Auto Blasting with Glass Grit

Coatingsguy (thank you!) posted a couple of great before and after pictures of an auto restoration blasting project. The van in the picture above was stripped and ready for priming after blasting with Fine Crushed Glass Grit. Per his comments (link below), the van required 5-1/2 bags of media and 4 hours.

Here is a link on contractortalk.com. Thanks again for sharing.

Auto Parts Polishing

Question: I am interested in starting a metal polishing business mainly for car parts. I am wondering if your wet tumblers would be best and what type of media would be best for polishing aluminium, rough cast intake manifolds? I have polished some by hand using sand papers, air grinders with various deburring bits and abrasive wheels, polishing wheels and compounds. This is very time consuming, dirty and tiring work. I am looking at an easier way! I am also interested in smoothing and peening other cast or forged metal parts for increased strength and durability!

Response: There are a number of different ways to clean and polish auto parts. Depending on the final finish required and the size, shape and geometry of the part, the final surface finish can range from a smooth, bright finish all the way to a near mirror finish.

If parts simply need to be cleaned prior to painting or coating, blasting with Glass Bead will result in a smooth, satin-like or matte surface finish. If additional polishing is needed, vibratory (or barrel) tumbling with a Polishing Precision Ceramic or Stainless Steel Media can produce much smoother, brighter finishes. The key with both processes is to select the proper media shape and size based on the part and areas of the part that need to be finished. The size of tumbling equipment is based on the size and quantity of parts that need to be finished.

High Performance Engine Parts

Restoring cars, motorcycles and trucks using abrasive blasting is achieved best when the proper media is selected for different areas of the vehicle. Just as it is important to use an aggressive media on a heavily rusted frame or a non-warping media on thin panels, blasting engine parts also demands the proper media selection.

Glass Bead is a very popular media for blasting engine parts. This media will strip paint, oxidation and soils without etching the surface. Glass Bead leaves a smooth, peened surface finish. In some cases (especially high performance engines), the surface tolerances are extremely critical. Blasting with Glass Bead can result in clean parts but potential diminished engine performance.

Before

This engine part (above) required the removal of oxidation on the metal. Blasting the part with Glass Bead produced a very clean finish but was too aggressive on the surface finish. The blasted part (below) was blasted cleaned with an Extra Fine Walnut Shell Grit. This much softer media removed nearly all of the oxidation with no impact to the metal surface. This part is now ready for further processing to prepare it for the high performance required.

After

Thin Aluminum Blasting

Using abrasive blasting for auto restoration can be a very challenging process due to potential warping of the thin metal panels. Many different blast media can be used such as Walnut Shell Grit, soda, Plastic Abrasive Media, sand and Crushed Glass Grit. While each of these media have different benefits, Crushed Glass Grit is growing in popularity for this application.

While the abrasive media being used is critical, the blasting procedure itself is just as important. The soda can -used to simulate a thin car body panel- on the left was blasted with Fine (70/100 mesh) Crushed Glass Grit at 60 psi. Notice the excellent stripping of the printing but also the warpage and deformation on the thin aluminum. The can on the right was blasted with the exact same media but at 30 psi. The stripping result was also excellent but there is no indication of damage to the metal.

While Crushed Glass Grit is a media generates heat during blasting (like coal slag, sand, garnet and others) which can warp thin metal, the process used by the operator to provide a quick strip rate -typically faster than Walnut Shell Grit and soda- is as important to achieving successful results.

Glass Beads for Auto Restoration

We have been receiving lots of calls from auto restoration companies and hobbyists looking for recommendations for stripping engine parts. A major concern is removing old paint, dirt and grime from aluminum parts that need to be repainted.

While each customer has a preference for surface finish they want to achieve, we have found that Medium Glass Beads offer the best balance of strip and clean rate with surface finish. This mesh size of glass beads leaves a satin-matte finish (if that makes any sense) which is perfect for painting or powder coating.