Формы для литья под низким давлением (LPDC)
Формы для гравитационного литья
Формы для литья под противодавлением (CPC)
Structural Parts Casting Mold
Форма для литья ступиц мотоциклетных колес
Форма для литья под давлением ступицы колеса с диф
Форма для литья под действием силы тяжести ступицы
Форма для литья под низким давлением ступицы колес
How to cure the deformation control of LPDC castings, such as shell warping and flange flatness deviation?
Thin walled shell and flange castings with excessive flatness and parallelism after machining are often attributed to machining problems; The root cause is uneven solidification gradient, unbalanced ejection, inconsistent cooling shrinkage, and deformation due to internal stress release.
1、 Key points for solidification and mold structure control
Establish unidirectional sequential solidification: the thick wall is first filled with shrinkage, and the thin wall is uniformly cooled to avoid rapid local solidification and the generation of huge internal stresses; Asymmetric wall thickness on both sides and inconsistent shrinkage are the main causes of warping.
The flange sealing surface should be prioritized on the parting surface, and a top plate should be added to the flange position to evenly distribute force and avoid deformation caused by single point protrusion.
Large area flat shell with added process ribs on the back to enhance casting rigidity and suppress free shrinkage and warping; Process reinforcement is removed by machining.
The mold cooling water circuit is symmetrically arranged, with balanced cooling flow on the left, right, and up and down; One side cools faster and the other side cools slower, causing asynchronous shrinkage and bending of the casting towards the side with faster cooling rate.
Perform shrinkage simulation during the DFM stage of Xinfeng Machinery, predict the direction of warping, reserve machining allowance or pre deformation compensation.
2、 Top out, pick-up, and time management control
The ejection must be synchronized, and the parallelism of the ejection plate should be calibrated regularly; The top rod is not synchronized, and the high-temperature casting is directly bent under plastic state, resulting in permanent solidification of deformation.
After the casting is taken out, it should be placed steadily on a dedicated fixture bracket and should not be suspended for stacking; High temperature castings have extremely strong plasticity above 250 ℃ and will deform under their own weight.
For castings that require machining, increase stress relief time: maintain at 180-200 ℃ for 2-4 hours, slowly cool with the furnace, release solidification internal stress, and reduce post machining rebound deformation.
The cutting amount of machining should not be cut with a large knife at once, and layered cutting should be used to avoid the superposition of cutting stress and original casting stress.
3、 Differences in deformation control for overseas customers
Southeast Asian customers increase machining allowance by using CNC milling for leveling, without time constraints, allowing for a small amount of rebound after machining.
The North American automotive sealing shell has strict tolerance on the flatness drawing, requiring deformation control during the casting stage, mandatory low-temperature stress relief aging, and first piece three coordinate inspection.
European customers prioritize symmetrical structural design and symmetrical cooling to reduce internal stress from the source and minimize post-processing costs.
Large scale shell castings in the Middle East have a large total shrinkage, and are designed with pre deformation compensation. The mold cavity is pre offset in reverse to counteract shrinkage and warping.
4、 Deformation defect chain
Asymmetric cooling → Inconsistent shrinkage rates on both sides → Casting warping;
Out of sync, single point top pressure → high temperature plastic state distortion → permanent deformation;
High temperature suspended stacking of castings → self weight bending;
The internal stress has not been released → After cutting the material through machining, the stress is released and the rebound exceeds the tolerance.
5、 Long tail traffic layout ideas
Casting deformation, shell warping, flatness, stress relief, aimed at structural, process, and machining engineers.
keywords LPDC casting distortion control、flatness tolerance low pressure casting housing;
Question type: Stress relief aging temperature A356 casting;
Comparison category: Casting distance from unbalanced cooling vs unbalanced ejection.
Suitable for DFM shell and precision casting special pages.
6、 Common misconceptions in the industry
Misconception 1: All deformation is solved by machining and milling a little more. Internal stress exists, causing rebound after machining and increasing instability with milling.
Misconception 2: Castings can be randomly stacked as soon as they come out. High temperature castings have high plasticity and their own weight can cause irreversible deformation.
Misconception 3: The faster the cooling, the better the rigidity. One side rapid cooling directly induces asymmetric shrinkage and warping.
FAQ
Q: What are the stress relief aging parameters for A356 castings?
A: Keep at 180-200 ℃ for 2-4 hours and cool slowly with the furnace.
Q: What are the core causes of shell warping?
A: Asymmetric cooling on both sides and inconsistent contraction rate.
Q: Large area flat anti deformation measures?
A: Increase process reinforcement to enhance rigidity.
Q: What are the requirements for removing high-temperature castings?
A: Place it on a dedicated bracket and do not hang it in the air.
Q: What is the priority for flange position and top out structure?
A: Top sheet, disperses pressure, prevents deformation under pressure.
Q: North American seal deformation control?
A: Casting shape control+aging, three coordinate detection of flatness.
Q: Principle of pre deformation compensation?
A: Reverse displacement of the mold cavity to counteract solidification shrinkage and warping.
Q: What are the consequences of out of sync?
A: Plastic distortion and permanent deformation of high-temperature castings.
Формы для литья под низким давлением (LPDC)
Формы для гравитационного литья
Формы для литья под противодавлением (CPC)
Формы для литья конструкционных деталей
Форма для литья ступицы колеса мотоцикла
Форма для литья ступицы колеса под дифференциальным давлением
Форма для гравитационного литья ступицы колеса
Форма для литья ступицы колеса под низким давлением
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