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 -

490 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

MUSE Mobile Ultrasonic Equipment

The MUSE, a portable ultrasonic imaging system, was developed for in-field inspections of light-weig
...
ht structures. The MUSE consists of a motor-driven manipulator, a water circulation system for the acoustic coupling and a portable ultrasonic flaw detector (USPC 3010). The MUSE provides images of internal defects (A-, B-,C- and D-scan).
>

Varex Imaging Large Field of View (FOV) Digital Detector Arrays (DDAs)

A larger FOV DDA can reduce the space and volume of the X-ray inspection system on the factory floor
...
, enable faster scanning times, better throughput and better resolution images at a lower dose. Customers can also save time and money. With these benefits in mind, Varex Imaging has designed a family of large FOV detectors (4343HE, XRD 1611, 4343DX-I, 4343CT) for our industrial imaging customers.
>

Wireless TOFD scanner

Quick, accurate and highly reproducible welds testing. The System operates wirelessly and is compat
...
ible with any type of Windows based Laptop, Desktop or Tablet.
>

Ultrasonic Probe Recharacterization Service

NDT Systems offers a comprehensive Aftercare and Recharacterization Service for all our ultrasonic
...
probes. The Recharacterization Service is fully compliant with International ASTM E1065 Standard Guide (and other applicable standards) and offers complete documentation, traceable to the ASTM E1065 Standard. For more details or to schedule Recharacterization Services contact ndtsales@ndtsystems.com
>

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