where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

488 views
Technical Discussions
Arman
Engineering,
Turkey, Joined Oct 2014, 42

Arman

Engineering,
Turkey,
Joined Oct 2014
42
15:48 Mar-24-2020
Perspex vs Rexolite

Hi,

Does anyone have any idea what is (are) advantage(s) of Rexolite over Perspex? As far as I know, Rexolite is now widely used in ultrasonic (conventional / PA / ToFD) wedges. As Rexolite is more expensive there should be a significant advantage of using it.

Thanks
Arman

 
 Reply 
 
Ali
NDT Inspector,
Iran, Joined Mar 2013, 117

Ali

NDT Inspector,
Iran,
Joined Mar 2013
117
16:20 Mar-24-2020
Re: Perspex vs Rexolite
In Reply to Arman at 15:48 Mar-24-2020 (Opening).

Perpex wedges have lot of ultrasound attenuation compare to Rexolite.

1
 
 Reply 
 
Edward Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1303

Edward Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1303
17:29 Mar-24-2020
Re: Perspex vs Rexolite
In Reply to Arman at 15:48 Mar-24-2020 (Opening).

Ali is correct. Perspex (also called Lucite) is the trade name for polymethylmethacrylate (PMMA) and has acoustic velocity around 2720m/s and an attenuation at 5MHz of about 0.57dB/mm. Rexolite is the tradename for cross-linked polystyrene. It has an acoustic velocity of about 2340m/s and an attenuation at 5MHz of about 0.15dB/mm. Therefore, over a few mm in the wedge it is not too significant, but over a few cm it can make a noticeable difference and another effect will be that higher frequency content is more likely to be reduced in the PMMA.

1
 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 528

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
528
17:35 Mar-24-2020
Re: Perspex vs Rexolite
In Reply to Edward Ginzel at 17:29 Mar-24-2020 .


I was always taught that Perspex Phased array wedges should not be used above 2 MHz, and Regular wedges (or delay lines) not above 5 MHz.

1
 
 Reply 
 
Nick Bublitz
Other,
VeriPhase, USA, Joined May 2010, 136

Nick Bublitz

Other,
VeriPhase,
USA,
Joined May 2010
136
18:32 Mar-24-2020
Re: Perspex vs Rexolite
In Reply to Arman at 15:48 Mar-24-2020 (Opening).

Some other advantages of rexolite:
1. isotropic material with constant velocity in each axis
2. Impedance close to water
3. tight machining tolerances

1
 
 Reply 
 
Arman
Engineering,
Turkey, Joined Oct 2014, 42

Arman

Engineering,
Turkey,
Joined Oct 2014
42
19:27 Mar-24-2020
Re: Perspex vs Rexolite
In Reply to Edward Ginzel at 17:29 Mar-24-2020 .

Dear Edward,
Thanks for your valuable information of attenuation rates. I believe stated attenuation rates are for longitudinal wave in Perspex and Rexolite. Do you know what are attenuation rates of shear wave in these 2 materials. I'm asking this because I understood from a discussion in this forum that shear wave attenuation is far more than of longitudinal which helps dampening of unwanted shear waves in wedge material. Is this a true statement?

Thanks a lot

 
 Reply 
 
Edward Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1303

Edward Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1303
21:15 Mar-24-2020
Re: Perspex vs Rexolite
In Reply to Arman at 19:27 Mar-24-2020 .




I did not specifically measure attenuation rates for these materials but I did make power spectrum comparisons. The uploaded image is for the PMMA analysis. You can also notice the downshift in frequency maximum for the shear component.
Both materials can support a shear mode but the amplitude of the shear component is much lower than the compression mode. For PMMA the shear component is about 12dB lower and for cross-linked polystyrene it is about 10dB lower. However, most probe manufacturers design their wedges with the appropriate wedge-angles and suitable damping to avoid seeing internally reflected signals that originate from inside the wedge for either mode.
3
 
 Reply 
 

Product Spotlight

Ultrasonic Testing Immersion Tanks with Unmatched Scanning Features

TecScan’s non-destructive testing Ultrasonic Immersion Tanks & scanners are designed for high pe
...
rformance and demanding NDT testing applications. Our Scan3D™ line of High Precision Immersion Tanks are specifically designed for automated ultrasonic testing of complex composites parts used in aerospace and industrial applications.
>

Eddy Current inspection : RotoETscan Rotating Head

The rotating head RotoETscan detects the presence of longitudinal surface or sub surface defects a
...
t high speed. The rotating head is often installed directly on the production line. It is generally dedicated to the control of long products such as tubes, bars and wires, made of ferrous or non-ferrous material. It can also be used for inspection of small parts (billets).
>

Sci Aps Z-Series Portable Handheld Analysers

The world’s only handheld analyzer that measures carbon content in stainless (yes even L-grades),s
...
teels, and cast irons. Also accepted for low Si analysis for sulfidic corrosion analysis, and is widely used in the power industry for Cr analysis, for flow accelerated corrosion applications.
>

Extended Range Variable Wall® Piping Calibration Blocks for Longseam Inspection

This set of two blocks has been specially designed for situations where ultrasonic examination tak
...
es place circumferentially or “around the curve” for applications such as inspection of longseam welds in piping and vessels. Jointly designed by PH Tool and Holloway NDT, the blocks feature side-drilled hole reflectors positioned within novel compound-curves, each with multiple thickness steps. The unique design results in a light and compact form factor, with the largest block weighing just over 15 lbs and spanning just 16 ¾”. Coverage is provided for nominal pipe sizes from 6” to 10” in the small block and 12” to a whopping 56” in the large block. The compound OD curves and multiple wall thicknesses actually exceed ASME requirements, providing exceptional signal response and measurement accuracy. Properly managing beam divergence off the ID and stabilizing beam skew due to probe rocking is essential to maintaining a consistent calibration when inspecting lengthwise on curved surfaces.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window