Frequently asked questions
Which hardness tester shall be used for chromium hardness testing?
Hardness of metal coating can be tested by ultrasonic hardness tester, MET-U1, which is based on contact impedance method.
We are thinking about the purchase of hardness tester of MET series. What is the time of delivery to Belgorod, Kharkov region? What are the advantages of your hardness tester as compared to othe hardness testers?
The time of delivery is 5 days after the payment. The cost of delivery to Kharkov is about 700 RUR by PONY express, the cost of insurance including.
The main distinctive feature of hardness testers of MET series as compared with all other hardness testers consists in the fact that they are calibrated on the hardness reference test blocks of the first category which are verified on the primary hardness standards of Russia (FGUP VNIIFTRI), that is why the transfer of a scale from standard to user is more exact. Moreover, all hardness tester scales (Rockwell, Brinell, Vickers and Shore) are calibrated directly, on hardness reference test blocks (without any conversion tables). This is one more significant advantage related to the testing accuracy. Our company is the developer and manufacture of this instrument, so we sort out all related to its maintenance issues ourselves.
And it is up to you to decide in what way it is better or not in comparison with similar instruments, proceeding from you requirements.
We are planning to purchase a portable hardness tester of MET series to test hardness of crankshaft journal. Could you recommend which hardness tester is the most appropriate.
Ultrasonic hardness testers do not leave any imprints on the tested article surface. Even if the mass of the article is more than 3 kg, we recommend to use ultrasonic MET-U1 hardness tester and not dynamic MET-D1 to test hardness of crankshaft journal. The guarantee period is 3 years. After the first year of application, the setting and adjustment of hardness testers is performed by MET centre free of charge.
Is it possible to find out the reference impedance of metal after testing its hardness?
Hardness testers of MET series make it possible to find out tensile strength (breaking stress rapture limit) of a tested article. This scale depends on hardness on Brinell (GOST 23766) and may be used for pearlitic steel only.
Recently, the question of your products certification on the territory of Ukraine is becoming an urgent issue.
All hardness testers of MET series have been certified in Ukraine, Byelorussia and Kazakhstan. You can see the certificates at our website.
Is it possible to bring our instrument together with the samples at your premises and calibrate it? How much it will cost?
It is possible. It is necessary to have not less than two samples of metal or alloy used by you, but they shall be of different hardness. Calibration of additional scales is free of charge. Additional scale were initially meant for measuring hardness of metals which are significantly different from steel in their qualities. We need additional scales to calibrate them directly (on samples of a metal or alloy which is used) for the user to have accurate measurement results. A certain factor corresponding to this or than metal grade is introduced at almost all existing portable hardness testers. The development engineers and metrologists of our company consider this method unacceptable because it brings about a significant error.
Which GOST requirements do your portable hardness tester comply with? (Or with any other document?
In this country, there is no standard for portable hardness testers. Hardness testers of MET series (MET-U1, MET-D1, MET-UD) have been introduced to the State Register of Measuring Equipment, there is type approval Certificate for them, the company has the license for their manufacturing and repair. They comply with their specifications and data sheet. FGUP "VNIIFTRI" developed verification procedures for them, which enable to perform periodical (once a year) verification of hardness testers at centres for standardization and metrology, which have accreditation for the right to perform measuring equipment verification.
Can MET-D1 be used for cylindrical surfaces?
Sure. As well as ultrasonic hardness tester. Radius of surface curvature for dynamic probe is not less than 10 mm, for ultrasonic probe it is not les than 5 mm.
Is it possible to use MET-UD for plastics and rubber?
No. Hardness testers of MET series control only hardness of metals and alloys.
Which hardness tester is suitable for testing hardness of pipes having the wall thickness of less than 16 mm?
Considering the error as fixed in the Data Sheet, it can be done only by ultrasonic hardness tester MET-U1, since the testing by dynamic hardness tester MET-D1 involves certain procedures and accessories which increases the testing error significantly thus reducing the accuracy.
What is the time of delivery for reference hardness test blocks of MET series?
From one day to three days after the payment, including their verification at FGUP "VNIIFTRI". If the order is for more than 100 pieces, then the time of delivery starts from seven working days.
Do we need to regrind reference hardness test blocks to the base plate for checking the readings of combined portable hardness tester MET-UD? Shall we calibrate hardness tester in case of testing using precision holding fixture?
To verify the readings accuracy obtained by dynamic method, it is necessary to regrind reference hardness test blocks to the base plate, since mass the reference hardness test blocks is 200 to 1200 gram. The dynamic method (by definition) is operated when the mass of tested article is 3 kg (5 is more preferable). Regrinding can be done with the help of grinding paste, for example, Tsiatim 201, Litol. Regrinding for ultrasonic method is not required.
It is better to perform calibration of hardness tester when it is operated with precision holding fixture. Though, when operator has certain skills, calibration may be not required.
Which reference hardness test blocks are included into the standard set MTR-1? Is it possible to order reference hardness test blocks by piece? Where are reference hardness test blocks verified?
In compliance with GOST 9031, a set of Rockwell MTR-1 includes five Rockwell hardness test blocks : three on HRC scale and one for HRA and HRB scales. We produce and sell hardness test blocks in sets and by piece.
All test blocks are verified at the Main Centre for Hardness Standards of Russia (FGUP VNIIFTRI).
What are the main advantages of MET-UD combined hardness tester?
All advantages of hardness testers are given on our website. However, the simultaneous use of ultrasonic and dynamic methods (for one article and when ultrasonic and dynamic probes are calibrated on one and the same hardness test blocks) of combined hardness tester makes it possible to significantly expand the field of hardness tester application and pass the limit of hardness control of one article only.