Machining, also known as subtractive manufacturing, is a prototyping and fabrication process that creates desired shapes by removing unwanted material from larger materials.
What are the different types of machining?
Various processing techniques have existed for decades, but most fall into three main processes:
Turning
Turning, or turning, involves rotating a workpiece on a machine while the single-edged cutting tool remains stationary. The cutting tool removes material by moving slowly parallel to the axis of rotation of the workpiece.
drilling
Drilling creates circular holes by rotating a cylindrical tool parallel to the axis of rotation of the workpiece. The hole formed is equal to the diameter of the tool.
milling
Milling is the process of removing material from a workpiece using a rotating tool with a feed motion perpendicular to the axis of rotation of the cutting tool. Milling is one of the most commonly used forms of machining today.

How does machining work?
In modern product development, machining requires the use of computer numerically controlled or numerically controlled machine tools. A CNC machine uses computer software to take a CAD design model and draw toolpaths to convert the design into a 3D machined part. It can manufacture parts in a variety of materials, with different finishes, and with tolerances accurate to 0.001”. Unlike rapid prototyping, machined parts use real materials that reflect the density, finish, and porosity of the final product. Machined parts are used to represent For performance testing, the model includes sliding components where friction is a factor, as well as sealing components where O-ring and gasket surfaces are required.

What are the advantages of machining?
Choice of finishes and materials
Tighter tolerances down to .001″
Real materials with real densities
What are the disadvantages of machining?
Only work from one side at a time. Objects need to be manually turned and repositioned
skilled mechanic required
Materials and processing time can be expensive

Sand casting or sand casting is a popular method of producing non-ferrous alloy castings. Invented over 6,000 years ago, the process has undergone many changes and modernizations over the years, but the basic principles remain the same. This technique has been replicated many times from small DIY operations to large commercial foundries! One of the main differences between variations of this process is the type of sand used. Read on to learn more about the types of sand used in sand casting.

What type of sand is used for sand casting?
green sand
Green sand refers to sand molds formed from green sand, sometimes called clay. Sand molds are in an uncured state when metal is poured. Sand casting with green sand is quick and cheap because the sand can be reused. The downside is that sand is a soft mold that can collapse or move during casting, rendering the casting unusable. However, the process is reliable enough that it has been around for centuries and is still used today.

Sodium silicate or water glass
Sodium silicate is also used to make casting molds. Sodium silicate can quickly change from a liquid to a solid by passing carbon dioxide through it. This causes the sodium silicate to dehydrate. This process is useful when a cavity is required within a casting. Although sodium silicate can form a solid core for castings, it must be mixed with other materials to break down after casting, thereby removing the core. If the mixture is incorrect, the core will become lodged in the casting, causing the casting to fail.

resin sand
Once mixed and heated, the resin sand becomes a solid mold with a smooth surface. Stronger molds mean fewer casting defects, but the downside is higher costs and slower production. Where green sand molds are created quickly, resin sand molds take more time because each must be mixed and fired to create the perfect mold. Resin sand costs much more, and while the resin can be reused, it needs to be constantly replenished. This makes the process more expensive.