http://www.forrestrace.com/oil-cutter/

why do I need oiling for the glass cutter (hand tool)?
I have a glass cutter with hardened metal mini-disc rolling at the tip (a small hand tool like a pencil) Pictogram instructions show oiling the tip of the tool. What is the reason for oiling?
- smooth roll on glass?
- smooth operation of the roll (fine glass particles stuck and inhibit rolling of mini-disc)
- to protect the cutting tip (from oxidation?)
- overheating during cutting? (which is unlikely for hand cutting)
Thanks
Tends to make the cut cleaner (‘chips’ tend to be created otherwise) and the wheel less likey to miss (ie be in constant contact with the glass), though I dont know the exact physics behind it.
Mechanised Oil Palm Cutter. SmartCut