Month's turning work done in two weeks

Turned parts subcontractor was surprised to finish a month's work in two weeks on a CNC sliding head auto - a four-fold productivity gain - and realise significant reduction in labour costs.

Alan Gretton of Autumn Engineering, a subcontractor and toolmaking company in Sandiacre, Nottinghamshire, intended to remain a one-man-band when he started his company in 1996 with a contract from his former employer to carry out manual, second-operation punching of plastic injection moulded components.

Three years later, an electronics company for which he had made some jigs and fixtures offered him the chance to start a new side to the business - subcontract turning.

He produced 100-off samples of a 6mm diameter by 18mm long component on his manual centre lathe, which did not have a bar magazine, by feeding manageable lengths of stock through the chuck.

He was then awarded a contract to produce 5,000-off per month, so he invested GBP 7,000 in a second-hand, microprocessor-controlled auto with single bar feed.

Further orders followed and two years later he bought a second, similar machine of 26mm bar capacity.

"I was surprised at how quickly the business grew with relatively little effort," said Gretton.

"It was a combination of getting the price and quality right and offering a fast turn-round, typically a couple of days for short runs".

"I was spending a relatively modest sum on each machine tool and it was not difficult to see where the work was coming from to pay for them." That changed in 2004.

He was promised a contract from a firm in the plastics industry to produce a family of four inserts, all 8mm diameter and up to 65mm long.

Clearly sliding-headstock capability was needed and the complexity of the components made a CNC lathe with sub spindle and driven tooling desirable; in any case, it was going to be easier to win additional, high added-value work with such a machine.

So in March 2004, Gretton researched the leading suppliers with a mind to invest again in a second-hand machine.

Instead, he was offered a new, 16mm bar lathe by Star Micronics GB at little more than the cost of a used 20mm slider.

Designated SB-16, the sliding-headstock lathe is Star's entry-level model supplied complete with FMB Minimag bar magazine, but nevertheless the package costs in the region of GBP 60,000, significantly more than Autumn Engineering had previously invested in a single machine.

Continued Gretton, "I hardly slept for a few nights wondering if I was doing the right thing, bearing in mind that I had originally intended to keep the business small".

"To maximise the SB-16's use, I decided to transfer all of the work booked onto the two microprocessor-controlled autos during May 2004 onto the slider".

" "To my surprise, I had finished the month's work in two weeks, which represented a four-fold productivity gain and also resulted in a significant reduction in labour costs.

There was a big saving in cycle times, many of which were halved due to the high speed of the spindles and axis movements on the Star.

In addition, most of the parts previously needed second operations requiring a separate set-up, such as cross-drilling and reverse endworking, whereas the Star performed these in-cycle, resulting in further time savings.

Immediately after the acquisition of the SB-16, with everything riding on the success of the investment, Gretton could not resist going in to work in the evening to check on the Star's unmanned running.

He only had to do this a few times before he relaxed, however.

Every morning when he checked the parts coming off the machine, they were always the same as those being produced when he left the previous day, or so close that any difference was not measurable".

""Suddenly it became clear that not only had I done the right thing buying the Star, but I had done the only thing that would keep me in business long-term, earning a reasonable living," enthused Gretton".

""Not investing in the capabilities and automation offered by machines like the SB-16 is really not an option, because it is impossible to compete with a subcontractor using such a machine if you have low technology plant".

"They will undercut your price, turn the work round quicker and likely as not, component quality will be better." A further benefit of the new sliding-headstock lathe is that it can be reset quickly.

Gretton changes over the microprocessor-controlled autos every one to four hours and each time it takes a couple of hours to complete.

With the Star, changeover if a different size of bar is needed takes about half an hour; and if the bar and tooling are unaltered and the program exists, it takes only a couple of minutes to start producing a new part.

Gretton also found programming at the Fanuc control on the shop floor quick and easy to learn and implement, advising that its cut, copy and paste facility is a big help.

One result of rapid programming and set-up is to maximise productive time during manned shifts.

Another advantage is the ability to machine very small runs economically.

While Autumn Engineering normally produces batches of between 10- and 10,000-off, Gretton has been known to program and machine 2-off complex parts if the right bar is in the magazine, finding this quicker than machining them on non-CNC equipment.

If he gets into difficulties with a program, he faxes or e-mails the drawing over to Star GB in Melbourne and the problem is sorted out quickly.

It prompts him to comment that he is "very happy" with the supplier's service, including the telephone help desk.

A good relationship has developed which is vital for a small subcontractor, as when assistance is required, a response is needed straight away.

As to the future, Gretton is encouraged by the success he has enjoyed during a difficult period for manufacturing industry in the UK and has given up the idea of staying small.

There is some capacity to fill on the Star SB-16 before it is running 24 hours a day, although it is already paying for itself and earning a profit.

The next step will be to buy a 20mm sliding-headstock lathe, then perhaps a 32mm model; after that, who knows?.

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