This way up

Oct. 1, 2002
A new HMC proves that fast is good, but increased uptime is even better.

A new HMC proves that fast is good, but increased uptime is even better.

Mori Seiki's NH5000 horizontal machining center incorporates several features — including transparent machine covers, a new concept in chip disposal, and fast spindles, ATCs, and APCs — that speed maintenance and boost cutting performance.

Transparent covers make it easy for operators to check out problems with the NH5000's tool magazine.

Good chip disposal gives shops more cutting time, so Mori Seiki used a special triple-trough conveyer that quickly removes high chip volumes from the machining envelope.

Adding an optional linear pallet pool lets users of the NH5000 eliminate extra setup times and keep the machine running continuously.

Mori Seiki engineers used finite-element analysis to ensure a stiff structure that could withstand high-speed machining

Sure, shops want speed and accuracy in their machine tools. But who would have thought a chip conveyor, transparent covers, and other features that maximize uptime would be just as important in today's manufacturing climate? The answer is Mori Seiki, Irving,

Texas, which integrated all these into its newest horizontal machining center, the NH5000.

"Our customers demand reliability, performance, speed, and accuracy," says Marlow Knabach, national technology manager at Mori Seiki. "And, of course, all of that is contained in the NH5000. But it also offers something more — specific features for lean manufacturing that directly impact machine tool capacity and address chip disposal, maintenance, and non-cutting time."

One of the first areas Mori Seiki concentrated on was a way to quickly remove high volumes of chips from the machining envelope. The company believed this area was crucial because shops, especially high-volume operations, can't afford to halt production to shovel chips. So it devised an innovative chip-disposal system using a triple-trough construction.

The triple trough consists of a center conveyor, which moves the bulk of the chips, and two spiral chip conveyors on either side that remove the rest. The resulting chip-flush area is a roomy 697.5 in. 2 . In addition, Mori Seiki fashioned the covers inside the machine with steep inclines that let chips slide into the troughs to prevent buildup.

The company also addressed mean time to repair (MTTR) in its new design. "In today's just-in-time environment, if a machine goes down, the end user is in trouble," comments Knabach. "Shops need to lower MTTR, and they need to know the average time it takes to get that machine back up and available for production."

For quick and easy maintenance, Mori Seiki kept the number of parts in the NH5000 to a minimum. It also grouped devices that require daily inspection in central locations and removed covers from components such as air valves and proximity sensors for better access. Where covers were required for safety reasons, the company made sure they were easy to remove and replace. And, in some cases, it used transparent covers so operators and maintenance personnel can check key areas at a glance.

Maintenance is further simplified through the machine's software and control panel. For example, Maintenance Navigator software includes instruction manuals, troubleshooting guides, parts lists, and disassembly procedures. Some of this information is animated for ease-of-use. In addition, the Mori Advanced Programming Production System (MAPPS) control has an alarm e-mail-sending function that lets operators, at the press of a button, display information about an alarm. If warranted, they can e-mail this information to Mori Seiki's service center through the MAPPS screen.

It's the opposite of cutting
Beyond chip troughs and transparent covers is Mori Seiki's overriding objective for the NH5000: Minimizing non-cut time. Obviously, maintenance is a big part of this strategy, but so are basic performance issues and automation support.

For instance, the company has boosted the NH5000's spindle, toolchange, and pallet-changeover speeds with an eye toward slashing wait time between cutting operations. Therefore, the machine sports a 30-hp direct-drive spindle that accelerates from 0 to 14,000 rpm in just 1.4 sec. To boot, its high acc/dec rates (0.54 G in X, 0.44 G for Y, and 0.58 G in Z), coupled with a 1-sec tool-to-tool time, yield a chip-to-chip time of only 3.2 sec. And to top it all off, the APC changes the machine's 19.7-in. square pallets in just 6 sec — even when loaded with the maximum payload of 1,102 lb.

Because continuous machining and unmanned operation are essential to lean-manufacturing operations, the NH5000 also provides several tool and pallet-changing configurations. Although the machine comes standard with a 60-tool magazine, shops may opt for a 30/40-tool, disk-type, automatic magazine; a 120-tool, chain-type ATC; or a rack-type, 150/240/330-tool ATC. And if the end user desires broken-tool detection, Mori Seiki can outfit the NH5000 with a contact-type sensor on the tool spindle or on the tool magazine. Whisker-type startup switches and a light curtain on the setup station are other choices for improving efficiency. To further add to the machine's lean-processing capability, Mori Seiki offers either a 3-station, turn-type APC, which is the same size as the standard 2-station APC; round pallet pools; or an optional linear pallet pool (LPP) that serves up to eight HMCs. The LPP has an automatic guided vehicle that carries pallets among machining centers, setup stations, and pallet stands. As for the round pallet pools, users can select a 6, 8, or 10-station version or a 3-level, 22-station arrangement.

A word on speed and accuracy
While Mori Seiki focused much of its development work on improving machine uptime, it didn't skimp when it came to cutting power and machining precision. But it also had an advantage in these areas from the onset.

To optimize the NH5000's structure, Mori Seiki used the same digital-design techniques it applied to its NV5000 vertical machining center, which debuted earlier this year. These 3D CAD digital designs — as well as Mori Seiki's proprietary analysis technologies — let the builder better under-stand machine performance in the design phase and devise such features as special rib constructions and optimal placement of strong ball guides. According to the company, digital design ensured that the machine combined a lightweight body for speed and a highly rigid structure for accuracy.