Although the MAT process is a primary element of the complete Enkei wheel making process, explaining the total wheel-forming process and the objectives for each step will produce a much more clear picture.
The MAT process is only applied to produce the rim/barrel portion of the wheel. This is significant because up to 80% of the stress occurs towards the outermost portion of the barrel. (Imagine a plastic cup. The bottom of the cup represents the face of a wheel. The top of the cup represents the outermost portion of the barrel. Now put the cup on its side and imagine where most of the tension would occur.) MAT essentially is an Enkei proprietary method of Flow Forming, but on a different level and currently performed only in Hamamatsu (for the aftermarket sector). Most manufacturers using the flow-forming (aka spun-forged, rim-rolling) method utilize a Low Pressure (LP) type of casting combined with the flow-forming process. Enkei’s MAT process differs in that 1) It utilizes an improved, Enkei proprietary method of Gravity Die Casting (GDC) (which has been coined GDC+MAP) combined with 2) the MAT flow-forming process that undergoes a series of precision constructive phases that improve the mechanical properties of the material. Standard flow-forming does not effectively alter the molecular micro structure.
Why Gravity Die Cast (GDC) instead of Low Pressure (LP) Cast?
Low Pressure casting injects aluminum into the mold from the face first and fills up the remaining rim/barrel portion of the wheel afterwards. This allows the face of the wheel to become strong by hardening first. However, it does not allow the rim/barrel portion of the wheel (the most crucial area) to be as strong because it has less time to harden. Hence, the most important area of the wheel is weaker.
In contrast, Gravity Die Cast allows for aluminum to be poured in from the rim/barrel portion of the wheel slowly filling it up and hardening first, ultimately creating a strong rim/barrel.
What is Gravity Die Cast (GDC) + MAP?
It is Enkei’s proprietary version of the standard GDC process combined with other processes dubbed MAP. First of all, Enkei uses A357 aluminum ingots combined with a special blended material to further increase the strength and life of the aluminum. Before being poured into the mold, the temperature is increased to xxx degrees. When pouring, Enkei uses a tilt method with precise angle and consistent rotation to decrease air bubble formation and increase overall balance. After the pouring, temperatures is decreased to xxx degrees for cooling. However, this occurs much quicker than standard casting processes allowing for a more balanced material content. Specific positioning and releasing of “pin mechanisms” enable this advanced cooling technology. Imagine sugar water and how the content between the top and bottom can easily differ. Basically, the quicker the better. The temperature is then increased back up to xxx degrees and then quickly dropped to xx degrees for the final cool off process. This helps to evenly spread out the silicone content throughout the material.
The levels of speed and the automated time and temperature management processes are highly advanced.
Finally, the MAT process is employed. A portion of the rim/barrel is cut off leaving behind only stubs. These stubs then forego the MAT process improving the micro structure of the aluminum creating a “Metal Flow” resulting in a stronger and more rigid rim/barrel. Imagine that this “Metal Flow” represents the material with a web/thread/weave-like linear flow creating an environment difficult for an impact to fracture, tear, split or sever the material. The complex GDC+MAP combined with the MAT process helps improve the wheel structure greatly. This is why AME specifically chose Enkei to produce the new TM-02 wheel debuting soon.