George Borke
4/9/2020 10:36 AM
With so many wheel options to choose from an with today's marketing word plays it can be confusing to choose the wheel that best fits your needs. Design, color all play a part but the most important part of all is How a wheel is made, In the wheel industry we have many construction methods and all though one can be thought as better then the other it douse not mean is better for your style of driving or that the cost merits your needs. The list below is a very easy and quick guide to current aftermarket wheel construction methods. note ** All wheels have testing and special safety requirements in order to be allowed to be used on highways or public roads no method shown below is considered to be unsafe or not to par for automotive use please look for properly tested recognition stamps as JWL, VIA and for European countries TUV ****
ONE-PIECE CAST WHEELS
This is the most common type of aluminum wheel. The casting of wheels is the process of getting molten aluminum inside a mold to form a wheel. There are different ways this can be accomplished and although it sounds simple, this is truly an art when done properly.
GRAVITY CASTING
Gravity casting is the most basic process of pouring molten aluminum into a mold utilizing the earth's gravity to fill the mold. Gravity casting offers a very reasonable production cost and is a good method for casting designs that are more visually oriented or when reducing weight is not a primary concern. Since the process relies on gravity to fill the mold, the aluminum is not as densely packed in the mold as some other casting processes. Often gravity cast wheels will have a higher weight to achieve the required strength.
LOW PRESSURE CASTING
Low pressure casting uses positive pressure to move the molten aluminum into the mold quicker and achieve a finished product that has improved mechanical properties (more density) over a gravity cast wheel. There is a slightly higher production cost over gravity casting, but low pressure casting is the most common process approved for aluminum wheels sold to the O.E.M. market. Some companies offer wheels that are produced under a higher pressure in special casting equipment to create a wheel that is lighter and stronger than a wheel produced in low pressure, but there's a higher cost associated with the process. Low pressure cast wheels offer a good value for the aftermarket while still maintaining strength and a lighter weight.
SPUN-RIM, FLOW-FORMING or RIM-ROLLING TECHNOLOGY
This specialized process begins with a low-pressure casting and uses a special machine that spins the initial casting, heats the outer portion of the casting and then uses steel rollers pressed against the rim area to pull the rim to its final width and shape. The combination of the heat, pressure and spinning create a rim area with the strength similar to a forged wheel, but without the high cost of forging. Some of the special wheels produced for O.E.M. high performance or limited production vehicles utilize this type of technology resulting in a dramatic reduction in wheel weight while enhancing structural rigidity vs. a standard cast wheel.
Wheel manufacturers define this process in many ways. FlowForged, Rotary Forged, Spun Forged, Pressure Forged, Hybrid forged etc
FORGED
The ultimate in one-piece wheels. Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure. This creates a finished product that is very dense, very strong and therefore can be very light. The costs of tooling, development, equipment, etc., make this type of wheel very exclusive and usually demand a high price in the aftermarket.
MULTI-PIECE WHEELS
This type of wheel utilizes two or three components assembled together to produce a finished wheel. Multi-piece wheels can use many different methods of manufacturing. Centers can be cast in various methods or forged. The rim sections for 3-piece wheels are normally spun from disks of aluminum. Generally, spun rim sections offer the ability to custom-tailor wheels for special applications that would not be available otherwise. The rim sections are bolted to the center and normally a sealant is applied in or on the assembly area to seal the wheel. This type of 3-piece construction was originally developed for racing in the early 1970s and has been used on cars ever since. The 3-piece wheels are most popular in the 17" and larger diameters.
There are now many options for 2-piece wheels in the market. The 2-piece wheel design does not offer as wide a range of application that a 3-piece wheel allows; however, they are more common in the market and the prices start well below the average 3-piece wheel. Some 2-piece wheels have the center bolted into a cast or cast/spun rim section and other manufacturers press centers into spun rim sections and weld the unit together.