el martillo

It is important to know that the shape of the sand has an important impact on the surface finish of the casting. Circular sand is better than triangular sand because the triangular sand has a large gap, which is easy to lead to defects such as porosity; According to the nature of the casting, the sodium silicate quartz sand is selected to form a spalling layer, and combined with the characteristics of cooling and shrinkage of the casting, the surface defects are reduced. Coating a protective layer on the surface of large castings, such as the film on a coated sand mold, can improve the surface finish of the sand mold and reduce the surface defects of the casting.  

...

One of the key determinants of price is the type of drilling machine. There are various categories, including handheld drills, bench drills, and industrial drilling machines, each designed for specific applications. Handheld drills tend to be more affordable, aimed at DIY enthusiasts and small-scale projects, while industrial machines are more complex and expensive due to their robust capabilities and heavy-duty construction. For instance, a basic handheld drill can cost as little as $50, whereas specialized industrial drilling rigs can range from thousands to tens of thousands of dollars.


...