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Behind The Scenes At Dale Earnhardt, Inc.
The DEI engine building operation uses the VMC-1250C Vertical Machining Center to add water lines and remove excess metal from cylinder heads.
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| The DEI engine building operation uses the VMC-1250C Vertical Macining Center to add water lines and remove excess metal from cylinder heads. |
If spring was any indication, NASCAR Winston Cup fans will see a lot of great performances from Dale Earnhardt, Jr., teammate Steve Park, and the Dale Earnhardt Inc. (DEI) team as they compete for the Winston Cup Championship this season. With Dale Junior in the #8 car and Steve in #1, they have already posted some impressive figures for the year. Dale Junior gained his first Winston Cup win in only his twelfth outing.
DEI has another team member. Cincinnati Machine has joined DEI, supplying three of its newest machine tools to a special CNC machining room at DEI's new racing center in Mooresville, North Carolina, near Charlotte.
Under a five-year agreement, Cincinnati Machine and its regional distributor, Davis-Taylor-Forster, Inc., are providing the Earnhardt facility with a 5-axis Arrow® VMC-1250 Vertical CNC Machining Center, a standard 4-axis Arrow VMC-1250C, and a Hawk® TC-250 Turning Center, along with technical assistance. The machines will support DEI's in-house engine development programs.
The DEI team had the machines cutting metal shortly after they were installed. CNC Programmer/Operator Steve Long currently leads the effort to machine ever-increasing numbers of parts in-house. "Being able to control quality and turn-around time for the specific parts we need for our cars, without reliance on outside sources, helps us ensure efficiency and accuracy. When engine assembly gets all the parts, everything is in position and correct," Long said.
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| By moving cylinder head work from manual machines to the Arrow VMC-1250, DEI technicians believe they can reduce cycle time to one or one-and-a-half hours from the current six hours |
Currently, the Arrow VMCs are used to machine aluminum and steel chassis parts such as brackets and motor mounting plates, but DEI is gearing up the operation to handle their cylinder head work. It's a critical operation that is necessary to assure consistently high engine horsepower in the General Motors engines used by the Earnhardt team.
Initially, they are doing general machining work on the heads such as adding water lines, opening up some of the holes, removing metal to reduce overall weight, and preparing heads for their special valve seat machining operation.
This work, previously performed on a manual machine, took about six hours. The group believes they can reduce that time to one or one-and-a-half hours using the Arrow-1250 VMC.
"Machining the heads on a manual machine sometimes requires up to half a dozen setups in order to make all the cuts that are necessary," Long said. Using the fully integrated rotary table on the Arrow-1250, Long and his staff are eliminating multiple progressive setups and improve dimensional and geometric accuracies between related machine surfaces.
The new Arrow VMC-1250, which comes standard with digital glass scales on X and Y axes giving accuracies of ±0.00011" (±2.75 microns) on positioning and ±0.00004" (1 micron) on repeatability. The Arrow's PC-based, open-architecture Siemens A2100 CNC can handle high-speed processing of 5-axis code, as well as Cincinnati Machine's proven 5-axis machining macros.
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| The Hawk Turning Center at DEI is in constant use producing a variety of engine and chassis components. |
With other machining systems, the tap goes through its entire cycle unless the emergency stop is activated. When that happens, the tap usually is stuck in the hole. Long said, "The tap cycle on the Cincinnati™ VMCs is a real advantage with the number of tapping operations we have to perform because it helps us prevent mistakes."
The Arrow VMCs installed at DEI both include a Renishaw MP700 surface sensing probe and a TS27R tool breakage monitor.
"These are valuable tools for setting the zero point in an operation. The probes are a real asset to running operations unattended," Long said. "At the end of the day we can simply load another cylinder head and it runs overnight. In the future, we plan to run the machines more unattended than we do now."
Pulling Horsepower From The Ports
The goal is to use the 5-axis Arrow-1250 to machine head ports.
Winston Cup cars are powered by engines tailored to strict guidelines established by NASCAR. The stock engines are usually rated at about 300 horsepower. Through modification, these same types of engines can put out about 750 horsepower on the racetrack.
Most of the improvements in engine performance have come from changes made to the cylinder head, specifically the intake ports. The port is a short, curved corridor where fuel and air enter the engine, at about a 14:1 ratio, on the way to the cylinder for compression and combustion. As the mixture of gas and air makes a sharp turn from the head into the cylinder, the lighter air loses its momentum as it rubs against the port wall. The faster moving gasoline becomes separated from the air, forming puddles on the walls of the port. These puddles reach the cylinder as droplets, which do not ignite completely. Incomplete fuel combustion significantly reduces engine performance, and even a small loss of horsepower can be the difference between finishing first or not finishing a race at all.
In the past, racing heads were hand crafted. It took skilled craftsmen 80-100 hours to make a set of heads with no guarantee that it would be suitable for racing when it was finished. And, when an optimum port design was crafted, it was extremely difficult to duplicate.
The introduction of CNC machining equipment has changed that. The dimensions of handcrafted ports can be captured using advanced metrology techniques and that dimensional data can be used to establish machine tool cutter paths.
The Earnhardt team anticipates producing 50 new engines for the two-car team in 2000.
That means that 100 heads have to be machined and ported.
That's a lot of machining work, and that's why they're pushing now to get more of the head work off the manual machine and onto the Cincinnati machines. In addition, the CNC machining operation will also be performing some engine block work, specifically adding oil lines and holes for fittings.
Long performs his own programming. The Arrow VMCs incorporate the Siemens A2100 CNC with a dual processor design featuring PC technology, Windows NT control and touch screen technology.
"The Resident Assistant Programmer feature is great," Long said. "It's a big help in G-code programming because it helps complete programs quickly and reduces the possibility for errors. The RAP feature even provides reminders from one machine to the next and lets us change to new specifications on the fly."
Shaping Things To Come
Currently, the Hawk TC-250 Turning Center "runs wide open all the time and is being used for anything that needs to be round", according to Long. The TC-250 features a 10" chuck, and its high-speed servo-drive reduces indexing time to just 0.2 seconds. Essentially, the TC-250 at DEI is making spool-like spacers used to mount the alternator to the engine. Previously these pieces were made on a manual lathe.
"We can make more mounts in less time than is necessary for the manual operation," Long said. "Plus, we keep finding parts that would be hard to make on a manual machine without some sort of special attachment to achieve the nice radii needed on the end of fittings, for example. Right now we're making lots of chassis pieces, along with brackets and suspension pieces."
The CNC machining operation at DEI is a new venture for the race team. In the skilled hands of Steve Long and his programmers, it is putting the Dale Earnhardt team consistently in Victory Lane.