Armstrong cuts setup time 94%, cycle time nearly 50%.
Armstrong International, Three Rivers, Michigan, is a leading supplier to commercial users of steam for heating, making steam traps, humidifiers, strainers, steam-powered water heaters, and more. Typically, water heated to steam is used to heat a process. It is circulated and returned to the boiler. Condensed steam is trapped and returned. Stainless steel steam traps are used in demanding petrochemical applications in cold areas where steam heat is pushed through a line wrapped around the pipe to keep oil flowing.
Reducing manufacturing cost and lead-time is important at Armstrong, as they are at other companies that are working to be globally competitive. Customers want their product shipped quickly and at the lowest possible cost. So Armstrong is always looking for ways to improve its manufacturing.
Armstrong’s process for one type of stainless steam trap took five operations to complete. First, multispindles would make the blank, then a broach would create a flat on the cylindrical part, then another machine would drill a deep hole the length of the part and another machine would drill other holes and cut other features.
According to Bill Hartman, manufacturing engineer at Armstrong, total time to setup for the part was 6.75 hours and over 4.5 minutes total cycle time. Based on that, the economic order quantity for the part was 4000 parts.
“We wanted to be the sole corporate supplier for this product line to our manufacturing plants worldwide, Bill said. “To do that, we needed to have the lowest cost per piece, and to accomplish that, we looked for a machine that could drop the part complete. We had it narrowed down to two companies—Traub and another solution which, although quicker, involved two machines and a robot. Which meant that if you had a problem, you had no back-up and would be down until it was solved.”
Bill continued, “For the same money, we were able to buy two Traub TNX 65/42 turn-mill centers. It was easy to justify because it replaced the five machines the process used to require, each of which took a day for each operation, including WIP (work-in-process) time, and took up a lot of valuable floor space. When we first saw the TNX at the PMTS show, I could hardly believe how fast it was, but Index proved the cycle time by programming and running our parts. As soon as we saw it, we knew it was the right choice.”
The Traub TNX takes only 15 minutes to setup and 2.5 minutes to run the part, dropping it complete. Economic order quantity was reduced to 2500--which fits into what Armstrong customers are asking for: no inventory on their floor and quick delivery.
There is a family of about 100 different parts in the steam trap line and most economic order quantities have been reduced 75%, making Armstrong much more responsive to market requirements and more profitable doing so.
“Special customer specifications out of the ordinary used to cause us real headaches, but now we take them all in stride,” Bill said, “dropping the parts complete with no need for any secondary operation, no matter what the part design.
“It’s unreal what these machines can do,” Bill said. And he has perspective, He has worked for Armstrong International for 39 years, 24 years in the shop, 18 of those years running New Britain and Warner & Swasey multispindles. Set ups could take up to 24 hours.
As far as tolerances required, “they are pretty much the same as previously, but during the transition from production parts made the old way to the Traub way, the welders noticed the parts were more consistent and surfaces held a weld much better. As far as accuracies, these machines just hold, Bill said. “I can’t say enough good about them,” he added.
The TNX not only reduced cycle time, but it has helped reduce tooling cost. “A deep hole is drilled in the workpiece with a carbide drill with tool life going to 2500 parts,” Bill pointed out. “We used to peck the hole until it was done, using three heads on the former machine. The drills did not last as long and could not produce at the rate the Traub does.”
“Before we got the machine, I took a 4-day programming class and learned how the Traub CAM package makes programming real easy. We had very attentive help from our Traub application engineer to help us get rolling,” Bill said. “We can program on a desktop or on the machine itself, either way. The CAM package really helped us take time out of our process—and we continually find ways to improve our cycle times,” Bill said. All the members of the 100-part family are now programmed and selection at the machine is simple, so lots of one are no problem, if needed.
“Once the program is proved out off-line, it is uploaded and the first parts are perfect, so scrap is zero—which is pretty important with stainless steel selling for $5 a lb. In addition, bar ends are 60% shorter than the ones that come off the multispindle so all told, we save a lot of cost in scrap,” Bill said.
The modular Traub TNX65/42 turn-mill centers are designed to machine complex parts from bar diameters to 65mm and a length of up to 300mm at costs that are globally competitive, thanks mainly to simultaneous use of four tool carriers—up to four tools in cut—plus identical main and counterspindles combined with powerful tool drives. The result is the ability to productively handle diverse machining processes complete in a single setup.
The machine has a 37.5/32.2 HP main spindle and counterspindle and may be equipped with two, three or four turrets, each capable of holding 10 live (with 7.4 HP, 6,000 RPM drives) or fixed tools. Each turret can travel in the X and Z direction 175mm and 650mm, and optionally +/- 40mm in the Y direction.
Symmetrically designed to assure thermo stability, the turrets are arranged on independent slides above and below the spindle centerline. The synchronous C-axis motor-spindles are identically rated at 24 kW / 5,000 rpm for the 65 mm bar capacity machine and 28 kW / 7,000 rpm for the 42 mm bar model of the TNX.
Thread milling and deep hole drilling – even at an angle – are all part of the process the Traub machines accomplish at Armstrong. Both machines are tooled alike and can do the others work. One of the tools in the turret is a heat code stamp, all done right in the machine.
The part feeds through the main spindle where the material is faced, drilled and threaded, then fed out more, and the flat is milled and then the part is drilled and thread-milled. Then the counterspindle grabs the material, pulls it out and the material is cut off, and then the part is further drilled and tapped, then the TNX drills, thread-mills, spotfaces, and produces an angled hole. No wasted time, so Bill’s group can respond to demand on a dime.
In fact, the TNX machines can reach cycle times typical of multi-spindle automatics and have proven themselves producing parts in a range of lot sizes for hydraulics, medical technology, the automotive industry, and in general machining.
Bill has noted that balanced turning of shaft-type workpieces or two dissimilar machining operations performed at the same time are key advantages of twin-turret turning characteristic of the TNX. Off-center drilling, side face milling and similar operations are performed easily. Because complex components can be completed in one setup on the TNX, Armstrong sees less work-in-progress, shorter lead times, zero fixture costs, and reduced labor.
The TNX is built on a heavily ribbed, cast iron 60-degree slant bed that dampens vibrations and promotes close tolerance machining, and permits free chip fall and good accessibility. Handling of the workpieces (loading and unloading, removal of bar remnants) is completely automated.
The control is the Traub TX8i-s running Traub's in-house developed software. The software can be optimally adapted to the requirements of the customer or application. INDEX Traub’s 3D Win FlexTM process simulation shortens set-up time and prevents collisions permitting first parts to be good parts. The real-time simulation on the control allows the operator to see what is happening by looking at the model. “INDEX spent a great deal of time training the operator at our plant. Went through a lot of information and our guys were working with the machine immediately,” Bill said.
The impact of the TNX on the processing of the steam traps at Armstrong also has had an impact on the way the manufacturing floor is organized. “When the Traubs came in, because they need only a fraction of the floor space of the old machines, we were able to reorganize our manufacturing layout to put the machining near the assembly operations, saving time in process,” Bill pointed out.
Once the bar feeder is loaded, the machines run fast. “I was out on the floor one day and noticed that the machines were not running”, Bill said, “so I approached our manufacturing planner and told him the operator said he doesn’t have any work. The planner said the machines are too fast and we did not want too much inventory on our floor. Needless to say, I’m finding more different work for the Traubs to do.”