How to improve the quality of castings to prolong the service life of mechanical equipment?

The working performance and stability of mechanical equipment are affected by many aspects. This article mainly introduces how to improve the different defects of castings, so as to improve the service life of Automatic Molding Machines.

Foundries use self-hardening resin sand molding or lost foam casting to produce castings. In view of the casting defects that appear, different defects can be dealt with from the perspective of casting technology as follows:

1. Strictly control the pouring time. Most of the castings are ductile iron castings, and the molten iron is prone to spheroidization decline over time during the pouring process, which will seriously affect the mechanical properties of the castings. Therefore, the casting and pouring time should be controlled within 8 minutes, and try to arrange to use the spheroidized early molten iron to pour the castings;

2. Strictly control the chemical composition of furnace molten iron. The final chemical composition of the molten iron determines the casting performance and mechanical properties of the casting. For example, if the carbon equivalent of the molten iron before the furnace is too high, the fluidity of the molten iron will become poor after nodularization, which will easily lead to the occurrence of pores, shrinkage cavities, shrinkage porosity, and graphite in the casting.Casting defects such as drift and spheroidization decline. Therefore, the composition of molten iron in front of the furnace is strictly controlled, and the addition of nodulizers and inoculants is reasonably configured to make the final chemical composition meet the material requirements;

3. Improve the gating system and increase the feeding process. Shrinkage cavity, porosity, and shrinkage of castings are often caused by insufficient feeding of castings, which can be improved by referring to the following methods:

(1) Change the position of the nozzle to avoid casting defects from occurring on the higher-required surface that needs to be processed and must be resistant to wear;

(2) Increase riser feeding, delay riser feeding time, increase feeding pressure head, place cold iron at the hot joint position of wall thickness or replace thermal insulation riser to ensure that castings can solidify simultaneously or sequentially;

(3) The pouring workers should reasonably control the pouring speed. For example, when the temperature of the molten iron is high, the pouring speed should be slowed down, and the second water replenishment should be carried out in time after the pouring is completed and the riser shrinks.

4. For slag holes and trachoma defects, the main reason is that the sand loss and loose sand in the cavity or sprue cup have not been cleaned in time, and the temperature of the molten iron is low and the fluidity is not good. caused by cavity. Pouring workers must check the mold cavity before closing the mold, handle the sprue cup well and ensure that the molten iron has good fluidity or install a filter at the position of the runner;

5. The foundry should strengthen the inspection before the blank is out of the warehouse, find casting defects and improve them in time, make up the number in time, and prevent unqualified castings from flowing out to the customer's processing workshop.

The above measures can significantly improve the defects of castings, thereby increasing the service life of the automatic molding machine. Since castings are not limited to automatic molding machines, the above measures are worth learning when choosing castings for mechanical equipment in various industries.