Feature

Materials Matter When Selecting Blasting Nozzles


By Richard Liebich, CEO, Cerbide Inc., Orchard ParK, N.Y.

Manufacturers achieve major improvements in blast nozzle life using CERBIDE™ vs. alternataive materials, including boron carbide, tungsten carbide and aluminum oxide.

ABSTRACT:
Towanda Metadyne, Inc., specializing in processing of tungsten carbide powders, and SPS Technologies, a leading manufacturer of engineered fasteners, fastening systems, and metal components and assemblies, each took part in different tests involving new blasting nozzles made from advanced hard metals. This article chronicles the results of those tests, which were based on comparisons of alternative nozzles materials.

From the beginning of abrasive blasting, when hardened steel was used for the nozzle, the industry has searched for nozzle materials that would provide better life.  Aluminum oxide and cemented tungsten carbide were the earliest improved materials. Subsequently, within the blasting community, boron carbide provided significant improvement and has become the prevailing material for blast nozzles due to its life-to-cost ratio. Clearly, a nozzle that provides a significant increase in life—even though it has a higher unit cost—is oftentimes the least expensive option. Now there is a totally new material called CERBIDE™ that dramatically outperforms alternatives.

Aluminum oxide and boron carbide are both ceramics, which means that the grains or crystals have attached to each other to form the bond that holds the material together. In cemented tungsten carbide (often called carbide or tungsten carbide) the grains are held together by cobalt or another binder which actually “cements” or glues the grains to each other. Aluminum oxide is relatively soft at 91 Ra and its typical mode of failure is straight wear. Cemented tungsten carbide (92 Ra) is harder, even though the grains of tungsten carbide themselves are about 96 Ra. The cobalt binder is much softer, so the typical mode of failure is wear of the binder, followed by pullout of the tungsten carbide grains. Boron carbide is very hard at 98 Ra, but it has a very complex lattice crystal structure. This structure results in weak planes inside the crystal, allowing failure and pullout to occur. Therefore, boron carbide’s mode of failure is some wear but mainly pullout of the crystals or parts of crystals.

CERBIDE™ is a tungsten carbide polycrystalline ceramic. The grains (crystals) have grown into each other, so it is binderless. It has the best of all attributes—very hard at 95.5 Ra; no binder to fail; and a very strong hexagonal crystal structure. This combination of attributes means that CERBIDE™ is an ideal material for wear applications. The tests described below clearly show its superiority.

The first test site was at Towanda Metadyne1, a manufacturer of precision powder metallurgy parts comprising tungsten carbide, tungsten, and molybdenum alloys. The application entailed finish blasting in a single nozzle blast machine using 80 grit media at 100 psi. All nozzles had a .240 ID x .875 OD x 1.40 L. Each nozzle was allowed to run until it reached a terminal inner diameter at which point it would not function properly. The Cerbide nozzle lasted 50 days; the cemented tungsten carbide lasted three days, while the aluminum oxide lasted just one day. The Cerbide nozzle was only pulled out at 20 days (see Figs. 1 and 2) and was then reinstalled.

Conclusion.  CERBIDE™ had a wear life 16 times greater than carbide and 50 times greater than aluminum oxide.

The second test was performed at SPS Technologies,2 a PCC Company, based in Jenkintown, Pa. The application entailed finish blasting in a Chamberlin Tumble Blast using a media grit size of 150 and a PSI of 40–60. A total of eight CERBIDE™ nozzles were run in two machines. In each machine eight blasting heads were installed (four Cerbide nozzles and four boron carbide nozzles that SPS currently uses). The test continued until all original nozzles were removed.

Conclusion. By the 16th day all boron carbide nozzles were replaced. The Cerbide nozzles were also checked at 16 days, 30 days and 60 days, but were found acceptable to continue. After 90 days the original eight Cerbide nozzles required replacement. Cerbide achieved six times the life of boron carbide. Given the results of this test, SPS has purchased Cerbide Nozzles for their various blasting departments. CERBIDE™ will save SPS an estimated $33,000 a year in just this one blasting application alone.

“These new Cerbide blast nozzles are, without a doubt, a significant improvement over our old nozzles,” said Robert Mihajlowitsch, continuous improvement engineer, at SPS Technologies. “My job is to constantly be on the lookout for new ways to improve production and save money, so when products like this come around that deliver huge savings on both production time and expense, I couldn’t be happier—and the company couldn’t be happier.”

SUMMARY
Like the paradigm shift from cemented tungsten carbide to boron carbide, we now see an industry-wide shift from boron carbide to CERBIDE™, a superior product that will change the current dynamic within the wear industry. CERBIDE nozzles last, on average, six times the life of boron carbide, thus saving the user the expense of purchasing nozzles and avoiding the downtime inherent in switching out nozzles. All of this translates into substantial savings for the end user.

For more information, please call 716-662-0274, ext. 113.  

ABOUT THE AUTHOR
Richard Liebich is CEO of Cerbide, Inc., earned his B.S. in engineering from Worcester Polytechnic Institute and a MBA from Michigan State University.

REFERENCES

  1. Towanda Metadyne, Inc. is a leader in the innovative processing of tungsten carbide powders. These powders are evolved from various sources of tungsten bearing raw materials. Towanda Metadyne, Inc. produces a high purity tungsten carbide grade powder using a carbo-waxed or paraffin binder system.
  2. SPS Technologies is a leading manufacturer of engineered fasteners, fastening systems, and metal components and assemblies. SPS’ product offering and investment strategy is focused on technically sophisticated components and materials that are necessary and vital to key end-user markets such as aerospace, transportation, power generation, racing, farm and construction equipment and general industrial.


 

Share this article

More services

 

This article is featured in:
Cleaning, Pretreatment & Surface Preparation

 

Comment on this article