Tip-1: Wax should have low specific heat
Specific heat of wax is the quantity of heat energy required to increase the temperature of 1 gram of wax by 1°C (degree Celsius) The temperature of a wax with low specific heat increases very quickly, as compared to a wax of higher specific heat.
Behavior of Low Specific Heat wax during de-waxing:-
- Wax will melt very quickly during de-waxing.
- Surface of the pattern will melt quickly, before heat reaches the centre of the pattern. This avoids pattern expansion and reduces the risk of shell cracking.
- De-waxing can be done at lower temperatures and pressures. This keeps the cost of de-waxing low.
- De-waxing is faster. The de-waxing cycle times can be reduced, with increased productivity.
Other advantages of low specific heat wax:-
- This wax melts and solidifies quickly thus reducing cost of wax melting.
- Wax temperature can be controlled easily as it quickly gains or loses heat.
- Moulding cycle time can be reduced as this wax cools quickly.
- Wax of low specific heat offers considerable advantages over wax of higher specific heat.
- The ultimate advantage is that it is both economical and easier to use a wax of low specific heat as compared to a wax of high specific heat.
Other advantages of using low viscosity wax:-
- This type of wax flows easily into the die / tool during injection. Lower injection pressures may be successfully used.
- The wax flows more easily, thus filling the dies / tool quickly helping in reducing the injection cycle times.
- Low viscosity wax easily flows into narrow die profiles and allows for better detail reproduction.
- Low viscosity wax has better flow properties than high viscosity wax.
- This gives better dewax performance and improves productivity
- Detail reproduction in small castings is better.