Why use glass beads in a blast cabinet?

Updated January 2022: Almost all of our blast cabinets are able to use glass bead abrasive media. Most operators and manufacturers know when to use glass beads and why. We’re sharing some tips that we’ve picked up over the last 50+ years in this industry remember Media Blast  manufactures more than 180 machine models.

5 Reasons to Use Glass Beads in Blast Cabinets

1. Recycle Rate. The harder the blasting abrasive the more times you get to use the abrasive, normally. This is known as the Recycle Rate and normally you can find the different harnesses on the Mohs Scale for Mineral Hardness. You can easily access a list but understand we are normally talking about minerals and this scale measures hardness from the softest (Talc) to the hardest (Diamonds).
2. The round shape of glass beads makes them stronger than glass typically ranks on Mohs Scale of hardness. Let us explain: Glass beads normally bounce off steel parts using 80 psi siphon delivery and 40 psi direct pressure delivery. Other abrasives with a similar ranking on Mohs Scale shatter the first time they hit a steel part at the same speed. This turns the machine area into a huge mess while overloading the dust collector.

ProTip: Garnet, slag abrasive, and glass beads all rate about 6.0 on the Mohs Scale. Garnet and slag are not recommended for blasting cabinets; yet glass beads are one of the most used recycle abrasives. Why? The secret is in the shape, ROUND!

3. Abrasive glass beads are fairly cheap considering they can often be recycled twenty to thirty times when used properly. Some operators might think it’s a good idea to turn up the air pressure to increase abrasive blasting pressure and cut processing time. Unfortunately, increasing abrasive blasting pressure can cause the glass beads to break apart. This reduces the recycle rate and increases the cost of the abrasive but more importantly it can overload a dust collector.

ProTip: If you are buying an inexpensive abrasive like slags that recycle very few times, it’s good to reference that glass beads recycle 20 to 30 times. So you may actually be paying more for slags which create a huge mess when they quickly plug up any dust collector.

4. Cabinet Visibility. Blasting glass beads, unlike dark, cutting abrasive, impact and spin against parts. They remove nothing from the surface and make a small, moon crater with the displaced material around the hole. This is called a physical part surface change and is technically making the part larger if you only measure the peaks of the surface. Chemically changed surfaces occur when the part surface is changed into something else. The sealed surface collects more light, similar to a mirror telescope, and makes the part brighter in color. This improves visibility inside the cabinet. Glass Beads are the same product used in the painted lines on roadways. Glass beads cause the lines to glow when your headlights hit them.
5. Peening and Part Strengthening. Peening makes a part stronger by eliminating surface scratches. When surfaces have flaws created by cutting threads, machine marks or something else, the integrity of the part surface is compromised. Shot Peening parts, normally done using round steel shot and direct pressure delivery, removes the deepest irregularities from the part surface. Softer parts like aluminum can be strengthened using glass beads and shot peening. Peening degree (intensity) has different scales based on how strong you want the part to become.

ProTip: Larger beads do not withstand the same pressure as smaller beads. Normally you need to reduce the pressure about 15% when blasting a stainless steel part, and even more when blasting super metals. The abrasive delivery method should also be accounted for because siphon and direct pressure have very different maximum impact velocities.

To Sum Up Using Glass Bead Abrasive Media

Blasting glass beads are a great choice for most abrasive blast cabinets because they recycle when used appropriately, maintain the integrity of most parts they contact, and improve visibility. Many of our abrasive blast cabinets are designed to use glass beads, check out our extensive line of machine models today.