Aluminum alloy wheels’ manufacturing process has developed a lot since 1970s. Due to sophisticated wheel design, casting has become the dominant manufacturing process. Alloy wheel material has evolved too: car wheels alloys now contain 7 to 12% silicon content, and varying contents of magnesium in addition to aluminum, in order to meet the demand for metal-mold casting properties, corrosion, and fatigue resistance.
Alloy wheels are typically created via casting or forging, though other production methods throughout their history have included gravity casting. In the end, they’re touted for being lighter than steel wheels, and those that are forged are generally also more durable than those that are cast. Whether created via casting or forging, the manufacturing methods allow complex designs to be created, which helps alloy wheels achieve the look that many drivers yearn for to complement the styling of their vehicles. Alloy wheels are generally more expensive to produce than steel wheels, and because of this they’ve historically been more of an aftermarket option. However, that changed around the turn of the century, and more automakers are currently offering alloy wheels even on certain trims of compact, sub-compact and budget vehicles.
Components which are manufactured from cast alloys have been widely utilized in automotive industry due to their high strength-to-weight ratio, low cost, and better fuel consumption. The strength of the spot welds in the unibody vehicle structure determines the integrity of the structural performance during the vehicle operations. Automotive wheels have a complicated geometry and must satisfy manifold design criteria, such as style, weight, manufacturability, and performance. Nowadays, reduction in wheel weight is a major concern in the wheel industry. Optimization of milling is very useful to reduce cost and time for machining mold. The efficiency of machining operation especially milling process is always determined by the material removal rate, tool wear and cycle time.
The alloy material has many advantages over others, many of which translate over into wheel benefits as well. Here’s a look at some of the top benefits to outfitting a vehicle with alloy wheels:
Design or material selection considerations can be the next:
Wheel manufacturing process is dominated by aluminum. Aluminum penetration in wheels was in the year 2000 for European vehicles about 30 to 35%, compared to largely more than 50% in USA and Japan. This is representing more than 14% of the average aluminum content of a vehicle and is expected to rapidly increase. In the US, the repartition of aluminum in wheels was in the year 1999: 82% cast, 11% forged (including all vehicles), 4% for sheet and 3% for plate. In Europe, the share of casting is slightly higher (more than 85%) due to the lesser extent of forged wheels for trucks (including light ones). However, many developments are on the way to reduce weight of present aluminum wheels without fully sacrificing style. With this purpose, a really attractive compromise could consist in cast central discs (or forged when competitive), assembled (mainly by welding) to extruded or laminated rims.
The main advantages of aluminum cast wheels, when compared to steel or other aluminum wheels are:
The major casting processes for wheels are:
Rarely used are the following processes:
After casting, wheels are 100% x-ray inspected and then eventually heat-treated prior to machining. This step is followed by a pressure tightness testing before drilling valves and bolt/nut holes. After a cosmetic inspection wheels are then painted or varnished. This process includes pretreatment (degreasing, phosphatizing and/or chromatin, etc.). 3D dimensional controls, dynamic balance checking, bending and rim roll fatigue as well as impact tests are statistically performed.