When US snowmobile racer “Monster” Mike Schultz lost his leg, he knew life would be different. What he didn’t know was how different. Schultz began his snocross career in 1998 when he was a junior in high school, a time when most of us are still learning to drive the family car. He quickly progressed to semi-pro, and by 2003 he was racing full-time on the pro circuit. “I worked my way up,” says Schultz. “Going into the 2008 season, I was in my prime, one of the top five guys in the world on a snowmobile. I was living my dream.” Schultz had a big break that year, signing on with Warnert Racing, a premier snocross team based in St Cloud, Minnesota. But during the second national round in Ironwood, Michigan, disaster struck. “It was the first qualifying race of the weekend,” explains Schultz. “I had a horrible start and was pushing hard for the transfer spot so I could make the finals. Coming down the hill, the sled got a little squirrelly and bucked me off. I’d crashed like that a hundred times before and walked away.”
Rotational molding was invented in the mid-1800s as a means of producing hollow objects with consistent wall thicknesses. Since then, the process has been used to make everything from playground equipment to artillery shells.
Today’s molds are filled with polyethylene powder the consistency of granulated sugar (the stuff plastic soda bottles are made of), then the mold is closed and heated in an oven. The heating and cooling process uses a machine that resembles the Tilt-A-Whirl at the county fair.
You wouldn’t want a ticket to this amusement park ride, however. With typical rototub oven cycle times of 15-20 minutes and temperatures exceeding 600 degrees Fahrenheit, this is an experience even the most seasoned fairgoer should avoid.
Rotomolding machinery manufacturer Ferry Industries Inc., based in Stow, Ohio, offers several types of machines, anything from single-station shuttle machines to four-arm, five-station production units. Whichever way you go, President Harry Covington explains that rotomolding beats the socks off traditional spa making methods.
“In a production situation, you’ll have one or even two spas sitting on each arm. While one’s cooking in the oven, there’s another sitting in the precool station, one at the water tower for final cooling, and on the other side, workers are loading and unloading product. So every time the machine indexes, you’re getting at least one spa shell. You can’t do that with traditional fiberglass or acrylic layups.”
Want to get yourself some of that? Covington would love to sell you a rotomold machine, but you’d better have deep pockets. A large model of a fully equipped four-arm machine described above will cost upwards of $500K, and that’s just the beginning. Aside from the machine itself, each spa model also requires its own aluminum mold.
“Spa molds can get pretty expensive,” he says. “The building process starts with a wooden pattern in the shape of the spa, which is used to make a sand pattern. That gets filled with aluminum, and then you have to polish it, frame it for the machine, and so on. You can figure 50 percent or more of the investment cost goes towards tooling.”
When I was a kid, I wore glasses that looked like Coke bottles and cost more than a Schwinn 10-speed. Thanks to ultraprecision machining, I now wear disposable contact lenses and spend less to replace them than I would for a cup of coffee at Starbucks.
As the grandchild of single-point-diamond turning, the same 1970s technology that made 14″ computer hard drives possible, today’s ultraprecision machining, or UPM, is responsible for making parts for everything from smartphone cameras to telescopes that can see back to the beginning of time.
Most shops are holding tight tolerances these days. What makes UPM parts different than those aircraft components you shipped last week?
“I think it depends on who it is you’re talking to—and how old the guy is,” said Thomas Sowden, owner of Contour Metrological & Manufacturing Inc., a job shop in Troy, Mich.
Sowden was making chips when the Nixon Administration thought it would be a great idea to bug the Watergate hotel. Since then, the accuracy of machined parts has progressed to levels unimaginable during the days of Flower Power and free love. “When I started machining, if you held a half-thousandth, it was pretty good. Today, we hold tolerances under a micron and impart finishes down to 30 to 50 angstrom RMS.”
Figuring out micro-sinker-EDMing is no easy task. As electrodes shrink, challenges grow, including maintaining the proper spark gap, minimizing electrode wear and determining the correct power settings. Plus, experienced EDMers know that using graphite electrodes can turn your hands black.
This wire EDMed electrode is for reverse burning the punch. For a burn like this, cavity spacing must be precise so that each burn can be made in succession without repositioning the workpiece. Running out of cavities before completing the final burn is a big problem, so too many cavities is better than too few.
But the challenges are worth it because micro-sinker-EDMing has a really big upside: “The whole point of sinker-EDMing is to machine parts you can’t get any other way—that means parts with features requiring crazy aspect ratios, steep-angled walls or sharp internal corners,” said Marcus Carius, proprietor of Implant-Mechanix Inc., Vancouver, British Columbia. “Any time that cutting the electrode would be far easier than machining the part itself, that’s the [deciding] factor for EDM.”
But, as Carius noted, burning parts with a sinker-EDM is often only half the battle. Just making a series of electrodes to produce a mold cavity or tooling component is an art. This is especially true when making electrodes for microparts.
Choosing the right electrode material—such as graphite, brass, copper or tungsten, among others—can mitigate some of those challenges, but the selection process itself can be a guessing game. While the guidelines for applying macroscale electrodes are well known, the rules for micro-EDM are a bit like predicting the next World Series winner.
It’s the 47th lap of the Indianapolis 500. You’ve been leading the pack all morning but the left rear tire is getting a bit squishy. After signaling the crew to get ready, you barrel down pit lane and slide to a stop before the garage, just as the tire changers come running out equipped with … monkey wrenches?
To a racecar driver, quick changeover means the difference between victory and defeat. But it seems machine shop owners and manufacturing engineers aren’t getting the message. Talk to most any machine tool expert and you’ll hear the same thing: fewer than 10 percent of all 2-axis lathes are equipped with quick-change tooling.
That Stuff Ain’t Cheap!
“A lot of people don’t see the benefit of quick change,” said Michael Minton, national application engineering manager for Methods Machine Tools Inc., Sudbury, Mass. “People are looking for ways to reduce setup time, but the perception of high cost gets in the way of the benefit of quick change. Machine and tooling suppliers need to do a better job of explaining the technology to end users. Given the proper application, the benefits clearly outweigh the cost.”
Quick change toolholders cost several hundred dollars each. The blocks to mount them to the turret could be more expensive than a Caribbean cruise. Adding insult to injury, lead times can be long. Once you’ve purchased a new CNC machine, you might wait 8 to 10 weeks for delivery of a quick change tooling package and spend another 20 percent over the machine’s $150,000 price tag. “It is very hard to convince a guy who just bought a 2-axis lathe that it’s a viable solution,” Minton said.
Read the rest: http://www.ctemag.com/aa_pages/2013/130403-Turning.html
The U.S. economy appears to be on the mend. In January, the Manufacturers Alliance for Productivity and Innovation gave a tentative thumbs up to sustained business expansion through the first half of 2013. And the Institute for Supply Management’s manufacturing index rose again in January, painting an optimistic picture. Maybe it’s time to buy that machining center you’ve been thinking about.
Before you whip out your checkbook, though, some homework is in order. There’s a lot more to machining centers than spindle speeds and rapid traverse rates. Sure, you’ve had good results over the years buying machines based on that, but that might be the wrong criteria in this brave new manufacturing world. You’re facing growing competition from overseas and down the street, so you owe it to yourself to take a look at what’s changed in the years since you bought your tried and true 20 “×40 ” vertical machining center.
Most everyone’s seen them at trade shows—5-axis wonder machines whittling away at intricate shapes such as motorcycle helmets, jet turbine blades and titanium knee implants. Recently, 5-axis machining centers have redefined many shops’ definition of complexity. But maybe you don’t do complex aerospace work, or you simply can’t afford to spend $500,000 on a machine tool. And 5-axis programming is way too complicated, right?
Endmilling is a mainstay of micromachining. And while micro and macro milling operations share certain similarities, there are several key differences—and surprises.
One eye opener when shopping for micro-endmills is their cost—as the size goes down, the price goes up. Sometimes way up. Where a commodity 1/8” endmill might cost $6, a micro version 1/10th that size can cost five times as much or more. Adding insult to injury, you’ll likely go through a lot of them compared to their larger cousins. These things are fragile. Why the price difference?
There are several challenges to making micro-endmills, starting with the grinder. “It sounds obvious, but the machine must be designed to grind small tools,” said Mike Wochna, president of Cleveland-based Melin Tool Co. “There are a number of things required for this, including thermal stability, vibration control and extreme accuracy.”
As the tool diameter decreases and its features shrink, the grit size of the grinding wheel must be reduced as well, according to Wochna. And as grit size goes down, complications increase. With tools smaller than 1mm in diameter, it becomes increasingly difficult to accurately see and measure features, so you’ll need special inspection equipment and trained personnel to operate the equipment.
Read the rest: http://www.micromanufacturing.com/content/not-same-old-grind
Once-revolutionary microdevices that allow doctors to examine internal parts of the human body are now commonplace. One of the most commonly used of these devices is the endoscope, and its use is growing.
The U.S. endoscopy market was valued at more than $9.87 billion in 2011, according to Sara Whitmore, analyst manager at iData Research Inc., a market research and consulting group based in Vancouver, B.C. “We expect it to exceed $16 billion by 2018,” Whitmore said. And a report by the market-forecasting firm BCC Research predicts global endoscopy sales will reach $33.7 billion by 2016.
That’s a lot of endoscopes.
Surprisingly, this growth has occurred despite a relative dry spell in technical advancements.The last big thing in endogadgets to gain market share, according to Whitmore, was capsule-type endoscopy, introduced in 2001. That’s not for lack of trying. Whitmore explained that new product development can cost more than a star NFL player’s contract and take years for approval by the U.S. Food and Drug Administration.
“Even if a company perseveres and makes it through all the required steps, there’s still no guarantee that physicians and patients will accept the new technology,” she said.
However, that doesn’t mean that existing technology isn’t being improved. Today’s endoscopes ride on the shoulders of better (and cheaper) electronics, improvements in micromanufacturing techniques, stronger, lighter materials and the engineering know-how to put it all together—the same sort of elbow grease that gave us smartphones and high-resolution televisions.
Read the rest: http://www.micromanufacturing.com/content/micro-scopes
Drilling cross-holes in some parts is no big deal. These are often simple parts, such as aluminum valve bodies, where the holes aren’t too deep and meet on-center, and the customer can live with a small burr at the intersection.
On the other end of the spectrum are P-2 tool steel injection molds for complex medical devices, with more holes than a block of Swiss cheese and tolerances that make even veteran machinists weep.
Even simple cross-hole drilling presents challenges, including high tool wear, poor chip evacuation, difficult-to-remove burrs and tool deflection that can snap the toughest of drills. But there are ways to turn the bane of holemaking into a more bearable task.
According to Dan Habben, applications engineer at Sumitomo Electric Carbide Inc., Mt. Prospect, Ill., cross-holes are always a problem child. “Probably the best tip I can give is this: don’t do it!” laughed Habben, who works with automotive suppliers and sees cross-holes in everything from transmission housings to hydraulic valves for diesel engines. “Our customers cut a lot of die-cast aluminum and gray cast iron, and one of the main problems we see, especially with aluminum, is burrs. In hydraulic systems, it’s important to get a clean hole. Any chips or hanging chads left in the workpiece might pass into the hydraulics, damaging a valve or pump.”
One possible cure is effective edge preparation on the drill, together with appropriate feed and speed modifications. “We usually recommend a corner clip in this case,” Habben said, “meaning a 45° chamfer on the outer margin of the drill, together with a small edge prep, say, a light T-land or a hone of around 0.003 ” to 0.004 ” on the cutting edge. And it’s especially important to use a sharp tool.”
Read the rest: http://www.ctemag.com/aa_pages/2013/130201-Holemaking.html