Turning is a fundamental machining operation, especially for creating rotational parts in mold making. Machines like lathes are used. The workpiece rotates while the cutting tool moves in a controlled manner to shape the material. For example, when making cylindrical cores or ejector pins for molds, turning can achieve high dimensional accuracy and a smooth surface finish. This process is crucial as the precision of these parts directly impacts the functionality of the mold.
Milling
Milling is another widely used process. Milling machines, including CNC (Computer Numerical Control) milling machines and machining centers, are employed. With a rotating cutting tool, it can create various shapes such as flat surfaces, grooves, and complex cavities. In mold making, milling is used to machine the mold
base, create intricate details on the cavity and core, and shape the runner system. The ability of CNC milling to follow programmed paths enables the production of highly accurate and complex mold components, greatly enhancing the efficiency and quality of mold manufacturing.
Grinding
Grinding is a finishing process that aims to achieve extremely high precision and a super - smooth surface. Surface grinding is often used to flatten and finish the
parting surfaces of molds, ensuring a perfect fit when the mold halves are closed. Cylindrical grinding is suitable for processing the outer diameters of shafts and pins. By removing very small amounts of material, grinding can meet the tight tolerance requirements of mold parts, which is essential for the proper functioning of the mold and the quality of the final products.
Electrical Discharge Machining (EDM) Processes
EDM Milling (also known as Die - Sinking EDM)
EDM milling is a process where an electrode, typically made of copper or graphite, is used to erode the workpiece through a series of electrical discharges. This is particularly useful for creating complex - shaped cavities in molds that are difficult to machine using traditional cutting methods. For example, molds with intricate details, undercuts, or very hard materials can be effectively processed by EDM milling. The process involves carefully designing the electrode shape to match the desired cavity in the mold, and through controlled spark discharges, the material is gradually removed.
Wire - Cut EDM
Wire - cut EDM uses a thin wire, usually made of brass or molybdenum, as an electrode. The wire is continuously fed through the workpiece while an electrical current is applied, causing sparks to erode the material and cut the desired shape. This process is ideal for creating precise holes, slots, and complex contours in mold components. It can achieve very high precision, often in the micron range, making it suitable for manufacturing parts such as stamping dies and injection mold inserts with tight tolerances.
Welding Processes
Tungsten Inert Gas (TIG) Welding
TIG welding is highly regarded in mold making for its ability to produce high - quality welds. It uses a non - consumable tungsten electrode to create an arc and inert gas (such as argon) to protect the weld area from oxidation. This makes it suitable for welding mold components, especially when high - strength and clean welds are required. For instance, when attaching inserts or repairing damaged parts of a mold, TIG welding can ensure the integrity of the joint without introducing excessive heat - affected zones, which could potentially distort the mold.
Laser Welding
Laser welding has become increasingly popular in mold manufacturing due to its precision and minimal heat input. A high - energy laser beam is focused on the joint area, melting and fusing the materials together. It is particularly useful for joining small and delicate mold parts or for making repairs in areas where traditional welding methods may cause too much heat distortion. Laser welding can also be used to apply hard - facing materials to molds to improve their wear resistance.
Surface Treatment Processes
Nitriding
Nitriding is a surface - hardening process where nitrogen atoms are diffused into the surface of the mold material, typically steel. This forms a hard and wear - resistant nitride layer. The nitrided surface not only improves the mold's resistance to abrasion but also enhances its corrosion resistance and fatigue strength. Molds used in high - volume production, especially those in contact with abrasive materials, can benefit significantly from nitriding, as it extends the mold's service life and reduces maintenance costs.
Chrome Plating
Chrome plating involves depositing a thin layer of chromium onto the surface of the mold. This process can enhance the mold's surface hardness, improve its wear resistance, and provide an excellent surface finish. Chrome - plated molds have better release properties, which is crucial in injection molding processes as it helps the molded parts to be easily ejected from the mold. Additionally, the shiny chrome surface can also improve the appearance of the final products.
In conclusion, the combination of these diverse processes - machining, EDM, welding, and surface treatment - allows for the creation of high - quality molds that meet the stringent requirements of modern manufacturing. Each process has its unique advantages and is carefully selected based on the specific needs of the mold design and the materials involved.
Yixun is the China first generation mold maker, specialize in mold and moulding, provide one-stop plastic manufacturing service, feature in building medical and healthcare device tooling.
