Die casting parts leak detection methods
Die casting parts methods and means of leak detection air tightness testing
With regard to the die-casting, air tightness testing,
A water check visually the most common direct method is the casting hole sealed, fill them with red gas into the water to see if there are air bubbles.
Gas inspection: direct pressure check and decompression check, direct pressure to check the accuracy, but the direct pressure of the lower cost of 100pa, the accuracy of the differential detection 1pa
Helium: the most sophisticated detection, but costs more.
Airtight detection principle:
Any substance normally solid, liquid, gaseous, while the gaseous special status in the state of material existence, which itself is neither a certain shape, no size, its shape and size depends entirely on the containers of gas. The gas can be any number of unlimited expansion and on into the container of any shape and size. According to the Boyle-Charle's law plot in a certain temperature conditions, the gas pressure and volume is certain.
The formula: PV = • certain (P absolute pressure)
This equation shows that a certain mass of gas, regardless of their status changes, the product of its pressure and volume in addition to the absolute temperature, the resulting quotient remains the same. This gas is used to seal performance testing of the basic principles of the workpiece.
Air leakage formula leakage (△ VL) = Ve × △ P / Patm
Airtight detect objects:
Automotive industry: engine assembly, engine block, cylinder head, gearbox, pump casing, intake manifold, exhaust manifold, the compressor shell, the cylinder head cover, reducer shell, the differential shell body, oil cooler and other auto parts.
Motorcycle industry: engine block, cylinder head, cylinder head covers, transmission and other engine parts, canister;
Fluid industry: All kinds of solenoid valves, actuators, cylinders, fittings, etc.;
The electronics industry: air-conditioning evaporator, condenser, radiator, capillary, etc.;
The medical profession: the infusion tube, experimental bottles
Positive pressure principle:
Inspected workpiece capacity cavity filled with a certain pressure gas (called a tracer gas or control the leakage of gas) or liquid, when the workpiece when the existence of the leak, the gas (or liquid) begins to leak Kong Zhongyi. Leak greater the greater the escape of the amount of the workpiece outside the appropriate instructions to identify the presence of gas (or liquid) escape, escape the amount so you can judge a seamless hole exists, leak location and size. More representative of the traditional "cheer leak testing method (also known as" water check ").
Negative pressure principle:
Changes in the pumping of the measured object (workpiece) the contents of chamber vacuum, measuring its internal vacuum pressure in order to detect whether there is a leak test.
First of all ready to leak standard to the analyte and standard vacuum. Then, stop pumping, due to leaks caused by internal pressure changes measured by high sensitivity differential pressure sensor (DPS), the differential pressure between the analyte and standard.