What first pops into your mind when you think of France? Paris? Perfumes?
Fashions? Wine? Food? Art? How about machine tools?
If you're a design engineer, you would do well to put machine tools on your
shopping list when planning a trip to France. On a recent tour, this reporter
got a first-hand look at what the French machine-tool industry has to offer,
particularly in the areas of high-speed precision and linear drive systems.
Here's a sampling of the findings:
CNC monitors jet-engine welding
The tour began with a visit to NUM Groupe Schneider (Argenteuil), a leading
manufacturer of computerized numerical controls (CNCs).
One of the latest NUM products, the NUM 1050 CNC, is a fully digital system
for controlling high-speed machining units. It can handle up to eight digital
axes and spindles in three groups, plus three handwheels or scales. Using analog
servomotors, the system can operate up to three independent spindles or axes
(turrets, turntable, or gantries). The compact CNC features a built-in PLC that
controls up to 336 I/Os, and a 50-key operator panel with a 9-inch monochrome or
10-inch color screen (CRT or LCD).
To illustrate the versatility of its CNC systems, NUM showed its equipment in
operation at a nearby SNECMA plant that produces turbine shafts for CFM56
aircraft engines. Here, a huge inertial friction welding machine was
re-engineered to improve the process. A NUM 1060 CNC with a user-friendly
operator interface has replaced a programmable logic controller.
ARO’s welding guns with integrated transformers weigh five times less
than external transformer units and reduce cable
Close process monitoring and regulation is crucial. At a rate of one per
millisecond, the NUM CNC acquires the parameters needed to analyze the reaction
of the materials, speed of rotation, pressure applied, and material used
according to the distance traveled by the rotating part.
The CNC transmits all data it acquires to the PC, which, after expressing
them as curves, outputs a tracer sheet of the operation. This ensures the
traceability of each part produced, an essential element that helps guarantee
the quality, reliability, and safety of a critical aircraft-engine part.
Conveyor of parts and safety
Next stop on the tour was Farman (Tours), a manufacturer of accumulating
conveyors and safety curtains for the machine-tool industry. Customers include:
Renault, PSA-Peugeot-Citroën, Ford, Rover, Audi, Opel, Volkswagen, Saab, and
The conveyors' carriers accumulate at the loading point, unloading point, and
at a waiting point using a built-in retention system. Inductive detectors
trigger the retention points, and an automatic stress system on each of the two
chains reduces maintenance costs.
Each carrier features four toothed wheels where limited-friction shafts allow
continuous movement and accumulation. A geared motor drive limits stress on the
system. The patented drive system retains the carriers as they pivot at the end
of the conveyor, and acts as a safety mechanism in case of jamming.
To improve machine-tool system safety, Farman's safety curtains serve as
retractable material protectors that allow workers to manually insert parts in
an automated cell. Operator safety is guaranteed by a reflex cell that stops the
panel from dropping. All protection features remove easily for quick access and
maintenance of the automated cell.
CNCs improve welding
From Farman, the tour continued to sister company ARO (Chateau-du-loir),
which specializes in state-of-the-art welding systems. Products range from
portable resistance spot welding guns for auto-body repair to heavy-duty
industrial systems for light-alloy welding applications.
ARO's line of 50 or more robotic welding guns includes a CNC system that
assures the weld cycle starts only when the programmed electrode force is
reached. According to the company, advantages of this CNC system include:
synchronization of electrode force/weld current, detection of improper electrode
fit-up, geometric check of components to be welded, detection of stuck or
missing electrodes, monitoring and reduction of electrode wear, low wear of
mechanical gun components, shorter weld cycles, and fast build-up of electrode
To illustrate the efficiency of its systems, ARO presented a comparison of
two welding stations: one based on the use of external transformers, the other
featuring ARO's integrated transformer guns (see diagram).
Lathes shave production time
The sprawling manufacturing complex of Defontaine Automotive (La Bruffiere)
turns out millions of starter rings and flywheels for automotive giants and
small-engine makers of the world. Visiting Defontaine was Dominique Boussaton,
president of RAMO Industries (Niort), whose company's specialized lathes labor
away on the shop floor.
One of RAMO's latest offerings is the RTN30 NC lathe with a tilted bed.
Customers have a choice of NUM, Siemens, or Fanuc control modules. A
bidirectional electric turret has a tool-station plate for 12 tools. Three
high-speed hydraulic chucks feature both hard and soft jaws. Spindle speed tops
out at 6,000 rpm, powered by a 20-kW brushless motor drive. A 0.55-kW pump
In one-cell operation, a RAMO lathe, specially configured by Defontaine, sits
in the middle of the cell turning out starter ring gears from bar stock. The
operation involves cutting, welding/trimming, and annealing/forging operations.
Robots hard at work
Visitors can get a first-hand look at how robots improve production-line
efficiency at the giant Renault complex in Cléon. The plant turns out pinion
gears and primary and secondary shafts for automatic-drive gearboxes.
Since September 1995, 21 RX90 Series and 10 RX130 Series robots from Staübli
Robotics Div. (Faverges) have performed effortlessly in Renault's gearbox pinion
and sliding shaft manufacturing centers. "Their efficiency and performance is
proven daily," reports Harry C. Beaver, Staübli's national sales manager for the
What makes the robots so efficient, Beaver says, is their ability to reduce
cycle times through rapid acceleration and high-speed performance for increased
production throughput. Precise path performance adds to that efficiency, as does
a rigid mechanical structure for material removal, polishing, and grinding
applications. A patented gear-reduction system reduces backlash to zero, while
integrated solenoid valves and the robot's forearm cable permit easy end-of-arm
Both robots feature the CS7 controller and user-friendly V+ programming
language to instantly display the number of parts machined by shift, the work
rate of the machines, and any errors made during production.
Milling center handles the hard stuff
With a 100-year history, Huron Graffenstaden (Illkirch) has installed more
than 100,000 of its milling machines throughout the world. Building on this
success, Huron decided to explore high-speed cutting, not for aluminum but for
cast iron and other hard, difficult-to-mill materials. Huron's R&D
department came up with a machine equal to this task--the Huron EX multiple-axis
machining and milling center.
The EX provides continuous head movement in the vertical plane and 3-, 4-,
and 5-axis machining. Other EX features include: machinable volumes from 1,200 ×
700 × 600 to 2,400 × 700 × 800 mm; a 14,000-rpm, 25-kW, 250-Nm spindle; a
24,000-rpm, 30-kW, 56-Nm spindle; and vertical- and horizontal-plane head
Huron's larger KX10 vertical-spindle machining and milling centers feature a
numerical controller that searches for the shortest machining time, increases
machine accuracy, and produces an exact finish in the shortest period of time.
It includes a Pentium PC, hard-disk drive with 200 Mbytes of work-piece program
storage, Windows 95, 1.5 Mbytes of RAM, 1.5-Mbaud transmission speed from PC to
NC, 10m/min working feeds, and a NURBS universal interpolator.
Jet-engine parts test milling machine
Milling composite parts for a next-generation jet engine can test the
capabilities of any machine. But machines from Forest-Liné (Capdenac) produce
parts for CFM International's 737 jet engines without breaking a sweat.
"Our ongoing target is to decrease production costs for manufacturers,
without reducing the quality of parts or productivity," says Claude Jean Mege,
Forest-Liné's general manager, commerce and marketing.
Mege showed off a prototype of Forest-Liné's latest machine, the LINEAR
MINUMAC. Initial machines will come with vector-controlled HF spindles in a
power range of 20 to 75 kW with speeds from 16,000 to 40,000 rpm. Axis feed
rates will run as high as 40m/min, and may be increased to 60m/min, depending on
Modular units adapt tomanufacturing needs
The last stop of the week-long tour was the Renault Automation factory
(Castres). The company specializes in the design and production of modular
machining and assembly units for the automotive industry, including transfer
lines, or flexible cells, that quickly adapt to changing production rates.
"In building their new-generation engines, car manufacturers are taking new
approaches, but no standard production architectures are to be found on their
shop floors," notes Jean-Paul Bugaud, Renault Automation's executive vice
For example, Fasa-Renault is installing highly flexible machining lines
designed to adapt to the evolution of cylinder block designs for its new Kxx
engines. The objective: change production from one variant to another in less
than 15 minutes. The lines combine Renault Automation's high-speed Urane
machining center and Saturne machines equipped with multi-spindle heads. With
its single spindle, the Urane can be retooled in an instant to machine new
components. Urane features include autosynchronous linear motors on three axes,
horizontal electric spindle, and 20,000-rpm spindle speed.
At BMW, says Bugaud, tests with the Urane machine proved it to be the most
economical alternative for several 10- to 12-year-old machines due to be
replaced. The tests demonstrated that Urane would reduce cycle times on a
variety of engine parts by 50 to 80%. They also showed that the machine's linear
motors performed better than machining centers fitted with ballscrews, which
provided only a 15 to 30% cycle-time improvement.
EMO show previews tooling for 21st Century
You can "test drive" all of the machines described in this story--and many
more--at this year's EMO show in Paris's North Expo Center from May 5 to 12.
More than 2,000 exhibitors from five continents are expected to display
everything from machine tools, assembly and welding equipment, and advanced
accessories to components, controls, tooling, and automation systems and
software. Pre-registration ( www.emo-paris.com ) will get you into the