In response to increasing competition, a pipe cutter manufacturer has invested in CNC sliding head automatics and latest tooling technology to help increase productivity.
Since its establishment in 1931, Monument Tools has always developed innovative tooling solutions for the plumbing, heating, roofing, gas, pipe testing and drainage industry. Today, the company's 700 or so products are facing increasing competition from low cost manufacturers throughout the world, and in response to its rallying call for help to improve its productivity, the activities of companies such as NC Engineering and Sandvik Coromant have not only strengthened the business through improved quality, keener pricing and better delivery, but they have also set the scene for continuous improvement across the Wallington, Surrey based operation. Following the installation of two Citizen M32 CNC sliding head autos in March 2004 and January 2005, to replace fixed head lathe and milling machines, Monument's works manager, Jon Norton has forged a strong and very close working relationship with NC Engineering's application engineering team and Sandvik Coromant's tooling engineers.

Since then, 35 different parts have been programmed and re-engineered - and the result is that production cost savings of up to 60% have been achieved.

Lead times too have also been slashed by combining the production of parts with up to five operations into single mill/turn cycles on the Citizen machines.

A prime example of Monument Tools' success is world leadership in the pipe cutting market.

Developed over some 50 years and involving five generations in the 48 employee family firm, 15 different types of tool are produced covering automatic cutters for pipes up to 28mm diameter, adjustable semi-automatic copper pipe cutters up to 22mm, copper pipe cutters up to 3.3/4in, stainless steel pipe cutters up to 1.11/16in and cutters for plastic pipe up to 3.2in.

Leading export markets cover the very difficult Far East including Japan alongside the Middle East, USA, South Africa, Australia, Canada, France and Germany.

John Collier, managing director, comments: '100% control of manufacturing is essential if we are to service all these areas efficiently'.

'We need ever-quicker stock turns and a thorough understanding of the quality issues that will maintain our brand credibility'.

'Our branding separates us from our competitors, and to continue to manufacture in the UK means we have to invest wisely in production equipment and processes'.

'We do not want to rely on lower cost overseas sources, which would add risk by taking much of the business directly out of our control.' The installation of the citizen machines is defined by Collier as the ideal reflection of the company's product branding.

He says: 'The quality of turning, the generation of aerospace finishes as a matter of course and the guarantee of geometric relationship of features has made a big impact on the business.' The decision to purchase Citizen followed a thorough investigation of the market for CNC sliding head autos following the suggestion by Sandvik's tooling engineers that this type of machine was more suited to generate higher productivity machining of the type of parts Monument were making.

Processes performed on the Citizens now include turning, milling and drilling with cross-drilling and milling, milling of tapered hexagons, wobble broaching internal hexagons, thread rolling of studding (which used to be a bought out item), slotting and milling of keyways, and polygon turning.

These are all now performed in-cycle on both the Citizen machines.

It is here that the Sandvik relationship between NC Engineering and Monument is perfectly demonstrated.

Previously, Monument produced components with hexagon shape requirements either out of hexagon bar or on a Profilator as a separate operation.

This process is now combined into the single machining cycle of the Citizens.

Sandvik's tooling engineers designed a special profiling tool body to accept Sandvik's standard boring cartridge units.

By using milling grade inserts to withstand intermittent cutting, the unit is used to polygon turn the required number of flats on materials as diverse as mild steel, brass and stainless steel.

As a result, up to 1,500 parts are now polygon turned before any insert change is required to produce flats, squares and hexagons directly out of round bar.

The new tool also uses just three inserts which cost just over GBP 3 against a previous tooling cost of GBP 45 each.

Further indications of savings on the Citizens are demonstrated by simply changing from 2.5mm to a 1.5mm width of Sandvik part-off insert, which has saved some 1000m of steel in the production of pipe cutter wheels.

In addition, Monument is now producing a shaft which previously took 316 seconds total machining time based on five conventional operations into a single 92-second operation resulting in a drastic reduction in production lead time, batch quantities and work in progress.

The operational sequence, is aided by NC Engineering's Cool Blaster 2,000 lb/in2 high pressure coolant system that not only improves metal removal rates and swarf clearance but it also considerably extends tool life.

Operations now include turning and producing a front chamfer, the milling of two flats, cross-drilling, counterboring and deburring followed by further cross-drilling and parting-off.

The part is then transferred in-cycle to the sub-spindle, centre drilled, drilled and tapped, turned and faced to length, followed by polygon milling of flats before being unloaded by a gantry gripper to a conveyor for transporting out of the machine without damage.

Both Citizen machines run 18 hours/day with most cycles taking between 60 and 90 seconds.

Each machine is fitted with NC Engineering's NC Alarm Alert system.

This monitors the production cycle and will automatically call Mr Norton on his mobile 'phone if there is a problem when the machines are left running out of hours to, say, finish a batch.

Both machines are also equipped with automatic fire extinguishers in case of any out-of-hours problems.

Due to the large capacity of the M32, which is able to carry up to 80 tools, Monument tends to use the machine as a tool store to reduce changeover time.

Spare pushers are also preset for different bar sizes, although to reduce setting times further, the company has instigated a bar rationalisation programme'.

''It is far quicker to turn down excess material using simultaneous cutting cycles on the M32 than have extended setting periods,' says Norton.

This also reduces material stock levels and deliveries.

Mr Norton has also compiled a tool life database which not only gives tooling information but is proving very useful for machine setting and tool selection, especially when introducing new components and controlling tool stocks.

Norton is very complimentary about the support available from NC Engineering and the way Sandvik has worked with both his company and NC Engineering: 'There are always two or three application people I can approach for any advice at NC Engineering, and when we need say, a new collet or guide bush, it is always with us the next day.' This is endorsed by Collier who has just placed an order for a third Citizen - this time direct from a specification sheet for the about-to-be-launched new generation L-Series machine'.

''By the end of 2005 we will be totally CNC orientated,' he says, 'which with Sandvik's help on tooling will further improve our productivity'.

'This will make it even harder for off-shore companies to compete against the brand of Monument Tools.'