From Coding to Chipmaking


Imagine running into a problem with your G-code—maybe one of the 3D surfaces on the mould cavity you’ve been programming is a little wonky, or a feature blend isn’t quite right. Wouldn’t it be cool if you could call up the CAD/CAM developer and get them to tweak the code for you?

If you were a machinist at Miltera Machining Research Corp. in Kitchener, ON, that wouldn’t be a problem. That’s because Miltera’s sister company is Truepath CAM developer CAMplete Solutions Inc., and the programmers work right next door. Any machinist with a toolpath problem can pick up the phone or take a short walk down the hall.

It’s probably not accurate to call them machinists, however. The folks who run the machines at Miltera are project managers, but ones with chips in their boots—they talk to the customer and collaborate on part design, quote the jobs, program the machines, design the workholding and pick the tools, then head out to the shop to make the parts.

“It’s virtually impossible to find someone with the skills we need,” says Miltera president Mike Blackburn. “As a rule, we’re training internally, bringing in engineers from the university and building them up from there. Maybe they have some experience in the school’s machine shop, but more important is a desire to work in high end manufacturing, whether it’s motorsports, medical, electronics, or whatever high end market interests them. From there, we teach them our way of doing things.”

They’re not cranking the handles on some greasy old machine tools. Miltera’s 1,000 sq m (11,000 sq ft) climate controlled facility houses some impressive equipment—a pair of Mikron 400U LP five axis machining centres boasting 42,000 rpm, a WT-series Y axis multi-tasking lathe from Nakamura Tome, and two additional five axis mills: a Matsuura MAM and a Mikron HPM800, purchased from distributor Elliott Matsuura Canada.

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Tilting Tools


Tooling up a CNC lathe was once a straightforward exercise. Mount and touch off an 80° diamond for roughing, along with whatever profile of finishing tool you fancy. A groover and threader might be needed, and since most turned parts have holes, a drilling station is called for, along with a boring bar or two to finish the hole. And if the machine has a barfeed, you’d best grab a cutoff tool. Allowing for differences in hole size, groove widths and so on, this basic tool assortment once covered the majority of all turning jobs. Lathe life was simple.

One day some big-brain machine designer decided live tools on a lathe would be just the thing. Suddenly all of us turning guys (and gals) had to start thinking like those mill folks. Strange new cutting tools such as slotting cutters and face mills appeared on the bench. Newfangled taper shank toolholders and complex milling routines became known to us, along with the feedrate and rpm conversions needed to program those spinning tools. When machine builders started putting automatic tool changers (ATCs) on the backs of lathes, and added multiple turrets and sub-spindles, along with the A, B, C, and Y axes to operate them, the simplicity of two axis turning became a nightmare of flexibility. Welcome to the world of multi-tasking.

John Winter, product application specialist for Sandvik Coromant Co., says there’s no need to be scared, but adds that a little common sense goes a long way when tooling up a multi-tasker. “Some shops get so excited about multi-tasking capability that they don’t stop and ask what the machine is for. If it’s lights out production machining, the tool magazine might be loaded up with redundant and multi-function tools. Low volume and prototyping work, however, may require a broad collection of general purpose tools to handle whatever comes through the door.”

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Building Bridges

Cherubeni bridge

If your bridge needs fixing, give Cherubini Metal Works Ltd. a call. As a member of the Cherubini group of companies, this Dartmouth, NS, company is well-equipped to fabricate a new double-tee or deck slab, bathtub girder or three plate girders. With 18,000 sq m (200,000 sq ft) of production space, an assembly bay boasting 14 m (47 ft) under the hook, and 420 employees across the Cherubini Group as a whole, there’s little this company can’t handle.

Cherubini doesn’t stop at bridges, however. Vice president of operations Steve England points to a number of massive projects the company has worked on in recent years—half a dozen wellhead protection structures for Encana’s Deep Panuke Project, a 400-tonne, 15 m tall subsea turbine base, 4000 tonnes of structural steel components for the Shearwater Airbase hangar expansion, and many more. “Business is good. Aside from all the bridge projects we’re doing, there’s a lot of structural and energy-related work.”

To meet its customers’ increasing demands, Cherubini made the decision in early 2013 to purchase additional cutting machines for the fabrication department. The request for proposal was placed and, after comparing the relative merits of five equipment brands, the company chose a pair of Avenger 2 cutting systems from ESAB Welding & Cutting Products, Mississauga, ON.

“The pricing was comparable to other brands, and ESAB’s equipment is a standard in the industry,” says England. “We use a lot of the company’s welders and consumable products on our bridge fabrication.” Cherubini’s familiarity with ESAB played a part in the selection process, and the machines were installed several months later.

Plasma cutting is nothing new to Cherubini—according to England, they’ve been doing it for over 25 years. The ESAB machines, however, were the company’s first experience with five axis. “This is certainly an update for us. We can now do plasma cutting to 50 mm (2 in.) thick, around twice what we can do with our old plasma machines. And before the new machines, we were cutting all of our bevels by hand with a radiograph. The five axis heads on the ESAB machines provide consistent and accurate bevels—the result is not only greater efficiency, but higher weld quality and a lower rejection rate.”

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Cutting it down to size


Without micromachining, we’d still be watching the Red Green Show on tube-style TV sets and calling Aunt Emma on a rotary dialer to discuss the family reunion. Contact lenses wouldn’t exist, smart devices would be dumb, computers would be the size of a house. But what is micromachining, and how does it differ from hogging out a block of 6061-T6 aluminum, or ploughing a hole big enough for a golf ball in a chunk of tool steel?

John Bradford, micromachining R&D team leader at Makino Inc., Auburn Hills, MI, defines it in several ways. “The first element is size. Any part or part feature 1 mm (0.0393 in.) or smaller is considered a micromachining application. Secondly, there’s surface roughness. A part may measure 300 mm square (12 in.), but require 0.1 micron Ra or better surface finish; that’s also micromachining. Lastly comes accuracy—location of a part feature relative to a datum or other feature to a tolerance of +/- 3 microns (0.00012 in.) is the third element of micromachining.”

Micromachining requires far more than tiny endmills and good eyesight. It takes ultra-accurate cutting tools and holders capable of near zero runout. Nor will any old milling machine work when interpolating pockets smaller than a bee’s knee. Bradford says there are a number of machine tool features necessary for milling microparts.

Plenty of spindle rpm is clearly high on the shopping list for micromachining, as is an HSK or comparably precise spindle interface. And with the accuracy requirements Bradford describes, a motion control system with sufficient resolution for micro-scale interpolation is critical. Yet those attributes mean little without stability. “Starting from the standpoint of machine design and construction, micromilling processes require a very high level of thermal stability,” Bradford explains. “Without this, you’ll be unable to attain high repeatability when you have to make a second part, a third part, or a hundredth part.”

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Red Hot

Reduced operating costs, better part quality and energy savings are just three of the benefits Pacific Energy has experienced with the introduction of fiber laser cutting technology.

Electricity is expensive on Vancouver Island. This was a large part of the reason why Pacific Energy Fireplace Products Ltd. had long steered clear of CO2 lasers, opting instead to stick with its tried and true CNC turret punches.

Yet fabricators have been successful with lasers for over three decades. Compared to punching, laser cutters are faster to set up, and require far less maintenance. And in Pacific Energy’s case, cutting complex part profiles was becoming increasingly difficult with its aging equipment, a task that’s far simpler on a laser than
on a turret punch.

General manager Shannon Sears knew all this, and says the company took a hard look at CO2 several years ago. “We found the operating costs represented a significant increase over our existing equipment. And we knew the utility companies were projecting a 30 per cent rate increase over the next few years, so lasers were eliminated from consideration at that point.”

Pacific Energy is an independently owned producer of fireplace heating solutions. It offers a wide variety of wood and gas burning stoves, fireplaces and inserts, and prides itself on manufacturing clean, efficient energy products. Located in Duncan, BC, the company employs 200 people, and has customers in Australia, Russia, and all points in between. Says Sears, “we’re a metal fabricator at heart. Aside from a few purchased components, we manufacture everything in house—that means we cut, bend, form, paint and finish roughly 20 different grades of steel into finished products.”

With 35 years in the hearth appliance business, Pacific Energy has gone through several generations of fabricating technology. Like many companies, it started with hand-operated shears, ironworkers and forming presses, then evolved to CNC turret punches and eventually to automated material handling. Through it all, laser technology was kept at arm’s length.

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Mini Mills

Haimer's shrinkfit holder, which president Brendt Holden says are the best option for micromilling.Nineteen minutes into the second period and the University of Ottawa’s women’s hockey team, the Gee-Gees, trails by one. Out of nowhere, the Montreal Carabins’ left wing bruiser Helga Lefèvre smashes Gee-Gees centre Holly McDuff into the boards, fracturing her cheekbone and leaving a ragged gash above Holly’s hairline. Blood turns the blue line red, but the crowd roars as the intrepid junior shrugs off the pain; she pulls a third period hat-trick and leads the team to victory.

At the hospital, the doctor repairs Holly’s cheek with a tiny metal plate, then uses staples to reattach the flap of skin to her forehead. Because he’s worried about an infection, several blood tests are needed. With Holly safely in recovery, her boyfriend uses his smart phone to snap a photo for Facebook. “Gnarly scar, Holly,” he says. “It looks like a maple leaf.”

Bone plates, surgical staples, blood testing equipment, even smart phones and their ever more capable cameras—none would be possible without miniature cutting tools. Yet as Cory Cetkovic points out, a host of things must go right before cutting tools smaller than a human hair can be used successfully, including the right toolholder and the right feeds and speeds.

Cetkovic is an application engineer for BIG Kaiser Precision Tooling Inc., Hoffman Estates, IL, and product manager for the company’s Sphinx brand of cutting tools. He explains that micromachining produces that realm of parts and part features measuring less than 0.5 mm (0.020 in.), with feature sizes smaller than 100 microns (0.004 in.) becoming more common every day.

Cetkovic will tell you microcutters are not simply smaller versions of that 12 mm (0.472 in.) endmill you loaded into the machining centre this morning. As cutters become smaller, web thickness relative to tool diameter increases, making chip evacuation vs. cutter strength a delicate balance. Edge sharpness, too, becomes more difficult to achieve as cutters shrink in size—the slight edge prep used on a roughing end mill may be larger than the entire flute depth on a microtool. This makes rubbing a real concern with Lilliputian cutters, since depth of cut during machining is often a fraction of the tool’s edge radius. Lastly, Cetkovic says to ditch the coating. Its benefits are marginal, and may even be detrimental on tool diameters smaller than 0.2 mm (0.0078 in.).

Built-up edge, rapid tool wear, unexpected tool breakage—all the problems seen in macro milling are magnified exponentially as tools become smaller. However, there’s a straightforward way to alleviate many of these microcutter challenges, Cetkovic says: crank up the speed. “It’s very common that customers are using micro-sized endmills without the appropriate surface footage.”

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5 X 5

The Kipp clamping system from distributor Mittmann.
Tooling up a vertical machining centre is easy. Just bolt a pair of 6 in. machinist vises on the table and call ‘er done. And while this path-of-least-resistance approach may be limited, it’s also fast, easy and cheap. Unfortunately for the owners of five axis vertical machining centres, machinist vises don’t cut the mustard.

Five axis machining can be broken down into two distinct processes. The first involves simultaneous movement of up to three linear axes (X, Y and Z) together with the machine’s two rotary axes, typically labeled A and B. This process is used to produce sculpted, three dimensional surfaces such as knee replacements, pump impellers, mag wheels or a mould for the next greatest motorcycle helmet.

The other type is called 3+2, where the rotary axes are used to index and position the workpiece, enabling five-sided machining of manifold blocks, valve bodies, and a host of other parts that, prior to five axis machines, would have been “tumbled” through multiple operations on a three axis machining centere. Today, five axis machines eliminate the handling and need for multiple fixtures, greatly reducing part lead-time while improving accuracy.

There’s more to five axis machining than spinning a part. Programming, process planning, and the machine tool itself are all more complicated than what’s needed for traditional three axis work. One aspect of this is how to best grip the workpiece. No matter what you’re making on a five axis machine, the parts must be positioned farther from the table, sometimes much farther, than on a three axis machine. That’s because, when the part is tipped on its side or rotated at some extreme angle, the cutters and toolholders need room to clear the machine table. If the part is snugged down close to the table, as with a machinist vise, interference is as sure as a February snowstorm in Winnipeg.

Workholding providers have responded with a variety of solutions. Mittmann Industrial Equipment, Rigaud, QC, distributes the Kipp five axis compact clamping system from German manufacturer Heinrich Kipp Werk KG. President Thomas Mittmann says five axis machining is prevalent in the aerospace, automotive and die/mould industries. “It’s especially useful for machining low volume, complex parts. You can do the whole part in a single clamping on these machines.”

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Tough Tubes

A high strength steel forming mill from Yoder. Note the progressive forming stations. Image: Formtek Group.

Ever wonder about the legs on a folding chair? How about the exhaust pipe on your car? Tubing is everywhere, but most of us don’t give it a second thought. The technology used to make this important product is quite amazing, however, requiring equipment longer than a football field and more expensive than a mansion on Vancouver Island.

Someone who knows all about tube rolling is Brian Kopack, senior sales engineer at Formtek Inc., Warrensville Heights, OH. The Formtek Group represents a number of metal forming equipment manufacturers, including Cooper Weymouth, Tishken, Hill Engineering, Dahlstrom, Rowe Machinery and the Yoder brand of tube and pipe mills.

Roll forming is a broad topic. It’s used to manufacture everything from bicycle rims and auto bumpers, rain gutters to aircraft fuselage. In fact, almost any shape—angles, channels, S, T, U, V, W and Z-shapes—can be roll formed, and done so quickly and accurately. Tube manufacturing is a small part of the roll forming process (see sidebar page 83).

Kopack explains that tube mills are just another type of roll forming machine, but one with a critical difference: these monstrous systems weld the rolled form shut partway through the manufacturing process, then trim and smooth the weld bead to create a strong, precise and mechanically stable product.

Almost any aluminum, steel or stainless steel, is a candidate for tube making, but as Kopack points out, high strength steel is being called for with increasing frequency. Automakers in particular have their eye on weight reduction, and this means maintaining or in some cases increasing the structural integrity of their products, and doing so with less material.

“The term high strength is relative,” Kopack says. “The generic, low carbon steel tubing that’s been around since the 50s is typically 40,000 to 50,000 psi yield strength material. By comparison, we have ultra high strength, low
alloy (HSLA) steels today that offer yield strengths of 150,000 to 180,000 psi. Those materials form much differently than do commodity grade materials, and may require additional forming passes, different tooling and even modifications to the machine configuration.”

As material becomes stronger, manufacturers can reduce tubing wall thickness with no loss of product strength. This provides for a lighter weight product, and allows manufacturers to cut costs. For example, the ratio of tubing diameter to wall thickness runs between 10:1 up to 50:1 in the “plain Jane” materials mentioned in the chair leg and exhaust pipe examples cited earlier, whereas high performance tubing like that used in a modern automobile could easily be 80:1 or higher.

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Shop Floor Evolution

Renishaw and its associated company MSP, support Tier 1 aerospace suppliers on a variety of setup problems, such as automating the alignment of Airbus A330 ribs prior to machining.

When I started in the shop, machine tools were dumber than fence rails. Load the paper tape, adjust the rheostats for feedrate and spindle speed, click, click, click the offset thumbwheels, push cycle start and pray. Programs were keyed into a Teletype machine; when changes were needed, the printout was redlined and sent back to the programming office for laborious corrections. CAD/CAM systems and the mainframes to run them cost more than a new house. Probes were something they sent into space, and the only thing high speed was the steel we used to cut parts.

What a difference a few decades make. Today, the combination of complex software, inline probing systems, and increasingly intelligent machine controls give machine tools uncanny decision-making abilities, anything from stopping the machine a split second before one of us error-prone humans crashes it, to automatically adjusting cutting tools and part programs based on the in-process inspection information.

Perhaps the best known of these technologies is in-machine probing, although Dafydd Williams, general manager of Renishaw (Canada) Ltd., Mississauga, ON, hesitates to call it adaptive. “In process measurement using a touch probe or inline CMM is more along the lines of process control,” Williams says. “It’s about checking tool wear and managing temperature fluctuations that may affect part size. Adaptive machining is when the actual part program is automatically modified based on in-process measurement.”

In Renishaw’s definition of adaptive machining, a touch probe is used to validate part location and condition, and the resultant information is sent to some “really deep and very clever software.” This software analyzes part features to determine whether the NC program must be adjusted or “morphed” in to bring part dimensions into spec, or to compensate for certain material conditions. “Let’s say that a customer has an expensive casting, and they need to discover what state the workpiece is in before machining,” Williams explains. “For example, is there too much material, or is the casting warped or oriented incorrectly?. Those arequite complicated problems to deal with on a machine tool.”

That’s where NC-PerfectPart comes in. Metrology Software Products Ltd. (MSP), an associate company of Renishaw located in Northumberland, England, has developed a software program that assesses current part conditions based on data collected via a probing system, and then rotates or shifts the machine coordinate system to suit.

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Choosing wire EDM workholders


There comes a time when some chipmaking shops add wire EDMing to their repertoire. This is often done to reduce costs, because bringing what were once subcontracted, secondary EDMing operations in-house often makes good financial and logistical sense. It can also be due to demands from medical and aerospace customers, who ask their suppliers to control the entire manufacturing process under one roof. In either case, merging these disparate machining operations can be a workholding challenge.

Substantial differences exist between workholders for conventional CNC machines and those for wire EDMs, starting with the material. Pull a cast iron vise off a machining center and submerge it in a tank of deionized water dielectric and you’ll soon have a rusty mess. For this reason, virtually all EDM workholders are made from hardened 400 series stainless steel.

There are exceptions. For example, some high-end wire machines use oil dielectric, so it might be possible to use a conventional vise in these instances. However, dedicated EDM workholding is often a necessity due to machine considerations.

EDM tooling can seem like alien Tinker Toys to those familiar only with conventional machine tools. Much of the confusion about what to order can be avoided by understanding the terminology.

For example, reference elements are rails that mount on pedestals inside the EDM work area. Together with reference stops, they provide a zero point to locate fixtures and other workholding components. Chucks are available in pneumatic and manually actuated versions and accept pallets that in turn accept workpieces and fixtures. Mounting heads are used as the “middleman ” between the chuck and a vise or universal holder. Add to that a plethora of adapters, f rames, blocks and clamping heads, and a phone call to an EDM workholding expert might be in order.

Some of these experts work at System 3R USA LLC, Elk Grove Village, Ill. John Roskos, vice president of sales, said many shops ease into EDM workholding with a starter kit. For example, a basic system containing a vise, mounting head and adapter might cost $2,000, whereas a full-blown package with reference rails and pneumatic clamps could easily cost 10 times that amount.

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