This Swiss shop discovered workholding collets that satisfy the needs of its very small, delicate and complex medical parts production on the subspindle, making once impossible processes not only doable but more efficient and esthetically pleasing.
Workholding, particularly for backworking operations, can be tricky when machining very small parts in a CNC Swiss-type lathe. Depending on their design, pickoff collets can produce a variety of problems, including poor concentricity and runout as well as poor control of clamping force, causing part damage. That is why when Dan Fifer, owner of Lane4 Precision (Santa Rosa, California) discovered collets that worked well for his applications, he became a dedicated customer of the manufacturer and trusted the company’s workholding system with his most delicate and complex parts.
In addition, Fifer says the Microconic collets enable fine adjustment of the collet tension on complex parts. These collets enabled the shop to machine parts it was formerly unable to create with other collets, as well as frequently and effectively perform backworking operations.
From Designer to Job Shop in 1 Month
Although he quickly learned about the workholding necessary to machine his customers’ parts most efficiently, Fifer did not initially have experience with CNC Swiss-type machining. In fact, when he opened Lane4 Precision in 2017, he had never stood in front of a CNC machine control panel before, let alone a CNC Swiss-type lathe. His background was rooted in design/product development for the medical device industry. After working for several startups for over 20 years, he says he was anxious to be the one to create the parts instead of designing them.
So, he took his passion for innovation and rented a warehouse space where he decided to do all the machining processes in-house. He says someone told him he needed a screw machine to do the work he wanted to accomplish. The timing was good for him to attend IMTS 2016 to shop for a machine tool, and that’s where he met Spinetti Machinery, a distributor that sells Marubeni Citizen-Cincom Swiss-types. He was impressed with the machines’ predictability, and he was confident that the Spinetti team would support him and help him learn how to operate his first Swiss-type, a Citizen L20.
Once this sophisticated machine was set up, an industry colleague asked Fifer if he thought he could make a part that had already been designed. His colleague said no one could build it for him, not because it was not able to be done, but because the colleague did not want to wait 12 weeks to have the order complete.
“I said, well, I have nothing else to do, so I will figure it out,” Fifer says. “So, basically, within a month I was absolutely swamped from a team of about six engineers feeding me more parts that I was able to do.”
With Spinetti’s assistance, he has since selected four more of the Citizen Swiss lathes with different work envelopes and capabilities such as a live B-axis, automatic toolchanger and the machine tool builder’s low frequency vibration technology that helps create small, easily evacuated chips. The distributor was also responsible for introducing Fifer to the Microconic workholding system. A very small part on an L12 was the first job he ran with the workholding system.
Extended Nose Without Extension
Three-quarters of the machining done at Lane4 Precision, which is mostly a prototype shop, is for the medical industry, and the rest are premium parts for the semiconductor, defense, aerospace and consumer products industries, according to Fifer. Parts range in size from fitting within a work envelope of a grain of rice (length or diameter of a half a millimeter or so) to long slender parts over two feet long.
Quickly moving from a designer to a job shop, Fifer never has put his eye for design on the back burner. He considers his niche to be that of helping his customers with design when appropriate. For instance, if he understands a more efficient way to machine something, he volunteers his expertise. “If I can see their design intent, I might say, ‘By the way, you can chamfer this edge, and it won’t cost you anything because I already have the tool’,” he explains. “They might have had two parts I was making that they were welding together.”
Because some parts produced by the shop contain thin walls and have short pickoff lands, it was critical that the workholding system installed offer acceptable tool clearances and fine adjustability for subspindle backworking. The shop also needed compact and reliable over-grip collets for the most complex applications (more about that later). Fifer found his expectations met and then some after installing the Microconic workholding system. In fact, he was so pleased that he eventually added it to all five of his Swiss-types.
Masa Tool, which only specializes in subspindle collet workholding, has designed the Microconic workholding system which consists of cartridges that are installed in a machine like a standard collet. The cartridge, which offers 0.0002-inch TIR, can be used as a gage to verify machine spindle accuracy. Also, the adjustment dial wrench offers precise and repeatable control of the clamping force, according to the company. Because the cartridge is built with an extended nose, extended nose collets are not necessary, making this system well-suited for Lane4 Precision considering most of its applications require an extended nose pickoff collet. Fifer explains that the Masa collet closure mechanism has been moved right up to the collet nose, improving rigidity relative to standard extended nose collets.
All Masa collets fit into the machine’s cartridge or an adaptor sleeve from the company, making it easy for Fifer to change back and forth between collet styles on all his lathes.
He also points out that it usually takes only 5 minutes when changing over his lathes from machining “large” parts (which for Lane4 are those that are a half-inch diameter and larger) to machining smaller parts when using the Microconic collets. According to Masa, the changeover from a 16C to a 5C collet usually results in a tolerance accumulation and can sometimes take more than 15 minutes to change the collets. But, with the Masa system, once the cartridge is in place, collets can be quickly installed and clamping pressure set right at the spindle nose without tolerance stackup in less than a minute.
Fifer also appreciates Masa’s over-grip collets for parts that require those. He explains that, although these collets are compact, they offer a large opening and rigid holding. He says they outperform any alternatives he has tried in the past. “My cycle times, rigidity, tooling, everything is better,” he says. “They took away the fear of doing over-grip parts.”
However, the over-grip collets open up to 0.156-inch diameter larger than the holding diameter. According to Masa, these collets are still capable of 0.0002 inch of TIR. With such reliable gripping, Lane4 Precision has been able to expand its capabilities, even machining some intricate parts “backward,” providing higher quality parts, with fewer defects and a lower scrap rate, enabling operation without interruption.
While learning the ins and outs of the Microconic system, Fifer says he realized how much confidence the workholding system’s design has given him to complete high-quality and miniature parts for his customers.For example, he appreciates that the collet nose is not chamfered. This design leaves more room for pickoff, he explains. “I used to have to face the collet before I could use it, so I could know what I was dealing with. But then it would alter the length of the collet.”
The advantages of excellent runout on the workholding system is another realization Fifer came to after he started putting it to use. It is possible to put very fine features on the backside of a part and maintain concentricity while also producing a “pretty” part. “If you have a 0.005-inch wall and you are trying to put 0.001-inch edge break on it, and you’ve got 0.001 inch of runout, the result is a really ugly part,” Fifer explains. “Using a Masa Microconic collet is like firm footing from the subspindle. At least you know you are starting in a good place for the most critical applications.”
To avoid crushing and ruining parts, Swiss precision manufacturer Micro-Matics turned to Masa Tool’s Microconic collet and cartridge system.
Since 1973, Micro-Matics of Fridley, MN, has been manufacturing CNC Swiss precision screw machine products including many kinds of contacts & pins, ground shafts, hardened bushings, rivets, screws, spacers and other custom parts for the medical, dental, aerospace, commercial, defense, computer, telecommunications and automotive industries.
According to Jason Wobig, Operations Manager, "Micro-Matics is primarily an aerospace and medical components, Swiss machining job shop. We make components that are thousandths of an inch up to an 1-1/4" in diameter. We started out with the old manual style, Cam driven Swiss machines and we're one of the largest Escomatic shops in the Midwest. And as the company's grown and evolved, we've turned into Swiss job shop, mostly Citizen machines like the M16, a L12, and a M32, as well as a few Star and Tsugami machines that give us a wide variety of capabilities."
A while back Micro-Matics was running a small medical part, a catheter part, that they were struggling with.
They had some custom collets made for pickoff and, according to Dave Thayer, Department Manager,
"It was a constant struggle. This particular catheter part has very thin walls, it got crushed with a standard M16 collet system because you have very little accuracy in how much tension you're putting on your collet. If you put too much force on it, my parts started turning to collapse into triangles. If you don't have enough tension on it, the part pushes back into the pickoff and you get varying part lengths and varying chamfer diameters. The parts would be out round and they wouldn't be on-center."
Wobig had heard about Masa Tool's Microconic™ sytems through Todd Pakiz, President of High Tech Representation Inc., New Prague, Minnesota. "Todd had told me about this system a couple years back. And we had been struggling with these parts. So I reached out to Todd and see if he's still selling that system."
Wobig continues, "I wanted to try this system for the catheter part which is a small thin-walled part approximately 0.040" in diameter and another 0.040" in length and with a wall thickness of 0.010". So I wanted something that wasn't crushing the part. It was really hard to adjust the machines pickoff spindle itself to any degree of accuracy without crushing a part."
What Wobig found with the Masa Microconic system was that they could set up the clamping with a gage pin and set the clamping tension with the Micrograd™ Dial Wrench which has little indicators to set an actual tension.
Cartridge and collet solution
The Microconic system consists of a cartridge and collet, with the cartridge fitting in the machine just like a standard legacy collet. The cartridge is a self-contained precision mechanism using the machine’s standard collet closing function, which means that the Microconic system can be used on any machine utilizing 5C, TF20, TF25 or TF37 collets.
According to Saccomanno "Since a collet system for any given machine must be made large enough to fit the maximum workpiece diameter capacity of the machine, the result is the standard collet mechanism is designed to handle the largest workpieces, which means it is excessively forceful and bulky when used for the smaller workpieces. Smaller parts get sacrificed, because they typically require a higher degree of accuracy and the workholding is more critical."
The Microconic system consists of the cartridge, which fits into your machine like a standard collet, and the Microconic collets which fit into Masa's unique cartridge. Every Microconic cartridge comes standard with extended nose for unsurpassed rigidity because of it's single piece construction.
"In fact, the cartridge is so accurate that it can be used as a gauge to verify machine spindle accuracy," said Pakiz.
Thayer explained how the Microconic system has worked for Micro-Matics "With the Masa system we're able to dial in a nice specific tension to hold that catheter part without crushing it or deforming it at all and having it on center. In a nutshell, we get better quality parts consistently with tighter tolerances. It's lead to a really significant improvement, it's increased throughput, so we have more parts at the end of the day."
"As a result of the implementation, the scrap rate on this part dropped dramatically once we added the new Masa system by at least 30%." added Wobig.
According to Masa Tool, the Microconic cartridge concentricity is guaranteed to be within 5µm (.0002") runnout and the collets are hardened and precision ground to the highest quality standards. The regular, UM10, 10mm collets, that Micro-Matics is using in their F20M10 Cartidge are available from Ø0.2mm (.008") to 10mm (.394"). In additon to the TF 20 spindles, the same collets can be used in TF25, TF37 and 5C sub spindles.
Applying technology to other applications
Micro-Matics has been running one of the collets for a couple of months straight now on a distal coupler.
Thayer explains, "The distal coupler part has a unique shape. It's not perfectly round. It has some small flats milled on either side of the part. It's like a cylindrical pill, like a capsule except with two sides of the long length milled in so there's flats on it. The part is 0.080" in length 0.040" in a cylindrical diameter. We then mill the cylindrical diameter 180 degrees from each other to a thickness of 0.030", so you're taking 0.10" off then drilling and centering two holes on each end of that through the flats."
"Our customer is extremely concerned about any collet indication marks or chip marks on the outside of that cylindrical diameter. The previous collets we were using were custom made collets that actually had the profile of the part basically machined into it" says Wobig.
Thayer picks it up, "It was a straight cylinder round collet it but it was split in half so it was like two halves of a collet so we were trying to keep the flats in the spaces and then the round cylinder on the collet part that's round. The holding portion it would move and we didn't have them pinned at all. And then we had the same issue as on the catheter part: If you squeeze it too tight you're starting to push the diameter into the flat so it would deform the OD into the flat and make deformed flats. If you squeezed it too hard, it would make the flat bump up. If it didn't sit perfectly right in the custom collet you'd have the split marks of the collet that start interfering with the transition between the flat to the diameter and it would make lines on the diameter."
Remedying the issues
Thayer continued "The extended nose pieces on the Microconic cartridge helps on the catheter tips because you can get closer up to where I actually have a supporting back end. Because if I'm too far away from that supporting back and you have more of a tendency to crush the front of that part. The Microconic gives me a better tension on the part. On the distal coupler, we have to use a boring bar, or a facing tool to create the back face, which is round. We'd have a lot of trouble trying to hold without nibs or anything on there. And this holds it so that the part stays a little more square, and we're able to turn it better."
When dealing with very small parts and setting with small gage pins, accidents do sometimes happen. "The only problem I've had with it was when somebody was trying to set the collet tension with a pin. They put the pin into the slot and not the hole and wrecked the collet. Because the pin was able to fit inside the slot so when they started tightening it up, and the pins started deforming the collet was wrecked because it wasn't in the hole in the center." said Thayer.
Masa has indicated that they will release a new TF 15 and TF16 Cartridge with an entire series of smaller 5mm capacity collets at IMTS 2022.
Microconic over-grip collets have unmatched rigidity and concentricity compared to other manufacturers. The same collets can be used in TF20, TF25, and 5C sub spindles. Microconic collets permit interchangeability between machines, and the collets fit in any Microconic cartridge, no matter which collet system is in the machine.
The cartridge system incorporates a solid extended nose and has the facility for micron-adjustment of the collet closure. To confirm precision levels, the hardened and ground cartridges can be used as gauges to verify spindle accuracy.
Masa’s Microconic also includes ‘over-grip’ collets where clamping behind a shoulder is necessary, for example. The cartridge/collet combination can accommodate openings more than 4 mm larger than the clamping diameter (depending on the application). This flexibility offers production engineers the potential to machine the part the other way around, which can sometimes help improve cycle times.
Microconic collets are available in 0.05 mm increments from 0.22 to 10 mm diameter. Each collet has a nominal clamping range from 0.05 to 0.1 mm depending upon the chosen collet diameter. With regard to the over-grip collets, the nominal clamping diameter starts at 0.5 mm with a maximum clamping diameter of 7.2 mm.
For further information
Extra spread is required to open the collet wide enough to go over the larger diameter. The correct over-grip collet for a specific part can be chosen based on grip diameter, width of the grip land and the largest diameter of the part.
According to the company, the collet expands machine capability, eliminates secondary operations and reduces cycle time. It features a standard gripping land length of two-to-three times the diameter. It is available with diameters ranging from 1.55 mm to 7.2 mm (0.061" -0.283").
The collet is said to grip with the same rigidity and accuracy as regular collets and features a fatigue-tested design built to last more than 250,000 full-load cycles. The collets are compatible with the company’s cartridges and come with its Microguide Brass ejection guide sleeve blank.
For use in high precision, small diameter CNC turning applications, it enables users to move more work to the sub-spindle for reduced cycle time.
The F201M10 cartridge is compatible with spindles that accept F20-201 collets including DIN 136E, Meister Swiss 136E, Schaublin F20 (76-201), Southwick & Meister F20-201, KEB (MasWerks) MC20-201, and Hardinge F20-201/4709 collets.
- Solid extended nose, minimal overhang
- Single piece construction of cartridge’s core diameter.
- Maintains 5µm (0.0002") concentricity at extended nose tip.
- Micrometer dial control of collet clamping pressure when using Micrograd Wrench.
- Suited for part diameters sizes from 0.2mm (0.0080") to 10.0mm (0.3934").
Today's Medical Developments
July 5, 2018
for concentricity within 5 microns (0.0002") in production use
The cartridge’s solid extended nose enables access for tooling and coolant with minimal overhang. Its core diameter is a single-piece construction that is designed to maintain 5 microns (0.002") concentricity at the extended nose tip. Used with the company’s Micrograd wrench, the cartridge features micrometer dial control of collet clamping pressure regardless of the machine’s hydraulic or pneumatic collet closing force. The cartridge is suited for small-diameter parts ranging from 0.22 mm (0.008") to 10 mm (0.3934") in diameter.
"Micro-movement" of the workpiece is reduced, resulting in a longer tool life, better finishes, fewer chatter problems, and less damage to the workpiece. The cartridge eliminates secondary operations, saves time and enables operations to be done in the subspindle. Broaching, milling, saw cutting/slotting, turning, boring and drilling can be machined in the subspindle.
Revolutionary Micro Workholding System with Tighter Grip and Greater Accuracy allowing Manufacturers to Produce Micro-Precision Products on their CNC Machines
Mr. Saccomanno, what is the idea at Masa Tool, Inc? What is your Microconic Workholding System
Masa Tool is basically formed from our life experience in the machining of micro-precision parts; primarily on Swiss-type screw machines, although the real focus is for high precision small parts manufacturing on any machine type to better the world of micro machining. Specifically, our first major product release is the Microconic line,
as you mentioned. Microconic is a high precision, collet-type workholding system that fits in conventional machine tools of all types. It provides extremely precise, extremely rigid and also very easy to use workholding for the manufacturing of micro precision products.
What are you replacing or enhancing? What are people doing now?
We are replacing an existing collet design. A collet is a traditional workholding device. It is like a split sleeve that has a taper on it and it slides into another tapered receptacle. It clamps down on the work piece and traditionally has been the most precise and rigid way to hold small work pieces for production machining. The most widely
used collet system design was invented about a hundred years ago. It has essentially been used to this day with very little improvement until now. The Microconic system was created to resolve many of the limitations of existing legacy systems.
The neat thing about Microconic is that we fit directly into the existing legacy workholding system, so that it is an
advanced, self contained workholding unit that fits within what is already in the machine. Therefore, the costumer does not have to modify their machine or anything. They can install our product right inside their existing spindle. Then we provide improved accuracy, repeatability, adjustability, consistency, rigidity and everything in every way. There are quite a few different ways that we improved the state of the art.
Have manufacturers been looking for a better way or is it once they find Microconic they are excited?
That is a great question! There is excitement when they see what we have, but it is not an easy sell at first. That is because, as you say, it is hard to look for something that you do not know exists. That has been a big part of our marketing hurdle to get over; to distinguish ourselves from the systems that are out there. To answer your question it is both a yes and a no answer. Yes, people have been looking for something else. There are pervasive complaints
throughout the industry about the quality of existing systems and the availability and the consistency. Those are just like part of the landscape. They have been around for years.
Everyone is kind of used to dealing with it and they are always trying to find better sources to get better collets and things like that. On the flip side, because people are so used to dealing with that, they do not really anticipate the revolutionary change that you can get by all of the benefits of the Microconic system. Therefore, it takes a skilled technical person to really talk to the customers specifically about what they can do with their own applications. The cost of Microconic is not trivial, so it is important to show how the value is created by providing capabilities to significantly improve productivity over what can be done with traditional legacy collets.
It was the cover story entitled: "Micro-Precision Machining" by Elizabeth Modic
Titanium alloy bar stock
Star SR20 Swiss-type CNC Automatic Lathe
The dental implant was machined almost entirely on the main spindle of the machine due to the need to have a powerful grip on the bar for a high-force, blind-hole, hexagon broach. Very little work was done on the pick-off spindle, so that sat idle for most of the cycle.
Cycle time reduction:
164 sec. to 98 sec. per part; 40% improvement achieved by moving all ID machining operations to the pick-off spindle, where they were performed in shaded time while the main spindle completed the OD. This was previously impossible to do with legacy collets, because the broaching force would push the part back in the collet. The 0.001" concentricity requirement of ID to OD could not be reliably achieved with legacy extended-nose collets, and they damaged the critical surface finish on the OD of the implant.
Production rate went from 18pph to 32pph, a 44% cost savings. In addition, a hand deburring operation was eliminated due to the cut-off being on the opposite end.
Cost of the Microconic system was recouped in 64 production hours; a $14,015 saved in direct production costs of a 10,000-piece order.
It was the cover story entitled: "Micro-Precision Machining" by Elizabeth Modic
“The cartridge can be used as a calibration gage to verify the machine spindle accuracy,” Co-owner Chip Prescott notes.
Microconic collets are finished to exacting standards with a five-step grinding process that removes the effect of heat-treat warpage. Also, the proprietary Microconic form of the closure surfaces is inherently more accurate than traditional collets, providing for a greater full-accuracy working range.
Cartridges are available to fit in push-type dead-length collet closers and also draw-type closers: F20M10 (for TF20 collet replacement), F25M10 (for TF25 collet replacement), and 5CM10 (for 5C collet replacement). All of these cartridges use the same Microconic UM10 collets, with more cartridge sizes in development to be released soon.
The Microconic system consists of two primary components: a cartridge that fits in the machine’s standard TF20, TF25 or 5C collet closer, and the collet itself, which fits into the cartridge. Each cartridge model has a solid extended nose and can accept both regular and over-grip collets. The over-grip collets open up to 0.157" (4 mm) larger than the clamping diameter.
The Microconic cartridge’s extended nose design directs all of the chucking pressure directly over the workpiece for concentricity and rigidity. Total indicated runout (TIR) for the Microconic system is guaranteed at 0.0002" (5 µm) at the workpiece, absent any runout introduced by the machine structure or other elements of the setup. The system capacity ranges from 0.008" to 0.394" (0.2 to 10 mm) in diameter, with all sizes available from stock.
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