by Andrew Brooks
The Problem: Sourcing parts for an aging CMM
The Solution: Bring a new CMM on board
A product that lasts is never a bad investment. But for Hiltap Fittings Ltd. of Calgary, Alberta, buying a seemingly immortal piece of equipment turned out to have a down side, though it didn’t become apparent until many years after the purchase.
Hiltap, which is part of OPW, a Dover Corp. company, makes fittings for customers in the aerospace, chemical/petrochemical, oil and gas, and nuclear fields, among others. The fittings are used in applications where chemicals are being transported between locations, whether that’s loading railcars and tank trucks, high- and low-temperature plant applications or a range of catalyst applications in plastics plants. The metal-to-metal sealing technology is ideal for high-temperature applications in particular. One notable example is the ball check valve Hiltap makes for an aerospace customer, who installs it in the autoclaves used to vacuum-form composite airplane parts.
“A lot of our fittings are used where people meet pipes, so we need to be able to guarantee a tight seal,” says Colin Bielesch, Hiltap’s plant manager. In addition to their highly efficient seal design, Hiltap’s products are constructed for ease of use. “The fittings are very user-friendly,” Bielesch says. “Users can achieve a seal at medium to high pressures easily and quickly. It saves them time per connection.” That user-friendliness is a direct product of Hiltap’s wedge seal design, which enables operators to achieve a high-quality seal without using a lot of torque or a complicated coupling procedure.
Unsurprisingly, quality assurance is one of the most important jobs at Hiltap. And that’s where the long-lived machine in question comes in. It’s a Mitutoyo FJ-805 CMM. Hiltap has been using it to verify the highly exacting tolerances of its fittings since 1987.
“Our couplings consist of a precisely machined metal-to-metal seal,” says Bielesch. “We use the CMM to qualify taper angles to ensure that we achieve a seal on all our components.” Hiltap has been using the FJ-805 to run quality checks on the first unit in a production run and then every tenth unit after that. The measurements are made within microscopically small ranges. When multiple measurements need to be made of the same fitting, the numbers generated need to be extremely close to each other.
The FJ-805 has been “a very solid machine” and has consistently yielded highly accurate readings over the years, Bielesch says. But age inevitably started to tell, and because the FJ-805 was Hiltap’s only CMM, when it went down, quality assurance ground to a halt, which in turn halted production. That wasn’t such a problem when replacement parts were easy to get. But as the decades passed, finding those replacement parts became more of a challenge. The spells of downtime started to grow longer.
Al Leskow started work with Mitutoyo Canada a couple of years after Hiltap acquired the FJ-805. The sales and application specialist has watched the company’s FJ-805 do its job over the decades, and he likens Hiltap’s increasingly lengthy searches for replacement parts in recent years to an automotive enthusiast’s attempts to find a generator for a 1958 Chevy–only he says Hiltap’s searches were tougher. “Over 28 years, you’re going to get maintenance issues with wear and tear. The technology changes so much you can’t always retrofit when you’d like to,” he says.
“For the last few years parts have definitely been an issue,” Bielesch says. “But the biggest issue for us has been the repeatability of the measurements.” Seal tolerances range between +/-0.001 inch and the angular tolerances on the tapers are within 0.05 seconds of arc. The FJ-805 is rated to extremely close tolerances, but as the years went by, repeatability was starting to suffer.
There were other factors too. The FJ-805 just wasn’t operating as smoothly as it used to within its full nominal measuring range.
Also, based on anticipated growth, Hiltap simply needed to expand its production capabilities, while at the same time reducing the cost and time associated with its demanding product inspection regimes. The FJ-805 is not nearly as automated as today’s CNC machines, and a higher degree of automation was looking like a better idea all the time.
Finally, in May of last year, Hiltap took delivery of its new Mitutoyo Crysta-Apex S574 coordinate measuring machine. While the trusty FJ-805 is still in use, the bulk of Hiltap’s measuring work now goes through the new CMM.
“We looked at other units and felt that Mitutoyo offered the best accuracy available for the budget we had,” Bielesch says. “We were more familiar with the product, and based on the experience we had with the old unit we knew that they stand behind their products.”
As expected, one of the biggest advantages of the new CMM has been the time savings. Much of that has to do with the fact that with the FJ-805, the operator has to use a joystick to position the CMM’s probe for measuring. “Some of the seals are very tightly toleranced with very small spaces, so you have to be very careful and operate at a slow speed,” Bielesch says.
The new machine measures much more quickly, with the average program taking 30 to 60 seconds to run, rather than the two to five minutes typical of the FJ-805. That’s a big difference when you consider that production runs range as high as 500 pieces. Setting up a program for the S574 to run still takes operators a bit longer, but as they gain experience Bielesch anticipates that program setup will take about the same time as it does for the FJ-805.
The S574 operates on a rack and pinion drive, which is robust and less sensitive to the local environment. The FJ-805’s controllers slide on air bearings, which meant that Hiltaphad to maintain a very clean environment for the machine to operate properly. “We have to lubricate the ways and clean them with the proper solution,” Bielesch says. Unlike the FJ-805, the S574 has a built-in temperature compensation system that maintains guaranteed measurement integrity between 16 and 26 °C.
And repeatability of measurement is no longer an issue. “With the new machine, we can measure twice and get an almost identical measurement,” Bielesch says. The variation between repeat measurements on seals is within tolerances, and the taper angle numbers are nearly exactly the same.
With the increased speed of operation, Hiltap can now do more measurements. “We rely on this as the primary quality control to ensure that the seal angle and sizing are accurate,” Bielesch says. The frequency of checks has gone from every tenth unit to every fifth, thanks to the reduced inspection time. On critical measurements they can check every unit.
While the FJ-805 will continue to be used in some applications where time isn’t as critical, the torch has been passed at Hiltap.
“The FJ-805 has been a warrior for us,” Bielesch says. But sooner or later even the toughest warrior needs reinforcements. SMT