by: Mary Beth Schwartz
Pages: S8-S9; October, 2000

Sun Hydraulics Corporation is a leading designer and manufacturer of floating style, screw-in hydraulic cartridge valves and manifolds for use in mobile and industrial applications. Worldwide, Sun has five manufacturing locations: Germany, England, Korea, China, and in Sarasota, FL.

Surry McFaul, an engineer with Sun, is in charge of the heat treatment facilities at the two plants in Sarasota. The heat treatment operations are used in the process of manufacturing the company's cartridge valves.

Keep it Clean

Integral to Sun's heat treatment operations is blast cleaning. "This method of cleaning was selected over traditional cleaning methods, such as aqueous cleaners," McFaul states, "because liquid cleaners just would not have done the job efficiently."

Blast cleaning is a method that relies almost entirely on mechanical forces (rather than chemical) to achieve cleaning performance. To blast clean, some form of media needs to be directed and "blasted" via some method towards a surface. Choices for media and method vary greatly, and depend on the nature of the application.

The blast cleaning is done with four Guyson Model T-40 Tumble-Blast Systems. Two Guyson systems are at each Sarasota facility. One pair has been in the heat treatment operation for about 10 years, and the other, about five months. According to McFaul, Sun chose the T-40 system because it was one of the most compact and economical units on the market.

Sun uses the Guyson systems to clean surface oxides off of parts. Normally, the cleaning is implemented after a heat treat operation, whether it is a nitrided surface, or a case hardened carbonitrided surface.

The company has no formal system, i.e., particle count, to measure the cleanliness of the parts. McFaul states that measuring is mostly a fit issue, as well as a visual issue. If the parts are not fitting together well, they are reblasted.

"Blasting a heat treated part not only cleans the surface, but gets rid of brittle, loose burrs. Clean parts are critical. Because we have such close tolerances, any contamination between close fitting parts could cause the parts to bind, resulting in malfunctioning of the hydraulic cartridge valve," McFaul states.

Guyson Corporation's Model T-40 features an automatic airwash cycle, a compact 40" by 40" machine footprint, a tilt basket design that tumbles more gently, and offers better circulation for even coverage. It also has a removable basket that can hold up to 55 pounds, or 1/3 cubic feet of components.

Sun fills its blasters with ceramic beads. This media is suited for the application, McFaul states, because it allows for mild cleaning. Tests conducted with sand, glass beads and metal shots proved to be far too aggressive.

"Our cleaning is relatively mild for blasting, but very effective for what we are trying to accomplish, in terms of removing surface oxides and burrs," McFaul states.

Before settling on one brand, Sun tested out several different ceramic beads. The company finally chose Sepr's B60 Zirblast ceramic bead. (The B60 refers to the size of the bead.) Each blaster, including the cyclone, requires 75 pounds of beads.

All of Sun's ceramic media is recycled. The company uses filtering systems, so the media is constantly in reuse. About every two months, the beads have to be replaced with fresh beads. The spent beads are sent away for recycling.

The Guyson system also does its part for the environment. Each unit has a dust collection compartment, to prevent operator exposure to the dust.

Cleaning Goals

Aside from environmental awareness, Sun is constantly striving to improve production.

For example, in the blasting area, the company has optimized the cleaning process, and made it more efficient, in terms of times, pressures and drum speeds.

Sun is also working on ways to economize other cleaning processes. One step in that direction has already been taken, with the purchase of a new aqueous cleaner, which arrived in September.

"The aqueous cleaning process will not replace the bead blast process. It will be used to remove rust inhibitor, machining oils and lapping compounds," McFaul states.

All in all, it is evident that cleaning holds high importance to Sun, just as it did to the ancient philosophers.

Engineer, Surry McFaul, has been working for Sun Hydraulics Corporation (http://www.sunhydraulics.com/) for 12 years. McFaul has a B.S. in metallurgical engineering from Purdue University.