Die castings can be confirmed by the machinist using on-machine inspection if post-machining is perf
Posted by JasonBatten from the Technology category at 18 Aug 2022 04:17:53 pm.
In a manner comparable to injection molding, the die casting machine can be used to manufacture the component parts after the molds have been made. The process of die casting consists of four primary stages: the preparation stage, the filling stage, the ejection stage, and the shakeout stage.
The casting process, on the other hand, takes a slightly different form depending on whether a hot chamber or a cold chamber is utilized. The two distinct iterations of the high-pressure die casting process each have distinct advantages to offer: one is better suited for casting at high speeds, while the other can accommodate a greater variety of casting materials.
Die casting in a hot chamber.
In the process of metal die casting known as hot chamber die casting, the machine used to make the dies contains the necessary components for melting the metal into a liquid state. However, it is only appropriate for a limited variety of casting materials, such as zinc, tin, and lead alloys, due to the fact that it is a self-contained system. This makes it significantly more efficient than the alternative, which offers shorter cycle times.
Die casting done in a cold chamber
In order to get the metal to the right temperature for the cold chamber die casting process, a separate furnace is needed. The fact that the molten metal needs to be transferred to the die casting machine using a ladle causes production rates to naturally slow down as a result. Metals with high melting points can nevertheless be cast using a separate furnace instead of a hot chamber die casting machine because the separate furnace is more powerful. Casting in aluminum can be accomplished using this method.
The process of metal die casting typically goes as follows, and this is true regardless of whether a machine with a hot chamber or a cold chamber is used:
Preparation of the molds
Ejection de remplissage
During the preparation of the mold, the interior surfaces of both halves of the die are lubricant-coated so that the castings can be removed from the mold more easily once they are finished. After that, the die halves can be brought together and locked in place with locking pins.
A pressure system is utilized in order to accomplish the task of filling the mold. The hot chamber system and the cold chamber system are not the same as this one. The end result of both processes is the same: molten metal is pushed into the mold cavity by a plunger through the sprue. High pressures, reaching up to 35 megapascals in a hot chamber and 140 megapascals in a cold chamber, ensure rapid and comprehensive filling, which, in turn, leads to consistent cooling, which prevents uneven shrinkage and, as a result, part deformation. During the process of cooling, the pressure is kept constant.
After opening up the two halves of the die, the ejector pins are used to remove the castings from the die. After the previous shot has been taken, the dies are typically re-closed and made ready for the subsequent one. In the meantime, the finished castings are prepared for shakeout, which entails the removal of scrap sections of the shot such as sprues, runners, and flash (material that seeps through at the parting line). This material removal can be accomplished with the use of manual tools, tumbling, or a hydraulic trim die. All three of these methods are available.
Many parts made by die casting metal require only a few secondary operations to be completed. This is because the high pressures that are utilized make it possible to achieve a high level of detail as well as a good surface finish. However, many castings that are either net shape or nearly net shape require additional precision machining for features such as holes, threads, and other details. Some types of casting metals are much simpler to machine than others. Die castings made of magnesium and aluminum, for example, lend themselves exceptionally well to subsequent processes of machining.
Post-machining die castings offers a number of benefits, one of which is the opportunity to use the on-machine inspection capabilities of the CNC machine. This gives the machinist the ability to verify the parts.