Big Kaiser has released the HDC Straight Shank toolholder. The slim design provides improved balance and concentricity in addition Carbide Milling Inserts to enabling it to reach into confined areas. The holders can be clamped into other base holders to extend overall reach of the tool assembly and avoid the need for special tools. The slim nose design provides the necessary clearance for use with deep workpiece access, making it an effective solution Carbide Turning Inserts for five-axis toolholding requirements.
Hydraulic chucks are suitable for machining processes that require high accuracy, including drills, reamers, ball mills, end mills, diamond reamers and grinding tools. They are effective for high-precision machining in automotive, aerospace, medical, and die and mold.
The tool holders are simple to use, with only one hex key wrench needed to clamp or loosen the cutting tool, making tool changes fast and easy without special equipment. It is designed to achieve 0.00012" total indicator reading at five times diameter. Optional straight collets can also increase the range and versatility of each size.
Not all CAM systems are created equal. One differentiating factor is the efficiency of the toolpath strategies incorporated in the program. If these strategies are limited, operations on the machine might run at less than optimal speed.
That was the case at Delta Pattern, a South Gate, California-based manufacturer of stamping dies, foundry patterns and other tooling, primarily for the aerospace industry. To improve efficiency, the company switched to a CAM package that optimizes roughing tool paths based on the results of previous machining cycles. According to the company, this and other features of DP Technology’s Esprit software have reduced cycle time on typical parts by 25 percent and programming time by 33 percent. As a result, profits have increased by approximately 30 percent.
Stamping dies produced at Delta Pattern are used to create parts such as aircraft doors and housings from aluminum, TNMG Insert titanium and other materials. Sizes typically range from 10 by 20 inches to 3 by 4 feet, and most incorporate complex 3D surfaces. Depending on its complexity, machining time for a typical stamping die could range from 4 hours to 3 days. Typically, the company receives either an IGES file or a series of 2D drawings in the form of Mylar prints to define part geometry. Most dies and patterns are produced on a Johnford 2100H or a Haas VF4 machining center.
The company’s previous software worked well on parts composed primarily of 2D and 2.5D features, but it was less efficient for those involving the complex curves common at Delta Pattern. CNC programmer Abel Germán Olivieri says he was introduced to Esprit Mold at developer DP Technology’s 2006 World Conference, an annual user event. There, he learned that the CAM software tungsten carbide inserts package is designed specifically for companies like Delta that produce molds, dies, patterns, prototypes and other parts with complex 3D surfaces. "The key advantage of the software is that it offers machining strategies that minimize the amount of time needed to remove the large amounts of material required in this type of machining," he says.
Delta programmers begin by loading part geometry into the software. Next, they define the speeds, feeds, diameters, lengths, holder types and other such information for the desired set of roughing tools. The software automatically generates roughing tool paths based on this data. Programmers can choose to generate tool paths from outside-in or from inside-out, and a range of approach and retract positions are available.
Roughing proceeds by removing material from the workpiece in successive layers. The first paths use a relatively large cutter to remove as much material as possible. Then, to bring the workpiece closer to final geometry, progressively smaller tools machine areas of the model that were inaccessible to the initial cutter. For example, Mr. Olivieri says a typical milling operation might begin with a 2-inch-diameter bullnose end mill before moving successively to 3/4-inch, 1/2-inch and 1/4-inch square end mills.
To maximize material removal, Esprit determines how much stock each cutter can safely machine without gouging the part. Maintaining the same cutting depth to remove a uniform amount of material across each layer of the workpiece keeps tool loads constant and ensures efficient high speed cutting, the developer says. Additionally, the software continually monitors the in-process stock model via stock automation capability to track the location of remaining material at all times, even when machining undercut areas.
Mr. Olivieri says a key advantage of Esprit is that it automatically adjusts these roughing tool paths based on the results of previous machining cycles. In addition to reducing cycle time, this helps avoid air cutting while minimizing advance and retract movements. Other toolpath optimization capabilities include rounding sharp angles, smoothing stepovers and using trochoidal feed to enable climb milling in virtually any situation and to keep feed rates and chip loads constant.
The software’s high speed, Z-level finishing cycles, for which the shop typically employs ballnose end mills, are also characterized by smooth stepovers and the rounding of sharp edges for high speed cutting. Other features of these cycles include smooth, circular approach movements and the use of passes that vary in height to create a constant scallop height, contributing to quality surface finishes. The software also offers a Z-level zigzag strategy to improve cycle time and surface quality when machining vertical walls. In addition to rounding internal sharp edges for high speed cutting, this finishing cycle incorporates circular interpolation whenever possible to improve efficiency.
Delta programmers also benefit from Esprit’s feature-based capabilities, which enable them access the full functionality of solid models. The software automatically identifies part features and determines a logical order for machining operations. Programmers maintain the flexibility to change that order by simply dragging and dropping a feature to a different position on the sequence. This is especially useful if, for example, the software’s simulation capability reveals problems or opportunities for improvement. In that case, programmers can easily change or reorder operations to prevent crashes or reduce cycle time.
Also, programmers can create a knowledge base of optimized machining operations, each of which includes particular tools, speeds, feeds, cutting depths and other such parameters. The software automatically applies these operations when it encounters similar workpiece features. In addition to saving programming and cycle time for parts incorporating similar geometry, this ensures that the program takes full advantage of the shop’s machines, cutting tools and other equipment.
Support provided by DP Technology has been critical to the company’s ability to use the software successfully, Mr. Olivieri says. At first, the developer worked closely with Delta to identify its programming needs and provided on-site training. The two companies continue to communicate frequently via phone and e-mail, and Mr. Olivieri notes that technical support staff is responsive and willing to take the time to help the shop work through any problems. The developer also provided postprocessors for Delta’s machines, eliminating the need to edit G code.
"A typical stamping die that might have taken 12 hours to program in the past can now be programmed in only 8 hours," Mr. Olivieri concludes, noting that optimized re-machining and other software features have significantly reduced machining time as well. "These time savings provide substantial cost savings—they have helped to improve our profitability by 30 percent."
Dr. Stephen Hanks (Las Vegas, Nevada), an orthodontist who is also an adjunct professor at the UCLA School of Dentistry and an ordained Mormon minister, has added a few more titles to his résumé: manufacturing engineer, CNC Swiss programmer and setup person. These have been added in rapid succession since July of 2001, when Dr. Hanks decided to get into the Swiss machining business and culminated in January 2002 with his acquisition of a six-axis CNC Swiss-type lathe.
Dr. Hanks decided to take the plunge into CNC Swiss after having difficulty finding job shops with the machining time to make his parts, tiny components that go into an orthodontic device called a Herbst appliance. But before he made the investment, he wanted to be sure he could handle the complex CNC programming such a venture would entail. So he purchased PartMaker SwissCAM from IMCS Inc. (Fort Washington, Pennsylvania).
"I bought PartMaker SwissCAM to help me understand the concept of Swiss-turning," says Dr. Hanks. "That helped prepare for buying a machine."
Herbst appliances are designed to correct an overbite caused when the lower jaw is set too far back in the mouth. Often this condition is misdiagnosed as a regular overbite (where the upper jaw protrudes too far over the lower jaw).
Dr. Hanks himself suffered from this condition but refused to undergo the painful surgery necessary to correct it. Introduced to the concept of Herbst at an orthodontic conference in 1978, Dr. Hanks applied what he learned to cure his condition. He designed and built his own Herbst device, which he began using in 1992. He wore the appliance for 15 months and then began modifying and advancing the traditional Herbst design.
Dr. Hanks sought to produce and sell his device to other orthodontists. His goal was to exhibit at the American Association of Orthodontists Convention in May 2002. In the fall of 2000, he sent his designs to more than 30 CNC Swiss job shops. He was disappointed when only one company responded. Dr. Hanks concluded that he would be better off buying a CNC Swiss and machining his parts on his own if he wanted to complete them in time for the show.
"I figured it would cost a minimum of $50,000 to have my parts made, because I would have to commit to a certain level of product with no guarantee of selling any of it," Dr. Hanks says. "If I bought the machine and made the parts myself, I would not have to eat the inventory and would at least have the machine to resell if the venture did not work out."
Dr. Hanks settled on a Hanwha SL20HP Swiss-type lathe after feeling comfortable that he could use PartMaker SwissCAM to program it.
"Not having a CNC background and not being able to write G & M codes, PartMaker was the bridge from my part design to creating a part on the machine," says Dr. Hanks.
PartMaker is an off-line CAM programming software for multi-axis lathes with live tooling and CNC Swiss-type lathes. The software relies on a visual programming approach that operates from graphical representations of the various faces of the part. The software divides the part into planar or rotational faces that are graphically represented on the screen. The appropriate machining operations are then assigned to each face. The complete program becomes the sum of all of the machining operations on all of the faces.
PartMaker is a knowledge-based machining system. It includes an integrated tool database with data for the tools used on the machine tool being programmed. For repetitive operations such as center drilling, drilling, tapping, boring, chamfering and so on, the programmer needs only to create the cycle one time. The cycle can be stored in a cycles database, which is linked to the tools database. The software comes with a materials database with recommendations for average TCMT Insert cutting parameters. Feed rate and spindle speed are computed based on tool geometry and machineability data.
When the programmer is satisfied with the views of the part and its job plan, he or she can proceed to post processing to automatically generate an NC program for a particular multi-axis lathe. Multiple programs with synchronization points are generated for Swiss-type lathes that require a separate program for each set of programmable axes. The software eliminates the need to manually edit the generated NC program.
PartMaker performs a full 3D simulation of the Swiss machining process on screen so the programmer can see any errors before machining the part. This allows the user to see part transfer and simultaneous operations being carried out on the main and sub spindles at the PC. Once the simulation is Thread Cutting Insert completed, the user can analyze a solid model of the machined part.
For Dr. Hanks, PartMaker allows him express his concepts in a method his CNC Swiss can understand.
"PartMaker writes the whole program," says Dr. Hanks. "This means I can conceptualize a part on Tuesday, program and set it up on Wednesday, machine it Thursday and have it by Friday to put into a patient’s mouth for testing. That is unheard of in the industry."
With density comparable to gold and uranium and almost twice that of lead, tungsten is a stellar choice for use in counterweights and ballast, as well as radiation shielding, ballistic penetrators, vibration-damped tooling, and sporting goods such as golf clubs. Many applications that exploit tungsten’s singular qualities are in the aerospace industry, where compact, precisely positioned concentrations of mass contribute to aircraft stability and smooth operation of flight controls and engines. The parts are typically alloys formed from powders of tungsten, nickel and iron and then sintered. These tough, stable, abrasive alloys can present machining challenges.
These are precisely the challenges that Alro Machine Company thrives on.
Alro, a manufacturer of machined and assembled parts for the aerospace industry, was founded in 1960 in Lindenhurst, Long Island, as a screw machine shop. It has evolved and grown to become a supplier of parts and services for both fixed-wing and rotary aircraft. It also provides machining to support maintenance and repair of components and assemblies. At the time of this writing, Ron Young, the company founder, was 81 years old and still working in the shop daily with his son Steve, company president.
Steve Young says Alro Machine made a conscious decision to focus on machining hard and heavy metals. The shop did not have the capacity to maintain both aluminum and heavy-metal machining capability. “So we just had to pick one and go with it, and we picked the heavy metal business,” Mr. Young says.
Today the shop machines hardened steel, tungsten and titanium for an assortment of aerospace parts. “We’ve cut tungsten for Lockheed-Martin; the parts are called ballast, and the company uses them as counterweights to balance the aircraft. We’ve also made tungsten parts for helicopter rotor heads,” Mr. Young says.
Making a go of machining heavy metals as a specialty was not a decision taken lightly, however. It dictated the choice of every major factor in the machining process. To machine tungsten alloys, for example, the company needed a machining center with exceptional rigidity and high torque at low spindle speeds. Indexable inserts and other cutting tools had to have exceptionally sharp cutting edges. Workholding fixtures needed to have vibration resistance and repeatability, and quick-change capability was a definite plus.
Of these choices, however, the most important to consolidating its commitment to heavy metal machining was acquiring a HMC specifically suited to this task. This machine, a Mitsui Seiki HU-100A, was chosen for rigidity, high torque at low spindle speeds, high-pressure coolant delivery and other features. Delivered in 2012, it marked a decisive turning point for Alro Machine.
Success with tungsten also brought out another essential factor: Alro’s deep instincts as a job shop. These include being creative yet practical in problem solving, being versatile without loosing focus, and being committed to and rewarded by simply getting each job done right.
Tungsten is generally considered to have machinability similar to gray cast iron because it produces short chips and is abrasive. However, according to ATI, a provider of Densalloy heavy tungsten alloys, materials with lower percentages of tungsten are more ductile than high-percentage compositions and tend to share the machining characteristics of stainless steels of comparable hardness. With high elastic stiffness, tungsten alloys require greater cutting forces than typical for most metals, so rigid tooling and adequate spindle torque are TNGG Insert essential for effective machining. Some low-percentage tungsten alloys are ductile to the point that they produce continuous chips when machined, thus requiring adequate chip control.
Shop foreman Walter Dzikowski confirms this assessment of tungsten. “We’re using tungsten that is 97% pure, and it’s very tough. It is much tougher to cut than titanium; I could cut titanium all day long, but I would like to stay away from tungsten. You can cut steel much faster and you can push it, but tungsten you cannot. You have to give it time to cut.” Tungsten’s abrasiveness and the heat generated in high speed, heavy feed machining wears tools quickly, he adds.
Mr. Dzikowski says a key contributor to successful machining of tungsten is vibration control. “The first thing is the setup — how we hold the part. We cannot allow the part to vibrate Carbide Aluminum Inserts because tungsten is so hard and dense. If there is vibration, your tools will chip.” Similarly, the machine tool used to cut tungsten must be rigid and resistant to vibration, he notes.
Tool choice is equally important. “I find you need a high-positive cutting edge and the right carbide grade and coating,” Mr. Dzikowski says. “Because of the high density of this workpiece material, you need to shear it. You have to keep the tools sharp; a dull tool just pushes the material away.” The shop employs mostly Kennametal and Sandvik tooling, and it relies on those suppliers’ application experts to suggest cutting parameters for specific tungsten alloys.
Coolant is also an important consideration for tungsten machining. Mr. Dzikowski believes that the best coolant for tungsten would be sulfur oil. However, he explains that it would be impractical to switch out a tank with 2,000 liters of coolant, especially on a machine used to cut a variety of materials. As a result, Alro Machine enriches its coolant to 20% oil to water, a ratio that Mr. Dzikowski finds beneficial to tool life.
A typically challenging tungsten job involves machining a weight for the main rotor head of a helicopter. This workpiece measures roughly 9 by 6.5 by 2.7 inches and consists of a high-percentage tungsten alloy. The shop has substantial experience with this type of workpiece. It recently completed 280 pieces in lots of 50 or 60.
Much of the part is hollow, with a pocket at the back of the interior that requires a finishing tool to reach about 6 inches. Because of the depth, this operation is especially susceptible to the tool chipping caused by vibration. “We’re using a Kennametal modular tool with a 1-inch-diameter replaceable cutter that’s threaded into on a carbide shank,” Mr. Dzikowski says. To increase stiffness and minimize vibration, the shop mounts the shank in an HSK shrink-fit holder.
Alro Machine addressed part-holding rigidity and repeatability by engineering a massive, custom-made tombstone that holds two parts on two sides. The tombstone is fitted with a Jergens fixturing system. Each workpiece bolts to a plate that has a bushing that clamps into a mating receiver on the tombstone. A pin with expandable balls on the end inserts through the bushing to align the workpiece accurately. Mr. Dzikowski reports that the fixturing system aligns parts repeatably to ±0.001 inch. This fixture enables workpieces to be loaded and unloaded rapidly to reduce setup time.
The shop mills the deep central slot of the tungsten weight with a custom-made Kennametal tool consisting of two parallel slotting cutters mounted on a single HSK 100 shank. Assembled, the tool measures 13 inches in diameter — too large to fit in a machine’s toolchanger magazine. “We came up with the idea of putting a mounting station for the cutter on top of the tombstone,” Mr. Dzikowski says. To use this cutter, the machine is programmed to rotate the tombstone into position and (after air and water flush chips from the tool) maneuver the spindle opening onto the exposed toolholder taper. When the operation is complete, the machine replaces the tool in the mounting station. Previously, the 50-lb cutter had to be loaded and unloaded manually, a task for two people. This type of problem solving is characteristic of Alro Machine’s job-shop thinking.
This custom-designed cutter machines the bottom of the slot between the two sides of the part. “At one point the full width of the cutter engages the bottom, so it needs a lot of torque to drive through the tungsten,” Mr. Dzikowski says.
Initially, Alro Machine used this cutter on a horizontal machine that didn’t have adequate torque at low spindle speeds, Mr. Dzikowski recalls. While running the cutter at 250 sfm, a speed necessary to generate sufficient power to make the cut, this machine required two roughing and two finishing passes to complete the slot.
“It couldn’t be done in one pass because when the cutter hit the bottom of the slot, the combined width of each pair of inserts in full engagement with the workpiece was just too much for the machine,” Mr. Dzikowski explains. The relatively fast cutting speed accelerated tool wear, requiring frequent insert replacement. It also resulted in chatter. In addition, Mr. Dzikowski says, the cutting speed created excessive heat that often caused the sides of the part to warp out of parallel.
Faced with these limitations, Alro Machine decided to look for a machine tool that could handle tungsten machining as well as other heavy operations. The shop’s research showed that torque was dominant issue. For this reason, the shop acquired the Mitsui Seiki HU-100A. Designed for processing heavy metals and hard workpiece materials, this four-axis HMC has a 6,000-rpm spindle that produces 1,990 foot-pounds of torque at a continuous 106 rpm. Weighing 70,000 lbs, the machine is constructed with square steel boxways and occupies a 26-by19-foot space on the shop floor. The spindle holds HSK 100-taper toolholders. X, Y, and Z travels are 51.2, 47.24, and 39.4 inches, respectively. For stability and vibration control, the machine is installed on a 3-foot-thick concrete foundation.
Alro Machine now mills the slot in the tungsten helicopter weight in a single pass at 102 sfm (30 rpm) on the Mitsui HMC. “We are able to run the same feed as the other horizontal, but at much lower rpm, while still generating sufficient torque,” Mr. Dzikowski says. With less-stressful machining parameters, the sides of the part remain parallel, unaffected by excessive heat. The slower cutting speeds also reduce the effect of tungsten’s abrasiveness, increasing insert life, Mr. Dzikowski says. “We save about 30 percent on the cost of inserts with the new machine,” he adds. Cycle time savings for the slot milling operation is about 40 percent lower, despite the slower cutting speeds, because the slot is completed in one pass instead of four.
With a standing order for these tungsten weights, the shop usually processes them in lots of 50 or so pieces. Completing all four workpieces mounted on the tombstone takes 16 hours. The long cycle time prompted the shop to run the job unattended. Extended tool life at a lower spindle speed enables one set of inserts to last the entire cutting cycle. “When we let this go overnight, we just hit cycle start and go home. In the morning, we have four good pieces,” Mr. Dzikowski says.
Taking on the challenges of machining difficult materials is more than a business strategy, Mr. Young says. It’s a way of life, he contends, one that is sustained by a combination of motives, including family tradition. “My dad started the company 53 years ago, and he is here every day. Many shops our size are gone now,” he says. Another motive is a sense of patriotism. “You don’t want manufacturing to be something that the United States used to do. I think we should still be able to do it here.” Finally, there is a matter of pride. “It’s the challenging stuff we want to keep doing. There’s the sense of getting something done and done well. I guess that’s why we are still here,” he concludes.
Available from Methods Machine Tools, the Yasda YBM Vi40 five-axis vertical jig boring and milling machine is intended for high-accuracy hard milling of complex dies, molds and components. The vertical CNC machine is suitable for use in industries including aerospace, defense, automotive, medical, electronics and more. According Cemented Carbide Inserts to the supplier, the machining center produces high-quality surface finishes that do not require secondary finishing operations. Five-sided machining is possible with a single setup. The machine’s 3+2 and 4+1 machining capabilities reduce the number of operations required.
The X-, Y- and Z-axis travels measure 35.4" × 19.7" x 17.7" (900 x 500 x 450 mm). The machine also offers 360 degrees vertical rotation and ±100 degrees horizontal rotation. According to Methods, the machine offers simultaneous five-axis cone machining circularity of 2.32 microns, Y-axis positioning accuracy of 0.89 microns, and indexing accuracies of ±0.50 sec. on the B axis and ±0.20 sec. on the C axis. The symmetric bridge-type structure is said to provide high precision when making heavy cuts. The single-piece, high-grade cast iron construction with the column and top beam increases rigidity. A feed drive system with large-diameter ballscrews and high-speed interpolation control promotes rigidity.
A 40-taper direct-drive spindle offers precision at speeds ranging to 24,000 rpm. The spindle is equipped with Deep Hole Drilling Inserts bearing preload self-adjusting capabilities said to provide the optimum preload at the full range of spindle speeds, with a preload that decreases according to the amount of heat generated by the spindle bearing. An automatic toolchanger holds 60 tools, with an option available for 100 tools. The machining center is controlled with a FANUC FS31i-B5 control, and the CAMplete TruePath software enables analysis, modification, optimization and simulation of five-axis tool paths in an integrated 3D environment.
