Have you ever wondered how machinists make those heavy aluminum tools and engine parts? They definitely did not make them with hands or cast them in a furnace. They make these parts from a process called CNC precision machining.
For those who are new to the manufacturing world, CNC precision machining is a manufacturing process that enlists the use of computer programs to create any product to exact specifications. Therefore, this article will define the process, the different pieces of equipment used, its applications, the different programming, and the processing involved.
What is CNC Precision Machining?
If the question “What is precise machining?” still lingers in your mind, here’s the answer. Just as the name implies, CNC precision machining involves shaping raw material into a finished product by cutting out excesses as designated by a Computer-Aided Design (CAD) or Computer-Aided Manufacturing (CAM) blueprint. What’s more, machinists use this process in different manufacturing processes and on different materials.
Before making any product by precision CNC machining, using CAD or CAM programs to make the product's blueprint is necessary. That is to say, these programs make highly detailed 3D outlines that a precise machining process must follow to replicate the product successfully.
From toys to medical devices, automobiles, or space shuttles, any product that has parts needs precision machining. Using Computer Numerical Control (CNC) equipment, the process utilizes actions like cutting, milling, turning, and electrical discharge machining to achieve the final product.
Although the process requires the overwatch of a skilled machinist, a machine does most of the work automatically. The Computer-Aided Design (CAD) software creates the design, and the Computer-Aided Manufacturing (CAM) software then translates it into manufacturing instructions for the machine. A final post-processor software codes the instruction into information the machine can understand. The machinists then load the instruction into the CNC equipment to start the manufacturing process.
Injection molding
Injection molding is a manufacturing process for producing parts by injecting molten material into a mold, or mold. Injection molding can be performed with a host of materials mainly including metals (for which the process is called die-casting), glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed (using a helical screw), and injected into a mold cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, molds are made by a mold-maker (or toolmaker) from metal, usually either steel or aluminum, and precision-machined to form the features of the desired part.
Injection molding uses a special-purpose machine that has three parts: the injection unit, the mold, and the clamp. Parts to be injection-molded must be very carefully designed to facilitate the molding process; the material used for the part, the desired shape and features of the part, the material of the mold, and the properties of the molding machine must all be taken into account. The versatility of injection molding is facilitated by this breadth of design considerations and possibilities.
Injection molding machine molds can be fastened in either a horizontal or vertical position. Most machines are horizontally oriented, but vertical machines are used in some niche applications such as insert molding, allowing the machine to take advantage of gravity. Some vertical machines also do not require the mold to be fastened. There are many ways to fasten the tools to the platens, The most common are manual clamps (both halves are bolted to the platens); however, hydraulic clamps (chocks are used to hold the tool in place) and magnetic clamps are also used. The magnetic and hydraulic clamps are used where fast tool changes are required.
What is Aluminum Die Casting?
Aluminum die casting ;alloys are lightweight and posses high dimensional stability for complex part geometries and thin walls. Aluminum withstands good corrosion resistance and mechanical properties as well as high thermal and electrical conductivity, making it a good alloy for die casting. Low-density aluminum metals are essential to the die casting industry. The Aluminum Die Casting process retains a durable strength at very high temperatures, requiring the use of cold chamber machines. The molten metal is still contained in an open holding pot which is placed into a furnace, where it is melted to the necessary temperature. The open holding pot is kept separate from the die casting machine and the molten metal is ladled from the pot for each casting because these high temperatures would damage the normal pumping system. The pressure requirements for cold chamber castings are typically higher than those of hot chamber die castings.
