Monday, January 28, 2008

Technology Helps Bike Builder Pick Up Speed

Technology Helps Bike Builder Pick Up Speed

The following was gleaned from the archives of Manufacturing Center.

If it weren't for his bad knees, Dave Lynskey would have never developed and built one of the world's premier titanium bicycles.

The Mazak VTC-30C vertical machining center is used to cut the axle drop-out and many other parts from solid plate or bar stock. It features a fixed table and traveling column.

Mr Lynskey, president of Litespeed Titanium Bicycles, was a competitive runner in the 1980s. But after seven knee operations over 21/2 years, his doctor said, "Enough." No more competitive running. Mr Lynskey still had that competitive urge, though, and as an alternative, he took up bicycling and became a competitive racer. He enjoyed the sport, but he was not satisfied with the bike frames available at the time. Then lightning struck. He had a better idea, and he acted on it.

Born was a titanium bicycle with a frame weighing about 21/2 lb, and a 1998 production level approaching 10,000 bikes.

Family Business

In 1962, Mr Lynskey's father and uncle started a metal fabricating business called Tennessee Machine in a Chattanooga, TN, suburb. One of their clients, a large chemical company, required large quantities of titanium parts, an unusual metal which Mr Lynskey and his three brothers, Mark, Chris, and Tim, learned to machine and fabricate. After their father retired in the 1980s, the four brothers took charge of the company.

This familiar-looking bicycle chain hub contains parts cut and finished on the Mazak VTC-30C.

In 1985, in his spare time, Mr Lynskey acted on his idea and built his first titanium bike frame. Then came a bit of serendipity: pioneering triathlete John Disterdick was visiting a friend near the company. When they visited Mr Lynskey's shop on an errand, Mr Lynskey's bike piqued Mr Disterdick's interest, and he asked for one. Impressed with the new frame, Mr Disterdick said other triathletes would probably want to buy them. He talked the Lynskeys into exhibiting at the 1986 Long Beach bike show, then the industry's largest.

The show generated orders and interest, but Mr Lynskey still looked at bike frame manufacturing as an enjoyable sideline. But word spread and orders increased, so the company decided to make the switch to bike manufacturing. The rest is history.

Working With Titanium

Mr Lynskey says that titanium is a tricky metal to machine. The right feeds and speeds and lubricants are important. Litespeed uses a combination of HSS, carbide, and coated carbide cutting tools. The carbides allow faster feeds and speeds than HSS.

"Titanium doesn't absorb cutting heat well," says Mr Lynskey, "so feeds and speeds must be carefully monitored. If they aren't right, the titanium will weld itself to the carbide. Titanium is also spongy. When you're taking a cut and it's too slow, the metal pushes back against the tool, building up heat and shortening tool life. High positive rake angles on the tools get underneath the metal to cut it properly. Feed pressures are also greater for cutting titanium, putting more load on the machines. This means that my machine tools must have excellent rigidity for this work."

A Litespeed frameset begins as a combination of US-made titanium tube, plate, and bar. The raw stock goes to the machine shop where more than 20 employees work with the latest CNC machine tools and fabrication equipment from Mazak Corp, Florence, KY.

Don Roberts from Pinnacle Machine Tools Inc, a Mazak distributor, sold Mr Lynskey on Mazak machines. The first machine Mr Lynskey purchased was a Quick Turn-8N, which Mr Lynskey says he has never had to service. He bought the machine in 1990.

"It's also important to have training, parts, and service quickly available, since we don't have any backup machines," says Mr Lynskey. "With Mazak, that's never been a problem."

Although some of the parts look like they should be made as castings, saving valuable machining time, Mr Lynskey says that the cost to cast them was more expensive than to machine them from a solid plate or bar. Also by keeping manufacturing in-house, the company can control the quality and have the parts available when needed.

For machining parts like a bullet-shaped connector that connects the rear frame tubes and axle drop out, a part that holds the rear axle and derailleur, Mr Lynskey uses a Mazak CNC Quick Turn-8N turning center and an AJV-18 horizontal machining center. For the axle drop out and other parts cut from solid plate or bar stock, the company recently purchased a Mazak VTC-30C vertical machining center.

The VTC-30C has a large table--78.7´´x29.9´´, with axis travels of X=65.4´´, Y=29.9´´, Z=26´´--for multiple parts production. Four or five jobs can be set up on the table for fast machining and increased production. The machine has a 15 hp spindle motor with a maximum speed of 8000 rpm.

Because it uses a fixed table and traveling column, it reduces operator fatigue and allows convenient accessibility for easy and safe part loading and unloading. The VTC-30C is large enough to make all the tooling, jigs, and fixtures the company needs.

On one job, the axle drop-out, four pieces of 1/4´´ titanium plate are mounted to the bed and multiple parts are machined from each plate. Doing it this way increases production, reduces setup time, and maximizes tool use. Redundant tools are also used with tool management for greater spindle uptime. If a tool goes beyond its wear limits, the controller automatically selects another redundant tool.

The company uses Mazak's Mazatrol Mplus CNC controller, programming both on- and off-line. The company uses CAMWARE for off-line, PC-based programming. In most cases, Mr Lynskey can give a print or part to the operator, and the operator will program the machine so when the raw stock is available it can be machined immediately.

"There's no book to tell you how to work titanium," says Mr Lynskey. "If there's a better way to make a bike frame, we make the machinery, jigs, and fixtures to do it. We don't compromise anywhere."

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