KATSUHIRO MIURA

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KATSUHIRO MIURA
Miura San known by tour players and club makers
in Japan as having the Hands of God
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• The first part of the manufacturing process is
  the cold cropping of the carbon steel which is
  supplied to Miura in bar form.

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The cropped billet is passed through an induction
heating process which heats the metal to 1200 ºC
The operator has 14 seconds to move the heated
billet to the air hammer for the first strike.
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• The one tonne air hammer in the Miura forge is
  located in an isolated position 1 kilometre from
  the main Miura factory. The hammer hits the
  heated billet 3 times, the first strike to
  flatten the billet the second to undertake the
  first press in the die and the third strike to
  make the second press in the die.

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• The operator has 5 seconds to move the offered
  billet from the first strike to the third strike.

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• The die used with the air hammer. First strike to
  flatten the billet.

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• Second and third strikes to form the head

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Grain structure of metal used in Miura heads
Raw metal
The grain structure of the metal used in Miura
heads changes during the forging process with the
removal of carbon deposits. ( Black areas are
carbon deposits. The smaller and tighter the
deposits the more solid the feel.)
First strike
Second strike
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• After the billet has been struck 3 times during
  the initial forging stage it is then passed
  through a press to remove the excess metal from
  the formed head

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• The die and cutter used to remove the excess
  metal from the formed head

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• After pressing the formed head is allowed to
  cool . This is the end of the initial forging.

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• When the heads are returned to the main factory
  a final forging process is initiated. The formed
  head is heated in a furnace

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• In the final forging the press changes again
  the density and grain structure of the metal.

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Grain structure of metal used in Miura heads
Raw metal
The final strike changes the grain structure of
the metal again and removes further carbon
deposits. ( Black areas are carbon deposits.
The smaller and tighter the deposits the more
solid the feel.)
First strike
Second strike
Final Strike
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In the final strike there is a change in the
composition of the metal and a small flange
which will be removed later is formed.
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• The die set used in the final forging.

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The press used in this process exerts 200 tonnes
of pressure on the head. (As can be seen clearly
the formed head does not have any hosel at this
point)

• Miura is unique in pressing the grooves into the
  head. This is seen by Miura San as important as
  there is no material loss and no temperature
  changes. It is his view that a cutting process
  for grooves increases the temperature of the
  metal and adjusts the temper of the metal in the
  head.

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• The hosel is manufactured in a CNC machine with
  a tool post containing 6 cutters. These cutters
  centre, bore and champher the finished hosel.

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In this operation the stalk on the head is
prepared to meet the hosel with an end milling
cutter. The hosel which is housed in a collet
within a high speed clutch is presented to the
head and spin welded onto the head.

• The spin forging of the hosel onto the formed
  head is another unique part of the Miura
  manufacturing process.

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• A grinding belt prepares the profile of the
  head. (this is the only mechanical grind in the
  head manufacturing process).

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• Hand grinding of the head is undertaken by a
  Miura trained craftsman grinder who is seated to
  provide stability when grinding.

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During the grinding process the head is weighed
for a finished weight tolerance /- ½ gm.
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• The first part of the finishing process is to
  tumble the heads in a tumbler containing
  stones for hours before the heads leave the
  factory for plating.

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• Final check and hand painting of the head before
  packaging and dispatch.

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The secret of the Miuraprocess
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KATSUHIRO MIURA
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• Miura
• A work of art ?
• Or just a golf club head?