Castings vs. Weldments/Fabrications
One common method is to convert a welding (fabrication) into a sand casting. The major consideration in cost saving is labor time. The amount of time that can be saved by converting to a casting varies on: the alloy being converted, amount of welding spots, assembly time, and the total amount of pieces to be combined. Other than total labor time saved; a major factor is the mechanical properties that a casting provides.
A common problem in weldments is durability due to strength concerns where the pieces are welded together. To combat such problems, engineers turn to castings to increase strength (among several other mechanical properties) due to the uniformity of pouring a casting. It is important to note that the quantities have to justify the conversion and may not be right for each situation. To the right is a picture of a casting that converted from a fabrication.
Benefits of Converting a Weldment to a Casting
- Overall Less Labor Time
- Time Until Part is Ready
- Better Mechanical Properties
- Better Appearance
Negatives of Converting a Weldment to a Casting
- Initial Pattern Cost
- Possible Surfaces that will Require Machining
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Provided below is a brief description and highlight of information that can be found in an article from Metal Casting Design's website that describes the benefits & process more in depth: Steel Fabrication vs. Cast Component.
One of the main points derived in reference to Steel cast component is the characteristic called directionality. From the Metal Casting Design's link “This characteristic, also known as anisotropy, means that a component has strength and ductility in the working direction but has lower transverse properties.” Cast components do not possess directionality, which allows for the absence of fear induced by lower strength, ductility, and toughness that is associated with a welding or fabricated component.
A common candidate for conversion to a cast component would be arm (really almost any component) that is combined with a bracket attached to it in assembly through welding. These are normally parts that are formed through bending, stamping, or rolling before they are welded. This conversion would allow for less time on welding and assembly, which in turn can increase a firm’s capability to get a product to market on or before scheduled.
Have a Welding or Fabrication that you think might potentially be a good cadidate to convert to a Sand Casting? Then click below to get CPM Approved!