an Auxiliary verb.
Costing (time, money)
When put together with acounter, it can describe costing/taking
撮影は3ヶ月かけて行われました。 The picture shooting was carried out costing/taking 3 months.
完成までに二年かかって上に、十億円かかった Up to the point of completion, it cost 2 years and 1 miljard dollar.
https://www.imabi.net/kakarukakeru.htm
In the middle of (...)
途中まで～して、まだ～し終わらない When combined with a continuous verb (継続動詞), it means you're still performing the action
息子はやりかけの宿題をおいて、遊びに出かけてしまった。 My son left his homework he was in the middle of doing, and went out to play.
書きかけのレポートを今日中に仕上げるつもりだ。 I intend on finishing up the report is currently in the middle of being written.
母は夕食を作りかけて、今ドラマに夢中だ。 My mom was in the middle of making food, (but) now she is dreaming away at a TV drama.
Just about to (...), on the verge of (...)
When combined with a momentous/instantaneous verb (瞬間動詞 (instantaneous verb)), it means you are about to start the action.
地震で家が崩壊し、死にかけたが、なんとか一命を取り留めた。 His house collapsed in the earthquake and he was on the verge of dying, but he managed to survive.
トムさんは何か言いかけたが、そのまま黙ってしまった。 Tom was about to say something, but then he remained silent.
Sources
nihongokyoshi-net.com - 〜かける / 〜かけの Youtube: Game gengo N3 - かける