Quality Waterjet Newsletter – 03/29/2005

Does Abrasive Waterjet Cutting Cause Surface Hardening?

Shot peening can induce surface hardening is a well-known fact. There were also reports of using plain waterjets for the similar purpose. Therefore it is natural to raise the question: does abrasive waterjet cutting have the same effect of surface hardening?

A few research studies have been conducted to investigate on this subject. Their findings are summarized in the book "Principles of Abrasive Water Jet Machining" (by A. Momber and R. Kovacevic, 1998), section 8.3.2. Micro-hardness measurements were done on several metals, cut with abrasive waterjets, including Steel 4340, Carbon Steel A 572, Tool Steel A2, Titanium, Aluminum 6061-T6, Magnesium, Cr-Mo Steel, and a type of metal matrix composite. Their conclusion is that no appreciable surface hardening occurs in abrasive waterjet cutting. Hardness alternation due to abrasive waterjet cutting is lower than that due to EDM-machining.

A later study by Groppetti et al. (*) took micro-hardness measurements extremely close (within 37 microns or 0.0015 inch) to the cut surface of a stainless steel sample (AISI 304), cut with an abrasive waterjet. They found that the hardness alternation is significant (60% higher) at about 8 microns (0.0003 inch) from the surface. But hardness alternation quickly reduces to almost zero as the distance from the surface increases to 20 microns (0.0008 inch) and more. They concluded that abrasive waterjet cutting introduces a hardened layer of about 20 microns in thickness.

* R. Groppetti, T. Gutema, and A. D. Lucchio, "A contribution to the analysis of some kerf quality attributes for precision abrasive waterjet cutting," Proceedings of the 14^th International Conference on Jetting Technology, Brugge, Belgium, September 21-23 1998, pp 253-269.

Beyond High Pressure

· USDTC, not satisfied with the waterjet bricks on the market, went out to manufacture its own, and is serious and bold enough to register a trademark "Best WaterJet Brick". Contact Charles Thiemann at crt@usdtc.com for information.

· Call for participation: WJTA American Waterjet Conference will be held on August 21-23, 2005 at the Marriott Westchase Hotel in Houston, TX, focusing on advances in HP waterjet technology, new techniques & applications, systems/supplies/ equipment. For details, visit www.wjta.org or call (314)241-1445.

· Job opening: seeking experienced CNC Programmer with solid 2D and some 3D programming experience for shop in Orange, CA. Ability to program various CNC machines is required. Send application to Jobs@laserindustries.com.

· Used waterjets for sale:

o 4'x8' Flow Flying Bridge, 40hp, 55Kpsi, contact bruceker@aol.com.

o 6'x12' IR, with 40hp IR pump or 100hp Flow pump; contactmgreen@northstate.net.

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Quality Waterjet

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· HDPP rather than softer HDPE material

· 4"x6"x48", 6"x6"x48"

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· Available in 900 g/m² standard density and 1,200 g/m² heavy duty density

· Contact info@qualjet.com for details.

QualJet LLC

12819 SE 38th Street, #240

Bellevue, WA 98006

1-866-QUALJET (782-5538)

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Email: info@qualjet.com

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