Iron head
A set of iron heads is primarily designed with progressive weighting,
size, loft and lie angle and centre of gravity on each head.
The secondary parameter is performance related - i.e. cavity
back or muscle back bladed. The bladed design has been the first
and oldest. The major significance between the modern cavity
and the bladed design is only the "feel" when the ball
strikes on the sweet spot of the clubface with all other technical
parameters being equal.
Cavity back can be generalised as perimeter
weighting. Perimeter weighting is characterised by toe/heel weighting,
with deep, semi or progressive cavity design throughout the set
of irons.
Perimeter weighting is a term used to indicate
the movement of the club-head mass towards the outside of the
club (perimeter) resulting in the increment of its moment of
inertia.
Effect on Golf Shotmaking
Performance Factors
The effect of perimeter weighting on club-head
performance is to increase the ball impulse achieved from
'off-centre' hits. The club-head designer calls the above effect,
expanding the 'sweet spot'. It is true that perimeter weighting
does improve the resulting ball velocity for off-centre hits.
From mathematical calculations and hitting tests, performances
show that the ball velocity increases as the moment of inertia
(perimeter weighting) increases.
It is important to note that hitting a
perimeter weighting head and a non-perimeter weighting head on
the centre of the face with the same head velocity will result
in the same or very slight ball carry distance. Perimeter
weighting takes its role in off-centre hits only.
