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Water glass casting is very similar to investment casting (i.e. lost wax), but is particularly suitable for larger castings and is less expensive to produce. The process provides a surface finish and dimensional accuracy far superior to sand casting, and more complex shapes can be achieved. In addition to steel, alternative materials such as iron and SG iron can also be cast using this method.
The difference between lost wax and water glass casting is simply the way the wax is removed from the ceramic mold:
Investment casting uses a high temperature autoclave to melt the wax, and in water glass casting, the mold is dipped in hot water to remove the wax. The wax then melts from the mold and floats on the water. This then allows it to be skimmed off and reused for waxing purposes.
Obviously, this also offers environmental advantages, and the wax is fully recyclable.
Advantages of water glass casting:
Better surface finish than sand casting.
Higher dimensional accuracy than sand casting.
Realize more complex parts.
Larger parts than traditional investment casting methods.
Cheaper than investment casting.
More metal options.
environmental advantage.
Casting tolerancedepend on the casting material and the production method used. General tolerances for metal alloy castings are specified by the International Organization for Standardization in their standard ISO 8062 for SG cast iron castings, manufactured using machine-produced sand molds. Suitable grades are Casting Tolerance (CT) 8 to 12. The capabilities of our green sand plant allow us to provide CT8 grade castings. The hand-produced castings are CT9 rated.
Closer tolerances may be available in certain cases.
The sand casting process has many advantages, especially investment casting, another popular casting method (to learn more, read our article on investment casting). This section will briefly explore why sand casting is so widespread in the industry, and its shortcomings as a manufacturing method.
The main advantages of using sand casting are as follows:
Sand casting can be used to make parts of almost any size, from triggers to engine blocks - if the correct mold is made, there is no limit to the size of the part required
Sand casting can produce very complex parts if the correct core/gating system is used
The process is highly adaptable and can be implemented in mass production of parts
Almost all types of alloys can be cast as long as they are molten and pourable
Low cost of equipment as it usually only involves sand and reusable patterns
Short lead times for making molds make sand casting ideal for short runs
Sand casting has low set-up costs and cost-effective modifications
The main disadvantages of using sand casting are as follows:
Sand casting creates a high degree of porosity in the metal, resulting in low final part strength
The surface finish of the mold is poor and must be cleaned
Castings have lower dimensional accuracy due to poor surface finish and shrinkage of the metal after cooling
Sand casting does not prevent defects, so cleaning must be done and can be time consuming
Sand castings with low tolerances must undergo some secondary machining
So, while sand casting may be a cheaper alternative to investment casting and can provide more complex shapes, more effort is required to achieve the same precision, finish, and overall part quality.
Application of sand casting
It is difficult to grasp how many different techniques use sand casting. Its versatility as a casting process makes it ideal for almost any complex part, and nearly all modern technologies benefit from this manufacturing process. Below is a list of just a few products manufactured using the sand casting process, showing how wide the range of possible applications is.
Sand casting is used to manufacture the following products:
Various pistons and valves
Blower/Impeller
Cams, Bushings and Bearings
Electronic equipment
Gas/Oil Tank
most hardware
engine block
car parts
Screws, Nuts and Gears
agricultural machinery
medical equipment
mining equipment
and more.
While far less precise than investment casting, sand casting is a low-cost, low-complexity manufacturing process that has repeatedly proven itself to be an integral part of modern manufacturing. If investment casting is too tedious, or if large parts are required, consider implementing sand casting in your production line.