Tungsten, molybdenum, tantalum le niobium ke thepa ea bohlokoa bakeng sa ho lifofane le tshireletso liindasteri ka lebaka la ho thepa bona: botsitso phahameng mocheso, segokanyipalo le matla tensile, lintho tse bonahalang bona babatsehang machinability, 'me tšireletso ea mahlaseli.