Creative Machine Fixturing Brings Success at Parkn Manufacturing
Machine fixture design is a balancing act to see how many parts you can fit into the machine at once without disturbing the tool path or exceeding the limitations of your machine tool.
“We know how to push the machine fixture design, accounting for tool path,” says Bill Scandlon, who owns Parkn Manufacturing of Litchfield, Ohio, with his brother, Bob. “One of the easiest ways to reduce the cost per part when you’re talking machine time is to optimize the number of parts you can get into the machine. From years of working with machine fixturing, we know that some machines limit how much of the workzone is actually usable.”
So when Bob and Bill Scandlon started Parkn Manufacturing, they knew they needed a machine capable of handling their creatively designed fixtures. They needed to use the whole workzone for precise features, machining even complex features and parts high up in the Y-axis, and the ability to use the full Z-axis force at the top of the workzone without tipping the pallet.
“When you have to account for the flaws of the equipment in your machine fixturing, it can severely limit your part production,” adds Bob. “If the machine won’t let me cut accurately at the top of Y, or the pallet isn’t held firmly and the Z-axis thrust causes us to scrap a part, we have to hold the process back, and that’s not acceptable in a job-shop environment.”
A History of Machine Fixture Design
At the age of 12, Bill and Bob Scandlon began helping their father build complex fixtures at his northwest Ohio machine shop. While their father’s shop exclusively manufactured fixtures for a variety of industries, the brothers saw the financial potential of manufacturing fixtures and producing parts. As adults, the brothers founded Parkn Manufacturing in 2005.
“We saw the opportunity to not only provide the machine fixture design but also to do the part production,” says Bob. “We can utilize our machine fixturing abilities and lifelong experience to control the whole production process, allowing us to produce better parts faster than most.”
Parkn’s revenue grew from $30,000 its first year to nearly $1 million in its third year of business. The Scandlon brothers admit they will do any job, but the company specializes in parts that other companies have trouble manufacturing on time. They are able to succeed where others fail, often thanks to the brothers’ background as complex fixture builders and the technology that allows them to utilize that background.
Today, Parkn Manufacturing specializes in high-accuracy parts for the sporting goods, defense, and automotive industries. They typically run jobs of 10,000 to 30,000 parts annually, though they have the capability to run thousands more.
Adding Technology To Win a Lucrative Contract
When Parkn first opened its doors, Bill and Bob bought a commodity vertical machining center to get things going. They quickly realized that this machine couldn’t handle the type of work they hoped to gain and didn’t allow them to fully utilize their machine fixturing skills. When they found an opportunity to produce parts for a crossbow manufacturer, they began looking at horizontal machining centers.
“We needed a machine that would allow us to quickly produce multiple parts on one fixture very accurately,” says Bob. “This was impossible to do with a vertical, even with an indexer.”
The Scandlons also wanted a machine that would show potential customers they were serious about production when bidding on a project, and one that would have everything they needed as a total package, including a BTSOMA, laser checking, full 4th axis, training, and excellent local support. They found Makino’s a51 was the right fit.
“The Makinos were the fastest coming out of corners. They profile quickly and are very accurate, and the machine included everything we were looking for in one package,” says Bill. “Not to mention that we knew from being in part production our whole lives that Makino was a brand that gets people’s attention. If you have a Makino, they know you’re serious and probably very capable.”
Most important, Bill and Bob knew that Makino HMCs were capable of machining accurately all the way to the top of the Y-axis and used a cone-pallet holding system that allows full Z-axis thrust at the top of Y. Makino’s HMC design would let them fully utilize the entire workzone of the machine, optimizing the number of parts that could be loaded onto each side of the fixture.
“We went back and forth with the customer for a few weeks. We said, ‘If you give us the job, we’ll buy the Makino.’ And they responded, ‘If you buy the Makino, we’ll give you the job.’ We finally just bought it, and as soon as we showed them the purchase order, we got the contract,” says Bob. “We got to work producing the fixture, but immediately ran into a problem. Neither of us had ever programmed a horizontal before.”
Anticipating this need, Makino provided the Scandlon brothers with a programming class at Makino’s Mason, Ohio, facility.
“We spent a week at Makino learning how to program a horizontal,” explains Bob. “At first we thought we were in over our heads—that we bought this machine with no idea how to program it. But Makino brought in the guy who literally wrote Makino’s book on how to program horizontals. He walked us through the process step by step. After the training, we went home and were cranking out effective programs.
“We were shocked that Makino had so much patience with us—that they would bring someone to come in and teach us how to program the machine, especially since no other manufacturers wanted to help us learn how to program their machine.”
As soon as they installed the Makino a51 and learned to program it, production times of their current jobs were slashed—many times as much as 80 percent compared to the company’s original vertical machining center. The brothers attribute this drastic reduction in production time to the machine’s increased speed as well as the ability to do horizontal machine fixturing.
“What used to take five minutes on our vertical machining center takes one minute on the Makino,” explains Bill. “One of our competitors machines a specific part in 17 minutes. Using the Makino, we machined the same part in three minutes, and it came out perfectly.”
Riser Requires Sophisticated Part production
The job that prompted the purchase of the a51 was a crossbow riser made from 6061 extruded aluminum. For this job, Parkn is the contract manufacturer that handles the part from start to finish. The first operation requires two stations and 16 tool changes to drill, tap, and cut the radius. The a51 uses a special ball cutter with through-spindle coolant to keep the chips out of the cut, which is especially important in deep pockets and holes when cutting at high speeds.
“The a51 profiles very quickly,” says Bill. “It profiles at 300 inches per minute using a half-inch end mill, buried one inch deep. It never slows down. The finish is completed using a two-and-a-half-inch fly cutter at 850 inches per minute.”
The first setup cuts two sides—the flat back and the inside. The second setup runs the bottom of the piece. The machine fixture design runs eight parts per setup per side. There is a difficult 45-degree radius up one wall, which requires the use of the ball end mill. This challenging radius is aided greatly by the a51’s accuracy and speed.
“The speeds on radius cuts are very important,” continues Bob. “The Makino is the only machine we saw that doesn’t slow down around curves. It maintains a consistent feed rate throughout the entire profile cut.”
The final step of the second setup is to radius around the corners of the part and then deburr it.
The third setup cuts the side with the pocket, drills, and counterbores five holes, puts in countersinks, and then deburrs that side. Most holes are plus or minus 0.0005 inches while some others are plus or minus .002 inches, drilled to size. The entire part is kept within 0.002 inches, and the fixture must be accurate to within 0.0005 inches. The part runs in three total operations, and setups are timed so the machine is always cutting. At the end of the three setups, they have eight finished parts.
“All the relationships of the part have to be maintained throughout part production, so we can machine all the critical parts in the same setup,” explains Bob. “To ensure this, cutting critical areas in the first setup reduces the potential for stack-up error and positioning problems.”
Being able to machine accurately high in Y becomes especially important on this part, as 32 parts are put onto the fixture, with several parts positioned far above the centerline of the workzone, the typical point at which many horizontal machine tools begin to lose accuracy.
“We needed to count on the fact that the parts on the top of the fixture would turn out exactly as the parts closest to the pallet, where most machines are capable of keeping good accuracy,” says Bill. “All the parts have to be identical, even if they’re on the very top of the fixture and we’re cutting the most critical features.”
Because at least one of each setup is on each side of the four-sided fixture, a batch of parts comes out finished each time the pallet cycles out.
“The key to this part is quantity without sacrificing quality,” explains Bob. “We have to be able to take finished parts out every time the pallet comes out of the machine to keep the parts flowing, but we can’t spend a great deal of time tweaking to make sure the parts are perfect. The machine has to do that for us, while running very quickly. Our machine fixture design, combined with the accuracy and speed of the machine, allows us to do that. In fact, the machines are so fast, our guys barely have time to load up a new pallet before the part is completed."
Previously, the crossbow manufacturer used four shops to produce the riser, but they were experiencing problems with consistency and on-time delivery. The combination of the Makino a51 and Parkn’s ability to creatively fixture 24 parts in one batch allow them to crank out perfect parts very quickly to meet demand.
The Makino was such an asset that the company purchased a second a51 a year later to keep up with the demand of the crossbow riser as well as other parts that were coming in.
“The a51s have helped improve productivity that even after anodization, we are still beating the delivery time,” says Bob. “And we’ve never had a part be rejected.”
Every Penny Counts
Like most small businesses, Parkn believes that every dollar saved is important. For Parkn, tooling was consuming a great deal of their bottom line. Since the Makino a51s provide the ability to use through-spindle coolant, Parkn’s tools last about 75 parts, compared to three to four parts per tool on other machines.
“We actually went out and found new tools that would maximize our speed and keep up with the machine,” says Bill. “It gave us the opportunity to get more efficient and more accurate tooling, and saved us a significant amount overall in the cost of tooling.”
Another advantage Makino provided was financing the tooling along with the machine tool.
“When we bought the machine, our biggest worry was being able to afford all the stuff that goes along with the machine: installation, tooling, accessories, training, and other things like that,” continues Bill. “Luckily, Makino Capital Finance understood everything we needed to get started, and financed it all along with the machine.”
Chris Lyle, Makino’s Customer Finance Manager, helped Parkn acquire the financing they needed to get started, even permitting a 90-day payment skip that allowed Parkn to learn how to use the machine, and even earn some income using the a51, before making their first payment.
“For a small business—just two brothers starting a shop—working with a financier who understands manufacturing makes a huge difference,” says Bob. “We went to our normal bank and checked with the online guys. No one could understand what it takes to get started in machining, the value of the equipment, and how much money we could make if we had everything we needed to win a big contract. Chris understood and got us up and running without an issue.”
The Secret To Parkn’s Success
Parkn is not a large shop. Including Bill and Bob, the total number of employees can be counted on one hand. But their size isn’t an accurate reflection of their capabilities. “When we first started the company, we were working 12- to 18-hour days, sleeping in the shop to get things up and running,” says Bill. “With the Makinos, we can run unattended much more efficiently, allowing us to go home to our families.
“We use creative machine fixturing to get as many parts on the tombstone as possible without disturbing the tool path,” continues Bill. “We usually fit six to 10 parts per face of each fixture design to get the job done right. Because we are confident using the whole workzone of the Makinos, we know we can optimize the number of parts, even cutting critical features high in Y.”
This creative machine fixturing ability enables Parkn to produce large batches of parts very quickly if needed. They can also set up the fixtures to run separate parts on the other side, if smaller batches are required.
The secret to Park’s success isn’t complicated. “We use Makino machines and creative fixture design,” explains Bill. “That’s all it takes.”
Parkn Manufacturing LLC