Shop Solutions: Breathing New Life into Old CDCF Iron
The forte at Lakes Precision (Three Lakes, WI) is creep-feed grinding, specifically continuous dress creep feed (CDCF) grinding to precise tolerances of 0.0002–0.0005” (0.005–0.01-mm) with surface finishes of at least 8 Ra. Materials range from the very tough, including A2, M2, S7 tool steels to the odd lots of customer-requested aluminum and cold rolled steel.
Lakes Precision, which started some 25 years ago, currently occupies 25,000 ft2 (2322.5 m2) and runs two shifts, five days a week. CDCF technology is provided by three Mägerle and three Blohm creep-feed grinders from United Grinding Technologies (UGT; Miamisburg, OH). Several horizontal CNC machining centers, a couple of belt-driven vertical through-feed grinders, some surface grinding, and EDM machines round out Lakes’ machining capabilities. Lakes Precision’s core business is manufacturing perishable tooling for wire stripping and wire crimping (termination) machines. Its market is everywhere wire stripping or crimping is needed, including automotive, aerospace, “white goods,” electronics, and medical.
Creep-feed or profile/form grinding is a process that allows a high rate of stock removal in a single pass. This grinding technique is often applied to high-performance alloys or hardened materials. Each CDCF machine is capable of either single-pass or reciprocating processing, yielding extremely consistent tolerances to 0.0002" (0.005 mm).
Through-feed grinding is a flat production machining process using a belt-feed system. Parts in hardened or soft state are passed under a vertical spindle wheel at varying rates of speed and grinding pressure for precise stock removal. This process yields high production, single-pass flat grinding for, but not exclusive to, stampings, fine blanked parts, or bar stock material removal. Stock removal to 0.100" (2.5 mm) and ±0.0005" (0.01-mm) tolerances are possible for finished parts.
CDCF technology uses a constantly in-feeding rotary diamond dresser that dresses the wheel continuously during the grinding cycle at a pre-programmed infeed rate. The initial CDCF process relied on heavy dressing rates up to 40 mils/per wheel revolution (0.000040"/0.001 mm) that resulted in high wheel consumption, measured as G ratio (volume of material removed in cubic inch per volume of grinding wheel consumption in cubic inch).
Designed for high stock removal of difficult-to-grind material, CDCF provides productivity improvements of 20 times that of conventional grinding and EDM processes.
The unique element of CDCF is the rotary-driven dresser unit situated above the wheel, with a separate CNC axis dressing into the wheel simultaneous to the grinding process. This is controlled via special grinding macro programs to maintain programmed infeed dress rates at a constant rotation speed that is matched to an ever-changing wheel diameter.
“A typical part would start with material procurement, usually bar stock,” said Herb Stuckart, vice president, manufacturing. “We cut it, grind it, drill holes, tap and mill to bring the material to the required form.” A family of parts might include 25–50 different items, different radii, starting at 0.0005–0.500" (0/01–12.7-mm) diameter. Parts may be a 0.250" (6.3 mm) square, 0.00030" (0.008-mm) thick to 36" (914-mm) long. Lakes sends the parts out to heat treatment, and Quality Control releases them for manufacturing. The parts are run through the vertical through-feed grinders to grind flats, edges and ends and prepare the parts for the Mägerles or the Blohms. The profiles are then ground to size with repeatability from part to part and a finish of at least 8 Ra.
Lakes Precision purchased its first Mägerles around 1988 with the Blohms following shortly thereafter. It is something of an understatement to say these machines are “vintage.” But as these old machines start to experience too much downtime, they became candidates for retrofitting. The company felt the machines were mechanically sound and retrofitting the right old machine would be the smartest thing to do.
“We decided to retrofit our three Mägerles with new Siemens 840D controls,” said Stuckart. “These machines mechanically were very sound, because we meticulously maintained them for all that time, nearly 25 years, and we never abused them; if anything, we babied them,” said Stuckart. Because of the age of the electronics, Lakes simply couldn’t get parts to fix the controls, even if they knew what was wrong. They might get replacement parts, but the drives and things like that were just no longer available because of the changes in control technology.
“UGT’s Total Lifecycle Solutions Group came in and did an initial survey of everything on the three Mägerles before they even began the retrofits: all the geometrics, the tables, the runouts on the spindles, and they couldn’t find anything that couldn’t be tweaked in,” said Stuckart. The first retrofit took three weeks, while the other two took about two weeks, from the time the team walked into the plant until the time they walked out. This was great, because Stuckart was expecting a longer period of downtime, and that didn’t happen. “That in itself is something almost unheard of,” Stuckart said. “Since the retrofits, the machines have been running like new. The result has been amazing. We’ve had little or no downtime, which is unheard of because I used to have two to three machines down a week. If anyone were to ask me about doing a retrofit on an old yet sound machine, I would tell them to go ahead.”
Stuckart said that if he were to buy a new Mägerle today, decked out with everything he wanted, it would cost almost $1 million. For all three retrofits, he did not spend in excess of $250,000 apiece. “You can’t buy a creep-feed machine for $250,000 that’s rigid, reliable, repeatable with highly precise accuracy. Plus, you’ll not get the kind of support you get from a supplier like UGT.”
Lakes Precision’s operators have been very open to the new controls, because the Siemens 840D is very user-friendly. “They say the conversational control is simple to use; the programmed cycles make programming as easy as selecting items on a menu. Should they have a problem, they just call UGT, and UGT will have a solution in a very short time,” said Stuckart.
“The controls are highly intuitive: you see the picture, you know the diameter, you just plug in numbers, and you’re not guessing at different codes. Everything is right there on the screen for the operator see. The Siemens 840D conversational controls are so much easier and result in quicker setups and complete repeatability. I have one control now instead of three different controls. As a result, I can move my people to where I need them, the setups are all the same. There is no difference from one setup to another, and I don’t have an operator saying, ‘Gee, I don’t understand that code,” said Stuckart.
“It’s true, we have one eye on our core business and the other looking into new business opportunities that will flow well with our current processes, something that stays within the current scope of what we do. Jet engines and power generation, blades and vanes, fit nicely within the scope of what we do and the machines we have.”
When opportunity recently knocked on Lakes Precision’s door (in the form of increased demand for wire stripping and terminating tooling), Stuckart knew immediately that he needed additional creep-feed grinding technology. He carefully considered his options. Should he buy another Mägerle? a new Blohm? or retrofit/rebuild one of his vintage (circa 1988) Blohm machines?
When he looked at the new Blohm Profimat MT 408, he noted there were considerable changes in this Blohm as opposed to his vintage machines. For example, the new Profimat boasted a powerful 60-kW, 8000-rpm motor with a guaranteed maximum cutting speed of 170 m/s using conventional, continuous dress (CD) or in-process dress (IPD) as well as all CBN grinding methods.
“This new Blohm has a large horsepower motor, which is something I don’t have on my other machines. This gives me a new added advantage,” said Stuckart. “In the past, there were jobs I couldn’t do, because I didn’t have adequate horsepower. Now, even though I don’t often use it, I know the horsepower is there should I need it. I’m not limited in any way. We have looked at jobs that required the additional horsepower, but we backed away, knowing that if we tried to run the job on the older machines, the project would prove less than profitable. Now, we don’t hesitate.” ME
For more information from United Grinding Technologies, phone 937-847-1229, or go to www.grinding.com; for information from Lakes Precision, phone 715-546-3070, or go to
Gives Shop An Edge
Finding better, more efficient and more profitable ways to produce parts and keep a competitive advantage is a daily pursuit at successful shops. It’s no different at Task Force Tips (TFT; Valparaiso, IN), a company which makes multiple different size and design nozzles, valve bodies, and other components for fire suppression and water delivery equipment for the forestry, municipal, and industrial firefighting markets as well as for aircraft de-icing. As a result, TFT does many short runs of hundreds of different part designs.
Within its fully integrated production plant, about 98% of the work is done in-house by more than 200 employees. It is a very team-oriented workforce which is encouraged by President Stewart McMillan to think of better ways to do what they do. McMillan has recently invested in a range of automatic lathes from Index Corp. (Noblesville, IN) that create opportunities for programmers and operators to come up with better processes.
“Index created an opportunity for us that was life-changing for our company,” said McMillan. “We started with a C100 automatic lathe, then a C200, and we are getting another C200. Despite its designation as a lathe, these machines are producing parts you would think came off a machining center. There doesn’t seem to be a limit on what we can get them to do well. For us, the key advantages to the C-series machines are speed of cycles [cycle time] and speed of changeover. When you are a short-run shop—as we are with 500–1000 piece runs—changeover times become extremely important. The speed of the machine lets us do more with one machine—more production, more setups.”
“The Index machines have made a fundamental shift in how people think in the machining side of TFT,” said a TFT manufacturing engineer. “Even the biggest skeptics come over and marvel as it turns out the parts in times that we thought not possible with accuracies that we did not think possible. Our programmer has it set up so that at most we are changing three tools for any job that runs across it and we have made a ton of different parts now.
“We are very happy with it far beyond the production levels. There are so many features of the Siemens control that when tied to Esprit software, it became the easiest machine to set up of all our mill-turns. Our programmer has told us that when he looks at a part that he does not think will run faster on the Index machines, he ends up cutting the time in half. And when he sees a job that is well-suited, it cuts the time by as much as 70%,” the manufacturing engineer said.
“For example, one of our new products, a part from our world-beater G Force nozzle, prompted a move to the INDEX, taking the cycle time we had from 14 minutes per part to 6 minutes each—and we think we can get it to 4.5 minutes, thanks to the capability of the Index. From watching the machine run, I believe it’s because this machine hesitates less when thinking, and I know it’s also because the spindle sync/pickup and spindle acceleration in the cut-off cycle are significantly faster. I was not expecting to see such a difference in cycle time,” he said.
According to Index, many of the so-called Swiss machines working today are actually making fixed headstock-type parts in the 1 1/4" (38-mm) range. Although the Swiss-style machines are built to handle this bar size range, it is a misapplication of the Swiss-style sliding headstock technology, so Index developed the C series machines which offer greater tooling variety, high precision, more power, and faster processing speed, plus greater flexibility.
The C machines can be provided in either of two spindle sizes: 65 and 90-mm diameter bar capacity. The main and counter spindles each feature a maximum speed of 5000 rpm (4000 rpm on the 90-mm machine ). With three independent tool turrets, the C200 provides up to 42 driven tools to handle the increasing workpiece complexity, and two Y axes each with 100-mm travel allows TFT to achieve an enormous increase in productivity through an ideal division of machining tasks.
All tools in the three turrets are equipped with the Index W serration, an Index-patented improved VDI interface that is extremely accurate and repeatable. “We preset the tool offline. W-slots in the tool turret ensure repetitive accuracies of ±8 μm during setup even with angled tools and at a distance of up to 100 mm from the tool mounting device,” McMillan said.
The Index SingleSlide plate-type slide system has proven its effectiveness. The toolslide for X and Z movement consists of a single piece and doesn’t traverse the turrets on anti-friction guides, but on flat slideways. Tool carriers 1 and 2 slide on slideways that are firmly fastened to the machine bed. The virtually wear-free sliding pair consists of through-hardened steel toolplates (slideways) and coated sliding elements (tool carriers). An exact adjustment ensures zero backlash of the sliding pair.
This design combines the known advantages of slideways—such as good damping properties and high rigidity—with good acceleration and rapid traverse values, achieved until now only in machine tools based on linear slideways. The system also assures low heat transfer and high accuracy of the machine. Because of the low masses to be moved, accelerations of up to 1 G can be obtained. “The rigidity of the machine due to this design is outstanding,” McMillan said.
High working travel of up to 50 m/min guarantees low nonproductive times and thus further reduction of cycle times. The vertical machine bed allows a free chip fall and is provided with completely enclosed guards with height-adjustable operating panel.
From the viewpoint of training, operating and setup, this machine is immeasurably better, McMillan said. There are several conditions which must be met before the machine allows a cycle to begin. Before, on other machines, this meant a machine would sit and the operator would have to figure out why. Now, the Index machine not only informs the operator what is wrong, it offers to fix the problem(s). Beyond that, navigation and operation of the control are much simpler and straightforward.
TFT has been able to eliminate all of its hex stock, because it can be milled so quickly with the Index machines. “We used to buy different size materials for all our parts, now it is down to three,” McMillan said. “The amount of chips coming off the smaller sizes is so minimal, the cost of the chips is more than made up for by the dramatically reduced cycle times on each part. We group the parts by the stock size. And the Index MBL bar feeder is like nothing else in the industry. We can run full 12' [3.7-m] bars up to 2.5" [63.5 mm] at the full 4000 rpm with practically zero vibration.”
A great example of how the Index C machine saved time and material is on a part for an automatic nozzle for which TFT had been buying extruded stock.
“Our B580 nozzle part had been made for about 38 years from a soft extrusion with fins which we had to inventory. One day one of our operators, after seeing what the Index could do, suggested making the part out of bar stock, fins and all. It sounded like a crazy idea, but it was crazy like a fox. We now make the part from solid, less expensive bar stock—the whole part, including putting points on the end of the fins for water flow, taking cycle time down to 35% of what is used to take machining extruded stock. And now it is a stronger part as well,” McMillan said.
Summing up why TFT has invested in what seemed like an expensive line of machine tools, McMillan said, “The more sophisticated the equipment, the more important the people become because it is the creativity of the people that is going to make the machines do things that other people cannot or will not do.” ME
For more information from Index Corp., go to www.index-traub.com, or phone 317-770-6300.
Controls Machine Motion
Wepco Plastics (Middlefield, CT) specializes in short-run prototype injection molds in aluminum and steel. Established in 1985, the company has grown to include more than 45 employees who work at its 10,000 ft2 (929-m2) facility. In the fall of 2008, Wally and David Parmelee, Wepco owners, found themselves at a crossroads in terms of milling capacity for their toolroom. Should they continue with their current milling technology (a known quantity with zero learning curve) or invest in the future by purchasing a higher performance machine? They knew this decision would impact their tooling and in-house molding business for many years to come.
Introducing new technology to a shop always presents a learning curve, which is an inherent risk, but new technology can also promote growth. For Wepco, the reward of reduced cycle times and increased productivity, which enabled them to book more jobs per week without sacrificing quality, was worth the risk. When Wally and David decided to break stride with their current equipment and purchased a Hurco VMX30 machining center from Brooks Associates (Norwell, MA), four factors were paramount to their decision-making process: a control with an open architecture, mechanical design, local service, and customer references.
As Wally and David evaluated control technology, they realized the importance of investing in a control with an open-architecture, because it is more likely to be compatible with future technology. The integrated Hurco control has a Windows-based operating system, which means they can easily add automation products in the future if their business warrants it. In addition, Wally and David understood the value of an integrated control that is specifically designed to work with the machine tool’s motion control system. Not only does it enhance performance, but it makes service a one stop proposition. Control features with measurable benefits, such as Hurco’s proprietary advanced motion control, were also important.
Hurco’s new motion control system called UltiMotion utilizes the power of software for motion control instead of relying on hardware. The secret to UltiMotion is the advanced trajectory algorithm in the software that generates significantly faster yet smoother motion than any hardware only solution. While there are numerous technical details, some of the straightforward results include cornering velocity that is 2.5 times faster than conventional motion, 50% less machine jerk, and a patented dynamic variable lookahead mechanism that doesn’t require a fixed number of blocks. Instead, the control evaluates the geometry and motion profile and makes sure there is enough lookahead information to make optimized maneuvers. This lookahead mechanism of UltiMotion is another reason why better surface quality can be obtained in a shorter period of time.
Mechanical design of the machining center is obviously important to any shop owner. Standard specifications, such as travels and rapids, are easy to compare from one machine tool builder to the next, but sometimes it’s harder to evaluate “what’s under the hood.” The design of the Hurco VMX30 incorporated into Hurco’s manufacturing process promotes rigidity and reliability. The linear rails are larger, and strategically spaced for increased strength. Also, Hurco wedge locks the rails to a machined shoulder instead of simply mounting them to a single surface, making the machine more robust. The double-nut, pre-tensioned ballscrews are anchored at both ends for increased accuracy and rigidity. A dual-wound 12,000-rpm spindle delivers the cutting power they need.
Local support and service are important for any purchase, but it’s critical to have reliable service people you trust when you have a small business. Brooks Associates, which has been a Hurco distributor for more than 30 years, has placed thousands of units throughout New England. And nothing can replace first-hand positive feedback from actual customers.
Since Brooks has so much experience in the region, they have numerous customers who are happy to talk to other machinists about their positive experiences with the Hurco machines.
The decision to move forward and invest in new technology proved advantageous for Wepco, which primarily focuses on aluminum molds for prototype and short-run batches. The Hurco VMX30 delivered superior performance and part quality in a fraction of normal cycle times. The dual-wound 12,000-rpm spindle of the Hurco VMX30, coupled with UltiMotion, dramatically reduced total part cycle time by as much as 200–300% in some cases with no loss of accuracy or finish. Before UltiMotion, Wepco would finish machine at 40 ipm (1 m/min). With UltiMotion, they are able finish machine at rates from 125 to 350 ipm (3.2–8.9 m/min).
And David believes that productivity will just get better. “We have really started to focus on pushing the machines to see what they can really do, and I have to tell you that every day we do something that just blows us away. With the UltiMotion [Soft motion] along with tweaking our post to make segmented or linear moves, we are achieving extremely high feed rates up to 800 ipm [20 m/min]. As an example, we had a cut that would have been at least 100 hours long on our old machines that we did in 30 hours and I believe that we could even cut that in half. We finish cut the cores with a 0.0469" [1.2-mm] end mill ground back 0.500" [12.7 mm] at 100 ipm [2.5 m/min]. We could have easily doubled the speed and gotten the same results, and I don’t have to polish the mold. The finish is that good," said David.
These productivity gains have yielded increased profit margin for existing jobs and additional capacity due to increased throughput. For example, a 30% productivity gain turns a 40-hour work week into a 52-hour week in terms of throughput with zero overtime for labor and zero increase in debt service on the equipment.
The Hurco VMX30 also offered opportunities for Wepco to expand its capabilities. For example, due to the rigidity and spindle speed of the VMX30, the shop can do hard milling on inserts. Wepco routinely machines RC58 mold inserts made from S7 tool steel. Parts come off the machine ready for assembly in the mold. Success with this type of material is due to advanced cutter technology and the Hurco UltiMotion software, which optimizes machining rep and feed rates based on part geometry. UltiMotion routinely reduces cycle times on 3D programs by as much as 40%.
Wepco was so encouraged by the productivity of the VMX30 that they added a second Hurco VMC shortly thereafter (Hurco VMX24). Both machines have proven to be reliable sources of production for Wepco’s toolroom as they continue to grow. Wepco attributes this growth to attention to detail and quality, as well as customer satisfaction by diligently following specifications, meeting delivery dates and offering competitive prices on short run injection molding. ME
For more information from Hurco Companies Inc., go to www.hurco.com, or phone 800-634-2416; for information from Brooks Associates, go to www.brooksmachinery.com,
or phone 781-871-3400.
This article was first published in the April 2013 edition of Manufacturing Engineering magazine. Click here for PDF.