----------------------------------------------------Business Index & ASAP------ AUTHOR(s): Vasilash, Gary S. TITLE(s): There's no such thing as 'free' SPC. (implementing statistical process control) Summary: Implementing statistical process control (SPC) involves careful planning, but it can have major quality and cost control benefits. Robert Bosch Corp (North Charleston, SC) electronic and technical computing engineering unit manager Lee Swenson feels that many companies are unsuccessful with implementing SPC because companies fail to recognize the costs in man-hours of conducting statistical tests. Bosch reduced the man-hours involved in conducting statistical measures in his unit by connecting measuring gauges directly to a computer which conducts the statistical analysis and provides operators with immediate feedback. The computerized measuring and analysis system has several advantages including: freeing workers to produce more parts; maintaining a constant measuring accuracy; and notifying operators of needed maintenance. Production p68(3) July 1989 v101 n7 DESCRIPTORS: Statistical process control_Analysis Quality control_Analysis There's No Such Thing as `Free' SPC Economists tell us that we can't get free lunches. Yet some companies think that they can add statistical process control to their operations without having to pick up the tab. They may also be interested in buying the Brooklyn Bridge. SOME COMPANIES COMMIT TO STATISTIcal process control (SPC) because someone gets a gut feeling that it will help production. This is the antacid approach. Another company will go with it because someone reads about it in a magazine or hears about it at a conference and becomes convinced that it's the thing to do. This is the converted approach. But Lee Swensen, unit manager for electronic and technical computing engineering at the Robert Bosch manufacturing facility in North Charleston, SC, says that about 90 percent of the companies that make the move to SPC do so for another reason. It's one that might be called the coercion approach. This 90 percent implements SPC because they are forced to by their customers. That is, no SPC, no orders. Neat. Clean. Binary. And plenty of customers--those in automotive, aerospace and the government, in particular--have such rules. Quality isn't an option anymore. Swensen knows a little something about such rules and requirements because the North Charleston Bosch plant produces fuel injectors, hydraulic pumps and other auto components. What not to do. Okay, so there are people who have somehow been led to the conclusion that SPC is what needs to be implemented. "So how do they do it?" Swensen asks, then answers, "They read a book. Build a chart. Mimeograph the chart. Get pencils for their machine operators to fill in those charts with, and some scrap paper for performing calculations. And maybe they'll even buy $9.95 calculators." To be sure, they do a bit of operator training, explaining what these additional pieces of paper are and why they can help do a better job. But with these few exceptions, that may be that. They are conforming to requirements, and it has cost them, for all practical purposes, nothing. Swensen comments, "Although they imagine that this is `free' SPC, it's actually very costly." Swensen cites the man-machine rate to explain. This rate represents the number of machines a person may operate effectively, taking into account all possible interruptions, including such things as tool change, chatting with a coworker, and paying a visit to the lavatory. Real life interruptions. Assume a person can handle more than one machine: say three. The process should be engineered such that the worker is able to handle 3.1 or 3.2, rather than 3 machines. Obviously, no one can work one-tenth of a machine. The additional "machine" to the right of the decimal point is to provide a little slack, to absorb events that hadn't been part of the original calculations. It helps deal with things like Murphy's Law. More is less. Swensen says that if it turns out that a person is capable of handling 3.6 machines in a setup, that's a bit too generous; it's excessive downtime. Something needs to be changed to bring that up to 4.1 machines, or the individual should be given additional work to do. Given that the average cost of a machine tool at Bosch is $225,000, the company likes to keep its investments active, as any company should. Say operators are capable of handling 3.1 machines and "free" SPC is introduced. "So," Swensen says, "you give the guys forms, pencils, and, because you are feeling generous, $19.95 calculators. The machine operators have seven parameters per part to measure on 50 parts per day, and they must do this for each of the three machines they're operating. This added work does not allow the 80-to-90 percent efficiency that's expected." These people are busy scrambling to fill out forms while trying to meet the production schedule. And what is the likelihood that broken pencil points or lost pencils are figured into the man-machine rate? Not even snazzy work tables help. If a process is engineered properly, "free" SPC is a myth. Swensen knows of a plant where a "free" SPC program was yanked from a pilot program in six weeks' time because despite the nice, specially built stainless steel tables upon which machine operators could pencil in their forms, they couldn't keep up with what they were doing. "The company had a choice," Swensen says. "It could keep the `free' SPC and hire 15 additional people, or they could get rid of it." Just as Swensen doesn't believe in "free" SPC, he does believe as strongly in the machine operators' being responsible for the quality of the products they produce. "How can a second party be responsible for the quality of your work?" Swensen queries, adding, "Quality is built into a product, not inspected in." This is not to say that there shouldn't be a quality department should perform some fairly specific functions, one of which is not to audit what the machine operators have done. Swensen observes that what a quality department ought to do is be responsible for the form, fit and function of products--those characteristics that are directly related to the customers' concerns. The quality department is responsible for the aggregate, not the elements. There is an audit function, however. The department must also audit certain critical parameters, but only to make sure that the gages are accurate. Making sure that the machines are producing parts as specified is something that the operators must do themselves; no one else can do it as effectively. They did it their way. Bosch operates with some 1,800 associates (as in "employees") and 400 machines in its North Charleston facility. Because it must have product quality, it developed, with the aid of Industrial Microsystems, Inc. (Columbia, SC), what's called BOQUIS: Bosch Quality Information System. BOQUIS is a tool that's used by machine operators--and it's a tool that they actually contributed to, providing some 60 percent of the information that was crystallized into metal, plastic and silicon--to operate effectively. Essentially, BOQUIS consists of dedicated microprocessor-based workstations on the floor that are connected to an area controller, which is a Hewlett-Packard minicomputer. In the first phase of its BOQUIS implementation program, Bosch installed 25 workstations. Phase two, underway now, will add 40 more and another minicomputer. According to a spokesman from Industrial Microsystems, plans call for the installation of some 200 units. The workstations are used in lieu of paper, pencils and calculators. The operators still use the same gaging tools as were used prior to BOQUIS. Specific interfaces were developed so that the various gages can be plugged into the workstation; gage interfaces exist for glass scales (Heidenhain), gages (Federal, Mitutoyo, Fowler, etc.) and LVDTs (Sangamo, Tesa, AG Davis, Standard). Industrial Microsystems refers to the setup of the system as being like "an industrial stero": components can be plugged in as required. Information, not data. The operator still performs the same measurements as before installation of the system. But once the measurements are taken, it's simply a matter of pressing a button to enter the data into the system. Then, those data are automatically translated into useful information that can be used by the operator, such as X-bar and R-charts, histograms, and alarm messages. (Observes Swensen, "Data doesn't mean anything.") And about the only other kink that the system adds to the activities is that when a new part is being gaged, a new part number must be requested. No forms are filled out (correctly or otherwise); no one has to wander around the plant from machine to machine to pick up completed charts. The data collected by the workstations are sent to an Oracle distributed relational data base. Information is analyzed with the BBN RS/1 analysis package that permits the development and generation of specific reports, charts and diagrams, which can then be used by management. (Industrial Microsystems has also developed a series of software packages as part of what it calls the "TQC Executive," which performs a variety of tracking, monitoring and planning functions.) The operator, based on the feedback shown on the screen, can make necessary process adjustments as he or she sees fit. Swensen believes that many of the feedback process adjustment systems available today are based on straight-line calculations that tend to go overboard on modifications to the point of setting up oscillations in the process. That is, whenever there's a slight drift, the process is tweaked; this tweaking goes too far beyond what is statistically sensible. "The operator is the best decision maker in the world. If he or she wants to move the process back to center, then this system provides the information to do it." Plenty of benefits. Swensen says there are several direct benefits being realized through the use of the system. For example, the company never really knew what the capabilities of its manufacturing system are. Now it has a comprehensive history about its processes. The subjectivities related to gaging--operators guessing at readings or splitting figures--are eliminated, which results in better parts. Values are actually measured values, not estimates. Swensen acknowledges that there are some departments in the manufacturing facility where there is zero scrap, but he doesn't think that this is necessarily a result of the system; he doesn't claim that BOQUIS is some sort of panacea for production ills. He points out that this zero-defect rate may have been the case before BOQUIS was installed; now the company knows it. Gage maintenance is improved. When recalibration is required, the operator is automatically notified. Then, after recalibration, the system indicates how well it's been done. At Bosch, the total spread between gage initialization and recall is 10 microns. There's little room for error. Timely toolchanging. The system assists the operators in changing tools when actually required. Swensen says that typically there's one operator for four machines. Consider that there may be nine tools per machine, each tool with a different change frequency, and each machine on a different cycle. Imagine trying to keep up with all that--in addition to doing the necessary parts measuring cycle. (And if that's not enough, throw in having to fill out forms, for good measure.) Swensen says that the workforce at Bosch is, primarily, young, intelligent, and dedicated; it had a tendency to err on the side of caution and changed tools before it was necessary. With the SPC system in place it's calculated that in just one section of one department direct tool savings of $35,000 per month are being realized. Tools are changed when needed. Cutter grinding needs are lessened. The tool crib needs to stock fewer tools in inventory...The effects are not just felt in the quality of the product. According to Industrial Microsystems, workstations alone (i.e., without gages or a network) cost about $12,000. Given that, it is apparently a much better deal than "free" SPC. PHOTO : The machine operator's task is no different than it was before--he must still gage parts PHOTO : with conventional gages--but what is different is that through the use of the SPC PHOTO : workstation, he is able to get real-time statistical feedback about the condition of the PHOTO : process. Adjustments can be made as required.