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Product category: Tool and cutter pre-setting
News Release from: Renishaw | Subject: NC1 non-contact laser tool setter
Edited by the Manufacturingtalk Editorial Team on 28 June 2005

Fine set-up saves 2h/job on orthopedic
joints

Orthopedic joint maker achieves spectacular set-up time reduction using quick-change pallet fixture system and non-contact laser toolsetter on VMCs used for instrument parts.

Reductions in machine tool set-up time typically come in small increments However, this is not the case on the four vertical machining centers (VMCs) used by the instrument department of Howmedica Osteonics, the leading maker of replacement hips and knees

The instrument department reduced set-up time of standard jobs from over 2h to only 5 min - and eliminated $1 million of inventory - by implementing a quick-change pallet fixture system, tooling carts and Renishaw's NC1 non-contact laser tool setter.

Pallet fixture systems and tool carts are proven setup timesavers used in a wide variety of shops.

However, Howmedica Osteonics is at the forefront of using Renishaw's non-contact laser technology for quicker tool setting.

The NC1 is commonly used for in-cycle broken tool detection, but Bob Mykytka, Howmedica Osteonics manufacturing engineer, found it just as helpful for 'hands-off' setting of tool length and diameter, thus satisfying one of the new set-up procedure's key time-reduction objectives.

"Machine shop floors are a buzz of activity, and it is often difficult to stop and examine how current procedures can be improved," says Mykytka.

"But it was readily evident that long setup times were killing throughput of our short-run jobs and rapidly increasing backorder".

"Our set-up procedures needed significant upgrading," he says.

Howmedica Osteonics' instrument department produces over 4000 different parts for 1000 tools and devices used for shaping bones and installing orthopedic devices.

The range includes specialized broaches, reamers, drill guides and clamps.

Most of the parts are machined from 17-4 or 300-series stainless steel.

The instrument department produces them using four VMCs, three HMCs, four lathes, three screw machines, two grinders, and a few small manual mills.

Most of the parts are processed on the VMCs, so Mykytka focused on those machines for the new setup program.

* Long set-up time means low productivity - according to Mykytka, the previous setup procedure was typical of many shops.

An operator with part order sheet in hand would collect tools from the tool crib; assemble tools in a tool holder; install, indicate and tram fixture in the machine; and then manually perform tool offset and diameter compensation and dry-run the program.

This took over 2h for standard machining jobs, which is terribly inefficient for small production runs, he stresses.

Mykytka assembled a team in early 2000 to brainstorm ideas for reducing set-up times.

"We wanted something similar to an automotive industry flexible manufacturing cell, with all machines in-line, all fixtures already mounted, rail delivery to machine, etc, but this was obviously beyond our budget," says Mykytka.

"So we set out to design the 'poor-man's' flexible manufacturing cell." Mykytka had the idea of using standardised pallet fixture tooling on all the verticals, and was surprised to find such a system covered in dust in the tool crib.

The Siegel tooling pallet was part of an attempt at a quick change fixture system program initiated the prior year that never gained momentum.

The system uses a pallet receiver that mounts permanently in the machine bed and receives an aluminum plate onto which is mounted the fixture.

The plates slide on and off the receiver in seconds, providing positioning repeatability to 0.002in without need to tram or indicate.

Mykytka began testing the quick change fixture system on one of the pallets on a dual pallet machine.

That way, when the machine was needed for production, he simply changed-out the test pallet, allowing the other to be used for a job, ensuring no production time was lost.

With the first piece of the setup puzzle in hand, Mykytka began investigating ways to automate the tool setting procedure to allow single-button cycle start with a 'hands-off' tool compensation procedure.

For that, Mykytka turned to Renishaw's NC1 non-contact laser tool setter.

"We heard good things about non-contact tool setters offered by a few different companies and went to the Eastec show to check them out," says Mykytka.

"We were familiar with Renishaw's name and reputation for product support, and were impressed with its new cost-effective system, so we purchased one for testing." The NC1 allows setting of both tool length and diameter to be carried out at normal spindle cutting speeds, enabling identification and compensation of errors caused by radial run-out of the tool and tool holder, notes Mykytka.

The NC1 can measure tools anywhere along its laser beam (up to two meters in length), eliminating a positioning move specifically for measurement and minimising cycle times.

The laser tool setter can measure tools as small as 0.2mm (0.008in) with system resolution of one micron (0.00004in).

NC1 non-contact laser technology ensures accurate performance, easy installation and maintenance-free operation.

A compact and robust laser-based transmitter sends a visible beam to a receiver unit.

System electronics detect when a tool breaks the beam, and output signals are sent to the machine's control, allowing the position of tips, teeth or cutting edges to be instantly established.

No additional M-codes are necessary for basic system functionality, simplifying installation.

A continuous stream of air flows through special apertures, Renishaw's MicroHole, to protect the NC1's optics.

There are no moving parts in the protection mechanism.

The NC1 runs off a single air supply and requires no adjustment or cleaning once installed.

"The NC1 is simple and reliable," says Mykytka, "and is right at home in the belly of a machine tool surrounded with coolant and metal chips." Mykytka admits that it took time for the operators to feel comfortable watching the tools rapid-down to the NC1 for touch-off.

"The guys were a little nervous seeing the tool move so quickly down to the NC1, and some even had their hands on the Emergency-stop 'just in case'," says Mykytka.

"Of course the NC1 always detected the tool and they never had to hit the button." Once he proved-out the fixture and NC1, the real work began, installing the receiver plates and NC1 on each of the verticals and converting the 4000+ jobs going to the verticals.

The tool room worked to mount all the fixtures to the plates, while the programming department updated the part programs with an NC1 macro so the operator could just push cycle start and the machine would touch-off tools.

This stage of the project took one year to complete.

The shop continued to use the dual pallet machine which had both old and new setup systems until all machines were converted.

All but three jobs now use the plate system (there is a height restriction for those three jobs).

Some even use indexers, vices, double vices, and other such fixture devices mounted on the plates.

The final step was streamlining tool retrieval and installation.

Tool carts were purchased which allowed operators to have all the tools selected and waiting for them to install in the machine, instead of wasting time at the tool crib picking out tools while the machine may be sitting idle.

The department also started keeping most commonly used tools permanently installed in the tool magazine.

Most machines had 20-tool capacity, so tools 11-20 were strictly end mills of all different sizes that are used on almost every job.

This way, the operator may have to load only half as many tools.

The tools are only removed when they are broken.

Now under the new setup procedure system, the operator goes to the cart parking area to choose a job/cart, loads tools into the machine, quickly slides in fixture plate (no need to tram or indicate), and hits cycle start.

The NC1 macro in the program automatically touches-off all the tools, then the machine starts making chips.

* Mykytka recruited by femoral department to implement setup system - "This was a high-profile project, so prompt service and support from Renishaw was especially essential as this was our first experience with non-contact laser tool setters," says Mykytka.

"Renishaw was helpful and quick to respond whenever we called on them." Needless to say, management was thrilled with the project's results.

Mykytka made a presentation at a quarterly meeting about success of programme, and the system was presented at the company's annual best practices meeting in Germany.

The company recently transferred Mykytka to the femoral knee department, where he has been charged to implement a similar set-up system there.

The femoral department currently has one NC1 mounted on a robo-drill, which is used not only for tool setup, but also for broken tool detection.

Replacement knees are made from Vitalium, Howmedica Osteonics' own cobalt chrome material, as well as titanium, and tool breakage is common when drilling these tough materials.

"If a drill breaks during a drill and tap routine and the machine continues, all the tools after the drill (tap, counter bore) would also break," says Mykytka. Request a free brochure from Renishaw ...

"A quick check with the NC1 between cutting routines ensures this does not occur.".

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