GLASS BEAD FINISHING ON ALUMINUM, STEEL AND STAINLESS STEEL SUBSTRATES
The aluminum clutch housing in the picture top left was previously stripped with nonabrasive walnut shell featured in pictures page one. The picture to the right is the clutch housing after glass bead blasting. In this case we are simply interested in giving the casting a bright appealing look, and not attempting to impart any specific peening or surface working standard to the aluminum. This casting will be used as a display model to demonstrate one of Eaton Corporations' heavy truck transmission lines.
The mild steel panel pictured middle left was previously stripped with walnut shell featured on pictures page one as well. Middle right is the same panel after satin finishing with glass bead. The substrate after glass bead resurfacing is now upgraded from a C to a B+. It still doesn't deserve a grade A rating because of its satin gloss. Paint will always exhibit better adhesion properties when placed on a flat matte substrate. On mild steel panels like the one above, glass bead provides a beautiful finish but still must be clearcoated, powdercoated, or wet coated to prevent rust.
On stainless steel, satin finishing with glass bead blasting will produce a high quality final product free of discoloration, grinding swirles and displaying a beautiful appearance. The lower row of pictures are some stainless steel sensor holding devices used in the pharmaceutical industry. Because they are relatively clean no pretreatment or resurfacing is necessary before glass bead finishing. When more severe weld discoloraton and spinning scale is present, resurfacing with abrasive before glass bead finishing is recommended.
To the right, a severly burned crust is covering this stainless steel spinning. Since stainless steel is a considerably harder substrate than glass, attempting to finish this without pretreatment of the stainless will take too long and cost too much. A ceramic shot is harder than glass and quickly produces a very nice finish, however, it also costs upwards of $3.15 per pound making it all but impractical for use at ten times the cost of glass. We use a pretreatment strip to help over come these problems and produce superior results at affordable prices.
STAINLESS STEEL SPINNING BEFORE
STAINLESS STEEL SPINNING AFTER
STAINLESS STEEL WELDT. BEFORE
The secret to effective finishing is to first resurface the stainless with a fine but fast cutting media. In this case a 60/120 black magnum followed with a 70/100 (#8) glass bead was used. The same process can be seen effectively employed to the left on stainless steel welds. Attempting to skip the resurfacing process will usually cause imperfections in metal tone on the finished product. It also takes three times as long and consumes twice the amount of costly glass bead v.s. cheaper black magnum.
STAINLESS STEEL WELDT. AFTER
GLASS BEAD FOR STRIPPING AND SATIN FINISHING AROUND MACHINED SURFACES
MACHINED PLATE BEFORE BEAD STRIPPING
The transmission display stand pictured left has been stripped using multiple medias. The machined surface and surrounding areas were blasted with glass bead. In this manner many structures that would normally have to be masked off, can be succesfully cleaned without additional labor and the possibility for damage when using abrasive can then be avoided all together. The remaining structure was then stripped with black magnum.
MACHINED PLATE AFTER BEAD STRIPPING
The photos to the right show the cart before processing. The wheels have been removed to prevent grit from entering the bearings. Some patches of paint delamination are clearly visible on the diamond plate. More than likely, this coating failed as a result of improper substrate preparation when the unit was first painted. By the way, diamond plate is one thing sandblasting companies dislike. It is difficult to completely clean around the diamond without leaving some material in the creases, and it must be approached from at least two separate angles.
DISPLAY STAND BEFORE STRIPPING
DISPLAY STAND AFTER BLASTING WITH TWO MEDIAS
The picture to the left shows the underside of the display half way thru the abrasive blast. Please notice that there is no paint or primer on the underside. In fact, the picture illuminates a primary cause of coating failures. The black color is a mill scale which is present on all hot roll steel products. It must be removed for good paint adhesion. And since no paint was ever applied to the bottom of the cart, we can presume mill scale is also present on the rest of the unit. You can see examples of this posted on our page entitled QUALITY.
The middle left photo is the underside after sandblasting with 30/60 Black Magnum abrasive. It has been blasted to a grade A, white metal classification for maximum adhesion and will prevent future delamination. Remember that your paint job is only as permanent as whatever you leave beneath it.
The lower left photo was taken after a two part epoxy primer had been applied. We believe epoxy is one of the best classes of primers available because of its strong resistence to a host of chemicals that attack most paints. We strongly discourage the use of cheaper noncatalized lacquer and alkyd based primers.