Total flexibility

A dedicated user of ProtoTRAK CNC/manual milling machines supplied by XYZ Machine Tools [1], PTG Precision Engineers is one of first in the UK to install the totally new XYZ ProtoTRAK LPM machining system. In fact, the company has now taken delivery of two ProtoTRAK LPMs with a third LPM on order. The ISO 9001:2008 accredited subcontractor describes its strength as being “in our flexible approach to machining, with a wide range of machine tools well-equipped for one-off prototypes as well as small and medium batch size quantities”. And it is this flexible approach that has prompted the latest investment.

What marks out the new ProtoTRAK LPM as different is that it is the first ProtoTRAK-equipped machine tool to be fitted with an automatic tool changer. It also has several other features designed to provide a competitive advantage on small batch production. What it is not, however, is yet another new machining centre. As Martin Beer, PTG’s Technical Manager, is quick to point out, the Plympton, Devon-based company already has several machining centres equipped with various makes of CNC system. This in itself does not present any significant programming difficulties but the fact is these machine tools are not ideally suited to prototype or low volume production - which is why PTG has 16 ProtoTRAK CNC/manual milling machines in everyday use and why the new LPM machining system has become an instant success.

The key attraction for an existing ProtoTRAK user such as PTG is that the ease of use of this control system - which does not require G and M coding knowledge because it is programmed by following plain English prompts on-screen - continues with the new ProtoTRAK PMX control. This means that any operator already familiar with ProtoTRAK can program the LPM, making light work of complex set-ups and reducing dramatically the cost of jobs that previously could take hours or days to produce. Even better, once the ProtoTRAK LPM is set up and running, the operator can revert back to working on an existing manual tool change ProtoTRAK mill. The net result is an instant productivity boost while avoiding the need to recruit additional staff.

To quote Beer: “With the LPM we get an extra spindle and great productivity without needing to employ more people”. In fact, PTG will soon be running a five machine cell - comprising three ProtoTRAK LPMs interspersed with two existing ProtoTRAK VM 4000 bed mills - with just two operators.The skilled operators involved are happy with the new arrangement, not least because by contributing to PTG’s competitive edge they are also contributing to their own long-term job security       
  
The XYZ ProtoTRAK LPM is a solid cast iron construction 15 hp/8000 rev/min BT 40 vertical spindle machine with a 900mm x 500mm table and axis travels in X. Y and Z of 785mm, 470mm and 530mm, respectively. It also has linear guides, a 16-station carousel tool changer and rapid feed in all three axes of 20m/min. But for all that it is much more than just a sturdy workhorse. At its heart is the latest generation PMX control that can be programmed in background mode for a future job while it is already running a different job. It provides flexibility in terms of file types and file storage, and encourages continuous improvement by way of updating stored notes and photographs within the program that encompass set-ups, tooling and other useful information relating to current and repeat orders, all of which are instantly accessible via the PMX control.  

“The natural progression for anyone with a ProtoTRAK CNC/manual machine - and ProtoTRAK is the subcontracting industry’s de facto standard - is the LPM, because it provides machining centre capability without having to learn a new computer language or install an expensive off-line programming system,” says Beer. “It is very cost-effective and very competitive as set-up times are extremely quick. It took just 20 minutes from delivery of our first LPM to machining a part, not least because our existing ProtoTRAK programs only need the tool change lines added.”

The LPM comes complete with a tool pre-setting system and tooling trolley to further reduce set-up times, while the table features locating bushings at precise points. This allows workholding fixtures prepared off the machine to be secured in seconds by a ball-lock system in a precise location known to the control system and repeatable at any time. Because there are several alternative locations on the machine table it is possible to load more than one fixture and, if required, separate programs can be combined into one to allow for the machining of different components in a single set-up. And because set-ups are quick and easy, there is no need to overload inventories. Says Martin Beer: “With the LPM we machine only what is required to fulfil an order as the time needed to set-up for a repeat order is negligible. On that basis, even if I had not been an existing user of a ProtoTRAK machine, I would still have opted for the LPM...not least because, unlike a machining centre, it can be run in manual mode, and this adds still more to its tremendous flexibility”.