Solution to Pore Defects in Investment Precision Casting

Solution to Pore Defects in Investment Precision Casting

Investment casting, as a special casting process, has certain differences from other ordinary mold casting. The permeability of investment casting is slightly inferior, so its scheduling design also has its own characteristics. Today, precision casting manufacturer Yufeng Metal will discuss in detail how to solve the problem of porosity defects in investment casting.

1、 Types and causes of porosity defects

Pores belong to the category of hollow defects, which are commonly classified into three categories:

1. Precipitation type pores, gas source is liquid metal

Reason: The metal liquid has a high gas content and poor deoxidation

2. Entangled pores, gas source from the outside or poor shell roasting

Reason: The design of the pouring system is unreasonable, the pouring is unstable, laminar flow is not formed, residual wax and gas emitting substances in the shell making material are not fully eliminated, or the permeability of the shell is poor

3. Reactive pores, gas source from chemical reactions

Reason: Gas formed by the reaction between oxides in the metal liquid or metal liquid and oxides or binders in the refractory material of the mold shell.

Precision casting inspection

2、 How to solve porosity defects

Pore defects reduce the stress area of castings, making it prone to stress concentration

One method to reduce porosity defects: opening exhaust slots

Precision machining