Material Analysis
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Large performance differences between different batches of low density polyethylene raw material
Problem Phenomenon
After changing the raw material batch number, the product shows dimensional deviations, appearance changes, or performance fluctuations.
Different batches of raw material differ in melt flow rate, density, molecular weight distribution, etc., requiring process parameters to be readjusted.
Cause Analysis
(1) The melt flow rate (MFR) of different batches of raw material fluctuates
(2) The molecular weight distribution and crystallinity of different batches of raw material differ
(3) Raw material supplier change or production process adjustment
(4) Different storage conditions and durations of raw material cause performance changes
(5) Differences in additive (e.g., antioxidant, lubricant) content
Solution
(1) Test key indicators such as MFR and density upon arrival of each batch of raw material, and compare with standard values
(2) Establish a batch management system; use different batches of raw material separately, and mix batches when necessary
(3) Adjust process parameters when changing batch numbers; conduct trial mold verification before production
(4) Communicate with the supplier, requesting control of batch-to-batch performance fluctuation range
(5) Use raw material on a first-in first-out basis, avoid excessively long storage
Key Takeaway
Batch differences are caused by raw material production fluctuations; a complete incoming material inspection and batch management system needs to be established.
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