LPDC casting infiltration process, can infiltration replace mold and process optimization?

LPDC casting infiltration process, can infiltration replace mold and process optimization?
Infiltration is a remedial measure for micro hole leakage in castings, and many factories consider infiltration as a universal solution to solve shrinkage and porosity problems; However, infiltration has clear applicable boundaries, and large pores and connected cracks cannot be repaired by infiltration. Overreliance on infiltration can bury the risk of quality claims.
1、 Applicable pore size and infiltration parameters for infiltration
Conventional vacuum infiltration can repair independent micro pore sizes ≤ 0.25mm; connected shrinkage holes and cracks larger than 0.3mm cannot be locked by infiltration glue, and leakage still occurs under pressure.
Infiltration process flow: Cleaning and degreasing → Drying → Vacuum pumping (-0.09MPa, 5-8 minutes) → Infiltration glue infiltration → Pressure curing (0.3-0.5MPa, 10-15 minutes) → Cleaning excess glue solution → Curing at 80-100 ℃ for 30-60 minutes.
The qualification rate of single pass infiltration is generally 85-92%; Leaking parts can be subjected to secondary infiltration, but the success rate of secondary infiltration decreases. Triple infiltration is not recommended in the industry, as there may be residual cleaning agents inside the pores and poor bonding strength.
Immersion glue is divided into water-based and anaerobic types; Priority is given to anaerobic infiltration glue for automotive hydraulic components, which is resistant to oil and temperature; Ordinary shells can use water-based adhesive, which is more cost-effective.
Xinfeng Machinery informed the customer in advance during the planning phase that infiltration is a remedy, not a design compensation, and that priority should be given to optimizing shrinkage cavities in molds, cooling, and gates.
2、 Defect types that must be prohibited from infiltration release
Connectivity cracks, thermal cracks, even if they are small, infiltration glue only fills the surface, and after being subjected to force, cracks expand and leakage recurs;
Large shrinkage holes>0.3mm, concentrated looseness, weak adhesive filling, and delamination and leakage under alternating pressure conditions;
Slag inclusion, inclusion of pores, adhesion of oxide scale on the inner wall of pores, insufficient adhesion of infiltration adhesive, and high susceptibility to failure.
Many North American customers do not accept relying on infiltration to meet leakage requirements for pressure alternating loads and safety components, and require the elimination of shrinkage at the source.
3、 Differences in infiltration policies for overseas customers
Southeast Asian customers generally accept infiltration as a routine process to compensate for deficiencies in technology and molds, and control scrap rates.
North American automotive safety parts and hydraulic pressure parts: Clearly marked on the drawings, key locations are not allowed to be infiltrated, and the infiltrated area needs to be separately identified and included in traceability. It is not allowed to cover up excessive shrinkage holes.
European customers have fatigue concerns about impregnated parts, and alternating load castings should be densified at the source as much as possible. Infiltration is only used for non critical micropores, and infiltration records should be fully archived.
Middle Eastern construction machinery static pressure bearing shells allow infiltration repair of micro pores, but the pressure testing standards are strict, and secondary leakage parts are directly scrapped.
4、 Hidden risks of relying on infiltration
Immersion glue has limited temperature resistance, and under high temperature conditions, the glue ages and decomposes, leading to later leakage and rework;
Infiltration can only solve leakage and cannot improve mechanical properties. The strength and elongation at the location of shrinkage cavities decrease, and the risk of fatigue failure increases;
Immersion covers up mold defects, and mold problems continue to worsen, with concentrated outbreaks of batch leakage in the later stages;
Infiltration increases process costs and delivery times. In the long run, it is better to optimize mold cooling and gating once and for all.
5、 Long tail traffic layout ideas
Infiltration, casting leakage repair, and micro hole patching are quality remediation topics aimed at quality engineers and procurement.
keywords LPDC casting impregnation process、can impregnation repair shrinkage porosity low pressure casting；
Problem class: Max pore size for aluminum casting impaction;
Comparative category: Anaerobic vs water-based impaction seal.
Suitable for casting post-processing and quality control pages.
6、 Common misconceptions in the industry
Misconception 1: As long as there is leakage, it can be repaired by infiltration. Connecting cracks and large shrinkage cavities cannot be repaired by infiltration for a long time, and they are prone to re leakage in the later stage.
Misconception 2: Infiltration can replace mold optimization, infiltration is only a remedy and cannot improve the mechanical and fatigue performance of castings.
Misconception 3: Immersion parts can be reworked infinitely, but after multiple infiltrations, the inner walls of the pores become contaminated and the adhesive strength continues to decrease.
FAQ
Q: Can infiltration repair the upper limit of micropores?
A: Independent micropores ≤ 0.25mm.
Q: What are the negative pressure parameters for vacuum infiltration?
A：-0.09MPa， Extract air for 5-8 minutes.
Q: What is suitable for anaerobic infiltration glue?
A: Automotive hydraulic pressure components, oil and temperature resistant.
Q: What defects cannot be released by infiltration?
A: Connected cracks, concentrated shrinkage holes larger than 0.3mm, and slag inclusion holes.
Q: Secondary infiltration short board?
A: The success rate decreases, the inner wall of the pores becomes contaminated, and the binding force deteriorates.
Q: North American safety component infiltration requirements?
A: It is prohibited to rely on infiltration at critical locations, and the infiltration area must be traced and marked.
Q: Can infiltration improve the strength of castings?
A: No, only the micropores are blocked, and the mechanical properties remain unchanged.
Q: What is the infiltration curing temperature?
A: 80-100 ℃, keep warm for 30-60 minutes.