Cleaning of alumininum gravity castings

Cleaning of aluminium gravity casting

Cleaning is the quite important process of the whole gravity casting process. When the casting is taken out of the mold, it is not a unique neat cast product, which was always solidified with sprue system, gating system, risers and other assistant casting features like sand core holder, process rids and so on. All of these parts should be removed away after casting. Therefore, there are quite a few of cleaning means developed for the purpose of removing them away clean and easy. The main cleaning means include cutting by saw, filing by handle of pneumatic file, grinding or sanding by sanding machines, buffing or polishing, tumbling, shot blasting and so on.

In order to reduce labor intension, HH gravity casting foundry abandoned almost all manual cleaning means like knocking by hammer and filing by file. We are using clean and safe belt saw for cutting off sprue and gating system, clean grinding and sanding machine for removing burs, sharp edges and extra material away from the castings, both hanging and barrelling shot blasting machine for quick surface cleaning and tumbling machines for surface grinding and tightening.

Removing away sprue,gating system and risers: The sprue and gating system and risers are the main assistant parts of a complete raw gravity casting. In order to get clean and neat casting body, we have to remove all these assistant parts away. In many foundries, they were knocked away by iron hammer rough with high damage rate. For the purpose of reducing rejection rate and keeping safe, rough knocking and cutting is forbidden in HH aluminum gravity casting foundry. Currently we are using advanced safety bent saw and disc saw to cut off assistant portion of raw casting. The casting parts were designed to facilitate cutting with certain locating mark and stress concentrated point. The cut castings were packed and stacked on the pallet or in iron cage for next manufacturing step. Such automatic cutting is swift and saves labor, furthermore it keep the rejection rate to minimum.

Trimming and deburring of the gravity casting: A cut casting part always has coarse cutting mark, besides, the burrs and sharp edges on its parting surface and ejector marks are still retained on the casting body. All of these casting marks should be removed away by the process of trimming and deburring. The trimming can also be differentiated from the deburring process. We normally use pneumatic file to trim the parting line of the casting part. While the deburring process is normally done by sanding machines. Trimming by pneumatic file can remove slight casting marks while the sanding is used for removing large area casting marks like the cutting marks. Besides,sanding is much preferred for casting cleaning,since it can be performed quickly and easily.

Shot blasting of aluminum gravity casting parts: Shot blasting is widely used for cleaning various kinds of casting such as steel casting, iron casting and the aluminum casting. There are two types of shot blasting machines namely hanging shot blasting machine and barrelling shot blasting machine. The hanging shot blasting machines is used for large castings or the castings should be prevented from touching and impacting with each other while blasting The barrelling shot blasting machines are used for small casting parts which can be touched and impacted each other. One thing we should be noted is that shot blasting aluminum casting parts should use certain stainless steel ball to prevent corrosion in case of blasting by iron balls. Besides, the diameters of the shot blasting ball should be between 0.3 or 0.4 mm.