LeSueur Inc.'s custom foundry in LeSueur, Minnesota, sought to detect part discrepancies in the production process as early as possible to improve the quality of the company's broad range of die castings. Critical to this goal was the ability to make rapid but precise measurements during in-process inspection operations--an activity for which the Fowler/Trimos V-600 electronic height gage was specifically designed.
LeSueur, a QS-9000-registered company, produces from 5,000 to 200,000 aluminum alloy die castings per year, depending on customer needs. The die-cast parts end up in a variety of industrial and recreational products, such as personal watercraft, small generators for recreational vehicles, diaphragm pumps, drive housings, brake-assembly plates, and office and military equipment. The castings range in size from 2 in. square to 48 in. long and weigh between 2 oz. and 40 lb. LeSueur's die-cast process allows it to produce parts that require very little secondary machining when compared to the output of other casting methods.
One of the V-600's most beneficial qualities is its high automation level, which speeds in-process inspections. The gage, which is available in both 24-inch and 40-inch sizes, can measure a variety of shapes, sizes and relative locations all with the same probe. The 14-inch height gage that inspectors used to use required probe attachments that had to be mounted by hand onto the outside of the gage. In contrast, the V-600 features a keypad function that allows the stylus size to be changed with the press of a button.
"When we measure total indicator reading with this instrument, we save between one and three minutes on a runout," says Mike Dobias, quality control supervisor of LeSueur's die cast division. "This operation used to take twice as long when we used another gage. With the V-600 all we need to do is bring the reading probe down onto the fixture and rotate the diameter, and the gage gives us continuous read-out instead of the point-to-point data we used to get. Instead of merely six or eight bits of data, we can now collect an infinite amount." This increased data-gathering capability results in higher measurement accuracy and repeatability.
The V-600 is used at LeSueur to check the size and location of holes on an aluminum die casting used for high-pressure commercial pumps. At 0.134 in. in diameter, the holes were too small for the gage previously used at the foundry, but the V-600 probes can accommodate the small size. The gage is used in conjunction with a staging fixture, a small piece of steel that holds the casting to its datum structure so that both the hole's diameter and location relative to the datum structure can be measured. The datum structure is composed of the alignment and starting points from which the measurements on blueprints of the casting originate. The staging fixture ensures that measurements for each casting begin on the exact starting points identified on the blueprint, which is necessary for consistent and reliable measurement results from part to part.
In addition to being able to measure the small cast holes, the V-600 meets another crucial need of LeSueur's: Inspectors can use the gage in real time on the production floor rather than having to transport the casting to a coordinate measuring machine in a quality control inspection lab. This capability makes the V-600 much more useful than other gages on the shop floor and saves a great deal of time during inspection.
The V-600 offers increased measuring capacity for assessing form variations, surface flatness and diameter runout. It's quickly learned by technicians, which is important to metrology operations where figures need to be obtained rapidly. "These data are key in real-time manufacturing," says Dobias. "And it's important when you're dealing with small cast holes, for example, because they'll exhibit greater variation than larger holes."
The V-600 gages offer accuracy of 0.00024 in. (for the 24-inch gage) and 0.0004 in. (for the 40-inch gage) and have resolutions of 0.00005 in. and 0.001 mm. They offer automatic centerline functions and internal and external diameter functions, incremental floating zero and preset, and measuring speeds of 60 in. per second. The electronic display, new to the V-series height gages, adds many features unique to gages of this type, including Min and Max functions and the ability to automatically calculate offsets, slot widths and grooves. Additionally, the large LCD is easy to read and understand, as it provides icons and visual cues for various measuring applications.
The gage was also designed with the operator in mind. It's simple to manipulate using a handwheel and has adjustable measuring pressure. A built-in pump, which takes the weight off of the gage so that it can be tooled (rather than slid) across the granite surface plate, provides an air cushion to reduce wear and fatigue. All of these features make the gage easier to operate and more useful on the shop floor, where good measurements are necessary to catch errors before they become major mistakes. "Early problem detection is basic to our success," concludes Dobias.