I don't know enough to be confident translating for you, but I can offer a little help:
Hiragana is the native Japanese alphabet, it is phonetic and can be used for most words.
Katakana is the Japanese alphabet used for words borrowed from another language. It is phonetic and a perfect copy of hirigana except for it's use. This is what is used when writing foreigners names, places or items.
Kanji is a pictographic alphabet that was learned from the Chinese and although uses most of the same symbols can have a different meaning and definately a different spoken word associated with it.
I know this doesn't solve your overall problem but it does give you an idea of useage.
I personally think that Katakana would work fairly well for both those items.
Bushing Press: ベアリング プレス
Motor Plate: モタ ぷれーと
Run those by your friend.