Filled and Unfilled Pattern Waxes:
Wax blends have been used for pattern making in Investment Casting process from decades. Initially the wax blends were unfilled or straight Pattern Waxes and they are blend of Paraffin Wax, Micro Crystalline Wax, Natural Waxes like Carnauba and resins, These waxes tends to shrink while solidification due to a pure wax blend.
The shrinkage of the Unfilled Wax is depend on wax temperature, tooling temperature, wax solidification rate and wax injection pressure.
To avoid the shrinkage of the heavy or thick cross section of wax patterns, wax chills are generally used, Wax chills are placed in to the wax cavity before wax pattern injection. These chills should be injected previously of the wax patterns and after Wax Pattern Production, there are chances of occurring chill marks on the wax pattern surface.
Filled Pattern Waxes are having different types of filler materials mixed in the base to avoid surface shrinkage defect also to accelerate the solidification.
Filler materials are solid cross linked polymer are in free-flowing powder condition and mix homogeneously with the base pattern wax.
While solidification of the wax patterns, Filled Patterns solidify fast compared to Wax Patterns produced by Unfilled Pattern Wax because it remain in solid form in the molten wax.
Filler Waxes are preferred for high productivity, better consistency and improved pattern quality and it has limitations of recycling.
Below mentioned are comparison of unfilled and filled pattern waxes,
|Criteria||Unfilled Pattern Wax||Filled Pattern Wax|
|Simplicity in wax Pattern Production||Proper wax conditioning must be done for proper wax pattern production||Can be work with wide range of injection temperature|
|Productivity||Unfilled waxes have low productivity because of higher cycle time||Filled waxes have better productivity because of low cycle time and solid filler material content|
|Surface Sink / Dishing||Chills must be used for thick cross sections to avoid surface sink / dashing||Chills are not required for wide range of thickness as well|
|Flow Lines||Flow lines / Non fill problems may occur due to minor changes in wax temperature||No flow lines / Non fill problem and surface quality of wax pattern is good|
|Ovality and Shape sustaining||Chances of ovality, Bending of wax patterns and variation in dimensions may occurs because of uneven cooling rates in variation of cross section||Ovality, bending and variation in dimensions avoids due to 30 % to 40% of filler content, solidification of wax pattern mostly complete in the cavity during injection takes place|
|Process Control||Close injection parameters, frequent inspection, process controlled and skilled operator required||Wide range of inspection parameters, semi skilled operator, better reliability in dimensional consistency and quality required|
|Dewaxing and Burnt Out||Maximum wax removal is possible while dewaxing and easy / fast burnt out while shell sintering||Some quantity of wax tends to remain in the shell cavity after dewaxing also high temperature and longer time required for total burnt out|
|Recycling||Recycling is easy after proper settling, filtration and centrifuge: ash content of used wax can be effectively removed||Filled waxes could not be filtered or centrifuged due to filler content and There are limitations for ash removal (Only way to minimize ash content is by settling the wax at controlled temperature)|
Considering all above features, Filled Pattern waxes are widely used in Investment Casting Industries, multi cavity dies and tooling can be easily used with Filled Pattern wax and it can be used for small wax pattern to large wax patterns.
Whereas Unfilled Pattern Waxes are used for small to medium size wax patterns.
Saffroshine Pvt. Ltd. is the leading manufacturer and supplier of water soluble waxes in across the world. Please connect with our wax expert for getting customized consulting solutions for your requirement at email@example.com or call us at +91-217-2357272.