The Pros and Cons of Forged Steel Wheels vs Cast Iron Wheels.
When comparing Forged Steel Wheels and Cast Iron Wheels, each has advantages and disadvantages which we’ll cover in this blog. One thing to note when comparing these two types of wheels is the manufacturing processes each undergoes, which in turn affect things such as cost, bonding ability, and strength.
Forged Steel Wheels, as the name implies, are manufactured in a forging operation. Forging is the term for shaping metal by using localized compressive forces. Forging can be done in a cold operation or a hot operation. For industrial wheels, a hot forging operation is used.
After the weight of the part is determined, a slug of steel round of appropriate diameter is cut and pre-heated to red hot. The steel is then drop forged, a process that shapes the slug through repetitive impacts. The flashed is sheared before the steel can cool. The part is then placed on a conveyor for a slow cooling process.
PROS AND CONS OF FORGED STEEL WHEELS INCLUDE:
- Can support 30% great loads than Grey Iron
- Are more costly to machine to final dimensions
- Not a good bonding surface due to the density of the molecular structure
- Excellent for applications with a significant risk of shock loading
- Can be heat-treated to increase hardness and is easy to weld
- Generally, 30-50% more expensive than a grey iron wheel.
Cast Iron Wheels are manufactured by melting pig iron while adding substantial quantities of scrap iron and steel scrap. At various steps, undesirable contaminates (e.g. phosphorus and sulfur) are removed that affect the overall strength of the material.
The melting process is done either in a blast furnace known as a cupola or electric induction furnace. During the process, the material is completely liquefied and then carefully poured into a sand mold. The casting is then removed from the sand mold and final cooling takes place. The final grade of the grey iron is determined by the final tensile strength (Grade 30 is 30,000 lbs. tensile strength).
The microscopic structure of the two materials is significantly different and impacts the overall strength of the material/product. During the forging process, the molecular structure is in alignment and never disrupted during the forging process. Hence, the strength in the virgin material is never lost. However, in casting, none of the original structure is maintained and a new structure is created that has very little continuity, resulting in an insignificant reduction in strength.
PROS AND CONS OF CAST IRON WHEELS INCLUDE:
- Can support a significant amount of weight
- Machine very easily
- Make an excellent bonding surface for a urethane tire
- Cannot withstand shocking loading without risk of cracking or failing
- Do not make good welding surfaces
- Cannot be heat treated to change hardness
- Considered a cheap alternative in an industrial application.
When choosing between a Forged Steel Wheel and a Cast Iron Wheel, there are many factors to consider. However, getting the correct wheel the first time will minimize long term costs by minimizing downtime and maintenance costs. The experienced engineering group at Caster Concepts, Inc. can help you determine the best industrial caster for your application.
