Subby let-down led to in-house CNC investment

When one of its principal subcontractors started to become unreliable, a toolmaking company quickly installed an electronic lathe, eliminated grinding and brought work back in-house.
With cost and reliability, two of the key elements in any precision toolmaking business, Redditch-based KFC Engineering knew it had to act fast when one of its principal subcontractors started to become unreliable. To bring control of its production back in-house and also cut the expenditure of subcontracting, KFC selected a DMT 400 electronic lathe from StarragHeckert UK of Brackley. Serving the needs of the automotive, medical and electronic industries for the past 23 years, KFC Engineering is a small but efficient precision toolmaking company.

As managing director, Kevin Creighton explains: 'We are a small firm, and we tended to subcontract a lot of what I would call our 'clever turning' to another company, unfortunately, they started to let us down and in toolmaking there is a low tolerance for any lapse in lead times.

We can't afford to let our customers down so we decided it was time to invest in our own CNC turning facility.' To add weight to the decision, some of KFC's components were being sent outside for grinding as a secondary operation, but as Creighton explains: 'We knew if we could meet the drawing demands from turning we would be able to eliminate grinding from the equation.' The search began, encompassing the full spectrum of new and CNC electronic lathes available.

'We looked very closely at a number of machines, but the DMT 400 definitely proved to be the best option for us.

Its accuracy combined with the tooling package and its ease of programming made it the clear favourite' he maintains.

In fact, the ease of programming became the most important factor behind the decision to purchase because the standard canned cycles it contains are extremely easy to apply and adapt.

He says: 'The combination of teach/repeat and canned cycles on the DMT 400 include threading, rough and finish profiling, undercutting, grooving, tapers and spiral groove type forming, which are just what we needed.' He has found the control provided as much or as little CNC assistance as the operator needed in a well-proven operator friendly style developed by Heidenhain in its 'Manual Plus' control system.

'With a memory capacity for 96 programs, a 96-tool inventory, a good range of macros and terminology that is very familiar to an operator, this means we have seamless program generation - which is ideal,' he says.

KFC produce components out of tool steel in batch sizes no larger than six and here, the DMT 400 is testament to the argument that it is no longer necessary to make a straight choice between CNC or conventional machines, by offering CNC capability on a conventionally configured lathe.

The machine can be used in CNC mode with typical high resolution of the Heidenhain dynamic graphics support, or as a conventional centre lathe with electronic handwheels making it ideally suited for single part followed by automatic repeat cycle turning operations.

The DMT 'electronic' turning machine range has a swing over bed up to 800mm and can be specified with up to 4000mm between centres.

In CNC mode, constant surface speed ensures high and consistent surface finish, while spindle speed and feed rates can be adjusted during machine cycles via the simple apron mounted travelling control panel.

Rapid traverse rates are 5m/min in X and 10m/min in Z.

'Since installation in December 2003 the machine has run perfectly,' says Creighton, 'in fact we haven't had to contact StarragHeckert UK since, as there simply hasn't been any problems.

As a small company we always have to keep one eye on the future and the accuracy and surface finish capabilities of the DMT 400 mean that we have saved both on the cost of subcontract work and especially the problems and costs associated with secondary operations such as grinding.

But what is most important, is that we are in control of our own destiny in terms of what we give and when we deliver to our customers.