February 13, 2007
Excessive fluid on finished parts, which required secondary cleaning operations, and additional cleaning of floors, aisles, and racks in the areas where parts were moved and stored were remedied by installing a roller system with a programmable controller.
Simpson Dura-Vent, a designer and manufacturer of gas vent and chimney products, produces stamped and drawn parts from galvanized steel, aluminum, zinc aluminum, and stainless steel with material thicknesses from 0.018 inch to 0.100 in. The stamper produces about 20 million finished goods annually on gap-frame mechanical and hydraulic presses from 30 tons to 175 tons.
The company was not actively looking for a new method to apply stamping and drawing fluids in its manufacturing operations; it already was achieving good part quality and satisfactory production levels that made it competitive. The manufacturer was fairly settled into a day-to-day routine common in most stamping companies—dealing with large amounts of costly and messy fluids and lubricants required to produce parts.
However, Simpson Dura-Vent's management team always was looking for ways to improve processes and reduces costs.
Senior Manufacturing Engineer Steve McIntyre led the charge to better manage day-to-day issues related to the usage, maintenance, and disposal of fluids. McIntyre routinely navigates efficiency improvements such as eliminating multiple operations and consolidating equipment needs and floor space requirements. The 22-year veteran investigated other methods of applying lubricants because of excessive fluid on the finished parts (see Figure 1), which required secondary cleaning operations, and additional cleaning of the floors, aisles, and racks in the areas where parts were moved and stored.
Even though the stamper determined optimal fluid amounts for its draws to eliminate defects, the lubrication process Dura-Vent was using was cumbersome and costly. The old process dripped fluid onto rags or the material and spread it out through a variety of means before the material entered the press. Because much of the fluid on the coil stock eventually ended up on the floor, cleanup also had to be performed frequently around the press area floors and on the machine. Additionally, excess fluid had to be disposed of at considerable effort and expense.
While attempting to fine-tune this process, McIntyre chose a positive-displacement low-pressure, low-volume (LPLV) roller system with a programmable controller from UNIST Inc.
"The uni-Roller® is specifically designed for coating coil stock and blank material in metal stamping, fineblanking, roll forming, and other types of coil processing operations," said McIntyre. "When used with the SPR2000 programmable lubrication controller, it can deliver the precise amounts of required fluid onto the stock, regardless of material size or feed rate."
After a month of evaluation, the stamper determined that the new application method provided a level of lubrication control not previously attainable. Dura-Vent purchased 15 systems, seven of which were installed in its Vacaville, Calif., plant.
The positive-displacement roller places a protective layer of lubricant at the interface between the tooling and the part being formed. Lubricant can be applied in different or equal amounts to both the top and bottom of the material, so that friction and force from either direction can be compensated for. "The roller system places an even, consistent layer of lubricant onto the blank just before it enters the press," said McIntyre. "Lubricant can be applied to any thickness according to predetermined requirements."
Fluid from an LPLV supply is introduced to the roller internally. Instead of applying fluid directly to the stock or external surface, the system sends fluid through a perforated tube located inside the roller, which allows the lubricant to be distributed evenly throughout the entire length of the roller. It then relies on the wicking properties of the roller material to absorb and distribute fluid onto the material. Flow into the perforated tube is regulated by a programmable lubrication control, which actuates a bank of valves at specified intervals and leaves them open according to programmed durations. Fluid can flow at the required rate from the low-pressure supply tank.
"This control feature allows for precise metering of fluid volumes and was one of the most attractive features about the system," said McIntyre. The actuation of the controller valves is signaled by the machine cycle so that fluid is disbursed at correct intervals. Varying parameters can be programmed for different parts, and one controller can contain up to 250 predetermined fluid programs, ready to be called up.
The system's precise lubricant control drastically reduced the stamper's fluid consumption.
Dura-Vent uses three lubricants for stamping and drawing. Depending on the application, each fluid was reduced by a different amount. In 2004 total consumption of the three fluid types was approximately 2,750 gallons. In 2005, with the roller system in place, the stamper used less than 730 gal. to perform the same operations—a savings of nearly 75 percent. This means that 2,020 gal. of the fluid previously used was unnecessary for cooling and lubricating parts being formed, and ended up in many other places that required attention and expense for its removal.
Secondary Cleaning Eliminated. Removing excess fluid on parts was a key problem that Dura-Vent wanted to resolve. Previously parts came out of the press covered in excess fluid and were then placed in baskets, which allowed fluid to pool on the floor and in the storage aisles. A secondary cleaning process was necessary to achieve the required part quality.
"Because the roller was applying less fluid evenly on the material's surface, cleaning was no longer required on most parts, which eliminated significant time and labor and permitted the finished part to be ready for assembly," said McIntyre.
In most stamping operations, lubricants and their subsequent handling account for 15 percent of total manufacturing costs. Dura-Vent was able to determine cost savings on individual parts that were directly tied to the fluid reduction achieved by the roller system with the programmable control.
For example, during a seven-month period, 520,000 units of a particular part realized a 4-cents-per-part savings over the period before the new fluid application system was installed. On this same part, the precise fluid control resulted in a 54 percent increase in the production rate. The previous rate of 250 pieces per hour rose to 385 pieces per hour.
A second part, a B-vent aluminum cap with an annual production of 650,000 pieces, yielded a 3-cents-per-part savings. "The savings on two parts alone already represent $40,300," said McIntyre. "This system has enabled us to save production dollars that were previously being wasted, while helping to create a cleaner, more pleasant work environment, speed up processes, and exponentially reduce maintenance," McIntyre said.
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