The Radicals Of Churubusco
Churubusco, Indiana, is home to a job shop that takes a radically different approach to grinding. But then, many things about this shop are radically different.
Dick Conrow, president of C & A Tool Engineering, is a radical. Ninety-five other radicals are work-ing with him in Churubusco, Indi-ana, a town of 1800 some 16 miles northwest of Fort Wayne. Together, they form C & A Tool Engineering, one of the most unusual shops you'll find anywhere.
This is a tool and die shop that also does production work. It has successfully married the traditional one-mold-at-a-time work with a "parts business"-orders for mid- -to high-volume lots that often re-peat on a regular basis.
More unusual is how the shop is run. Dick Conrow doesn't believe in supervisors. "Why should I pay someone to watch other people do the work?" He doesn't believe in management, at least not in the conventional sense. "Management means control. Nobody wants to be controlled." Instead, Dick Conrow believes in the people who work with him. "They know their jobs. I trust them. I don't have to make decisions for them." He also be-lieves in respect. "Everybody here has to find his or her own level and not feel diminished, whatever that level might be. My job is to help them make the most of their individ-ual strengths and not get in the way."
Apparently, C & A's customers also believe in this radically differ-ent way of doing business. Since its founding in 1969, C & A has grown every year, an average of almost 30 percent per year in the last ten years. In 1989, the company's business jumped 60 percent.
It has built a solid reputation for handling especially difficult jobs---complex molds, dies, special tool-ing, and production runs of tightly toleranced, high-quality workpieces for the automotive, medical, appli-ance and other industries.
Cylindrical grinding is one of C & A's specialties. Whereas most tool and die shops of this size would be thrilled to have one or maybe two new high-precision grinders, C & A has eight, four of them with computer numerical control (CNC), and one of these equipped with a CNC diamond wheel dresser.
These machines do double duty. One day it might be a subtly tapered core for a mold to make clarinet bodies (which the instrument maker had to have by yesterday); the next day it might be rollers for state-of-the-art multicolor copiers (each roller must have a 2-rms finish and 0.000025-inch roundness and 0.0002-inch TIR across their length-all 40 inches of it).
This is not to say that C & A tool is in the grinding business. It is in the business of making complete parts, whether it's one or ten thousand pieces, and usually to close tolerances. Many of these parts are round, so cylindrical grinding is a key process, but most parts also require more than grinding. So the shop also specializes in milling, turning, electrical discharge machining, surface grinding, in fact, all of the varied metalworking processes one expects to find in a good tool and die shop.
Nevertheless, C & A's cylindrical grinding operation is the heart of their operation. It is a good place to see C & A's unconventional approach to shop management in action. It is also a good place to study some very unusual ideas about grinding as well as to examine some unusual precision grinders. Even the building C & A's grinders are in is out of the ordinary.
A Swiss Chalet
All of C & A's cylindrical grinders are housed in a building decorated like an alpine chalet, complete with flower boxes and brightly painted wood beams. A big wooden sign standing at the corner has carved on it Das Schleifhaus (German for "the grinding house"). These touches make the place blend in attractively with the retail stores, dentist's offices, and other buildings of downtown Churubusco. Three renovated storefronts along Main Street are also occupied by C & A.
The chalet motif is symbolic. The grinders inside were all built in the German-speaking part of Switzerland, for one thing. For another, many of the local residents are descendants of the German-speaking immigrants who settled much of northeast Indiana in the last century. (Churubusco, however, takes its name after a place in Mexico where the American army won an important battle in 1847. A new post office was soon to be opened in that part of Indiana and naming it after the recent victory was the patriotic thing to do.) Most important, the appearance of the building is meant to reflect the dedication to quality and careful craftsmanship of those who work within.
Inside this environmentally controlled building are eight Kellenberger grinders. Offices, a break room, and an inspection lab line one side of the building, which was completed in 1989. Grinding wheels and accessories, such as a small fortune in automatic gaging heads, are stored in cabinets that line the other walls.
Given the extraordinary nature of this shop, no ordinary grinders would do, especially with the mix of jobs that pass through the shop. Tool and die work demands extreme accuracy, so the machines must be exceptionally stable and rigid. Yet, for production jobs, they must be flexible, uncomplicated to operate, and highly reliable. Dick Conrow found all of these characteristics in the Kellenberger grinders. The first of these grinders was acquired in 1975; the last one in 1989.
Six of these machines are Model UR 175-1000, one is a Model 1000U and one a Model 600U. Four of the six are equipped with Kelco 70 CNCs that feature continuous path operation for contouring, tapers, and radii; and one of them has an Engis three-axis CNC Diaform dressing unit. A manual Engis Diaform dresser, which uses 10 to 1 templates, has also been installed on the Model 1000U machine.
These grinders are built for high precision. The machine resolutions are as fine as five millionths (0.000005 inch) for offsets in both grinding and wheel dressing. C & A routinely grinds to tolerances of one "tenth" or less on both OD and ID applications and is often required to achieve finishes down to 1 rms, including workpieces in-carbide.
The shop makes extensive use of diamond and cubic boron nitride (CBN) grinding wheels as well as other superabrasives. Due to the stability, rigidity and vibration-free design of the grinding machines, C & A finds it possible to achieve extremely fine finishes using these superabrasives.
C & A's grinding shop represents a total investment of $2 million, of which the grinders account for three quarters that total. The typical tool and die shop might feel this to be a large investment but Dick Conrow rationalizes it this way: The ability to grind with such close tolerances opens new markets and brings a tremendous confidence when working with today's quality requirements. He feels that if a shop can grind cost effectively within 0.000025-inch roundness and within 0.000020 inch on size, it can handle just about any job cost effectively. If you have the precision available, it is ideal for not only tool and die work, but also for many production jobs: small to medium batch sizes with close tolerances and fine finishes.
Several of C & A's machines are equipped with Kellenberger's own menu-driven Kelco grinding controls. Advanced software built into the machine control units allows for ease of programming on the shop floor. Tool and die work is usually handled this way. Quick setup of the machine can be achieved through a "teach mode" in which the machine memorizes X and Y coordinates with the press of one button. This feature is handy for the operator during initial setup, but also when a diamond or grinding wheel has to be changed. Programs can be stored and recalled when needed, as repeat orders are an important aspect of this parts business. The advanced software is valuable for another reason. It makes CNC operation easier to learn.
The Right Mix
So mixing tool and die work with production jobs seems to make perfect sense from an equipment standpoint. Not only is it possible to mix the two, it's profitable. Dick Conrow even considers it a necessity. But his main reason is that it is good for the people in the shop, and what is good for the people in the shop is good for business. A certain synergy develops between tool and die work and the "parts business."
Tool and die work builds skill; production jobs build proficiency. Tool and die work stretches the operator's creativity and ingenuity; production jobs teach efficiency and speediness. Tool and die work can be challenging and a change of pace; production jobs provide continuity and just enough routine.
The beauty of this arrangement is, these experiences cross over. With production work becoming increasingly complex and tightly toleranced, bringing the skills of a tool and die maker to the job is a real advantage. At the same time, tool and die work is becoming increasingly competitive, with a growing emphasis on quick turnaround. Here, the ability to set up and change over quickly, developed on production jobs, comes in handy for the tool and die maker.
Most important, the operators like the variety this mixture presents. It makes their jobs more interesting and gives them a chance to learn new skills, like CNC operation. Das Schleifhaus is a lively place to work.
What makes this unorthodox arrangement workable is balancing the two kinds of work. Operators in the grinding shop set their own schedules and choose their own jobs. They get together at weekly planning meetings and decide among themselves how work will be distributed. Each worker makes his own commitment to finishing work on time, and decides for himself what overtime, if any, may be required to meet due dates. There are no supervisors.
There are no quality control inspectors, either. Each worker is responsible for his own quality. The inspection room, which is equipped with a coordinate measuring machine and various high-precision measuring equipment, provides whatever inspection services the operator needs to set up and check his own work. Inspection personnel never play watchdog.
The engineering department supports the operators as well. For example, if the CNC program for a job requires some mathematics beyond the skill of the operator, engineering will come up with the numbers. Responsibility for programming, however, remains with the operator.
Finding people with a "can do" attitude about grinding makes a difference. This is one reason why Mr. Conrow likes to see younger workers in the grinding shop. They have no preconceived notions about grinding to get in the way of taking it past conventional limits. Also, today's advanced grinders like the Kellenberger machines are so different that experience on older grinders just means there is more to unlearn.
Obviously, good communication is an absolute essential in a shop like this. Almost everyone who visits any of C & A's machining departments, including the grinding shop, notices and comments about the large white marker boards at each workstation. These boards, complete with colored marking pens and felt erasers on the ledge, are part of the company's communications network. Operators leave messages and important information such as tool offset data, maintenance alerts, scheduling updates, progress reports, even sketches to record setup details. The next shift knows exactly where things stand. Mr. Conrow is always a bit amused by the attention these boards attract. "It's so simple," he says, shaking his head, "People need to talk to each other."
Most managers would hesitate to give workers so much freedom and grinding often depends on good turning because many workpieces are roughed on a lathe. But because grinding is often misunderstood, many shops defeat themselves when they turn the part. Turning the workpiece to reduce grinding stock to a minimum is a common error. It is based on the belief that grinding is more efficient if it has less material to remove. However, this minimum stock condition is likely to be inconsistent piece to piece, given the inherent variability of the turning process. This inconsistency must now be addressed by the grinding process, where variability means constant adjustment of settings and other parameters and, thus, less consistent grinding results.
Another commonly overlooked fundamental: lathe and grinder setup must be compatible. For example, both machines must use the same construction point for center depth in relation to shoulder length. Likewise, quality control requirements for lathe work should not be underestimated by thinking that the capabilities of the grinder make tight control of turning unnecessary. Approached with the right attitude and discipline, precision grinding is, in fact, a very economical process. For shops faced with trends to tighter tolerances and fine finish requirements, precision grinding is a growth opportunity. C & A expects its grinding business to continue to grow about 15 percent a year.
Dick Conrow and his partners did not set out to be radicals. That was about the last thing they had in mind. Their original goal was to provide high precision and high quality services to solve the customer's tooling, engineering, and production needs. C & A has never gotten away from these roots. Since the Latin word for roots is where radical comes from, calling them the radicals of Churubusco is precisely right.