1, Adjustment content
After the die casting mold manufacturing is completed, it should be adjusted after the mold test to choose the correct die casting conditions in order to achieve stable die casting of qualified castings.
Before the mold test, mold test personnel should do die casting with alloy materials for inspection, to understand the characteristics of alloy materials and die casting characteristics; should also understand the mold structure, die casting machine performance, die casting conditions, and operating methods.
The correct choice of die casting formation conditions is the key to die test adjustment. Often encountered even if the mold design and manufacturing are correct, due to improper selection of die casting forming conditions, the same can not press qualified castings. On the contrary, in some cases, can be used to adjust the die casting forming conditions, to overcome the shortcomings of the mold, press out the qualified castings. For this reason, mold test personnel must be familiar with the role of the die casting molding conditions and the relationship between, mold action principles, in order to correctly select and reasonably adjust the die casting molding conditions.
Die casting molding conditions of the adjustment of the following points.
1) Material melting temperature, die temperature, and solution temperature during die casting.
2) The injection pressure of the die casting machine, clamping force, mold opening force, and the required injection ratio pressure, injection speed size, etc. according to the condition of the parts.
3) The condition of the die-cast product should be trimmed in order to get a perfect part.
2, Trial mold process
Mold test is the last part of the mold manufacturing, is in the die casting machine on the die casting mold molding effect of the field inspection process. The purpose of the mold test is not only to test the mold design and manufacturing but also to seek the best molding process conditions for formal production.
The process of mold trial is divided into three stages: mold loading, mold trial, and adjustment.
1) Mold assembly
Mold assembly includes pre-inspection, mold installation, and adjustment, etc.
2) Mold test
The main contents of mold trial are as follows: ① mold preheating ② the pouring temperature ③ select the ratio of pressure injection ④ to select the speed of pressure injection ⑤ to determine the filling time
3, Adjustment method
Possible defects, causes, and adjustment methods in die casting mold trial
Defects | Causes | Adjustment |
The surface of the die casting has patterns and traces of metal liquid | 1, the inner gate to the casting inlet flow channel is too shallow; 2, pressure injection ratio is too large, resulting in too high metal flow rate, causing splashing of metal liquid. | 1, Deepen the gate runner; 2, reduce the pressure injection ratio pressure. |
Cracks or local deformation on the surface of the die casting | 1, uneven distribution or insufficient number of top material rods, uneven force; 2, the fixed plate of the pushing rod is skewed at work, resulting in a large force on one side and a small force on the other side, deforming the product and producing cracks; 3, the casting wall is too thin and deformed after shrinkage. | 1, increase the number of pushers and adjust their distribution position to make the force on the top part evenly; 2, adjust and re-install the push rod fixing plate; 3, redesign the casting to make its wall thicker. |
The surface of die casting has small convex tumor | 1, the inner surface of the cavity is scratched or has pits and cracks produced; 2, Surface roughness. | 1, replace the fixed side or make repairs; 2, polish the fixed side. |
The surface of die casting has top bar marks, the surface is not smooth and rough | 1, the top bar is too long. 2, Rough surface of fixed side, or debris. | 1, adjust the length of the top bar; 2, polish the fixed side and remove debris and oil. |
Die casting surface with air holes | 1, too much lubricant applied; 2, Exhaust slot is blocked, gas can't be discharged. | 1, Use lubricant reasonably; 2, Repair or add exhaust groove to make it exhaust smoothly. |
Shrinkage holes on the surface of die casting | 1, unreasonable die-casting process, too much variation of thin wall thickness; 2, metal liquid temperature is too high. | 1, add process holes in the wall thickness to make the wall thickness uniform; 2, Reduce the temperature of metal liquid. |
There are pores in the die casting | 1, incorrect direction of metal flow, frontal impact with the casting fixed side, generating vortex, surrounding the air and generating bubbles; 2, the inner gate is too small and the metal flow rate is too large. prematurely blocking the venting hole before the air is discharged, leaving the gas in the casting; 3, the fixed side is too deep, making ventilation and exhaust difficult; 4, exhaust system design is unreasonable, exhaust difficulties. | 1, amend the size and shape of the manifold cone to prevent causing the frontal impact of metal flow on the fixed side; 2, appropriately increase the inner gate; 3, improve the mold design; 4, Reasonable design of exhaust groove to increase air fixed side. |
The outer contour of die casting is not clear, can not be shaped, local under-material | 1, the pressure of the die-casting machine is not enough, the pressure injection ratio is too low; 2, the thickness of the feed opening is too large; 3, incorrect location of the gate, which makes the metal have frontal impact. | 1, replace the die-casting machine with a large die-casting ratio; 2, reduce the thickness of the inlet runner; 3, change the location of the gate to prevent frontal impact on the casting. |
Part of the die casting is not formed, the fixed side is not filled | 1, the temperature of the die casting mold is too low; 2, low temperature of metal liquid; 3, pressure of die casting machine is too small; 4, insufficient metal fluid and too high die casting speed; 5, air can't be discharged. | 1, increase die casting mold temperature; 2, increase the metal liquid temperature; 3, replace the large pressure die-casting machine; 4, add enough metal liquid, reduce the pressure injection speed, increase the thickness of the feed opening; 5, trim the exhaust system to give good exhaust. |
Die castings at sharp corners are not filled | 1, the inlet of the inner gate is too large; 2, poor ventilation at sharp corners, with air not being discharged; 3, pressure of die casting machine is too small. | 1, reduce the inner gate; 2, improve the exhaust system; 3, replace the pressure die casting machine. |
Die casting structure is loose, strength is not high | 1, pressure of die casting machine is not enough; 2, the inner gate is too small; 3, The air vent is blocked. | 1, change the pressure die-casting machine; 2, increase the inner gate; 3, check the exhaust hole to keep the exhaust open. |
There are impurities in the die casting | 1, the metal fluid is not clean and has impurities; 2, Alloy composition is impure; 3, mold cavity is not clean. | 1, clear out impurities and slag when pouring; 2, replace the alloy; 3, Clean the mold cavity and keep it clean. |
Metal splash during die casting process | 1, the mold is not tightly closed between the moving and fixed mold, and the gap is large; 2, the clamping force is not enough; 3, die-casting machine moving and fixed mold mounting plate is not parallel. | 1, Reinstall the mold; 2, increase the clamping force; 3, adjust the die casting machine to keep the movable and fixed mold mounting plates parallel. |