One machine squeezes out extra work by eliminating multiple-machine operations.
Before adding the Integrex 30Y, H.R. Krueger manufactured many of its automotive parts using several different CNC machine tools. Part throughput suffered because of multiple-machine setups, part transfers between machines, and labor spent fixturing and programming each machine.
An operator programs a Mazak Integrex 30Y. The large capacity of the machine is complimented by a powerful 35-hp, 3,500-rpm main spindle that delivers high torque for roughing and high speed for finishing.
It's a familiar tale to many shops: A supplier to the auto industry was under pressure to increase throughput. Ramping up production, however, required that the shop not only have the ability to manufacture its complex parts with vastly shorter lead times but also the flexibility to control quality.
It found that accomplishing both with separate machining operations was impossible, so it combined the operations on one machine — a multitasking turn/mill center.
H.R. Krueger of Farmington, Mich., is a manufacturer of metalcutting transfer line equipment including high-production drilling machines and specialty machines such as fuel-injector test equipment. Its precision machines require components with tolerances running around 1.81 to 2 Cpk. The shop had been machining parts using several different CNC machine tools. But part throughput suffered because of multiple machine setups, part transfers between machines, and labor spent fixturing and programming each machine, says Gary Van Schoick, vice president of manufacturing. For instance, if a cylindrical part needed off-center holes drilled in the ends and holes drilled, tapped, and spot faced, the company had to turn the part, remove it from the lathe, and put it on a milling machine for the hole-making operations.
To compound the problem, H.R. Krueger had to use a dividing head on critical holes. The part would then have to be carefully fixtured in the dividing head to maintain overall precision in relation to the new holes and spot-faced surfaces. An operator was needed to remove the part from the lathe, fixture it in the dividing head, prep it for machining, and program the machine. And if not fixtured or prepped correctly, errors quickly stack up on the part.
According to Van Schoick, such complex parts were perfect candidates for multitasking. "Multitasking lets you eliminate additional setups and different machines so you eliminate the extra handling and idle time between operations. It also allows you to put more work through the machine. Quality is increased and fixture costs are decreased because the part doesn't move from one fixture to another."
Multitasking also shortens cycle times and saves costs, letting a company go from several machines to one. And having fewer machines do the same amount of work reduces labor costs and allocated floorspace.
Although Van Schoick had been keeping tabs on multitasking machine tools for a number of years, he waited until he found one that offered both a high degree of flexibility and the sizes needed for the company's product line. The machine not only had to tackle everything from steel parts to aluminum, brass, and cast iron castings, but it also had to deal with parts ranging in size from 1 1 /2-in. long by 3 in. in diameter to 6 in. in diameter and 30 in. in length.
Obviously, tool capacity and spindle size were important to Van Schoick. "We needed almost a 7-in. stroke on the Y axis with 3.45 in. on either side of center. The early machines in this class did not offer sufficient Y-axis stroke. We had to do quite a bit of research in order to select a machine tool that would cover all the parts and their sizes."
Van Schoick eventually selected an Integrex 30Y CNC multitasking center made by Mazak Corp., Florence, Ky. The machine tool has a maximum machining diameter of 20 in. and length of 60 in. It also has an automatic toolchanger with a 20-tool magazine.
The 30Y's two-position turret indexes in 2 sec and allows tools, either turning or rotary, to be used both horizontally and vertically. Y-axis turret travel is ±3.45 in., which permits off-center drilling and tapping and cross-cut milling.
Complimenting the machine's large capacity is a powerful 35-hp, 3,500-rpm main spindle that provides the necessary torque for heavy cutting operations and the speed for finishing. The 30Y's 40-taper, rotary-tool spindle is powered by a 10-hp, 6,000-rpm motor.
Other features of the 30Y include an integral AC spindle/ motor that eliminates belts and pulleys, thereby improving machine accuracies, and a rigid Meehanite cast iron base for vibration dampening and heat dissipation. In addition, Mazak's tool eye automatically measures a tool and inputs the data in CNC memory. It will also compensate for tool wear and inspect tools for breakage.
H.R. Krueger added several optional features, including rigid tapping, a larger through-hole in the spindle, and a 40-tool capacity toolchanger.
The 30Y's Mazatrol T-Plus CNC control gives H.R. Krueger the ability to program parts on the machine quickly and easily. It helps with initial job setups because the company can program parts prior to having them done on its CAD system. The shop also uses the control as a backup to its EIA programming.
The company does most of its programming off-line, says Van Schoick, because it keeps the spindle time up on the machine. "In-stead of programming at the machine, we do it with a CAD system that outputs in EIA. With programs written off the engineering CAD drawings, we don't have anybody misinterpreting figures."
Also because of the multitasking benefits, H.R. Krueger now programs only the Integrex, rather than two or three older-generation CNC machine tools, to manufacture its complex workpieces. So part programming benefits from multitasking in the same way that fixturing and machining do.
Mazak's Mazatrol T-Plus provides an interactive programming format. Also EIA/ISO and G code can be used for programming. Mazatrol has graphic verification of the toolpath to reduce trial cutting time to a minimum. In addition, the programmed feedrate automatically adjusts to compensate for actual variations in spindle motor loads. Also featured is tool-life monitoring, which lets H.R. Krueger input predetermined tool-life figures then have the machine automatically select spare or redundant tools as the service life expires.