Vertical Turning Big Parts Delivers Big Savings

Frank Earl Sperry, a mechanical engineer from the University of Illinois, founded Mechanical Devices Company in 1914 in Aurora, Illinois. Today, in Bloomington, Illinois, Mr. Sperry’s descendants operate the company successfully in a modern manufacturing facility and logistics building totaling about 250,000 square feet.

What the company does for its customers had been adapted often over the generations to meet capacity demands and capability requirements. The company has developed expertise in machining materials from ductile iron, grey iron, steel and aluminum for structural applications in transportation, pump and compressor customers.

However, not satisfied with doing the same work the same way year in and year out, the family has looked ahead and thoughtfully prepared itself for the work it saw coming. Many shops are capable of smaller size parts, but the capacity of Mechanical Devices puts it in another league with its bigger machines.

Getting Lean

“Our processes are designed using TS-16949 quality requirements and employ a solid production system to deliver quality, cost competitive full services for casting, forging, machining and logistic support,” says Mark Sperry, V.P. of engineering and sales, and a grandson of the founder.

“The U.S. manufacturing industry today faces high levels of local and international competition, so Mechanical Devices has developed a production system that comprises management philosophy and practices. We organize suppliers, manufacturing and logistics to meet our customer goals built on the 5S guidelines.

“By implementing a 5S program and operating with OEE efficiency, we eliminate waste and run
a lean operational process at more than an 85 percent optimum level. This saves both time and money for our customers. We also implement sales and operational planning both internally, and externally, which allows us to demonstrate performance for future production planning. This also allows us to develop relationships with our customers and establish shared interest for success.

“Finally, we use Six Sigma methodology for problem solving for continuous corrective improvements for day to day quality. By continual pre-planning, monitoring inventory levels, and quality testing, we are able to lower job cost and provide savings for our customers.”

Serious about its Work and Customers

From parts that are measured in microns to workpieces weighing up to 1,000 pounds, Mechanical Devices uses a number VMCs and turning machines to process parts through lean cells or in a single machining operation. Processes meet customers’ precision, accuracy, repeatability and surface finishes, and the company often finds ways to minimize the number of steps in production.

In the last few years, it saw the need to replace worn machine tools and to upgrade its turning capability to meet the needs of customers including CFR Engines (Pewaukee, Wisconsin). Robert Waller, Mechanical Devices plant operations manager, evaluates the equipment the company purchases.

“Most of the shop is run by production planning where we monitor rough-cut capacity and sales and operation planning,” Mr. Waller says. “We run a lean shop where most of our manufacturing is initiated or dictated by the parts we have from our customers. The tool matrix we have in the shop defines the value streams that we create according to the processes required. This is to operate as lean as possible.

Adding Capacity

“Beginning in 2005, we saw the need to add machine tool capability to handle orders for large parts. We had no machines with the capacity we needed, so our machine tool rep suggested we try a Hwacheon. We had never heard of it,” Mr. Waller recalls.

Since then, Mechanical Devices has invested in 15 Hwacheon machines, typically matched up in lean cells.

“We were looking for two 24-inch capacity machines to run a part we were asked to produce for one of our customers. We tried it on a horizontal lathe, but found the heavy part could be processed more efficiently and accurately in a vertical turning lathe.

“We looked around at other shops that were running Hwacheons, and in 2006, we decided to bring in the VT-550 vertical turning machines. We paired them with a VMC, creating a cell to produce the part. One operator runs the machines, one person packs up the parts, all at the cell. So it is rough in, rough out and out the door,” Mr. Waller says.

Hwacheon’s one-piece machine bed design limits thermal distortion and absorbs vibration effectively, assuring high surface quality and precision at high speed while taking heavy cuts. The fast and effective chip disposal and the environmentally friendly oil-water separation supports stable, efficient machining.

A boxway design disperses loads efficiently on the VT-550. Smooth axis motion with Hwacheon’s advanced air levitation system on the X-axis guideway maintains high precision even during roughing. A class-leading rapid feed rate (X/Z) of 24 m/min shaves cycle times.

The cut is 3 mm in a 24-inch diameter cast iron hub. In the center of the part is a 1-in-8 tapered bore to accommodate a part that is added to it later. The taper also had to be maintained correctly and the vertical turning machines’ Z axis doesn’t vary through its 790-mm stroke, according to Mr. Waller.

Holding Up to Hard Work

“Since 2006 we’ve been running the same parts on those machines, and we have had to put in very little money to maintain them as they continue to perform very well. They took some abuse as the raw parts weighed 250 pounds, but they kept on going,” Mr. Sperry says. Downtime since installation is less than 1 percent, according to Mr. Waller.

“Because of our heavy cutting jobs, we purchased our Hwacheons with the geared drive—one of the distinguishing features of these machines. For our type of work, we felt the direct drive design that is so popular in some machine tools today would not be adequate to our task,” Mr. Waller says.

“Overall, we were able to increase production of the hubs by about 40 percent using the Hwacheons in 2006 compared with the previous method, and for this reason, we looked into Hwacheon again when the time came to replace older machine tools,” Mr. Waller says. The company, which turns a lot of cast iron, found the Hwacheon design allowed the machines to take heavier cuts while maintaining tolerance, thus reducing cycle times and opening the door to more throughput.

“Machine rigidity and the solid cast meehanite base permits heavy cuts without vibration or chatter—problems we had been fighting on our other machines. We now consistently achieve tolerances of 0.0005 to 0.0006 inch on an 18-inch diameter hub with no vibration, thus no variation part to part.

“Next, we decided to retire a couple of older, worn out Cincinnati 10-inch horizontal lathes. We quoted all the major builders in 2011. The price was good at Hwacheon, and the product was in stock. We saw it demonstrated and decided to buy the HiTECH 200 10-inch lathes. We plugged them and ran them, Mr. Waller says.

“Then we decided to replace the Cincinnati 300Ts fourth-axis lathes that were worn out,” Mr. Waller says. “Maintenance was costly and their control was a problem. We decided on six VT 550s—two with 10-inch chucks, two with 18-inch chucks and two with 24-inch chucks to handle the range of work that we had in-house.”

The 24-inch chucks added capacity that Mechanical Devices did not originally have in order to process a new package, a cast iron flywheel, from one of its customers.

“We picked up a new customer that manufactures the motor drive unit that raises and lowers passenger elevators,” Mr. Sperry says. “One of the parts they produce is a 30-inch tall by 30-inch diameter spacer. We brought in three part numbers, but we could not get them to run well on our horizontal turning machines.

“That’s when we bought the two Hwacheon VT-950s with 30-inch chucks and put them in a cell with an HMC. Our engineering department created a set of quick-change jaws for the vertical turning machines. One person runs all three machines in the cell and also packs the part to ship. The former process was doing eight parts a day. Now it is 13 to 16 parts, depending on the part size. In the cell we run all three sizes.”

Good Position to be In

Mechanical Devices showed it could produce parts faster and with more consistent accuracy than its customer could, Mr. Waller says. “The parts were about 30 inches tall, and the customer’s machines could not hold the tolerance over that dimension.”

Trying the parts on the Hwacheon VTL, Mechanical Devices ran the parts consistently within tolerance and eliminated the in-process manual parts inspection. The result was that Mechanical Devices was able to double production compared with the customer’s rate.

“Then in 2013 we ordered two VT-1150s with 50-inch chucks to turn a 900-pound flywheel, taking a depth of cut of 0.400 inch,” Mr. Waller says. “The force on the chuck is heavy. Hwacheon also offered live tool heads on this machine. This saved a secondary operation.

“We were planning on using the machine to turn the parts, then take the parts to a VMC for drilling holes for 22-mm taps and then balance it, then add a ring gear for the starter ring. But we knew that doing all the machining, including drilling and tapping on one machine, would save us handling and machining time.”

Hwacheon suggested that the VT-1150 with live tools could do the large drill and tap operation.

“We tested it,” Mr. Waller says, “turning the flywheel with 0.400-inch depth of cut, taking away 350 pounds of material on one of the three parts. The material removal was so aggressive, however, that the heat generated was huge. So we flooded the work area with coolant to manage this. But all we did was drain the sumps. To take this much material off, you need to maintain adequate coolant on the inserts. We also added high-pressure coolant pumps to the right-angle heads so we could keep coolant running through the work area to remove the chips. There was also a problem removing all the chips.”

Then, Mr. Sperry pointed out that Mike Huggett, Hwacheon president, got involved and “helped us with this issue. He visited the plant, talked with Mr. Waller, and offered the solution—larger capacity coolant sumps—without any question, pushback, or cost to Mechanical Devices. That included putting the two bigger coolant sumps on an airplane and delivering them within 2 weeks. We were very impressed with that.” Now, the big machine consistently holds tolerances to 0.001 inch and eliminates heat distortion in the part.

More Work across Fewer Machines

Adding the Hwacheons for the large flywheel tripled the shop’s capacity for that part because these machines are faster than the previous machine, thanks in part to the toolchanger.

“The tool change on the turrets and setup with the Hwacheons contributes to the productivity,” Mr. Waller says, “reducing setup times by about 40 percent. Tool blocks can be removed easily compared with other machines, and the operators really appreciate that.”

The tool turret is located over top of the table and has a fast indexing speed; the rapid is the same as the smaller VT-550s. They move fast. And programming and operator interface is simple, according to the operators.

The investment in the low-maintenance machine tools’ durability and consistency is exactly what this fourth-generation, family-run contract shop will depend on to advance its reputation among its customers and the industries they serve.