Source of die-casting flash defects, key points for mold processing and mold clamping control
Casting edge flying is a high-frequency complaint from cross-border customers, which not only increases polishing hours, but also poses safety hazards. Xinfeng Machinery has sorted out control measures from the mold end.
1、 Poor fitting of the parting surface is the primary source of burrs
The flatness deviation of the parting surface processing and the collapse caused by long-term mold locking impact, when the locking force is insufficient, the aluminum liquid drills into the gap and forms flying edges. Statistics show that about 39% of persistent burrs are caused by insufficient machining accuracy of the parting surface, large alloy wheel mold parting surface area, and higher difficulty in planar control than small shell molds. The tolerance of the parting surface plane is generally controlled within 0.02mm.
2、 Locking force matching and equipment selection boundary
The locking force of the die-casting machine is insufficient, and the aluminum liquid filling pressure opens up the parting surface, resulting in large areas of thin burrs. To calculate the clamping force, the projection area of the casting needs to be multiplied by the specific pressure. The conventional specific pressure value for ADC12 is 40-70MPa. Many overseas factories have insufficient mold locking capacity for old equipment, and even if the molds are qualified, mass production still continues to produce burrs.
3、 The clearance between the top pin and the insert exceeds the standard and has flying edges
The clearance between the insert, ejector pin, and slider is too large, causing molten aluminum to seep into the gap and form small flying edges. Die casting mold is produced for a long time, and the inserts are subjected to repeated thermal impacts, resulting in wear on the mating surfaces and gradual expansion of gaps. The number of burrs increases with the number of molds. Regular grinding of parting surfaces and replacement of worn inserts are routine maintenance actions.
4、 Comparison of Flying Edge Characteristics in Low Pressure Casting
Low pressure casting has a lower filling pressure and a much lower specific pressure than high-pressure casting, resulting in a lower risk of flash edge under the same clearance conditions. The flying edges of low-pressure wheel hub molds are mostly concentrated at the sealing position of the riser, and the sealing is aging and leaking aluminum material. The flying edges of the appearance parting surface are relatively rare. Die casting high-pressure filling exposes tiny gaps as burrs.
5、 Risk points that are easily overlooked during the procurement phase
Low price molds will simplify the grinding process of the parting surface, only perform rough machining, and exceed the flash edge standard in the early stages of delivery. During die and mold acceptance, checking the fit of the parting surface through light transmission during no-load mold closing is a simple and effective acceptance method. The feeding viscosity of metal injection mold is high, and the flying edge control strategy focuses on the gap between the inserts, with a completely different pressure mechanism.
FAQ
Can tiny flying edges be solved by polishing?
Temporary handling is possible, but if the root gap issue is not resolved, it can be continuously reproduced after production.
Can the collapse of the parting surface be repaired?
Shallow collapse can be welded and ground, and the repair cost for collapse depths exceeding 0.15mm is relatively high.
Can increasing the locking force eliminate burrs?
There is an upper limit to the locking of equipment molds, and the deformation of the mold parting surface itself cannot be cured by pressure.
How to deal with aluminum leakage at the low-pressure seal?
Replace the sealing ring, check the flatness of the mating surface, and re tighten the components.
Will flying edge affect the X-ray inspection results?
The flying edge polishing is not clean, and residual metal debris can easily interfere with the detection and interpretation.
6. Is it normal for the new model to have flying edges during the trial?
A small amount of controllable flying edge belongs to the scope of trial mold debugging, while a large amount of continuous flying edge is abnormal.
7. Where is the high incidence position of flash edge in the slider mold?
The mating surface of the slider and the sealing surface of the slider are prone to aluminum leakage after wear.
8. Should an exhaust groove be opened on the parting surface?
The exhaust groove is independently designed, and the depth of the exhaust groove is strictly controlled and cannot be used as a sealing surface.
แม่พิมพ์หล่อแบบแรงดันต่ำ (Low Pressure Die Casting Molds, LPDC)
แม่พิมพ์หล่อแบบแรงโน้มถ่วง
แม่พิมพ์หล่อแบบ Counte‑Pressure Casting (CPC)
แม่พิมพ์หล่อส่วนโครงสร้าง
แม่พิมพ์หล่ออานรถจักรยานยนต์
แม่พิมพ์หล่อแบบความดันแตกต่างสำหรับห hub ล้อ
แม่พิมพ์หล่อแรงโน้มถ่วงสำหรับล้อแม็ก
แม่พิมพ์หล่อความดันต่ำสำหรับล้อแม็ก
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