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      04-06-2008, 01:19 AM   #14
GregW / Oregon

Drives: 2015 M4 Coupe, 2012 ML350
Join Date: Nov 2005
Location: Lake Oswego, OR

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Originally Posted by crimsone90 View Post
There are three types of manufacturing, ALL involve CNC machining. There are wheels machined from an impressiun die-forged wheel blank, from a non-impressiun die-forged wheel blank and from a forged round block. The ones forged from a die-forged wheel blank whether impression or non-impression have very similar properties and as you mentioned the choice of manufacturing process is based on cost effectiveness. As of my experience an impression die-forged wheel cost about $100 LESS than a non-impression die-forged wheel. The non-impression will require additional material that is wasted (although recycleable) and will require additional machining time. An impression die-forged wheel requires less material and less machining, however, the high cost of the tooling will require a higher retail price. The ones forged from a round block are very inferior in quality since all the benefits of forging are virtually lost.
HRE gets forged blanks (their designs) from APP (aerospace supplier) in SoCal and machine them in-house to their final design.
Now, there are two types of frorgins that APP produces, open die and closed die.

"Open Die Forgings, also known as "Hand Forgings" or "Forged Block," are manufactured in flat dies, eliminating the requirement for nonrecurring tooling. They are characterized by specific grain directions (ST - Short Traverse; LT - Long Traverse; and L - Longitudinal), and are produced in many shapes, from the classic "block" configurations to bent, stepped, or curved shapes."

"Closed Die Forging is the process whereby this deformation is confined within a shaped cavity in the dies to achieve a desired engineering configuration. Depending on such factors as complexity, tolerances, economics and performance, the dies required to produce Closed Die forgings range from complex multi-segmented PRECISION wrap dies to simple two-piece CONVENTIONAL top-and-bottom dies."

I'm not sure which method HRE uses, but I believe the latter. I am defiinitely not an HRE fan-boy, just trying to get to the bottom of the real issues here.

APP forging operation:
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Greg Lake Oswego, Oregon, USA
2015 M4 Coupe - Silverstone/Sakhir/CF
2012 ML350