What are the key items to be checked during the LPDC mold trial process?
Trial molding is a key step in verifying the entire solution of LPDC mold flow channel, cooling, exhaust, and ejection, which determines the stability of subsequent mass production.
1、 Step by step verification and quantitative judgment criteria during the trial stage
Priority should be given to checking the integrity of the filling process during the first trial mold. The filling pressure should be adjusted according to the gradient between 0.3-1 bar, and samples should be retained for each pressure level to determine the under filling and curling windows. According to industry statistics, about 65% of mold problems will be exposed during the first three mold trials.
X-ray inspection of castings to verify internal shrinkage and porosity. The acceptance standard for automotive parts generally requires a single porosity diameter of less than 0.8mm, and dense porosity areas are not allowed to appear in pressure bearing areas.
The size inspection covers the assembly benchmark, wall thickness, and reverse dimension. The size tolerance is determined according to the product drawing ± 0.1mm or customer specifications. Only when the size of 5 consecutive pieces is stable, can the size be judged as qualified.
Surface appearance inspection for scratches, aluminum adhesion, and burrs. The thickness of the burrs should be controlled to be ≤ 0.15mm. If exceeded, the parting surface and exhaust groove need to be ground.
During the trial stage of Xinfeng Machinery, pressure, temperature, and cooling flow parameters are synchronously recorded to form a trial report and deliver it to the customer.
2、 Adjustment direction corresponding to trial mold defects
Underfilling and insufficient pouring at the end: Prioritize increasing the filling pressure, extending the liquid lifting time, or optimizing the sprue section to reduce filling resistance.
Thick walled position shrinkage: Adjust the cooling timing, increase local point cooling, strengthen sequential solidification, and ensure the replenishment channel.
Disperse pores: Priority should be given to reviewing the smoothness of the exhaust groove, followed by investigating issues such as excessive spraying of release agent and water accumulation in the mold cavity.
Casting strain: Check the draft angle, mold cavity nitride layer, mold release agent film formation status, and adjust the spraying parameters.
3、 Differences in acceptance standards for customer trial molds in different regions
Southeast Asian customer acceptance is mainly based on appearance and size, and X-ray inspection is generally not mandatory. The criteria for determining the qualification of the trial mold are loose, and the number of trial molds is usually 2-3 rounds.
Tier 1 customers in North America must submit X-ray, metallographic, and dimensional reports for mold testing. The first piece PPAP data is complete, and the mold testing cycle is longer, usually 4-6 iterations.
In addition to non-destructive testing, European customers also verify whether solidification simulation, filling simulation, and physical defects match, and require simulation models to reproduce defects.
Middle Eastern engineering machinery castings, with a focus on pressure leakage testing. No connected air holes are allowed in the pressure bearing position, and the appearance requirements are loose.
4、 Delivery Content of Trial Model Report
The trial report includes a process parameter table, sample photos, size record table, defect record, and rectification plan. The English version is standard for cross-border delivery.
Each round of rectification records needs to correspond to the location of drawing modifications, facilitating subsequent maintenance of mass-produced molds and traceability of changes.
5、 Long tail traffic layout ideas
Trial mold PPAP、 The first article acceptance belongs to the procurement and quality search category, and the target audience is quality engineers and procurement.
keywords LPDC mold trial run checklist、low pressure casting first article inspection；
Question type: What tests are needed for LPDC mold trial;
Tutorial class: LPDC trial defect troubleshooting guide.
Suitable for supporting service pages, undertaking pre mold acceptance standard consultation traffic.
6、 Common misconceptions in the industry
Misconception 1: One successful trial mold represents long-term stability, and a qualified first article does not necessarily mean continuous stability after ten thousand molds. Small batch continuous trial production verification is required.
Misconception 2: All air holes are exhaust problems, and mold release agent water accumulation and turbulent filling can also cause air holes, which need to be investigated item by item.
Misconception 3: If the size is qualified, it can be directly mass-produced. Pressure bearing parts must be equipped with non-destructive testing, and internal defects cannot be recognized by the naked eye.
FAQ
Q: What is the pressure range for LPDC conventional mold filling?
A：0.3–1bar， Adjust according to the casting wall thickness and structural gradient.
Q: What are the common thresholds for gas hole acceptance in automotive parts?
A: The diameter of a single pore generally does not exceed 0.8mm, and dense pores are prohibited in the pressure bearing area.
Q: How many rounds do Southeast Asian customers usually need for mold testing?
A: Most of the 2-3 rounds are based on appearance and size inspection.
Q: What materials are provided for North American customer trial molding?
A: First piece size, X-ray inspection, PPAP complete set of technical documents.
Q: What parameters should be prioritized for adjusting under charge defects?
A: Fill pressure, rise time, and recheck the sprue section.
Q: What verification needs to be done after the trial mold is qualified?
A: Small batch continuous trial production to verify long-term stability.
Q: How to deal with excessive flying edge?
A: Grind the parting surface and check if the depth of the exhaust groove exceeds the limit.
Q: What content does the trial report need to include?
A: Process parameters, sample records, dimensions, and defect rectification plan.
