Rake angle of a lathe tool can be positive, negative or zero.
Positive rake angle a lathe cutting tool makes it sharp and pointed.
Since negative rake angle of a lathe cutting tool increases area of contact, in increases the friction between the work piece and the cutting tool.
A reamer is a multi-point cutting tool used for enlarging by finishing previously drilled holes to accurate sizes.
Cast iron does not require any coolant during reaming because, graphite in the cast iron acts as a lubricant.