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Gentz Aero's 64-Year Balancing Act

 

Reducing lead times yet maintaining quality and profit margins: A tough act—made easier with standardized tooling.

 
Like most suppliers to the aerospace industry, MB Aerospace portfolio company Gentz Aero (Warren, MI) is under constant pressure to reduce job lead times yet still maintain healthy profit margins to grow and prosper. It’s a delicate balancing act, but one the shop has been able to successfully achieve over its 64-year history.

Gentz Aero attributes much of its success to three core business practices. One is that the shop takes on the tough parts that most other suppliers shy away from. Another is that it keeps all necessary part processes in-house and always invests in the latest equipment and technologies to do so. But most importantly, Gentz Aero adheres to a strict ongoing plan of continuous improvement in regards to all aspects of its manufacturing operations.

When it comes to its continuous improvement philosophy, Gentz Aero evaluates its manufacturing cells, specifically those performing part-machining operations. Production managers and machinists work closely with the shop’s engineering department to establish better ways to machine parts and efficiently move them around the shop floor and through the manufacturing cells. The group also tries to combine or separate operations—depending on which is most beneficial to increasing cell output. Lately, however, some of the most significant gains in cell and machining productivity have resulted from the shop standardizing its tooling wherever possible.

Prop turbine case made from 718 Inconel encompasses all of the shop’s processes from EB welding to milling to EDM holemaking and deburring.

So far, standardized tooling has contributed to reducing overall job lead times by making machine changeovers easier and faster and allowing for higher machining speeds and feeds to shorten part-cycle times. The tooling also makes it possible for Gentz Aero to standardize and simplify certain machining operations so that the shop’s less-experienced machinists can handle them, thus freeing up its more seasoned machinists for the more complex work.

For almost all of its tooling needs, Gentz Aero has been working closely with its key supplier Seco Tools for about 15 years. But it was only recently that the shop approached Seco for help with tooling standardization, as well as carbide insert optimization, and with the idea of having an in-house Seco technical representative on site a few days per week.

“Today, most cutting tool suppliers can provide the latest in cutter technology,” said Roger Bartolomei, program director at Gentz Aero.  “However, the more important issue is actually getting a specialist to come in and work with you on a particular tool to ensure you use it to its full potential, and that’s what I believe differentiates Seco from its competitors.”


Complex Parts and Assemblies

For Seco, working with Gentz Aero in standardizing its tooling came with significant challenges, one of which was the sheer complexity of the shop’s parts/assemblies. Gentz Aero is a Tier One supplier to all three of the jet engine OEM primes. It is well known in the industry for its aerospace/aircraft fabrications used mostly in the hot sections of jet engines. The company is among the few suppliers with the necessary expertise to join sheetmetal components with those made from forgings and/or castings to form single assemblies that are then finish machined to tolerances held within ± 0.001" (0.025 mm).

“These are highly complex hardware assemblies,” Bartolomei pointed out. “They involve multiple tiers of build and lots of details and subassemblies. With every manufacturing operation, we have to deal with different shrink factors or part warping because of the materials used.”

One job that epitomizes the complexity of the assemblies Gentz Aero produces is a prop turbine case. This assembly essentially encompasses all of the shop’s processes from EB welding to milling to EDM hole making and deburring. It’s made from 718 Inconel and is typically between Rc  40 and 45 in hardness.

But what really makes the part a challenge, besides all the processes involved, are its individual components. Each is extremely complicated and intricate and once they are welded to one another, completing them as a final assembly takes about 10 days. This is fast when considering the assembly previously took over a month to produce.

This is one of the jobs where Gentz Aero worked with Seco to evaluate the whole manufacturing process, and Seco provided a complete solution. Seco looked at every operation and targeted the longest ones first and, in this case, it was the milling operations. The company also recommended several places where multiple operations could be combined and standard tooling applied. As a result, Gentz Aero was able to reduce and combine two seven-hour milling operations into a single seven-hour operation, which contributed immensely to reducing the assembly’s overall turnaround time.

The Goal of Standardized Tooling

According to Bartolomei, the goal of standardized tooling at Gentz Aero is more about reducing the amount of different tooling as opposed to reducing overall tooling inventories. At one time, he said, the shop used more than 650 different types of inserts, keeping a significant amount of each in stock at all times. Now, thanks mostly to standardizing, Gentz Aero keeps only about a third of that amount in inventory.
With TS2000 grade inserts, Gentz has increased the speeds and feeds for turning containment housings made from 718 Inconel.
Besides helping the company standardize, Seco gives the shop immediate access to the latest tooling advancements—new geometries, carbides, substrates and coatings—to help increase machining speeds and feeds to further shorten part-cycle times. For example, Seco tooling, in addition to other tactics, was instrumental in helping to remove about 26 hours of processing time for a particular job that wasn’t proving as profitable as the shop had hoped it would be.

One of the Seco tools introduced was the TS2000 insert that allowed Gentz Aero to boost its sfm feed rates by almost 40%, an increase that translated into a 25% reduction in machining cycle time. Machining was a huge portion of the overall part processing time for that particular job.

Designed specifically for superalloys and titanium alloys, TS2000 inserts feature a new edge preparation process that provides superior edge integrity and improves the adhesion between the tool’s substrate and coating. This ensures consistent high-quality performance and superior surface finishes, while allowing for faster cutting speeds and feeds. Plus, Seco’s unique PVD coating on the TS2000 inserts prevents plastic deformation to further extend the tool’s life.

Practically any amount of machining cycle-time reductions can prove monumental for Gentz Aero, especially when machining an Inconel part that starts out weighing 225 lb (101 kg) and after machining weighs only 15 lb (6.75 kg). Or when it machines an aluminum part that weighs 2200 lb (990 kg) and finishes at about 60 lb (27 kg).

With so much metal removal, it’s no surprise that machining cycle times can range from one to 15 hours. On top of that, parts can involve anywhere from five to 150 operations with the longest being a 20-hour milling process. It should be noted that this particular 20-hour milling time was previously much longer. Seco worked with Gentz Aero in the past to get it down to that amount of time. In fact, that was one of the first jobs the shop worked on with Seco.

Over the past five months Gentz Aero, together with Seco, reviewed over 19 jobs/products involving 97 operations and was able to reduce cycle times for 93 of those with tooling changes—that in addition to toolholding and other equipment changes.

“Basically, we are revisiting all our programs and cleaning up the tooling so to speak,” added Rafal Blaszkiewicz, programming supervisor at Gentz Aero. “We are also looking closely at part designs to figure out where we might combine tooling. For instance, there have already been several instances where we’ve gone from having to use five different diamond-shaped inserts to just one trigon or square-shaped Seco insert that, in addition to that, helps conserve cutting edges for longer tool life.”

Besides cycle time reductions, Gentz Aero was able to improve upon machine changeover and part setup times through standardized tooling. One of the first such major efforts involved the shop’s vertical turning lathes (VTL) where setup times were outrageous, according to Mike Larry, project engineer and NPI (new product introduction) team leader at Gentz Aero.

“When you run small job lot sizes like we do, fast setups can be the difference between being profitable on a job or taking a loss on it,” said Larry. “We re-evaluated over 250 part programs within approximately 20 different jobs to see where standard tooling could be applied to the VTL cells. From that, we established 12 standard tools and only eight specials with which we would equip each of our VTLs. This much standard tooling, along with the custom fixturing we use, allows us to quickly and easily set up our larger parts on the VTLs.”


Fixture Fixes

As with standardized tooling, part fixtures are critical to Gentz Aero’s machining operations and the shop stocks well over 1000 of them. In addition to contributing to faster setups and easier, more accurate part repositioning, fixtures help locate part diameters and faces and provide support where part features are thin and may move during machining. The fixtures also help prevent part distortion that can result from removing large amounts of workpiece material.

Gentz Aero’s goal is to use as few specialty tools as possible, and it continues to work with Seco to accomplish that. Larry said that already many of the machines in the shop’s cells have been re-equipped with as much of the same standard tooling as possible.

“For our cells, we look at part families and sizes involved. Then we determine the necessary sizes and types of standardized tools that would work for all those various parts,” explained Larry. “These tools will then remain loaded in the machine tool magazines, thus allowing us to run more parts through the cell because over 75% of the machine’s tools are already loaded for every part it will run. So, basically tooling setup time becomes a nonfactor when changing over from one part to the next.”

Working with Seco is definitely an ongoing process for Gentz Aero, and the shop has many more projects and operations targeted for tooling evaluations. “We currently have a core group of parts and a team designated for improving the processing of those parts,” said Bartolomei. “As the mix of parts in that core group changes, hundreds, if not thousands, of additional operations will have to be evaluated for possible improvement. Plus, as new cutting tool technologies are developed, we’ll have to revisit those operations that were already evaluated to see if they can be further improved again with that new tooling, and for that, we will rely on help from Seco as well.” ✈

This feature edited by Yearbook Editor Michael Anderson from information provided by Seco Tools.

 

This article was first published in the 2013 edition of the Aerospace and Defense Manufacturing Yearbook.


Published Date : 10/18/2013

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