Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations IDS on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

metallographic polishing and grinding machine

Status
Not open for further replies.

CoFe2

Industrial
Sep 20, 2018
7
Hello Everyone!

I have been looking to get a metallographic polishing machine for my company to start processing our in house tube to tubesheet weld qualifications. The scope is really just a weld cross section metallographic evaluations to measuring the penetration of the weld. It is quite an expensive test to outsource anywhere from $1800 to $3700 depending on the local lab, and that's if my guys pass first try. So I got the go ahead to invest in some equipment to run the testing in house. I have been looking at metallographic polishing and grinding machines and the prices vary quite significantly anywhere from $800 to $10,000, I would like to keep it under 1500 if possible but was curious if anyone had experience with these more economical machines?

Thanks
 
Replies continue below

Recommended for you

In a previous life we had to evaluate the weld penetration depth of a laser welded product. We would sample a product from the production line, section it with an abrasive cut-off saw, manually grind & polish, apply Nitinol to etch the surface, then evaluate the weld penetration depth. Frequency was once at the beginning of every half-shift. Purpose was to "qualify" our welding process prior to start of production. This was not research-level sampling and the requirements were fairly lax and forgiving:
[ul]
[li]sampling frequency 2X per shift[/li]
[li]sample mounting in a polymer puck was not required and hand polishing OK[/li]
[li]measured the weld penetration depth with a low-magnification calibrated inspection microscope with measurement reticle[/li]
[li]results were PASS or FAIL based on measured range & tolerance[/li]
[/ul]

The grinding & polishing process was done with a manual strip-type grinder device similar to those sold be Pace Industries (image here stolen from their website) and other companies. These types of units are relatively inexpensive and suitable for low-volume work.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1721327805/tips/PENTA-5500-b_msevnc.webp[/url]

The next step up would be the more automated rotary turntable units for higher volume and higher precision requirements.

Suggest you start a conversation with your Production & Quality Departments and get their agreement on requirements that will satisfy both groups.

TygerDawg
Blue Technik LLC
Manufacturing Engineering Consulting
 
Depending on how fragile the samples are will determine if you need to mount them or not.
If you mount, I would just go the cold two-part resin route.
They aren't great but they are easy.
The next step up from the strip manual grinding would be simple rotary unit with multiple platens for different grits.
This makes it easy and helps save paper.
You need to figure out how fine of a polish you need.
A simple manual one would work fine.
Don't buy a used one unless you can check the bearings and motor.
There isn't much to one of these and bearings are super critical.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
 
In addition to a polishing machine, do you have anyone in house qualified to evaluate the cross section photos?
 
Is the macro a requirement?, or may a RT?.
Contact a qualified personnel in RT if this give you a sufficient image interpretation.

Regards
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor