Iscar Metals
Cutting Space & Time Out Of The Process With High Velocities

This may be the first engine machining facility that is based on machines that make remarkably quick moves. And it may represent the means by which Ford will maintain its cutting-edge position in manufacturing powertrains—and not insignificant profits.

While driving to the Ford Motor Co.'s Dearborn Engine and Fuel Tank Plant, south bound on Schaefer, I passed I-94 and went by an assortment of small shops, Rouge Steel, countless semi-rigs, and other industrial evidence. I went too far, all the way to I-75, but the bracketing by the interstates is metaphorically fortuitous: One thought struck me: "This is the buckle of the Rust Belt."

To be sure, "Rust Belt" was a term used with certain derision in the late 1980s by people who were more enamored of places like Silicon Valley. Don't get me wrong. I find the environment in Silicon Valley to be much more pleasant than in the midwest during the damp part of winter; it is a whole lot nicer driving down Stevens Creek Blvd. (and certainly more beneficial to the steering and suspension of one's vehicle) than pot-holed Schaefer.

But, for example, on April 16,1997, Apple Computer announced the financial results for its fiscal 1997 second quarter, the same day Ford announced its first quarter results. Apple announced revenues of $1.6 billion. Ford announced earnings of $1.5 billion. (Apple lost $708 million.)

The buckle of the Rust Belt is shining. And within the Dearborn Engine and Fuel Tank Plant there is an initiative underway that should help solidify future earnings for the automaker. It's called the "Factory of the Future."

The plant was actually built on the Ford Rouge complex in 1941 to build rotary aircraft engines. Ford purchased the plant in 1947. Currently, there are some 1,500 people in the 2,227,300-ft2 plant, most of whom are involved in the production of steel fuel tanks—some 3 million per year—and 2.0-L engines for the Escort and Tracer—350,000 per year.

That's the main part of the plant. The Factory of the Future takes up 45,759 ft2 of space within it. There is a cylinder head line taking up 16,178 ft2 of that space; the remaining 29,581 ft2 is for a cylinder block line. According to Ted Grekowicz, manager of the Factory of the Future, there are three people who run the head line and four people who run the block line with one swing person who may go to either. They run one shift. The head line has been running since December 1995. They are meeting the shipping schedule of the Romeo Engine Plant for the two-valve aluminum heads at 128 pieces per week (this is a supplemental manufacturing line). The block line has been producing 4.6-L cast iron blocks since October/November 1996. The goal is to produce 26,000 blocks and heads per year (which will certainly be useful for the corporation, as the engines are installed in the best-selling F-Series pickup trucks).

 

A New Approach


This is a radically new approach to engine manufacture, one that Ford has been working on since 1986. Grekowicz puts the advanced nature of what is occurring into sharp perspective by remarking, "The speed and flexibility gains being achieved promise to transform the machining process as we know it today."

To put some numbers around this, consider these:

  • Drilling at 250 ipm instead of 12 ipm
  • Milling at 10,000 sfpm instead of 400 sfpm
  • Boring at 300 ipm instead of 32 ipm.

The "instead of" relates, of course, to traditional transfer line equipment, which is the norm at Ford, as well as at all other engine manufacturing companies.

Transfer lines don't just cut comparatively slowly (and their speed can be explained by the fact that they aren't using ceramic bearing spindles and high-force linear drives like the comparative machining centers in the Factory of the Future do). They are also a whole lot bigger.

Grekowicz points out some differences:

  • The number of spindles needed to machine the head would be 371 on a transfer line. It's 6 (4 CNC; 2 dedicated) for the Factory of the Future.
  • The number of spindles needed to machine the block would be 550 on a transfer line. It's 18 (5 flexible; 13 dedicated) on the Factory of the Future.
  • The number of fixtures for the head would be 76 on a transfer line. It's 5 for the Factory of the Future.
  • The number of fixtures for the block would be 111 on a transfer line. It's 7 for the Factory of the Future.

All of which means that the footprint of the Factory of the Future is comparatively modest.

What's more, there is the issue of the rapid shifts in market demand that are typical today. "The planning horizons for transfer lines are too long," Grekowicz says, noting that design changes can result in the obsolesce of the dedicated machinery. He acknowledges, of course, that when the issue is one of medium- to high-volume production, transfer lines are still the machines of choice. But he points out that the advantage to the flexible approach being implemented at the Factory of the Future is that there is the possibility of ramping up production to meet volume demands, then of redeploying the equipment—as much as 95% of it—in fairly short order should there be shifts in demand.

 

High Velocity


The core of the head line are four High Velocity Machines (HVMs) from The Ingersoll Milling Machine Co. The "high velocity" references a combination of high spindle speeds and rapid axis movement. The machines are equipped with spindles from Bryant Grinder and linear drives from Anorad. In addition, there are a special cam boring machine, a valve seat and guide assembly machine, and a variety of ancillary equipment. Machine loading is done via a gantry system. The block line uses five HVMs, in addition to a special crank bore machine, special bulkhead milling machine (with a linear motor-equipped gun drilling station), a multispindle main bearing cap bolt rundown unit, a honing machine, and two single-spindle rundown units for side bearing bolts, as well as ancillary equipment. Gantry loading is used here, too. Tooling is provided by a number of sources, including Ingersoll, Valenite, Mapal, and Tapmatic. An off-line horizontal arm Zeiss FC 900 coordinate measuring machine assures that machining is being performed as required.

The Factory of the Future setup indicates that special, dedicated machines aren't out moded. They are used because they fulfill some necessary functions. What is clear is that they are no longer the status quo.

To help avoid collisions—something that is certainly undesirable when you're milling at 10,000 sfpm—there is an engineering room within the machining area where a Tecnomatix Robcad 3.2 simulation package is running real-time cycle simulations on a Silicon Graphics workstation. This system also helps in making rapid changeovers. For example, Grekowicz says that when the Romeo Engine Plant made a shift to the 1997-1/2 model block, the change required four months. "Our implementation took one day," he remarks, pointing out that the actual machine programming change was done in about two hours and the rest of the time was spent on dimensional control plans, visual aids, and related ISO 9001 activities.

This is just the start for Ford. Grekowicz says that one of the things they are doing in Dearborn is proving out the reliability of the equipment. "Will it work day in, day out?" he asks. They'll also be establishing the mean time between failure (MTBF) and mean time to repair (MTTR) numbers. There is high-speed machining equipment at the Lima Engine Plant in Ohio. The Livonia (MI) Transmission Plant is getting a high-speed machine. And next year, high-velocity machines (these supplied by Ex-Cell-O) will be running at the Ford Cologne Transmission Plant in Germany for a manual transmission application.

"Where it is a good business decision we'll use this equipment," says Grekowicz.

 

The Cutting Tool Connection

Abhai Kumar is the manager of Technical Services at Ingersoll Cutting Tools, which is affiliated with the Ingersoll Machine Tool Company. His previous title was manager of the Automotive Team during the development period of the Ford Factory of the Future line. Which means that he helped coordinate the tooling decisions for the equipment. As Ingersoll Cutting Tools doesn't make all types of cutting tools, and as Ford has its particular preferences, Kumar and his team were involved in specifying tools from a select array of companies: "We use the best tools, irrespective of who makes them," he remarks.

Cutting when spindles rotate at 10,000 or 15,000 or even 20,000 rpm is certainly somewhat different than the norm in automotive applications, where "fast" might be characterized as 5,000 rpm, so Kumar provides some recommendations that should be considered when thinking about high-speed machining as it relates to cutting tool requirements:

  • Safety first. The centrifugal forces created during tool rotation become extremely high. So it is vital to make sure that the tool is held together as firmly as possible. This might mean using one-piece tools. Where inserts are employed, Kumar recommends the use of screws that have been tested to hold at rpms in excess of 30,000, thereby providing a good margin if machining is being performed at 15,000 to 20,000 rpm.
  • Test off-line. Make sure that the speed and feed values for all tools are established off-line to help assure that nothing is likely to break during actual machining.
  • Balance. Each tool used should be balanced. (Lee Reiterman, product development manager at Valenite, one of the companies providing tools to the Factory of the Future, observes, "Balance is the one physical feature that's most important.") Kumar notes that drills and reamers are symmetrical, so they don't need to be balanced.
  • Stiffness. It is key for high speed machining. Otherwise, there's chatter. So there are a couple of things that may be useful to do:
  • (1) Keep the tools as short as possible
  • (2) Use integral tools (i.e., no joints; joints are a weak point).
  • Control runout. This is an important consideration when running at high speeds. Integral tools can help. Hydraulic chucks are recommended for drills and reamers. Be sure that drill point centrality is right-on. (Kumar says that if the drill point is centered properly, it is actually possible to achieve a workpiece surface finish good enough to eliminate the need for reaming).
  • Use multipoint boring. In testing of boring a 100-mm hole it was determined that when a single point tool was used, the out-of-roundness measure was 13 microns. When a multipoint tool was used, the measure was just 3 microns.
  • Edge condition. Tool edge condition and geometry are always important in machining. Kumar says that edge condition plays a major role when high speed cutting of high silicon aluminum and cast iron.