★This column is a commentary on lost wax casting with a block molding method
This column has been presented by Yoshida Cast
The sprue system is one of the most important casting techniques.
Ensuring "directive solidification" when the molten metal is poured into cavity inside a mold, "suppressing turbulence" and "reducing hot spots" of the molten metal during casting, taking into consideration the static casting theory.
It is a measure to reduce casting defects from the viewpoint of molten metal flow and metal solidification by examining the gas replacement action.
How to install sprue is one of the basics to prevent casting failure.
No matter how much casting temperature and mold temperature are adjusted appropriately If sprues are attached incorrectly, "gas porosities" and "turbulence (roll-in) porosities (blow holes)" will occur.
And at the same time, if correct directive solidification is not ensured when the molten metal solidifies, it may induce various casting defects such as "cracking of castings" and "shrinkage porosities".
It is necessary to control mounting location, shape, thickness, area of ingates, angle, quantity of attachment of sprue.
And a shape of the casting tree depending on the difference in casting method, solidification time of metal, viscosity of metal, shape of casting, etc. should be changed for better results.
In this "SPRUE SYSTEM for better results in JEWELRY CASTING", the following themes are explaining as below.
KEY FACTORS for SPRUING SYSTEM
■ How CASTING METAL FLOWS
■ Wax trees related to VACUUM SUCTION CASTING
■ Wax trees related to CENTRIFUGAL CASTING
■ Wax trees related to PRESSURE CASTING
■ Prevention for CRACKING & POROSITIES: Basic concepts for attaching GATE SPRUES
■ Countermeasures against TURBULENCE
■ Shapes of INGATES to prevent TURBULENCE
■ "HOTSPOTS" where area get hot in casting and its countermeasures
■ “RESERVOIR” To prevent shrinkage porosities
■ "GAS VENT" for air releasing
Author : M.Yoshida