SPRUE ,SPECIFICATION,FUNCTION- short notes

HELLO DOCTOR VANAKKAM,

Warm welcome to stencildent family 

Contents:

Introduction to casting procedure

Sprue

Specification of sprue

Methods to prevent

Function of sprue

HAND WRITTEN NOTES

Introduction :

vCasting procedure steps:

1) Tooth preparation

2) Impression

3) Die preparation

4) Wax pattern

5) Sprue former

6) Casting ring liner

7) Investing

8) Wax elimination and burnout

9) Casting

10)Quenching

11)Sandblasting

12)Finishing and polishing

 

SPRUE

·       It’s a channel created in the investment through which molten alloy enter the mould space which is created due to burnout of wax pattern.

·       Sprue former are material used to form sprue

·       They are made up of wax, metal,resin.

SPECIFICATION OF SPRUE:

1)   SPRUE DIAMETER:

Ø Same a size as thickest area of wax pattern

Ø If large cause distortion

Ø Small : suck back porosity

2)   Sprue position :

Ø At greatest bulk in pattern

Ø The reasons are :

Ø To permit flow of alloy into the mould cavity

Ø To avoid distorting thin areas of wax

3)   Sprue length:

Ø In gypsum bonded investment material up to 6mm

Ø For phosphate bonded investment material about 3-4 mm and it should be placed in centre of ring

1)   SPRUE DIRECTION:

Ø      proximal surface -45 degree

Ø  135 degree to axial wall pattern

Methods to prevent:

§  Air entrapment

§  Occurrence of suck back porosity

Functions of sprue :

ü It forms mount for wax pattern

ü Channel for elimination of wax

ü Entry of molten alloy during casting

ü Compensate shrinkage during solidification




I Hope this short notes must have helped you if it had helped you do let me know in the comment section below as this will motivate  me to post more such content

For further contact me through contact information provided in the contact us page .

Thank you have a wonderful day

 


Comments

Post a Comment

Popular posts from this blog

Sterilization technique in microbiology

STAGES AND STEPS IN TOOTH PREPARATION

Hypersensitivity microbiology notes