Old base, new machine

Old base, new machine

Old iron is the rock on which some companies are building successful, new machine tools.

Old iron is the rock on which some companies are building successful, new machine tools.

Bardons & Oliver starts with an existing base (right) and builds its own line of CNC turning machines.

Drake Manufacturing integrates robot part loading/unloading for automating its thread grinding systems, most of which are built on existing bases.

Bardons & Oliver updates beyond original machine designs by adding such features as live tooling.

There is a saying that everything old is new again. This holds particularly true for used machine-tool bases. They aren't going to the bone yard, but instead into new product lines. Building a new machine on an old base eliminates fabrication costs and speeds product delivery. It also provides a solid foundation for updated drive systems, new controls, automated part loading, and increased horsepower.

Old bases are strong, explains Tom VanHorne, an engineer at Bardons & Oliver, because they were designed without the benefit of finite element analysis in the 1950s, 60s, and most of the 70s. Companies over-engineered bases for safety because they couldn't predict what conditions a machine might see. This is why B&O can run a full 56-hp, sustained cut on its 2SC turning machine and not tax the gear system, originally engineered for a 100-hp cut. B&O builds on bases, says VanHorne, having gussets and ribs running everywhere. The cost to fabricate a similar design today would be astronomical.

Working from a stock of old Warner & Swasey CNC turning-machine bases, the Solon, Ohio, machine builder constructs its own line of custom-speced CNC turning machines. The process is fast because the base iron is done. After their order is filled, customers can turn in an old machine. Two-thirds of all B&O customers do. This replenishes the supply of old bases.

Drake Manufacturing in Warren, Ohio, engineers complete systems for internal and external thread grinding, bore grinding, and gear hobbing. Drake builds many of its machines on existing bases. "The integrity of the base is important," says John Drake, company president. "Aged iron doesn't move, and certain fabricated bases are usable."

Drake machines, engineered from the base up, are being placed in industries demanding repeatable precision and high-volume production. For example, about 40% are making automotive parts—steering and engine components; 30% are producing consumable metal-cutting tools; and the remaining machines are interspersed among industries manufacturing medical equipment, precision bearings, and industrial drive components.

Under an ISO 9001 quality system, Drake manufactures its machines to exacting tolerances. Fanuc hollow-shaft servomotors, says Drake, contribute to a 1-µin. velocity-loop resolution. And combined with Heidenhain glass scales, the positioning-loop resolution is 4 µin.

A new and better machine
Bardons & Oliver, once a competitor of Warner & Swasey, now builds SC series based machines more advanced than original W&S designs. For example, B&O's 2SCs and 3SCs have updated features such as live tooling, gaging, and repeatability to 80 µin.

For the 2SC, engineers have developed a special, cast-polymer headstock which expands through-hole spindle size from 5-in. to either 6.5 or 8 in. The cast-polymer construction also dampens vibration to improve part accuracy. In addition, B&O increased 2SC maximum-part-size capacity from 25 to 30 in. and upped turning speed from 1,500 to 2,000 rpm.

The company starts by rescraping and regrinding base ways so they are perpendicular to the spindle bore centerline. A CMM with a 6 3 8 3 10-ft. cube checks all component dimensions, something Warner & Swasey couldn't do, says VanHorne. Technicians replace all bearings, then regrind the nose and spindle face to run concentric with the bearing journal. At final assembly, spindle runout is under 0.0003-in-TIR.

B&O machines have new Siemens model 611-A Simodrive ac spindle drives, all updated electronics, the latest GE Fanuc controls, and new hydraulic systems. "We don't even consider keeping any old control components," says Van-Horne. In addition, GE Fanuc ac digital alpha servo drives and motors deliver quick machine movement and include absolute rotary encoders for accurate positioning.

Engineers have also corrected an old design flaw. According to Fran Routh, B&O project engineer, the gear-driven indexing system tended to drop towards the side weighted with heavier tools. So B&O incorporates a stronger servo-motor to compensate.

Drake Manufacturing not only builds the machine tool, but also engineers the complete part-making process. The company offers three grinding systems—GS:TE-series external thread machines, GS:TI internal thread grinding, GS:I for aggressive internal grinding to tenths; and the GS:H gear hobber series.

On a pre-NC system, Drake engineers define customer processes and create custom software for the machine's new GE Fanuc CNC. These menu-driven systems, with over a Mbyte of software, let operators quickly fine tune complete sequences of specs and program operations for a given part and setup in minutes, rather than hours. On thread grinders, for instance, all thread forms are in the software. Operators simply enter part parameters such as diameter and threads/in. The controls do the rest.

Drake technicians force-test all bases and look for wear patterns. These patterns point to flaws in the original design that the company will correct. Ballscrews replace hydraulic drives, and ac servomotors working with linear scales control part size to ± 0.0002 in. And for several customer applications, Drake has developed and integrated robot part loading.

For a GS:TE thread-grinder setup, a conveyor brings taps to the machine, and a robotic arm with grippers lifts and loads parts. What makes the system special, says John Drake, is that the robot responds to part parameters entered in the CNC menu, so there's no separate programming. The company also offers automated loading for Drake grinding systems already in the field.

It's alive, again

DeVlieg-Bullard gave this JIGMIL model 5K-96 the full treatment—remanufactured to OEM specs, added GE Fanuc 15-MA CNC, and updated electrical components.

With just a scraping of its ways here or a CNC package there, an old re-liable machine tool can once again hold original tolerances and even incorporate the latest electronic advances. All of which is possible because companies, such as De-Vlieg-Bullard Services Group in Twinsburg, Ohio, breathe new life into machines by rebuilding, retrofitting, or remanufacturing. Rebuilding brings a machine back to as-good-asnew with the same level of controls and electrics. After disassembling, cleaning, and inspecting the entire machine, DeVlieg restores all alignments to OEM specifications and replaces all bearings and seals. All hard ways are re-ground, and soft ways rescraped. The firm recuts or replaces acme screws and sends ballscrews to a certified manufacturer for inspection.

On a mechanically sound machine with existing NC or CNC, retrofitting entails updating the controls. DeVlieg does not re-scrape or rebuild, but simply installs new controls, servo drives, and motors. However, acme feed-screws, nuts, and ballscrews are recut or replaced if necessary because they affect machine movement accuracy.

An old machine tool gets the works when it's remanufactured. For these projects, DeVlieg automates manual machines by adding CNC and updating electrical components, besides under-taking a complete rebuild.

To accommodate the automation, technicians modify axes to accept servo feed drives and motors. New precision ballscrews and nuts move each controlled axis, and scales or encoders provide position feedback.

TAGS: Features
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