Cycle and method for retesting mold dimensions

Cycle and method for retesting mold dimensions
Mold retesting is arranged according to the number of molds: initial testing for 5000 molds, retesting for 10000 molds, and every 5000 molds after 20000 molds.
Why retest
The mold will slowly deform under thermal cycling and mechanical loads. If the cavity size drifts by 0.1mm, the wall thickness of the casting may exceed the tolerance.
The purpose of retesting is to discover trends, not to wait for deviations before processing. Trend data can provide early warning.
Without baseline data, drift cannot be determined. The first retest should be completed before production as a benchmark.
Which dimensions should be retested
Key dimensions of the cavity: wheel rim diameter, spoke thickness, and sprue size.
Flatness and fit clearance of the parting surface. These two factors affect the stitching and flying edge.
Wear amount of positioning hole and guide column hole. If the gap exceeds 0.05mm, the precision of the mold will decrease.
How to determine the cycle
5000 initial tests, with a focus on initial wear and tear. The running in period of the new mold wears out quickly.
Conduct 10000 retests and establish a second data point. The drift rate can be seen by connecting the two points.
Encrypt to every 5000 cycles after 20000 cycles. At this stage, wear and tear are accelerating, requiring more intensive monitoring.
measurement method
Three coordinate is used for key dimensions, with high accuracy but time-consuming. Suitable for initial testing and annual retesting.
Specialized gauges are used for high-frequency retesting, with high efficiency but can only measure specific dimensions.
Manual measurement serves as an auxiliary tool for quickly identifying anomalies. The accuracy of calipers and micrometers is limited and cannot be used as a basis for judgment.
Usage of data
Establish a size modulus curve. The sudden increase in the slope of the curve indicates that it has entered an accelerated wear period.
Compare the drift at different positions. Large local drift indicates abnormal cooling or stress at that location.
In the maintenance recommendations for wheel hub molds, Xinfeng Mold will provide a retest list and judgment threshold for key dimensions.
Handling after exceeding the tolerance
Minor deviations can be repaired. The cavity can be reworked after welding, with a cost of about 15% -25% of the new mold.
Serious out of tolerance or crack propagation, it is recommended to replace the insert or the entire mold. Continuing to use will result in a large amount of waste.
After repair, a new first article inspection is required and cannot be directly put into production.
Management of retest records
The data from each retest is archived according to the mold number, forming a size mold curve. Curve is the core basis for determining lifespan.
The record should include measuring equipment, ambient temperature, and measuring personnel. When conditions are inconsistent, data comparability decreases.
Coordination between retesting and production
Retesting requires shutdown, usually scheduled at the changeover or maintenance window. Advance scheduling to avoid affecting delivery.
Comparing the retest data with the factory data in the same table, the absolute value alone does not show any drift.
When abnormalities are found during retesting, retest first to eliminate clamping and measurement errors, and then determine the mold problem.
The retest cycle can be adjusted according to the actual wear rate, and the wheel type with fast wear can be increased to 3000 cycles.
Frequently Asked Questions
Q: How often do you retest?
Answer: First test with 5000 cycles, retest with 10000 cycles, and encrypt after 20000 cycles.
Q: Which dimensions should be retested?
Answer: Key dimensions of the mold cavity, flatness of the parting surface, and wear of the positioning hole.
Q: What if there is no baseline?
Answer: Please retest as soon as possible as a benchmark for future comparison.
Q: Can I use a caliper to measure?
Answer: It can only assist in judgment and cannot be used as a basis for judgment.
Q: Can it be repaired if it exceeds the standard?
Answer: Minor repair welding and heavy processing are possible, but severe cases require replacement of inserts.
Q: Do I need to test the mold after repairing it?
Answer: Yes, a new first article inspection is required.
Recommended search keywords
Mold size retesting, mold accuracy testing, mold cavity wear, mold maintenance cycle, wheel hub mold manufacturer, mold testing, parting surface wear, mold repair, mold life management, casting mold manufacturer