Ko ngā wāhanga whakapā matua (ngā impeller me ngā liner) he mea hanga mai i te maitai pakari-teitei, ātete-mau, i ngā koranu motuhake rānei, ā, kua arotauhia kia tu atu ki te mau pakari-teitei o ngā rauemi ātete-mau (pērā i te corundum, te silicon carbide, me te spinel), ka roa ake te ora o ngā taputapu me te whakaiti i ngā utu tiaki.
Whakapai ake i ngā āhuatanga whakakoi o ngā mea whakakāhore;
He ōrite, he ōrite te paru e whakaohokia ana, e whakaranua ana, ā, kāore e wehewehea;
I raro i te kaupapa o te whakarite i te kirihou, he tiketike te matotoru o te ranunga, ā, kāore he wetewete o te paru.