feeds on all his machines preferring to extend tool life and ensure production consistency, which also helps the complete process to run smoothly.
As part of the machine package, PPE has added Citizen’s CNC Wizard programming software with wireless transfer and is able, through Delcam’s Featurecam, to share cutting data from its materials library.
Production, scheduling and program information is via Jobshop shopfloor data collection, while MRP and scheduling can all be accessed remotely whenever Bargery is away from the works.