Mizuno Golf – JPX 921 Irons and The Art Of Forging.

The history of Japan’s expertise in forging steel and the history of Mizuno as a brand.

When you think about artisan steel, Japan will always come to the forefront of your mind. History dictates Japan’s love affair with forging and is still world-renowned as the best metal workers in the world.

Legendary swordsmith Amakuni was said to have created the single-edged Katana in the 8th century. 

Working for the Emporer of Japan, Amakuni and his son had noticed warriors were coming back with broken swords and diagnosing it with improper forging technique.

 

 

Amakuni along with his son were determined to fix this and legend says, this is the day swordsmith forging changed forever.

Fast forward to today and some of these techniques are still adopted today and you can say Japan’s skillset with steel has been forged into history and will no doubt withstand the test of time.

Founded in 1906 by brothers Rihachi and Rizo Mizuno, the sports brand didnt actually make the move into clubs until 1933 under the moniker “Star line”.

Just two years later in 1935 Mizuno actually had the worlds largest Golf showroom. It was only in 1970 when the brand received critical acclaim that they started to export its golf clubs to players in Europe.

Notable players using or have used Mizuno irons include Luke Donald, Sir Nick Faldo and Tiger Woods.

Sir Nick Faldo went on to win 6 Majors using Mizuno and Tiger woods took his first win at the Masters in 1997 using a mix of MP-29 and MP-14 Irons.

What is the difference between forging and casting?

Whilst they both produce products made of the same elements, there are fundamental differences to how these products are made and noticeable differences to the properties and finished products as a result.

Casting is the process whereby you take your chosen metal, find the desired temperature to melt it down into a liquid or molten substance and then pour this into a pre-made mould.

The benefits of casting is that it’s for mass-manufacturing. It’s a cheaper, more efficient method of making goods and its easier to add a mix of different alloys in the molten stage than it is when forging

Whilst still strong, Casting will lose its ‘grain’ and be more porous than forged products meaning it will be weaker.

Forging, on the other hand, used the method of pressure to shape or form the metal. The metal itself doesn’t enter a liquid state, instead, it is heated up enough to deform and then reform again whilst still in a solid-state.

The process of shaping can come in different forms of pressure, namely hammering, pressing or rolling. In the case of Mizuno Forged Clubs, it would be hammering down to shape the clubhead.

The thermal changes and deformation process result in grain refinement. It is this grain restructure and manipulation that gives forged steel its strength which is much stronger than metals that have gone through the casting method.

As a result of this, whilst still just as strong, each Mizuno forged club is unique with its own grain structure.

 

Grain Flow Forging

In 1998, Mizuno patented the idea of “Grain Flow Forging”, but what is it?

Essentially it is the process of forging in multiple stages but only using one single piece of steel to carry consistent and fluid grain flow through the head, hosel and neck of the club. The preservation of the metals natural grain ultimately aids the clubs precision when it is finalised.

Other manufacturers will forge but weld two bits of steel together at the head and the neck, thus causing inconsistent grain flow.

 

How Mizuno clubs are forged, the process

The process of Mizuno’s forging happens in 6 stages. These are :

• Taking stock of Steel and cutting billets to size
• The shaping of the metal billet
• Stage 1 forging or Primary Forging Stage
• Cookie Cutter Stage
• Stage 2 Forging or Precision Forging Stage
• Grinding and Plating to Finish

Stage 1

The first stage is taking delivery of metal that would eventually become the head of a club.

The giant steel rods come into the Chuo Plant in Hiroshima with each steel rod measuring in a 6 metres a piece. Mizuno take delivery of both 1025E pure select mild carbon steel or boron infused steel. Each type will eventually go into making a different club head.

The 1025e, for example, will be found on the MP-5 blade and the boron infused metal will go into making the MP-25. Given that the MP-5 blade is a sleek and a less complex head to design it doesn’t need the complexity of boron.

1025e is used for clubs like the MP-25 needing balance and strength and it reduces unnecessary elements such as Phosphorus and Sulphur doing the forging process.

Once the steel rods are in they’re cut into 10in billets where they are cleaned of any surface debris or weathering prior to the heating process.

 

Stage 2

Once each billet is cut to size they are ready for the heating and bending process.

A furnace puts out a whopping 1200 degrees celsius, which is the optimum temperature for the forging process. Each billet is stretched and bent into a rough shape that would resemble the early parts of the clubhead and hosel.

The billet must only be forged from one piece to ensure every cutting has perfect grain flow throughout the process.

Stage 3

Once the bent billet has taken its rough shape, it moves quickly to the next stage which is called Stage 1 forging.

The steel is hit 4 times by a 1000 tonne hammer to tightly align all of the grains in the metal. This is a manual task operated by some of Mizuno’s most experienced staff. 

Before becoming an operator, you must have worked for Mizuno for 3 years. After that you’ll be supervised by a Master Operator before being allowed to move to the hammers alone.

The weight is actually controlled by a foot-pedal and there is a very little margin for error.

Once hammered down and still piping hot, the club heads make their way down a conveyor belt to cool down.

Stage 4

The now cool club heads are ready for the next stage which is the cookie cutter.

Each club would have excess metal from the hammer and this needs to be removed so that they begin to resemble more of the finished article. This is known as the flash.

Now the club heads will make their way down another conveyor belt to be re-heated a second time.

Stage 5 and 6

Each clubhead is now heated up but now pressure squeezed to create the final shape of the club head we all know and love.

To ensure quality control, the club heads must be inspected by at least 30 people before they pass the test to move on. 

Even the smallest defect means its the end of the line for that club head and only the perfect club heads can be passed on.

The clubs then need to be sandblasted for 15 minutes and It is only then that the club heads will get their grooves and also be ready to be plated, polished and stamped with the Mizuno logo. The final part of the finished product.

From here it will go to an assembly part where it will become some of the best set of irons in golf.