All steel castings go through sand casting processes, which require a certain number of standard finishing operations and ultimately, we provide the casting surface finish required by the customer. Some allow for gouges, pits, and roughness, while others require the whole casting to be ground smooth. For example, a rock crusher jaw typically allows for a rougher surface than the front bow stem of a maritime vessel.
After what is called shakeout, the casting is ready for casting cleaning, or the finishing process. With our castings ranging from 200-20,000 lbs., a great deal of manual labor is required to finish the castings. Once the casting is poured, only about 30% of the labor is completed.
Typically for our customers the main processes in finishing include burning, shot blasting, arc-air, grinding, and chipping. All these processes take place in what we call the “cleaning room”. The surface finish as required by the customer is acquired by means of shot blasting and hand grinding. Depending on the application we can allow surface defects like pits and gouges or provide a 100% buffed casting finish.
In the casting process, gauge grinding is useful for the secondary and final applications for our castings. Where necessary, we will gauge grind the locating datums for easy machining setup. We can also gauge grind certain casting features that need a tolerance held, but not enough that a machining operation is required.
For final application, we can gauge grind castings for fit-up in final assembly or out in the field. Metal Gauges are used, and material is ground off the casting until the appropriate tolerance is reached that the casting will fit.
This is practically used for applications such as bucket lips, track shoes, shrouds, tips & adapters, and as cast bolt hole patterns. This process benefits the customer by having the casting fit right onto the mating part, with no modifications needed in the field.