Coolant critical element of Six Sigma conversion: the mission for the new management team of a machine shop that had been devoted entirely to the repair of industrial pumps was to quickly convert the facility into a sizable and efficient plant for the production of new parts.
Richard Lenahan, manager of the plant--the Scranton Parts Manufacturing Center of Flowserve Corp. (Scranton, PA)--remembers the situation well. He had arrived from another Flowserve plant along with Steven Loiacono, shop superintendent and programmer, to join Robert Davis, controller. Lenahan and Loiacono are both Six Sigma black belts.
"We wanted to make substantial headway quickly, and were convinced that this was the way to do it," says Richard. "We set out to measure and analyze the performance of everything, including the coolant, because it's a process input variable with great potential impact on shop output. It has worked out well."
Flowserve is one of the world's largest single-source providers of flow management products and related repair and replacement services. The products from three divisions include pumps, seals, valves, actuators and a host of others used in a range of industries, notably oil & gas, chemical, power generation, and pulp & paper.
The Pump Division is a major international supplier of industrial, engineered, and special purpose pumps. And the Scranton plant is now one of its Excellence in Manufacturing Centers, producing select pump parts for fabrication and aftermarket use around the world.
"Six Sigma is about creating excellence," Lenahan notes, "excellence in quality, productivity, processes, and any other aspect that reflects on the business."
It is a way of thinking about how things should be done in a plant or machine shop, he says--recording and analyzing data and observations about how things work, in order to be able to make informed decisions about the best ways to proceed.
There is great emphasis on study and measurement as a means of improving processes and procedures. Statistical and anecdotal information reveal the opportunities for improvements, whether it's cost, customer satisfaction, or production input and output variables.
Relying on "process mapping" and "data mining," Scranton soon established product areas in which the plant quickly could excel, looking at costs, techniques, tooling, layout, and other factors. And goals were established for quality, timeliness, scrap, rework, set ups, throughput, cycletime, productivity, quality verification, an orderly, clean and pleasant work environment, and so forth.
All areas of the operations were studied: from order taking, routing and machine staging to fabrication, inspection and final shipment. Meeting tolerances and surface finishes is important, but so is appearance and packaging--customers appreciate parts received in a good condition.
The entire shop layout has been changed twice.
Half a dozen CNC machines have been added to the shop's population of manual machines, as well as automatic inspection and gauging equipment. The lighting is upgraded, the floors improved, and on it goes.
"If you don't change the process, you can't change the outcome," Lenahan notes. "You have to define objectives, look at the processes, analyze results, and be willing to make changes."
Results? The on-time delivery percentage now is in the high 90's; scrap and rework is less than 1%, and capacity utilization is approaching 90%. These statistics contribute to a Six Sigma manufacturing quality rating that currently is at 5.3. A 5.0 rating suggests fewer than 1000 "defects" in all processes per one million "opportunities."
Part of this success is explained by the careful Six Sigma-based selection of the metalworking fluids.
When time came to address the coolant, the team decided to draw on an exhaustive Six Sigma evaluation performed at another Flowserve plant with similar machining operations and materials. Approximately 30 CNC mills of different types, including many large boring mills, were used in drilling and milling machined castings for standard Flowserve industrial pump products--operations that put a premium on speed without compromising quality.
Several types of fluids had been studied in the methodical Six Sigma "characterization" of coolants, with the idea of arriving at a fluid suitable for universal application; one that would strike the most favorable balance of coolant properties to address machine shop requirements.
The fluids were evaluated on factors such as cutting performance, stability, and maintenance issues, work environment, operator health and safety, consumption, and "bottom line" cost-effectiveness. Anecdotal commentary from machine operators and maintenance staff was analyzed, along with statistical input on various performance parameters.
Statistics on uptime, production rates, tool life, and scrap immediately reveal opportunities to improve the cost-effectiveness of machining operations, for example. Any drag on productivity and the costs associated with coolant maintenance become obvious from anecdotal and statistical data on stability, tramp oil rejection, ease of monitoring, and other indicators.
Recurring problem areas received special attention. Skin irritation, a sticky work environment, dangerously slippery surfaces on the large machines, and general cleanliness were pervasive issues.
Slippery surfaces were hazardous for machine operators who needed to move around on worktables to prepare tombstones. The "sticky" film produced by some coolants would impede cutting performance and gum up chips in the indexable drills, causing inserts to break or wear prematurely, or reduce the tools' ability to hold tolerances. And the condition would also often slow down or halt the machines' automatic tool changing operations, which could result in significant downtime.
The Six Sigma evaluations had resulted in the selection of a water-miscible, mineral oil based coolant. The fluid--Blasocut BC40SW, provided by Blaser Swisslube (Goshen, NY)--had been in universal use for several months at the time of the Scranton startup.
Improvements had been noted in several areas. Cutting speeds on the indexable tools, in particular, were up. The tool life of milling inserts and boring cutters was longer, and tolerances and surfaces were distinctly better than before. Tool changes were performed with greater ease, and the downtime associated with keeping machines clean and the work environment manageable for operators was down significantly.
Overall, taking into account all machining operations, shop productivity in the fabrication of the castings had improved by 30%.
"That coolant had indeed provided an excellent combination of performance and behavioral characteristics at the plant, and should prove valuable at Scranton too," notes Lenahan.
Uptime And Quality
Machining at Scranton had started out by drawing down inventoried supplies of three different coolants that had been used on the manual machines for some 15 to 20 years during the repair shop days; different types of fluid for vertical matching centers, lathes and grinders.
Aside from stability and health issues, coolant maintenance tended to impede productivity.
"We lost machines for longer periods of time than could be accepted," Lenahan says.
But more important was a general suspicion that machining performance on the CNCs that had been added to the shop required different coolant properties than the manual machines; machining performance likely could be improved.
"We were sure we could transfer the coolant technology from the other plant, but we still decided to do some testing and data mining of our own." Lenahan notes. As a result, the Blaser coolant was introduced gradually on the basis of "I say" estimations--Six Sigma terminology for proceeding without supporting data.
Would the product be met with operator approval? Would it work well on the still extensive selection of manual machines? And, critically, would the mineral oil based Blaser coolant yield the same results, given some differences in materials, operations, and the types of machines and cutting tools?
Scranton manufactures all turned stainless steel items and laser hardened parts for Flowserve pumps; items such as balancing and ring devices, orifice rings, and sleeves in many sizes. But a high volume of turned and cast parts in iron, steels, and bronzes also flow through the shop: turned parts, such as bushings, and cast parts, such as bronze pump impellers, sometimes 6' in diameter.
It turned out that the experiences with the coolant at the two plants closely paralleled, and the mineral oil based coolant was adopted throughout the shop. Later, following some testing in Scranton, a vegetable oil based coolant emulsion was introduced on the grinding machines, a product called Vasco 1000, also from Blaser Swisslube.
"Blasocut seems to be mild on the skin," Lenahan notes. "It has been well received by the some 60 machinists here. No complaints about health and odor."
Production has improved on the manual machines, as well as the CNCs. Downtime due to tool changes, sump charges, cleaning and the like is down over 100%--especially on the CNC side, the workhorse of the facility.
All materials are machined at higher feeds and speeds. "Our cycle times are considerably shorter than when we first started," Lenahan notes. Overall, machining times are down by an average of 20%.
The coolant has proved stable, and to effectively reject tramp oil; there is no evidence of secondary emulsions. The machines are quipped with tramp oil skimmers that run about two hours per day during idle machine time.
"Consumption is lower and we economize further by buying in bulk," notes Lenahan. "Instead of 55-gallon drums, we buy totes holding 270 gallons each. They are square and fits nicely on top of the vessel used for coolant mixing and storage."
"The great value of Six Sigma manufacturing," notes Lenahan, "is that it makes it possible for you to establish a vision, to set goals for individual areas, and then develop the strategies and methods for achieving them."
"In the beginning, you don't know what you don't know, so you have to collect data and then make concrete decisions."
It is a strategy that clearly is paying dividends in many ways at Flowserve's Scranton Parts Manufacturing Center, including in the selection of coolant, one of the process input variables too often simply an afterthought. Blaser Swisslube Inc.
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|Publication:||Modern Applications News|
|Date:||Feb 1, 2004|
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