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Shop Solutions: Five-Axis CMMs Speed Small-Engine Inspection

 

Kawasaki encourages motorcycle enthusiasts to "let the good times roll," but good times of another sort are rolling at the company’s Maryville, MO, small engine plant. There, two five-axis scanning probe systems are slashing CMM inspection and probe calibration times and speeding up QC feedback for machining of small engine components. The five-axis Revo systems from Renishaw Inc. (Hoffman Estates, IL), installed on Mitutoyo Crysta-Apex 121210 CMMs, replaced two PH10 articulating heads using SP25 scanning probes on traditional three-axis CMMs.

The Revo-equipped CMMs have cut inspection times by half or more on scanning- intensive applications. They have eliminated the need for custom probe configurations, cut probe calibration times from 6 to 7 hr to about 45 min, and collected large amounts of form measurement data, improving part quality. Of primary importance, the Revo systems have greatly increased inspection throughput, data quality, and flexibility of the QC department, enhancing its value as a strategic support asset to both manufacturing and R&D.

Kawasaki’s 800,000 ft² (74,322 m²) Maryville plant, which opened in 1989, produces single and twin-cylinder air-cooled or water-cooled engines, 1000 cc or smaller, for commercial and consumer lawnmower OEMs, as well as for a sister plant that manufactures ATVs and Mule utility vehicles. Operations at Maryville include aluminum die-casting, plastic injection molding, extensive amounts of machining, painting, and assembly. All engines—about 500,000 per year—are run-off before shipping as well.Revo system Kawasaki

"We use the Kawasaki Production System [KPS]," explains JC Watts, quality control technical group supervisor at the Maryville plant. "Our quality and engineering requirements are comparable to the best in the automotive industry, though our manufacturing is focused on lower volumes of many different kinds of products." The plant has 50 machining lines, typically arranged in a U-cell pattern with start and end machines across from each other. "Primarily, it’s one-piece production with machining lines running a part through multiple processes at a high rate," Watts says. Kawasaki utilizes automation in many die-cast and some machining operations, accomplished through the integration of Kawasaki robots. On one of the crankcase lines, robots load raw materials and unload finished parts that are placed into inventory for assembly to draw upon. Machined parts include aluminum, cast iron, and steel.

"We’re running similar tolerances that automotive powertrains use for high-end products, and there are probably four or five critical processes for our aluminum parts and 15 for the steel parts," Watts adds. It isn’t uncommon to find tolerances "in single digits in microns" for form, and 0.05-mm true position.

The QC lab is responsible for inspecting 125 different mass-produced parts, as well as vendor parts and those produced for engineering development. The environmentally controlled lab is located adjacent to the machining lines, and parts intended for routine inspection are delivered on carts or via train (an electric vehicle towing several trolley carts). Critical components may be hand-delivered for priority inspection during a line changeover or if an operator suspects a problem.

"When I started here, we had a couple of three-axis CMMs with PH10 articulating heads and SP25 probes, and another CMM with a fixed probe head," Watts explains. "We were frustrated with having to make probe configurations and being limited to what we could do even with the articulated heads. We had so many different probe configurations that calibration times of six to seven hours took a bite out of our inspection throughput, too. We wanted to do better than what the industry considered the norm, so we looked at several options and the five-axis Revo system appeared to be the fastest and most flexible available. It was the best fit for our requirements."

Kawasaki bought a new Mitutoyo Crysta-Apex 121210 in 2009 with the Revo system installed from the factory, and retrofitted an identical machine in 2010, after the first machine was up and running with all the part programs. The Revo five-axis scanning probe head can collect up to 6000 data points/sec. It is engineered for high-speed precision measurement of contoured surfaces and complex geometries requiring high-volume data collection to validate fit and form with high accuracy. It uses two rotary axes, one in the vertical plane and one in the horizontal, for infinite rotation and positioning. Five-axis software drives the measuring head and synchronizes its motion with the linear axes of the CMM. Look-ahead algorithms drive the probe path and CMM in coordinated continuous motion. The head adapts position while measuring on the move, maintaining stylus tip contact with changing contours at scanning speeds of up to 500 mm/sec.

"Though our SP25s were scanning probes, we were doing 95% touch probing because scanning was too slow with a three-axis CMM," Watts explains. "Our cylinder and crank bores are probably the best examples of where we believed touch probing was inadequate. To accurately collect enough data points to measure the geometry of a bore 80–100 mm in diam and 150 mm in length, the SP25 probe took so long we limited those inspections to machine setup or special requests from our design department. Now on every crankcase we measure, the Revo does a spiral scan of bores and the system outputs the values to software. We also send a graph of the data points to our network that can be used by anyone in QC, engineering, or production, and it really helps troubleshoot problems. You can visualize the problem. What would take 3-4 min with an SP25, we’re measuring in 10 sec with the Revo."

The Revo scanning heads have all but eliminated the need for touch probing. Now 95% of inspections utilize scanning, with no time penalty as before, allowing Kawasaki to collect so much data that it challenges the speed of computers doing the analysis. The Revo probe can also do head-touch probing or be used for traditional machine-touch probing when the situation calls for touches.

"With scanning inspections, our production and engineering people have a lot more confidence that the data are valid," Watts adds. "With touch probing, it’s easy to get one speck of dirt that causes an out-of-round condition if you’re only sampling seven or eight points. It can throw the location of that circle off. We have specific documented examples of where there were flatness errors we would not have caught with touch probing, and cylinder-bore geometries that would not have been caught with touch probing because of the amount of data sampled with the touch probe. We still caught these problems before they left the plant, but the parts were scrap. The Revo scanning capability allows us to catch form errors much more quickly, without a time penalty on our inspections. It has definitely made us more proactive in catching quality problems early in the game. We are now able to measure all our mass production parts with just two probe configurations," says Watts. "We were able to eliminate the large ball-stylus configurations because of the large approach angle the Revo creates between the stylus and the workpiece. During scanning the Revo maintains the approach angle, which allows a large cylindrical feature such as a cylinder bore to be measured with the same stylus used for measuring a 5-mm bore, with no chance of shanking the stylus."Two Mitutoyo Crysta-Apex CMMs with five-axis Revo systems have cut inspection times by half or more on scanning-intensive applications as well as eliminating the need for custom probe configurations at the small engine plant

Special configurations for vendor parts have also been eliminated because the infinite positioning angles of Revo allow measuring a part without special fixturing or consideration of which probe to use. With so few probes, calibration time has dropped to around 46 min. Now QC technicians monitor the calibration instead of calibrating every shift.

"We can measure any part on either machine with a limited amount of fixturing and no special calibrations," says Watts. "We measure all our parts on three types of fixturing. The Revo probe orients itself to the part after it’s initially aligned. The utilization of special fixtures has almost been eliminated, without concerns of measurement error due to part alignment." 

Kawasaki programs all of its inspection routines in-house using Mitutoyo’s Mcosmos 3.1 software. The upgrade to Revo inaugurated a shift to parametric and modular programming of inspection routines through in-house development of coding. This allows a program to be used for a part family. "We might have 30 different crankshafts, for example, but because everyone has the same features, only in a different sizes or locations, we can use the same inspection program to measure all the parts," Watts states. "That’s one of the big advantages we gained." Infinite angles of the Revo system make it simple to create parametric programs because there is no concern about the stylus interfering with a part feature, due to size or orientation of the feature. The probe automatically aligns normal to the feature being measured, simplifying programming.

The Maryville facility has run more than 50,000 parts through the two Revo-equipped CMMs, and Watts indicates there are plans to expand the use of the Revo system to gear inspection and cam lift if it proves feasible. "We’ve developed our own algorithm and subroutine in our software for cam lift, and that’s something that would have been more difficult to do without the Revo system due to the angle the probe requires to measure the lift on the lobes." ME

 

For more information on Renishaw, go to www.renishaw.com, or telephone 847-286-9953; on Mitutoyo America Corp. go to www.mitutoyo.com, or telephone 888-648-8869.

 

 

Measuring Close Tolerances
with Confidence

 

Operator measures precision mechanical part for the defense industry at Smiths Machine with a Zeiss Contura G2 aktiv CMM with the VAST XT active scanning technologySmiths Machine LLC (Cottondale, AL) knows all too well the importance of actively responding to the needs of its customers. In 2008, Smiths began ramping up both production and CMMs to meet customer needs for handling larger orders, with more complex parts and requiring tighter tolerances, and in the three years since, Smiths Machine has achieved compelling results.

Begun in a garage in 1974 as Smith’s Welding & Machine Shop, this family-owned business now has two manufacturing facilities and specializes in CNC machining, with three, four, and five-axis milling, turning, and grinding with assembly and CMM inspection. About 60% of the company’s orders come from the defense industry, with the rest accounted for by automotive, aerospace, and general manufacturing industries. Typical part materials include mostly aluminum and stainless, but also copper, bronze, and special alloys.

Smiths Machine purchased its first Zeiss CMM, a Contura 700 with a VAST XXT articulating probe in 2004, so the company was familiar with the Zeiss systems when management started searching for two additional CMMs in 2008. They needed to measure complex parts requiring tighter tolerances of about 3µm. Before starting research on the CMMs, a list of all the requirements that would be needed in the new measurement equipment was made. These included some of the same characteristics as their CNC milling machines. They wanted to match the CMM tables to their largest machine tables with respect to both size and volume. Accuracy of the CMMs had to meet new target tolerances and be tighter than on their CNC machining centers. CMM durability and easy-to-use software were also at the top of the list.

As a member of the sales team, Mike Bruce explains, "We expect to give our customers the utmost quality, therefore, we expect the same from the measuring equipment." Smiths Machine determined that the ideal CMMs would still be within the Contura family, the new Contura G2 aktiv 10/16/10, but with the VAST XT active scanning technology. They liked the robust design of the Contura G2 with ceramic guideways in X and Z axes, providing rigidity and protection against environmental influences. In addition, its size matched up nicely with the company’s CNC milling machines.

The VAST active scanning technology enables Smiths Machine to efficiently work with larger batch inspections at maximum speed while meeting targeted tolerances of 3µm. The VAST XT sensor is able to use complex stylus configurations, including styli up to 500 grams in weight and with lengths of up to 500 mm. These systems worked so well with new projects that after continued growth, the company purchased a third Contura G2 aktiv just two years later in 2010.

With the additional Contura G2 machines and production equipment, Smiths Machine was able to secure orders with tighter tolerances and in larger quantities. A new production facility was also built to house a second CMM inspection lab that ran parallel with the additional machining equipment in order to streamline all production processes. Several new employees were trained on the new Contura systems within only a few days of installation. When the dust settled, Smiths Machine had successfully acquired and fulfilled their new contract orders and by 2011, and had grown sales by 300% from 2008. VAST XT active scanning sensor is able to use complex stylus configurations, including styli up to 500 grams and 500-mm long

Today, the Contura systems typically measure about 70–100 parts per day. The CMM measuring plans range from raw materials to finished product on the production floor. CMMs are also used for incoming inspection and the design of measurement fixtures. Parts from the automotive industry typically require less than 2% inspection and increasingly more customers, especially in the defense and aerospace industries, are requiring 100% inspection.

"Calypso metrology software really stands out compared to other metrology software," says Joshua Arington, quality engineer at Smiths Machine. Benefits include user-friendliness, flexible programming, and numerous measurement capabilities. "The ease of simply selecting the features on a CAD file saves a lot of time. There isn’t even an option to write code because this software does it for you, and screen prompts walk you through the programming process. Evaluation parameters are easy to understand and Calypso uses the same language as standard metrology and design."

Calypso software also aids Smiths Machine with measurement documentation required with ISO 9001 and AS9100B certifications. "We provide PDF documents to our customers on a regular basis," says Arington. They can also easily export measurement information to Excel files, and export tables (characteristic results) to text files. "With the Excel files, we can manipulate information into whatever kind of report we need, such as developing SQC information."

Arington says the Zeiss systems offer greater efficiency, allowing precise measurement in little time. "It’s amazing the minimal amount of time spent to get such a high level of accuracy and repeatability," Arington comments. Overall, the firm estimates that the Contura machines have helped them reduce their inspection time by about 70%. "Some GD&T specifications such as surface profiles would be nearly impossible to measure without the Zeiss CMM."

Looking to the future, Smiths Machine anticipates even more demand for CMM inspection. "By far, the most important benefit of owning Zeiss CMMs has been accuracy, accuracy, accuracy," claims Bruce. Repeatability and flexibility are also company favorites. "Our experience with this new contract work that included these complex, high-precision parts, with large quantities has led us all to the conclusion that a major component of our success was our ability to effectively measure parts with Zeiss CMMs." ME

 

For more information on Carl Zeiss IMT LLC, go to
www.zeiss.com, or telephone 763-744-2409.

 

 

Rotary Table Handles
Big Oil Field Parts

 

Workpieces for the oil field can take many shapes and sizes. Parts that are long, heavy, and awkward to handle for turning, milling, and then finish turning are not uncommon. RTI Energy Systems (Spring, TX) a subsidiary of RTI International Metals, was able to expand its machining capabilities by acquiring a Tsudakoma RNCV1501 1.5-m NC rotary table from Koma Precision Inc. (East Windsor, CT) to handle a deepwater component that was 20' (6-m) long and weighed 6000 lb (2721 kg).

RTI Energy Systems specializes in oil and gas systems engineering and manufacturing services, producing deepwater and ultra-deepwater riser systems and other specialized equipment for production, export, completion, and workover operations used in the search and recovery of hydrocarbon reserves globally. The primary part the rotary table was purchased for is a flanged, alloy-steel stress joint for deepwater riser systems. "Without the rotary table, we wouldn’t have been able to handle a workpiece of this size and stay within the strict tolerances required to produce a quality part while maintaining efficiency," explains Steven K. Hensley, manufacturing engineer, RTI Energy. "The workpiece is an oil-production piece that starts out as a 6000-lb [2721-kg] steel alloy forging that is first turned on one of its two large lathes, and then fixtured in the rotary table for milling on a Toshiba BTH-130.R24 horizontal boring and milling machine."

Customization of the rotary table was done by Flanagan Industries, which custom-milled the center bore to meet the specifications provided by RTI. The main reason for the custom bore-through rotary table is to handle large parts of that size and weight and be able to index and maintain greater than 0.5° tolerance and the correct orientation of the workpiece to the milling machine. The majority of the parts that RTI is looking at machining with the rotary table have features that are clocked around the OD or related features on different planes and are long, heavy large-diameter parts.

The workpiece posed a challenge because of a number of special features. "The workpiece has several pockets, slots, and tapped holes of various sizes, and an intersecting hole in the face of the part. The rotary table had to meet the precision requirements of these features and maintain repeatability for multiple part production runs," says Hensley. "These features are oriented to two rows of 16 holes—16 tapped and 16 thread-milled holes—in each row along the OD of the part that are clocked at 22.5° increments with a tolerance of ±0.5°. There is also an API ring groove on a milled flat behind the hub of the OD that is oriented to these OD features and has an intersecting hole from the face of the part," says Hensley.

The Tsudakoma RNCV1501 features an NC controller package and has the ability of the through hole to be modified to accommodate the intended part. The rotary table can be vertically mounted without the need of a support structure, or horizontally mounted for other applications. The rotary table is equipped with a Pratt Burned chuck and a Schmidt Tool steadyrest. The chuck is a 32" (813-mm) diam independent four-jaw chuck with a 16" (406-mm) diam through bore and custom adapter plate for mounting to the table. The Schmidt mill steadyrest is a RIP-144 model that has a range from 4.6 to 24" (117–610-mm) diam with a 25,000 lb (11,340-kg) capacity. The table itself weighs in at about 17,000 lb (7711 kg) and is mounted on the milling machine table which has a maximum capacity of 44,000 lb (19,958 kg).

Future plans for the rotary table include full integration of the control system with the Toshiba NC control to allow more efficient off-line programming. This will also give RTI the ability to use the rotary as a programmable axis, which would add the ability of contouring more complex components.

An added benefit of having the Tsudakoma rotary with the NC controller package is the flexibility to use the rotary table on any larger mills that RTI may purchase in the future.

Other services and capabilities of RTI Energy Systems include procurement of raw materials, NDE (Non-Destructive Examination) such as AUT (Automated Ultrasonic Testing) and MT (Magnetic Particle Testing). RTI also specializes in welding, cladding and fabrication of valves, fittings, wellheads, trees, pipes, specialty joints, and other components. RTI has large part machining capabilities that range from a 65' (19.8 m) and 21' (6 m) in length CNC lathes that can swing 40" (1016-mm) diam parts to a CNC VTL (vertical turning lathe) that has a 90" (2286-mm) diam chuck and 33,000-lb (14,968-kg) capacity. The company also has several other medium slant-bed CNC lathes and manual lathes. ME

 

For more information on Koma Precision Inc., go to www.komaprecision.com,
or telephone 860-627-7059.

 

Short-Run Moldmaker Buys
Effective Machining Solution

 

Donnelly Custom Manufacturing (Alexandria, MN) began in 1984 in a small one-story building with eight employees and no customers. Today, it has transformed itself into an industry leader operating 24 hr/day, 360 days/year in a modern 105,000 ft² (9755 m²) facility with over 220 employees. The company specializes in short-run injection molding and related services for a variety of leading industrial OEMs. Short-run molding can be defined as any run that, including setup and tear-down, lasts less than 48 hr. Short-run molders focus on low-volume, intricate parts, and Donnelly currently has over 2500 active molds and launches more than 125 molds per year.

Known for its best-in-class processes, quality systems, and training programs, Donnelly brings expertise, commitment, and continuous improvement to the table to provide the best design and implementation solutions for their customers. For example, the company recently identified the need to expand its internal capabilities in order to have a greater measure of control when tools need revisions, or, because of normal wear, are in need of repair.

Short-run molding is characterized by extremely short lead times. When tools needed to be repaired, Donnelly sometimes found itself subject to the vagaries of mold shops. These shops could at times be very busy and unpredictable, and a tool repair might take anywhere from two days to two weeks. Donnelly recently purchased a laser scanner and Solid Works and SolidCAM software, which help dramatically reduce lead times on projects involving complex geometry. The company began to consider additional new equipment that might further improve and enhance the fluctuating tooling lead times issue.

A molded part that has a gasket "overmolded" onto the plastic part with a very tight specification for allowable flash on the gasket material required an adjustment to tighten the shutoff between the molded part and the overmold toolDonnelly heard about an auction in North Dakota where a shop owner, who had previously built tools for Donnelly, was retiring and closing his doors. At the auction, Donnelly acquired a 2004 Mazak Super Mold Maker 2500i Vertical CNC milling machine, which features a 25,000-rpm, liquid-cooled spindle for high-speed/hard-milling capabilities. It also has a ballscrew core and saddle cooling. These features maintain thermal stability during long high-speed milling operations on small or large mold components weighing a maximum of 1763 lb (800 kg). It is equipped with special CNC functions specifically for machining molds to achieve high-accuracy finishes, which can significantly reduce or entirely eliminate the need for polishing.

The machine also includes a Mazak/Renishaw laser toolsetter and Renishaw spindle probe to further enhance precision, accuracy, and speed on setups. Donnelly is using the machine to repair tools, re-cut cavities, and remake mold components. The company has also found it useful to build and repair fixtures. The Mazak is significantly faster in comparison to their alternate machines, and the employees using it are happy with the addition. Although they aren’t using it as much as a mold shop might, Donnelly is using it on a daily basis to support the many requirements in a molding operation that features over 2500 active molds.

Among the machine’s many benefits is that the machine often cuts down on lead times and actually provides Donnelly with an opportunity to expand its business reach. In one case, a brand new mold was sent to Donnelly by one of its customers who had the mold built. The molded part is one that has a gasket "overmolded" onto the plastic part and has a very tight specification for allowable flash on the gasket material. The mold required an adjustment to tighten the shutoff between the molded part and the overmold tool.

The solution was found putting the mold on the Mazak Super Mold Maker. Sending the mold back to the mold shop that built the mold would have required three to four days for shipping plus the time to schedule it through their shop to get the work done. Prior to having the Super Mold Maker, Donnelly could have built electrodes and EDM’d the detail with existing equipment in its tool room, but that would have taken two to three times longer than machining the tool steel core block. Because of the part’s geometry and design of the core block, a 3/32" (2.38-mm) diam single-point cutter sticking out nearly 3" (76.2 mm) from the spindle was needed. Because of the high-speed spindle and hard milling capabilities of the Super Mold Maker, Donnelly was able to cut the detail directly into the core block and will be back molding parts with the mold in less that 24 hr from start to finish. For Donnelly, this purchase has been a clear internal asset to the team and the company’s mission: "To Deliver Good Products On Time." ME

 

For more information on Donnelly Custom Manufacturing, go to www.donnmfg.com; on Mazak Corp, go to mazakusa.com, or telephone 859-342-1700.

 

This article was first published in the September 2011 edition of Manufacturing Engineering magazine.  Click here for PDF 


Published Date : 9/1/2011

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