The correlation between maximizing shareholder value at an automaker and manufacturing engine blocks is hard to understand at first, but one look at an old-fashioned powertrain machining line makes it clear. These giant "transfer lines," which seem to stretch the length of a football field or longer, cost $100 million to $150 million apiece. Make mistakes with a few of these babies, and as the saying goes, it starts to add up to real money - even to an automaker.

Transfer lines are specialized machining systems that transform raw metal castings into precision components such as engine blocks and heads. Until recently their layouts hadn't changed much since the Ingersoll Milling Machine Co. invented them in 1924 to make engines for Henry Ford's Model T.

Now rapid technology shifts and automaker demands to lower the risk and capital costs associated with building these gigantic machine tools is shaking the industry to its core. Instead of spending huge sums on lines that can produce only one engine with great precision for 10 years, automakers want to hedge their bets and produce numerous engines on the same line. Of course, they also want to reduce the cost of the machinery.

This emphasis on flexibility is the same philosophy automakers are pursuing with most of their vehicle assembly plants, but it is having a major impact on suppliers of big machining systems. It's not a wholesale change, of course. Old transfer lines aren't scrapped until a brand new engine design comes along, and that typically happens every 8 to 12 years.

Nevertheless, tougher environmental and fuel economy legislation and more discerning consumers have auto-makers replacing old engines at an increasing rate. Insiders say there has been more change in the engine block machining business the past five years than in the previous 20 or 30.

The supply base for these gigantic systems already has consolidated dramatically, leaving just two major U.S.-based players - Lamb Technicon Machining Systems and Ingersoll Milling Machine - plus a handful of mostly European suppliers.

Many of the companies that died or were consumed in consolidation were highly respected names in the machine tool business. They just couldn't keep up with the pace of change, says Roger W. Cope, vice president of Business Development at Lamb Technicon. Unova Corp., an industrial conglomerate once known as Litton Industries, owns Lamb. Ingersoll is a privately held company formed in 1887.

That doesn't mean the survivors are sitting around with thousand-yard stares. "We have big signs hanging up all over that say 'Change is good,'" says Mr. Cope.

The makeup of workers at these companies has changed drastically, too, adds Mark Tomlinson, vice president of engineering at Lamb Technicon. Ten or 15 years ago they employed lots of draftsmen with good technical skills. Now most have engineering degrees, including some with PhDs and masters in engineering.

This higher level of sophistication is reflected in the products. Transfer line designers used to just make machines and fixtures more massive to make them stiffer and more precise. Now they increase precision with high-tech adaptive controls such as laser-guided boring tools that turn at 6,000 rpm and can make minute cutting changes as they measure bore tolerances 30 times per revolution.

One of the biggest issues now among automakers and their transfer line suppliers is balancing the conflicting demands of flexibility, machining precision and cost.

A conventional transfer line consists of an array of dozens of machine tools lined up sequentially to perform a large number of specific operations, such as milling surfaces flat, drilling holes and cutting cylinder bores. They work very quickly, machine to extremely precise tolerances and typically produce 400,000 or 500,000 components annually.

After each operation is completed, the part is automatically moved to the next operation down the line. The process works perfectly when there's a steady demand for the same engine for years, but sudden shifts in the marketplace can spell disaster because traditional lines are inflexible and completely dedicated to one engine design.

In pursuit of flexibility, some automakers have almost completely abandoned the transfer line concept for big arrays of complex computer numerically controlled (CNC) machines. Looking like the machine-tool version of a Swiss Army knife, they act almost like robots, constantly repositioning the part at one station and performing many operations with multiple cutting tools and spindles, rather than constantly pushing a part down a long line. They can be programmed to handle almost any type of engine, but critics say the constant to-and-fro movement of their cutting tools and fixtures makes them less precise and more susceptible to wear.

Many new machining systems try to combine the best aspects of transfer line and CNC machine strategies, sacrificing unlimited flexibility for lower costs. At Ford Motor Co.'s Windsor, Ont., engine plant, for instance, a Lamb machining system can process three different variants of V-8 and V-10 engine blocks and their heads in batches as small as one. That means it can switch from one of the three engines to another without a pause, but it can't manufacture Ford's entire engine lineup.

The company recently introduced the Hardpoint 300, a CNC machine that combines turning, drilling, milling and grinding. It is a modular concept machine and can be configured with up to four main spindles and a variety of tooling combinations, depending on user needs. The machine can machine the front and rear faces of a single part; machine a single face on two parts simultaneously; machine the front and rear faces of two parts simultaneously; or machine a single face on four parts simultaneously.

The company says its product represents a flexible and economic machine concept for high-quality, complete machining of small components. The axes is variable, with up to ten possible. The machine offers fully automatic, synchronous complete cutting of complex workpiece geometries, up to a diameter of approximately 3" x 3" (80 mm x 80 mm).

The modular machine concept is said to ensure machining efficiency and flexibility. The various platforms are said to allow several cutting processes to be combined, thereby eliminating the need to operate multiple machines. The company says this reduces floor space requirements and operation costs. The machine incorporates an internal gantry loader. External loaders are also available as is a post-process measuring system.

Abstract

This paper presents a description of how CNC milling can be used to rapidly machine a variety of parts with minimal human intervention for process planning. The methodology presented uses a layer-based approach (like traditional rapid prototyping) for the rapid, semi-automatic machining of common manufactured part geometries in a variety of materials. Parts are machined using a plurality of 2 ½-D toolpaths from orientations about a rotary axis. Process parameters such as the number of orientations, tool containment boundaries, and tool geometry are derived from CAD slice data. In addition, automated fixturing is accomplished through the use of sacrificial support structures added to the CAD geometry. The paper begins by describing the machining methodology and then presents a number of critical issues needed to make the process automatic and efficient. Example parts machined using this methodology are then presented and discussed.

Keywords: CNC Machining, Rapid Manufacturing, Rapid Prototyping, Process Planning, Computer-Aided Manufacturing

Introduction

The cost of producing small numbers of parts has been driven by the cost required to process-engineer the part(s). Traditional computer-aided process planning (CAPP) systems have reduced the time required to plan machined parts, but the cost for one or two-of-a-kind machined parts is still dominated by the cost of planning the part. The current use of CNC machining for these small quantities of parts is further limited by special tooling costs and machine setup.

The typical approach to planning parts for CNC machining has been to define the "features" of the part and match these features and tolerances to a set of processes that can create the required geometry to the specified accuracy. This approach has worked reasonably well for medium to high-volume parts, but it has had marginal success for the production of very small quantities of parts. In most cases, the time required to plan the part, kit the required tooling, and set up the machine (both fixture and tooling) has limited the use of CNC for these applications. The result is that rapid deployment of CNC machining has been relegated to a simple set of part geometries. The promise of minimal process engineering is a major factor that has driven the use of freeform rapid prototyping (RP) techniques. Unfortunately, many of these processes have been restricted to a small variety of materials with limited geometric accuracy.

In the literature, process planning is often approached with a set of goals driven by high production levels of parts-that is, a set of plans that strives for cost effectiveness through maximizing feeds and speeds and creating repeatable setups that can be paid for through economies of scale. Process planning for CNC machining includes tasks such as fixture planning, toolpath planning, and tool selection. There is a considerable amount of work in the literature pertaining to these three areas (Maropoulos 1995; Chen, Lee, and Fang 1998; Joneja and Chang 1999). The concept of flexible fixturing has been the topic of much research, though a completely autonomous fixture design system has yet to be developed (Bi and Zhang 2001).

Some exploration into the use of CNC machines for rapid prototyping has been published. Chen and Song (2001) describe layer-based robot machining for rapid prototyping using machined layers that are laminated during the process. The process is demonstrated using laminated slabs of plastic, machined as individual layers upon gluing to previous layers.

A hybrid approach using both deposition and machining called shape deposition manufacturing (SDM) continues to be developed (Merz et al. 1994). For each layer, both support and build material is deposited and machined in a combined additive and subtractive process. Sarma and Wright (1997) presented Reference Free Part Encapsulation (RFPE) as a new approach to using phase-change fixturing for machining. The approach was discussed recently in conjunction with high-speed machining (HisRP) (Shin et al. 2002). RFPE, in combination with feature-based CAD/CAM was proposed as an RP system (Choi et al. 2001).

Another approach is to use CNC machining for prototyping dies, an area called rapid tooling (Radstok 1999). One approach to rapid tooling uses machined metal laminates stacked to form dies (Vouzelaud, Bagchi, and Sferro 1992; Walczyk and Hardt 1998).

Many of these methods utilize CNC machining but do not address the fundamental problems of automating a fully subtractive rapid machining approach. This paper presents a method for "feature-free" CNC machining that requires little or no human-provided process engineering. The methodology described in this paper is a purely subtractive process that can be applied to any material that can be machined. The method described herein was developed in response to the challenge of automating as much of the process engineering as possible.

The highest levels of precision in metalworking technology today can only be achieved through a delicate balance of sound mechanical design, a powerful computer control and a highly-responsive servo system.

Today's world-wide competitive market has resulted in a quality-driven consumer. The customer demands products that will work right the first time, and he expects that they will provide levels of reliability that were unthought of just several years ago. As countries with lower-cost labor enter the industrial race, price competition is becoming more fierce. These factors have driven the industrial powers to focus on their strengths. They have begun to concentrate on more reliable end products and shorter development cycles of a more sophisticated nature. Statistical process control and continued process development is a way of life in many manufacturing facilities. There is a need to constantly improve part accuracy and finish, while at the same time, reduce scrap and manufacturing costs in order to remain competitive.

These changes in market requirements have created the need for a new generation of milling machines that are more accurate, faster to set up, more reliable, and have the potential to continue to be upgraded as applications require. The machine tool builder is faced with a series of performance trade-off decisions which is further complicated by the consideration of final cost of the product. Some builders have decided to target their machines for high performance while others have opted for lower accuracy and cost, or simple prototype work. Still other have designed their machines for precision applications. Here, we will address the requirements of precision milling, primarily because the technological advances in this area provide so many opportunities for future competitiveness.

Precision is defined not simply as the measured static linear positioning accuracy in a single plane, but as the machine's consistent ability to impart the required accuracy to the work-piece. The mill must be able to support the complexities of accurate contouring, generate superior surface finishes, and enable the user to deal with a rapidly changing list of materials and applications.

A precision milling system can be subdivided into three general areas. The mechanical design and manufacture, the CNC functions, and the capabilities of the servomechanisms. We will look at the critically important areas in each of the categories.

Machine Configuration

The basic configuration of the machine has a lot to do with its potential for precision. Knee-type machines cannot be expected to impart high accuracy because they do not provide adequate support of the moving saddle and table. Machines with quill-supported spindles do not keep the spindle rigidly contained, which can result in spindle droop in horizontals, or vibration sensitivity. Fixed bed, travelling column designs address some of these problems, but have the tendency to wear and reduce the capabilities of dynamic performance due to the need to move the column mass. The fixed-bed, vertical-spindle configuration, when approached with care in the early design stages, affords the highest potential for optimum performance. Spindle overhangs and compound stage stack heights must be held to a minimum in order to reduce the effects of geometric errors and optimize stiffness.

Mechanical Accuracy ... Behind The Covers

Unlike basic machine configurations, there are many areas that contribute to machine accuracy which cannot be seen. As accuracy requirements, spindle speeds and feed rates increase, the quality of the components and the care taken in assembly become more critical. The quality of the design and manufacture of machine tools can be measured by the attention that the builder pays to the principles of roundness, flatness, straightness, parallelism and squareness.

Roundness of ballscrew and spindle support pockets as well as rolling elements of linear guideways have a direct contribution to bearing heat, life, and system rigidity. Guideway surfaces, table tops, motor and spindle housings, and mating sections of castings require grinding, or in some cases, manual scraping, to provide adequate bearing surfaces. As these surfaces compress with their mating counter-parts, geometric distortion takes place, resulting in alignment errors. Some of these errors can be easily measured on the final product, but others cannot. One example is the alignment of the ballscrews and drive motors. Precision applications require higher servo responses which, in most cases, eliminate the use of couplings which provide a reduction in torsional stiffness. This necessitates that motors and drive housings be hand-scraped and fitted to the appropriate castings.

Guideways should be spread as widely as possible to provide maximum rigidity to the moving members. The straightness and parallelism of these way surfaces will affect the overall geometric accuracy. The straightness of the ballscrews and their alignment during installation can also have a direct effect on geometry. The variability of these parameters throughout the axis travel can also result in premature wear and stiffness reduction. The straightness of moving machine members has its greatest influence on accuracy when we consider the compounding effect of adding other perpendicular axes to the machine.

It could be said that the Bridgeport Series I represents both the past and the future. The basic design of this turreted knee mill dates back to the late 193 Os, when it was introduced by the Bridgeport Machines Co. of Bridgeport, Connecticut. Incorporating an innovative turret and swiveling ram, the Series I was quickly recognized as the most versatile milling machine of its day. Improved and refined over the years, the Series I held its position as the classic standard milling machine right up to the second year of this century. That year, the parent company of Bridgeport Machines encountered financial difficulties, forcing the Connecticut plant to close. Whether or not the Bridgeport milling machine would ever be made in the United States again was a question.

However, the investment firm that acquired many of Bridgeport Machines' assets believed that the Series I was still very much a viable product. The firm soon identified a U.S. machine tool builder that appeared capable of returning the Series I (and its CNC version, the EZPLUS, formerly called EZTRAK) to production. After negotiations were completed in the fall of 2002, Hardinge Inc. (Elmira, New York) emerged as the builder taking on the challenge to reintroduce this classic milling machine.

Remarkably, in less than 6 months, Hardinge has apparently met this challenge, taking the first Hardinge-built Series I to WESTEC in March 2003. In doing so, the company has not only kept the classic Bridgeport alive, but it has also made a strong statement about machine tool building in the United States. The company has contradicted all predictions that only low-wage sources overseas could build and market such machines economically. By early April, regular shipments of the Series I standard machine with power feeds on the X or XY axis were underway from Hardinge's Elmira manufacturing facility. Production of the CNC EZPLUS machine was scheduled to commence shortly thereafter. The company has met its goal of being able to maintain the present pricing for these machines and says the quality and reliability standards also have been maintained or exceeded.

Hardinge's rapid re-introduction of the Bridgeport milling machine may well become a textbook case history of how the principles of lean manufacturing can be applied. It is also a striking example of effective project management.

The Bridgeport production line in Elmira takes up floor space that is only 10 percent of the size occupied by the previous production line in Connecticut, yet it has 75 percent of the old line's capacity. On the new line, cycle times have been reduced by 50 to as much as 80 percent. Further contrasts between the old and new lines are summed up in Table 1.

Of course, the company that has learned the most is Hardinge itself. According to Doug Rich, vice president and general manager of U. S. machine operations for Hardinge, techniques learned and refined on the Hardinge/Bridgeport line are being introduced elsewhere in the Elmira facility. "We had already started the transition to lean manufacturing. The Bridgeport line is helping us speed up the transition by giving us an opportunity to validate what we've already learned and to apply this knowledge in a startup application," he says.

Bridgeport division manager Rick Elliott, who headed up the Bridgeport project, adds that there is no cookbook formula for applying lean manufacturing. "We drew on many sources for the principles and techniques of lean manufacturing. Our big accomplishment was pulling together what we needed for this application." The new line applies such concepts as minimal piece flow, setup reduction, Kaizen (planned improvement blitz), Poke Yoke (error proofing), statistical process control (SPC), total product management (TPM), Kanban (pull through inventory management) and others.

Mr. Rich says of the effort: "I set some high standards for Rick and his team. Rick did the hard part-he took that vision and turned it into a reality with better than expected results."

Hardinge seems to have secured a future for the Bridgeport Series I. According to Mr. Elliott, this future includes further improvements and evolutionary changes--not only to the production process but also to the performance and features of the machine. "A methodology for achieving continuous improvement on several levels at the same time is integral to the concept of lean manufacturing. From the outset, we knew our vision for the Bridgeport project could not be limited to maintaining cost, quality and reliability. It had to include a dynamic path to adding value, improving performance and enhancing reliability," he says.

A CNC sliding-headstock lathe is so fast, it can outside diameter-turn, drill the front end, part off and drill the back end of a component - under 10mm diameter - in just five seconds.

For mill-turning components up to 10mm diameter, Star has introduced a new, sliding-headstock lathe that is so fast, it can OD-turn (outside diameter), drill the front end, part off and drill the back end of a component in five seconds. Even a few years ago, it would have been almost impossible to achieve such a process in less than 10s. Designated SR-10J, the bar auto from Star Micronics GB is a highly productive mill-turning centre that rivals the output of a cam auto, but with the added flexibility of CNC to allow rapid changeover to produce a different component.

It is therefore another weapon in the armoury that manufacturers in the West can call upon to help compete with low-wage economies, according to Star Micronics GB's engineering manager, Stephen Totty.

He said, 'If you are making sub-10mm parts, it is preferable to use a small capacity machine, because the moving elements are smaller and faster than on a 16mm capacity lathe or larger.

Our new machine is ideal for smaller work, as it has 35m/min rapids with extremely fast acceleration, and front-working tools positioned very close to the bar on three sides in a yoke formation.' The SR-10J is also competitively priced, as it costs only a little more than Star's entry-level SB-16 model.

However, the 10mm machine occupies 30% less floor area.

Moreover, it has been demonstrated to produce parts significantly faster owing to quicker movements and the availability of a 2-axis sub-spindle.

In conjunction with a four-station endworking unit whose tools are driven at up to 10,000 rev/min, the sub-spindle is capable of working independently of, and simultaneously with, main spindle operations.

In all, there are 21 cutters in the working area including three live cross-working tools attached to the left of a six-station gang toolpost.

Positioned on the other side, behind the spindle centerline, four tools are available for front endworking and a further four further tools for rear endworking.

The 15,000 rev/min main spindle has full C-axis control as standard and there is the option of 15 deg indexing on the 10,000 rev/min sub-spindle.

Headstock stroke is up to 135mm.

Concluded managing director, Bob Hunt, 'One of our customers commented recently that we are living in a world where things are getting smaller - he was referring in particular to electronic goods such as mobile telephones, but there are other good examples in the medical and automotive sectors.

We therefore believe the new SR-10J will be particularly popular and look forward to demonstrating its capabilities to our existing user base and future prospects at MACH this year, where the machine will be making its UK debut.'

'Streamline Machining' is a major factor influencing faster cycle times, by reducing the non-cutting elements, giving improved flexibility and introducing features to assist unmanned running.

'Streamline Machining' will be the focus depicted at NC Engineering of Watford's MACH 2006 display of the latest technology from Citizen for producing components up to 32mm diameter on CNC sliding head turn/mill centres or 42mm through the Citizen Boley fixed-head machine range. By the start of the exhibition there will be more than 1,000 Citizen machine installations in the UK demonstrating the significant market-leading position in producing largely single-cycle operations involving combinations of turning and milling tasks. One of the major reasons for Citizen's world-leading success in this sector is the continuous development strategy that saw almost the entire range of its machines either updated with significantly improved specifications or the introduction of totally new models during 2005.

Here 'Streamline Machining' has proven to be a major factor influencing faster cycle times, by reducing in particular the non-cutting elements, giving improved flexibility and further features introduced to assist unmanned running.

In short, Streamline Machining is delivering the opportunity to obtain a massive 30% reduction in cycle times on the new machines against the same programs already well-proven on a previous generation machine.

The NC Engineering stand will have six of its high technology machines on demonstration plus Citizen's latest Cool Blaster III 2,000 lb/in2 high pressure coolant system, a new CNC editor and a demonstration of palletised unloading.

Five of the six machines will be shown for the first time at a UK exhibition.

The recently introduced and very competitively priced Citizen K-Series sliding head lathe available in 12mm and 16mm bar sizes; the best-selling L20-VIII now even faster than ever with customers benefiting from up to 40% quicker cycles; the top of the range M32-V with the added bonus of three-tool simultaneous cutting and the flexibility of two Y-axis cross-feeds to the turret and toolslide, will all be producing features on components in single 'one-hit' cycles.

Linear slide technology will be demonstrated on the Citizen R07 with high speed cycling and 16,000 rev/min, ceramic spindle bearings producing parts up to 7mm diameter to extremely close tolerances while on the fixed head 42mm, Boley BE42-Y with twin driven-tool turrets, and Y-axis will be showing three tool simultaneous cutting.

Major elements of the Streamline Machining package include a vastly improved control system software able to help shorten non-productive times, and handle up to five-axis simultaneous machining and a 30% increases in motor power for the servo drives.

Rapid traverse rates are up to 32m/min with simultaneous movements created through shockless acceleration and deceleration curves and acceleration improvements of up to a factor of 1.6 for each axis with overlapped axis movements further reduce lost time.

Believed to be world's first 10mm capacity single-spindle CNC sliding head lathe without guidebush, this machine has five linear axes and provides an excellent price-to-performance ratio.

MACH 2006 will be the first opportunity for Tornos to present two exceptional new machines to the UK. On stand 5076 the Swiss sliding head turning centre specialist will present the new Tornos Deco 8sp and the Deco 20s - the first machines of the new S-line range. Tornos will also exhibit the Deco 26a 10-axis turning centre.

The first machine launched in the new S-Line range is the Deco 8sp.

The 8sp is world's first 10mm capacity single-spindle CNC sliding head lathe without guidebush.

With five linear axes, the Deco 8sp provides an excellent price-to-performance ratio whilst the kinematics have been adapted to execute reasonably complex parts.

It is a technological solution that allows Tornos to offer an automatic lathe that guarantees a degree of precision of +/-1 micron (0.001mm) never seen before.

The Tornos 8sp addresses new markets such as the electronics and especially the hard mini-disk sector for mobile IT applications.

The second machine launch of the new S-Line range, the Deco 20s is designed to execute relatively complex parts up to 25.4mm diameter.

The programming and kinematics of the Deco 20s are geared towards simplicity, which is coupled with strong mechanical elements to guarantee high precision.

With six linear axes, the 20s has been designed for producing reasonably complex parts with an excellent price-to-potential ratio.

Numerous market studies were conducted and the Deco 20s is the resulting machine that is well suited for the automotive, medical, electronics and connector and general manufacturing sectors.

The considerable strength and power provide the lathe with a very large machining capacity.

Another important aspect is its versatility - the machine has 22 tool positions and a high level of interchangeability to give the DECO 20s exceptional flexibility.

Specialist machining subcontractor's sliding head turning centre is used for making critical parts used medical gas, anaesthesia and optical equipment to tolerances under 0.005mm.

When family run Advanced Coil Slitters (ACSL), a specialist contract manufacturing supplier to the medical, aerospace, hydraulics and instrumentation industries needed a functional and productive turning centre - it turned to Tornos Technologies. ISO: 9001/2000 registered ACSL provides a rapid response 'emergency service' to customers needs. To fulfil this demand, Stevenage based ACSL operates a high specification production facility on a 24h basis with 30 employees covering a three shift pattern.

An integral part of the high specification CNC equipment at ACSL is a Tornos Deco 26a sliding head turning centre.

Used for the manufacture of critical parts incorporated into medical gas, anaesthesia and optical equipment with tolerances less than 0.005mm, the 32mm diameter capacity Deco 26a has been a valuable asset to the company.

ACSL production director Steve Ward said: 'In the time we have had the Deco 26a; it has been an excellent machine.

It runs 24/7 on a diverse range of materials from Hastelloy, stainless steel, brass, aluminium and plastics.

The 12-axis machine is capable of very complex work and this capability has reduced some jobs from five operations to one.

One component, an oxygen regulator underwent drilling, milling and turning with five set-ups - when moved to the Tornos the 12 minute production time was reduced to 3 minutes with only one set-up.

There are many more examples similar to this.' Ward said the average cycle time has been cut by 40-50% since the introduction of the Deco 26a and believes that the high number of machine axis has increased the company's flexibility.

'Whilst 12 axes may seem a daunting prospect, the machine is very flexible, highly productive and extremely easy to set-up.

We can now do jobs that were previously outside our scope.

It has changed the way we quote jobs and it has increased our capabilities and confidence to go after more complex work.

Some of the jobs that come off the Deco 26a are so complex you would not believe they came off a lathe,' commented Ward.

Discussing the simplistic set-up of the Deco 26a, Ward said the Tornos control system, the TB-Deco may be different to all other control systems but once understood is very simple to understand.

'The TB Deco enables us to run simulations before starting machining cycles; this has given us a high level of confidence and guarantees we avoid tool collisions.

Tornos regularly provides us with TB Deco updates and enhancements; this improves productivity and makes life easier when programming the machine.

We run some extraordinary program variations and the Deco 26a does some amazing things using the combination of axis,' continued Ward.

When choosing a turning centre, ACSL needed a flexible machine that was easy to set-up, productive and had an easily accessible work envelope.

When the company chose the Deco 26a, it found a solution capable of producing batch runs of anything up to 10,000 on an extremely diverse range of products.

Commenting on this, Ward said: 'There are a lot of product variations going through the machine and during changeovers the spacious work envelope provides plenty of room to change tools.

'It rarely runs for less than 24h and often runs for up to four days with just reloading of the barfeeder.

Once the tooling and program combination has been established the machine proves extremely productive and cost effective.

It has seen us change the way we operate and gets us thinking with a different mindset.

The Deco 26a has reduced our costs, improved productivity and capability and has enabled us to relocate staff to alternate tasks and machines.' Ward concluded: 'Tornos provide us with good service and are a very approachable company.

This was epitomised by the well run training course that saw our operators learn their way around the machine very quickly.'

By adopting off-line programming software for CNC automatics, a small precision turned parts maker has cut programming times for new jobs from around 1.5h to 10-15 minutes each.

Ronco Engineering, facing a surge in business for its small precision turned parts has just added a Citizen C16 CNC sliding head automatic lathe from NC Engineering of Watford, UK, to its existing fleet of two Citizen L20 and one L32 machines. By adopting Citizen's specially developed off-line programming software, Alkartpro, Ronco has gained a massive leap in productivity cutting programming times for new jobs from around 1.5h to between 10 and 15 min each. Production director Paul Cottrell explains how in recent months the company has seen a significant increase in volumes against existing orders: 'We have three existing citizen machines and their accuracy and repeatability has proven to be second to none.

For this reason we did not look anywhere else when placing the order for the C16.' Based at Stanley in County Durham, UK, 23-employee Ronco Engineering supplies precision components to industries including off-road, electronics and oil and gas.

Its biggest customer is the Articulated Trucks Division at Caterpillar, where Ronco was the first company approved to Caterpillar's Certified Supplier status.

Since its installation in May 2005, the Citizen C16, along with the other Citizen sliding head autos, was immediately engaged on one particular family of components that form a solenoid assembly as part of safety critical braking systems.

Ronco produce 40 different stainless steel parts in the contract in batches ranging from 500 up to 20,000 and when introducing the components to the Citizen machines, NC Engineering's Alkartpro offline programming software, based on its operator friendly Windows based machine tool control, made an immediate significant difference.

Maintained Cottrell: 'Alkartpro has been a revelation, by increasing our programming output and accuracy.

What used to take 1.5 hours can now be done in just 10-15 minutes and on this family of 40 solenoid components alone, it equates to a saving in excess of 50 man-hours.' Alkartpro can be applied to the best selling Windows-based machining sequences on the C, L and M ranges of Citizen machines.

Based on five material groups, with relevant speeds and feeds generated from its customisable tool library, programming is based on a 'picking list' of machining cycles such as turning, grooving, drilling and milling.

Important for Citizen users is that incorporated within the cycle generation are operational functions and cycle elements such as sub-spindles, workpiece-unloading, C-axes and even long-part machining.

'In use, it becomes a simple matter of adding finish sizes to a schematic diagram that is automatically created for the part as the required operations are input,' informed Cottrell.

'When first deciding to invest in sliding head technology we selected Citizen because it offered the best price per part produced to specification ratio,' said Cottrell.

'This has turned out for us to be a very wise move.

The ease of use and consistency of the machines in production has proven to be so important.

Also, whenever we need backup from NC Engineering it could not be a better support service.

It all means we now run the Citizens round-the-clock, six days a week, without any concerns whatsoever.

It is certainly helping maintain our credibility with important customers.' NC Engineering has its own software/system specialist Tom Purnell who, armed with a physics degree and MSc in Information Technology, works with NC's sales and applications team, customers in the UK, as well as Citizen specialists in Japan and the European headquarters in Germany.

As Geoff Bryant managing director of NC Engineering explained: 'UK customers have invested a lot in the Citizen product and if we can help to gain more return on the investment, it is to everyone's benefit.

There are plenty of companies that can provide specialist services - but they do not understand the background to problems and the way our customers think.

Other countries such as Japan, the US and even Germany, have totally different needs which is especially so at shopfloor level.' On-going development of the Alkartpro off-line programming system is currently underway between NC Engineering and Japan, where the UK agent is providing a technical consultancy to the Citizen development team.

This, according to Bryant, is an important credential for his company because it is enabling contributions based upon UK customers' experiences and needs, to be worked into the software.

At the heart of Alkartpro is its ability to automatically arrange the finished machining program in order to minimise the cycle time.

Should the programmer want to change to a different set of toolholders, for instance, or output the program for different Citizen models, Alkartpro instantly updates the process to compensate for the request.

With the ability of the 14-axis, 80 tool capacity M-Series Citizen lathes, in particular, to machine with three tools simultaneously, the software will automatically re-arrange the machining process and even determine the best use and optimise elements such as peck cycles when drilling.

And, prior to CNC code output, the system graphically presents the programmed sequences in a simple bar chart format, enabling the user to target the longest elements to see if further cycle improvement can be made.

NC Engineering's CNC program Editor, is a prime example of providing a shopfloor based solution with a simple visual representation using split screen editing that avoids the confusion and normal inconvenient process of having to scroll up and down a single screen list presentation.

According to Purnell, this is a major advantage when up to three tools are engaged on a part at any one time.

The user can read across the columns of program on a single screen and copy text between the multiple programs that are open.

Also, when using synchronised spindles, which require special codes, as these are set side by side, it is easy to check the various elements to confirm the synchronisation.

'In this respect conventional off-line programming layout is not 'operator friendly,' he maintained.

Central to NC Engineering's CNC Editor is the incorporation of a low cost DNC for program transfer with built-in communications templates for Citizen machines.

It can also be used on other types or makes of machine tool if the communication settings are available.

Also included is a queuing code and co-ordinate system setting (G-5O) validation, which significantly relieves the tedium and de-bugging time on the machine.

The editor will also support wireless LAN drag and drop program transfer.

When it comes to on-line customer support, by using a modem or the Internet, any Citizen Windows-based machine that is installed can be operated or controlled remotely through every operational or functional cycle by NC Engineering staff with the exception of 'cycle start'.

With customer agreement, programs can be transferred and process parameters changed, which can often save an on-site visit.

According to Bryant, most of the latest machines now have this capability and through Broadband Internet, is very rapid to execute.

This enables the normal high levels of productivity and machine utilisation to be maintained in the event of problems.

For new users in particular, this is a bonus which quickly builds a high level of confidence by hand-holding allowing programs to be communicated between Watford and the customer for advice and problem solving.

So far NC Engineering has either been totally responsible for or has been a major contributor to a wide range of additional high tech services such as Alkartpro as well as a low-cost CNC Program Editor.

Sliding head automatic lathe drastically simplifies allocation of the various machining operations to hip screws machined from bar and for back operations (counter-spindle).

Every year in Europe, roughly 700,000 people suffer a hip fracture, which is frequently linked to osteoporosis. The medical facilities currently available mean that rapid surgical intervention can be conducted to reduce the fracture by applying plates and retaining screws, thereby allowing patients to quickly regain their mobility. The hip screws used for surgery are highly complex parts that require numerous machining operations involving swarf evacuation.

The highly resistant materials used in these implants including stainless steels and titanium often entail several rough-working, finishing and deburring operations.

Without doubt, the best solution in terms of productivity and feasibility is to proceed with the complete machining of the parts in a single chucking operation using one machining unit.

Thanks to the A-line products from Tornos (the Tornos Deco 20a in this case) it is now possible to machine specific parts in minutes.

The Tornos Deco sliding head lathe is fully adapted to this family of parts.

It drastically simplifies allocation of the various machining operations from the bar (main spindle) and for back operations (counter-spindle).

The kinematics of the Tornos Deco (12 numerically controlled axes all with simultaneous interpolation) allow up to 4 tools to be used simultaneously and execution of back-operations is 100% in hidden time.

The lathe and various devices developed to date offer numerous facilities for different types of machining operations, giving finished parts in a single set-up.

The procedure to manufacture hip screws involves turning, centering/drilling/reaming, high pressure drilling to 120 bar, tapping, hexagon broaching/swaging, external hexagon milling, external thread whirling in back-operation mode, deburring, part support and over 20 tools to conduct the numerous operations.

The Tornos Deco 20a sliding head lathe lends itself particularly well to hip screws, due to its dimensional geometry, chucking facility, re-chucking for back-operation and facility to change between main operations and back operations.

* Process improvements - Tornos continually improves its machines for the medical sector and the main technical reason for further improvement to the overall machining process of these difficult materials is to provide the operator with improved versatility and flexibility during setting up work or when retooling.

This can be achieved from pre-adjustable tool systems - available both for the fixed tools and rotating tools.

The setting up or retooling times are significantly reduced, which further reinforces the well-known productivity of the Tornos Deco lathes.

Benefits have also been obtained from the introduction of 'coolant through' tool holders to bring about improved swarf management.

Another addition is the simultaneous machining facility with respect to roughing and finishing (balanced turning), which leads to good swarf management, increased tool life and improved surface quality.

The main sequences for machining a hip screw on the Deco a lathe involve hexagon swaging, external hexagon milling with two tools simultaneously and end piece support, back operation thread whirling in hidden time and back-operation high pressure drilling at 120 bar using a guide bush.

The latest 7-axis fixed-head Boley BE42-Y CNC lathe with Y-axis cross-feed to one of its two 12-station all-driven turrets enables complex three-axis interpolation.

The latest 7-axis fixed-head Boley BE42-Y CNC lathewith Y-axis cross-feed to one of its two 12-station all-driven turrets enables complex three-axis interpolation, off-centre cross-drilling, milling and slitting with standard tool holders and fast and precise setting of tooling centre height for machining components up to 42mm diameter to high orders of geometric and size tolerance in a single hit cycle. The Citizen Boley BE 42-Y to be exhibited in the latest two-tone silver livery on the NC Engineering Stand 5262 at MACH 2006 has the added capability to perform cycles such as eccentric cross-milling and machining requiring three-axis helical interpolation on components out of a maximum bar size of up to 42mm bar or on chucking applications up to 140mm diameter, and to further its machining capability and reduce cycle times up to three tools can be engaged with the component in the main and subspindle machining positions. Able to transfer parts between its main and sub spindles, which have full C-axis capability for mill/turn sequences, the two identical 12-station turrets with one second indexing and a 1kW, 4,500 rev/min drive to each tool position are able to carry up to 48 tools.

This is achieved because both turrets have additional index positions set between each station which means up to 24 tools can be set on each turret.

When this tool carrying capability is combined with the addition of the +/-40mm Y-axis cross-feed to the top turret, the versatility of the machine increases further due to the freedom of turret axis movements to both main and secondary spindles.

The spindle is a high precision unit able to create enhanced ceramic surface finishes due to the employment of bearing technology with liquid cooling.

The spindle is powered by an 11kW, AC built-in motor giving between 80 and 8,000 rev/min.

The collet is hydraulically operated for bar machining and to create a higher gripping force when using the optional 140mm capacity chuck.

The sub spindle is powered by a 3.7kW 6,000 rev/min drive.

In its chucking lathe guise, the Boley BE42-Y has the facility to carry a collet in the sub spindle and is able to pick-up the component from the main spindle by locating from a previously turned diameter.

It is then transferred at a traverse rate of 24m/min ready to position for second operational machining.

In addition, the sub spindle also incorporates an 110mm X-2 cross-feed axis to enable component features that are dimensioned from the centre line to be accurately machined.

The Boley BE42-Y has a 30deg slant bed and adopts many of the proven features of the existing Boley fixed spindle and citizen cnc sliding head range including a common CNC control system with high speed processing capability, and handwheel control for easy program prove out.

The machine is compact with a floor area of 2350mm by 1560mm.

Options available include chute-type workpiece outfeed or conveyor, a back-spindle thread chasing device, automatic part-off, tooling monitoring and breakage detection and an automatic component loading system for chucking work.

Latest linear motor technology is being used to remove any likelihood of deflection and backlash and to optimise slideway structure of the most recent CNC sliding head turn/mill centre.

The latest linear motor technology is being utilised by Citizen to remove any likelihood of deflection and backlash from the power transmission system and to optimise the structure of the slideway on the latest R07 Type VI CNC sliding head turn/mill centre. With this design, which is exhibited under power on the NC Engineering Stand 5262 at MACH 2006, Citizen has been able to create a very compact machine and capitalise on combining super precision with high speed 'one-hit' machining cycles on components up to 7mm diameter by 40mm long. The RO Series, which features the RO4 and RO7, has proven to be an outstanding success in Switzerland and particularly in the watch making sector due to its compact dimensions that enable an easy substitution to traditional cam auto machines.

Productivity being found to be higher with the added bonus of consistency of production and the flexibility of CNC to enable development of the turn/mill process to further reduce cycle times.

With six-axes, a main and subspindle and up to 13 tools available, of which three are driven, two tools can be brought into action simultaneously, which means the new Citizen R07 is reckoned to be significantly faster than a traditional cam auto when machining small parts in single cycles.

It has the advantage of a very compact footprint of 560mm by 1265mm when installed on the shopfloor, has no hydraulics or pneumatics and is totally electric and electronic in operation.

The 16,000 rev/min, 1.1kW built-in main spindle has precision ceramic bearings for optimised machining of small diameter parts and a 0.5kW secondary spindle with an 8,000 rev/min capability.

It has two independent toolposts able to hold 13 tools, of which three are driven by 0.2kW, 8,000 rev/min spindles.

An important development with the R07, that significantly increases machine utilisation, is the ability to open and close the collet at normal machining revolutions without adding to the cycle time by slowing the spindle.

Accuracy is high with increments of 0.0001mm in each axis and repeatability of one micron is possible.

By combining linear drive technology to both tool posts, high productivity is guaranteed with rapid acceleration to maximum traverse rates of 20m/min.

The maximum machining length is 40mm and with the two slide arrangement, five turning tools can be mounted on the gang tool post with two cross-driven tool positions.

In addition, three end working tools can be applied to each of the main and sub spindles to optimised orders of positioning accuracy through the use of glass scale encoders.

The main spindle has 1 deg indexing and both spindles have rotational synchronisation for part transfer.

There are a number of canned cycles for polygon turning, thread cutting, drilling and rigid tapping and constant surface speed is standard to minimise cycle time and maximise surface finish.

Sliding-headstock mill/turn autoamtic lathe is so fast, it can OD-turn, drill the front end, part off and drill the back end of a component in 5s, a job that took 10s a few years ago.

For mill-turning components up to 10mm diameter, Star has introduced a new, sliding-headstock lathe that is so fast, it can OD-turn, drill the front end, part off and drill the back end of a component in five seconds. Even a few years ago, it would have been almost impossible to achieve such a process in less than 10s. Designated SR-10J, the competitively priced, compact bar auto will make its UK debut at MACH 2006.

It is a highly productive mill-turning centre that rivals the output of a cam auto, but with the added flexibility of CNC to allow rapid changeover to produce a different component.

Said Star Micronics GB's engineering manager, Stephen Totty, 'If you are making sub 10 mm parts, it is preferable to use a small capacity machine, because the moving elements are smaller and faster than on a 16mm capacity lathe or larger'.

'Our new machine is ideal for smaller work, as it has 35m/min rapids with extremely fast acceleration, and front-working tools positioned very close to the bar on three sides in a yoke formation.' The 2-axis sub spindle is capable of working in conjunction with a four-station endworking unit, independently of, and simultaneously with, main spindle operations.

There is a total of 21 tool positions in the working area including three live cross-working tools, four tools for front endworking and a further four for rear endworking.

Commented managing director, Bob Hunt, 'One of our customers observed recently that we are living in a world where things are getting smaller - he was referring in particular to electronic goods such as mobile telephones, but there are other good examples in the medical and automotive sectors.' He said: 'We therefore believe the new SR-10J will be particularly popular and look forward to demonstrating its capabilities at MACH this year.

The machine will be fitted with a new bar magazine from FMB, called MicroMag.' Established sliding-headstock model, Star SR-20RII, will be comprehensively equipped as a cell with FMB Turbo 3-26 bar magazine, 2,000 lb/in2 high-pressure coolant supply, mist extraction and a full suite of swarf extraction equipment.

Demonstrations will include gun drilling, roller burnishing and polar programming for fast, accurate milling.

The ECAS-32T twin-turret, 11-axis, sliding-head auto will also have high-pressure coolant and, as part of the demonstration cycle, will show angle drilling and accurate thread rolling.

The latter is assisted in particular by the machine's rigid build and six tonnes installed weight - nearly twice that of its main rival.

The heavier construction of Star mill-turning centres compared with competitors' lathes will be a major theme throughout the exhibition.

The fourth Star sliding-head lathe on the company's stand will be an SV-32 featuring gear hobbing and extensive driven tool capabilities.

It will be fitted with a JBS guide bush that is able to compensate continuously for variations in the diameter of each bar as it is fed through the guide bush, leading to higher accuracy machining.

This contrasts with other systems on the market which, although adjustable, cannot self-compensate to suit the varying bar diameter, as the bush is fixed once it has been set.

To be exhibited on the Floyd Automatic Tooling stand - 5251 - will be entry-level model, Star SB-16C, fitted with a new, eight-station platen capable of accepting Applitec tool holders and high pressure coolant.

The sixth Star sliding-head machine at the show will be found on stand 5290 - that of WNT UK - which will demonstrate its tooling products performing polar milling, face drilling and tapping on an SR-32J.

High pressure cooling system on a CNC sliding head automatic lathe provides high levels of security of process to cover the wide range of materials such as nickel alloys, brass and titanium.

Over 95% of the small precision machining capacity between 4mm and 32mm diameter at GBP 1 million turnover Riverside Precision Engineering (RPE) is generated by single operation 'one-hit' cycles. Located in Blackburn, in the heart of aerospace subcontracting country, RPE's order book is dominated by medical, marine equipment, hydraulics, furniture and brewing customers. Most of the up to 32mm diameter components supplied to the 50 or so long-standing customers are produced by double shifting three citizen cnc sliding head autos, an L20-Vll bought in 2001 and the latest M32-lll and L32-Vll machines installed in November 2004 and January 2005 by NC Engineering of Watford, UK.

And, as is becoming more common with leading contractors using advanced sliding head technology, RPE's joint managing directors Michael Ditchfield and Scott Whalley are increasingly involved with in-depth consultation with customers on design for production and application issues.

As a result of applying their advanced machining knowledge, RPE customers are able to achieve either higher performance or improved application of components or, enjoy more cost-effective pricing gained by applying the advantages of Citizen's fast developing machining technology and latest available tooling solutions.

RPE, which is now running at the forefront of small part turning by offering advanced production machining, started as a toolmaking business 15 years ago using manual machine tools.

A local furniture maker requested batches of 500 or so parts against a target price that set RPE on the path to progress by using automated capstan lathes.

Orders followed for diving equipment components, resulting in the first two CNC lathes installed and, eventually, a second-hand Citizen L16-lV sliding head auto was purchased as the only way to become more competitive and meet customers challenging cost down targets.

The Citizen L16 is well remembered by both directors who describe it as being very effective on small part machining cycles due to its twin turret configuration.

But according to Ditchfield, it could never come anywhere near the capability of the modern Citizen lathe.

In 2001 the company moved into its current 5,000ft2 premises and a new Citizen L20-Vll was quickly installed to satisfy a large contract that RPE describes as having to 'hit the ground running' to meet the delivery date.

Needless to say, it proved to be a highly successful venture.

Said Ditchfield: 'But at the time we could not even think about being trained on the L20 as we had two months of continuous production to get out the door so it was some time before we finally learnt how to get the best out of the machine.' Describing the business, Whalley maintained that forward planning is very difficult and they have become very accomplished at reacting quickly to customer demand.

That is why, he said, the latest Citizen M32 has 'all the bells and whistles'.

The machine was ordered with gantry off-load, Cool Blaster, the 2,000 lb/in2 programmable high pressure cooling system and NC Engineering's Alarm Alert which automatically calls for attention when unattended if the cycle is stopped for any reason such as batch completed, bar jam or tooling fault.

The NC Alarm Alert tends to be used when running unmanned and is connected to Whalley's mobile phone.

'It is really proved its worth over weekends when running against the clock to deliver critical components,' he maintained.

But it is the Cool Blaster that really provides a bonus and high levels of security of process to cover the wide range of materials such as nickel alloys, brass, titanium, 303 and 316 stainless steel, plastics, acetal and nylon the company often has to machine.

Said Ditchfield: 'Without Cool Blaster we could not effectively machine half the parts we have to produce and on one particular 'banjo' component, which has awkward internal grooves, swarf could be a big problem that would compromise the operation.

Cool Blaster solves all these problems.' batch sizes tend to vary between 100 and 20,000 and Citizen machine changeover times vary between two and six hours.

Because of the advantageous tooling capacity of the M32, RPE tends to leave common tools permanently set on the machine to speed changeovers.

Ditchfield maintained that the high speed cycle check on the latest control system of the Citizen is invaluable when programming at the machine, and takes any frustration out of proving cycles.

RPE also make use of the CNC Editor to edit programs and optimise cycles on a remote PC prior to setting a new job.

As the system totally replicates the control system it provides exactly the same visual appearance and program data which is retrieved and transmitted between machine and the PC by wireless link.

As Ditchfield outlined, they are currently considering adopting the Citizen Alkartpro off-line programming system from NC Engineering which would completely take program generation away from the machines.

The inclusion of the fully programmable gantry off-load on the latest M32 has proven to be more of a boon than originally thought, especially on components up to 180mm long.

Says Whalley: 'With the unload fingers able to grasp the component directly from the subspindle, rather than adding a delay to the cycle for the spindle to eject parts to the normal part collector, the unload cycle can be carried out while the turret and gang tooling slides are simultaneously working on the next component in the main spindle.

By getting hold of the parts, any possible chance of damage is taken away and with the added power of Cool Blaster, this ensures we have clean, swarf free parts ready for final cleaning and dispatch.'