A Friendlier Oil Filter

April 24, 2006

6 Min Read
A Friendlier Oil Filter

eRemoving an oil filter can be a real mess. Metal filter bodies get slippery when covered with oil. And domed bottoms make full filters prone to tipping. If you’re not careful, you could end up with your own personal oil spill. Or you could try the new User Friendly Filter from Cummins Inc.’s Fleetguard business unit.
This patented spin-on filter for heavy-duty diesel engines does away with the stamped metal housing that made previous filters so easy to drop or spill. Instead, it features a textured, flat-bottomed housing made entirely from injection-molded, glass-filled nylon 66. More than just a cosmetic change, the use of plastics enabled the company to mold in features that make the filter easy to handle and remove. Plastics also helped the

Fleetguard had been doing just fine with metal filter bodies for years when the idea of plastics first came up about two years ago, and initially cost was the driving force behind a possible materials switch. “Steel prices were going up at the time, and we were asked to look at alternative materials just in case,” recalls Ismail Bagci, a staff mechanics lead who worked on the filter. But once the design team started investigating plastics, they quickly realized they had an opportunity to add ease-of-use features during the molding process.

company hit its cost targets, in part by enabling a significant amount of parts consolidation. Finally, the plastic filters can be incinerated at the end of their life, an increasingly attractive alternative to draining and landfilling spent filters. “Stamped metal wouldn’t have allowed us to do all that,” says Kevin South, one of the Fleetguard design leads responsible for the new filter.

Fleetguard had been doing just fine with metal filter bodies for years when the idea of plastics first came up about two years ago. Initially cost was the driving force behind a possible materials switch. “Steel prices were going up at the time, and we were asked to look at alternative materials just in case,” recalls Ismail Bagci, a staff mechanics lead who worked on the filter. But once the design team started investigating plastics, they quickly realized they had an opportunity to add ease-of-use features during the molding process.

Ease-of- Use Features

Two of those molded-in features immediately stand out. One is the beefy set of ribs that form a flat resting surface on the filter bottom — as well as giving users finger holds to make tightening a bit easier. According to South, these ribs give the oil-drenched filters a lot more stability than a domed metal surface found on nearly all previous filters. And stability counts given that these filters go on tractors and earth-moving equipment that have their oil changed in the field. “There isn’t always a flat place to set down the filter once it’s been removed,” South says, adding that Fleetguard conducted a user survey that highlighted the importance of making filters less prone to tipping and spilling. The other noticeable feature is the built-in recess for a standard socket wrench. Nestled in the center of the rib structure, the socket hole allows users to remove the filter using a half-inch socket — a helpful feature for hard-to-reach filter locations. Bagci notes that the hole, whose design is patented, has ramped surfaces that prevent users from using the hole to over-tighten the filter. “It only works in the counter-clockwise direction for removing the filter,” he says.
Plastics offer yet another benefit related to improper installation. Because the softer nylon threads will strip before those on the metal filter spud, plastics provide built-in protection against over-tightening and cross-threading. As South points out, “a broken filter costs a a whole lot less to replace than a spud.”

Cost Play

The use of plastics also worked to Fleetguard’s advantage from a cost standpoint. Neither Bagci or South would reveal how much the company saves on each filter. And at first glance, it might seem like plastics wouldn’t beat out steel, especially when you have to build new injection molds. Nylon, however, offered significant parts-consolidation opportunities that helped make it cost-competitive. According to Bagci, a typical metal filter consists of 13 components. “With plastics, we brought that number down to seven,” he says. For example, the design team eliminated a welded nut plate and retainer assembly and a related press fit seal with a single plastic part that holds a molded-in gasket.
Other cost reduction strategies involved the use of off-the-shelf nylon rather than any specialty compounds. South describes the material as a “readily-available, 33-percent-glass-filled nylon.” It’s nothing special, but it still met all the application requirements, which include dynamic strength and burst tests to 300 psi at 300F. In order to get UL approval for marine applications, the filter had to pass salt spray and burn tests (at 1200F). Fleetguard also tested the nylon filters to establish acceptable creep loads, something it didn’t have to do with metal filters. Fleetguard’s other cost reduction strategies related to optimizing tooling and assembly lines for plastics. South explains that the design team favored modular filter components that could be used on different product lines. “It’s harder to commonize parts for the metal filters,” he says.

Doing It Right
While Fleetguard’s design team started on the new filter — the first of its kind — they had a limited amount of plastic design experience. But they managed to take it from concept to production in just six months. Bagci credits much of the speed to extensive use of computer-aided engineering tools. “We went through hundreds of iterations on the computer, but only had to build one prototype assembly before going to production tooling.”

In the course of analyzing those virtual design iterations, Fleetguard’s engineers used Ansys for much of the structural analysis work. And they ran mold-filling simulations, using software from Moldflow Corp. to establish gate locations that would keep knit lines away from high-stress regions of the filter housing.
Fleetguard introduced its User Friendly Filter in February and now has models for a wide variety of heavy-duty diesel engines.

Reach Senior Editor Joe Ogando at [email protected].

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